Yoga and behavioral memory interventions for the aging brain

Yoga and behavioral memory interventions to prevent age-related cognitive decline

A study examined changes in brain metabolites and structure among individuals undergoing memory training and yogic meditation. We demonstrated that memory training over 3 months is associated with decreased choline levels in bilateral hippocampus and increased gray-matter volume in dACC, suggesting that behavioral interventions like MET may ameliorate markers of brain aging. These effects are somewhat modest, and would benefit from independent validation in larger samples and perhaps over longer-duration interventions. However, these findings suggest that engaging in cognitive activities and mind-body practices may affect the brain in positive ways, and may be combined as part of a multi-faceted approach to encourage healthy aging.

Behavioral memory training is also popular, based on the notion that cognition is plastic in older age (Acevedo and Loewenstein, 2007; Eyre et al., 2016). For example, traditional memory training interventions that teach mnemonic techniques involving verbal association and visual imagery and practical strategies have been shown to boost cognitive performance, memory, and quality of life in healthy older adults (Verhaeghen et al., 1992; Jean et al., 2010). Given the growing popularity of online “Brain Training” programs, clearer understanding of behavioral memory training programs already demonstrated to be effective in the clinic is needed.

In recent years, mind-body therapies have also been studied as potential preventive measures for MCI (Grossman et al., 2004). By simultaneously targeting multiple physiological and cognitive processes, as well as their dynamic integration, meditation may offer a more efficient alternative to other behavioral interventions. Indeed, some studies indicate that senior meditators have better memory, perceptual speed, attention and executive functioning compared with non-meditators (Prakash et al., 2012), though results are mixed (Chiesa et al., 2011; Goyal et al., 2014). A combination of Kirtan Kriya (KK) meditation and Kundalini Yoga (KY), as used as an intervention in the current study, is specifically shown to affect physical and mental health outcomes (Shannahoff-Khalsa, 2004; Krisanaprakornkit et al., 2006), including older adults with memory complaints (Moss et al., 2012). Like other forms of mind-body practice, KY and KK have been demonstrated to benefit cognitive function, depressed mood and anxiety, sleep and coping (Black et al., 2013; Lavretsky et al., 2013), including older adults with cognitive impairments (Newberg et al., 2010).

Role of Anterior Cingulate Cortex in Cognitive Aging

In our study, we provide novel evidence that a behavioral memory intervention (MET) can modestly increase cortical gray matter in dACC, a region of the brain linked to multiple key cognitive functions, such as error detection (Gehring et al., 1993), and executive processing (Carter et al., 2000). Gray-matter volume has been demonstrated to decrease with age in the ACC in both cross-sectional (Sowell et al., 2003) and longitudinal studies (Resnick et al., 2003). Correspondingly, age is negatively correlated with blood flow in dorsal and rostral ACC regions (Vaidya et al., 2007). Seniors who engage more in cognitive games and puzzles in their daily lives also tend to have greater ACC gray matter volume (Schultz et al., 2015), which is consistent with our results and raises the possibility that engaging in cognitive-behavioral games or training could prevent age-related structural atrophy in this region. Indeed, a recent study indicated a trend towards increased rostral ACC thickness in seniors after MET; however, this effect did not survive a stringent validation analysis (Engvig et al., 2010). Although our effects are modest, they do indicate that participating in effective behavioral interventions may help to ameliorate age-related brain changes associated with poor memory and cognitive performance.

Yoga and the Aging Brain

Structural plasticity in the dACC and hippocampus has also been associated with yoga practice in previous studies; however, we did not find evidence of gray-matter volume changes in dACC or hippocampus after our 12-week yoga intervention. Yoga has been linked to anatomical changes in frontal cortex (Baijal and Srinivasan, 2010; Froeliger et al., 2012; Villemure et al., 2014; Desai et al., 2015), anterior cingulate cortex (ACC) and insula (Nakata et al., 2014; Villemure et al., 2014, 2015), and the hippocampus (Froeliger et al., 2012; Villemure et al., 2015). However, many of these studies compare the brains of practiced yogis with several months or years of experience to yoga-naive controls (Froeliger et al., 2012); perhaps the relatively shorter length of training in the current study (12 weeks) was less conducive to detecting structural plasticity associated with our yoga intervention. In this same cohort, we have already demonstrated that memory improvements after yoga and MET may induce functional plasticity in similar brain regions (Eyre et al., 2016).

http://journal.frontiersin.org/article/10.3389/fnagi.2016.00277/full

Vagus nerve stimulation thru breathing, laughs and yoga

 

The benefits of vagus nerve stimulation (other than relaxing the body, mind, and soul – and really, isn’t that enough of a reason?):

  • It reduces the inflammatory response throughout our system.
  • It helps the brain emit new cells.
  • It decreases depression and anxiety and lifts our mood. Forty million Americans are affected by mood disorders. Enough said!
  • It assists in developing razor-sharp memory, and there are so many applications for increased memory capacity in our culture like Alzheimer’s work, traumatic brain injuries, and plain-and-simple everyday life.
  • It raises your immunity. How about staying healthy and taking vacations to beautiful faraway places instead of lying on the couch suffering through yet another bout of bronchitis?
  • It raises the level of endorphins, which bring about positive feelings in the body and reduce the sensation of pain.

Kundalini serpent tail whips the immune system into action

Have you ever seen the list “100 Benefits of Meditation“?  Of course, many of these benefits are psychological. You know, things like: helps control own thoughts (#39) and helps with focus & concentration (#40).  But many of the 100 benefits are rather physical, bodily, physiological, immunological and even biochemical benefits (such as #16- reduction of free radicals, less tissue damage).

These are awesome claims, and I’ve certainly found that mediation helps me feel more emotionally balanced and physically relaxed,  but I’m wondering – from a hard science point of view – how legit some of these claims might be.  For example, “#12 Enhances the immune system – REALLY?  How might yoga and mediation enhance my immune system?

In a previous post on the amazing vagus nerve – the only nerve in your body that, like the ancient Kundalini serpent, rises from the root of your gut to the brain – AND – a nerve that is a key to the cure of treatment resistant depression– it was suggested that much of the alleviation of suffering that comes from yoga comes from the stimulation of this amazing nerve during postures and breathing.

Somehow, the ancient yogis really got it right when they came up with the notion of Kundalini serpent – so strange, but so cool!

I happened to stumble on a paper that explored the possibility that the vagus nerve might also play a role in mediating communication of the immune system and the brain – and thus provide a mechanism for “#12- Enhances the immune system” Here’s a quote from the article entitled, “Neural concomitants of immunity—Focus on the vagus nerve” [doi:10.1016/j.neuroimage.2009.05.058] by Drs. Julian F. Thayer and Esther M. Sternberg (Ohio State University and National Institute of Mental Health).

By the nature of its “wandering” route through the body the vagus nerve may be uniquely structured to provide an effective early warning system for the detection of pathogens as well as a source of negative feedback to the immune system after the pathogens have been cleared. … Taken together these parasympathetic pathways form what has been termed “the cholinergic anti-inflammatory pathway

The scientists then investigate the evidence and possible mechanisms by which the vagus nerve sends immunological signals from the body to the brain and also back out to the immune system.  Its not a topic that is well understood, but the article describes several lines of evidence implicating the vagus nerve in immunological health.

So bend, twist, inhale and exhale deeply.  Stimulate your vagus nerve and, as cold and flu season arrives, awaken the serpent within!

What if you had magic fingers and could touch a place on a person’s body and make all their pain and anguish disappear?  This would be the stuff of legends, myths and miracles! Here’s a research review by Kerry J Ressler  and Helen S Mayberg on the modern ability to electrically “touch” the Vagus Nerve.

The article,  Targeting abnormal neural circuits in mood and anxiety disorders: from the laboratory to the clinic discusses a number of “nerve stimulation therapies” wherein specific nerve fibers are electrically stimulated to relieve mental anguish associated with (drug) treatment-resistant depression.

Vagus nerve stimulation therapy (VNS) is approved by the FDA for treatment of medication-resistant depression and was approved earlier for the treatment of epilepsy20.  …  The initial reasoning behind the use of VNS followed from its apparent effects of elevating mood in patients with epilepsy20, combined with evidence that VNS affects limbic activity in neuroimaging studies21. Furthermore, VNS alters concentrations of serotonin, norepinephrine, GABA and glutamate within the brain2224, suggesting that VNS may help correct dysfunctional neurotransmitter modulatory circuits in patients with depression.

This stuff is miraculous in every sense of the word – to be able to reach in and “touch” the body and bring relief – if not bliss – to individuals who suffer with immense emotional pain.  So who is this Vagus nerve anyway?  Why does stimulating it impart so many emotional benefits?  How can I touch my own Vagus nerve?

The wikipedia page is a great place to explore – suggesting that this nerve fiber is central to the “rest and digest” functions of the parasympathetic nervous system.  As evidenced by the relief its stimulation brings from emotional pain, the Vagus nerve is central to mind-body connections and mental peace.

YOGA is a practice that also brings mental peace.  YOGA,  in so many ways (I hope to elaborate on in future posts),  aims to engage the parasympathetic nervous system (slowing down and resting responses) and disengage the sympathetic nervous system (fight or flight responses).  Since we all can’t have our very own (ahem) lululemon (ahem) vagal nerve stimulation device, we must rely on other ways to stimulate the Vagus nerve fiber.  Luckily, many such ways are actually known – so-called “Vagal maneuvers” – such as  holding your breath and bearing down (Valsalva maneuver), immersing your face in ice-cold water (diving reflex), putting pressure on your eyelids, & massage of the carotid sinus area – that have been shown to facilitate parasympathetic (relaxation & slowing down) responses.

But these “Vagal maneuvers” are not incorporated into yoga.  How might yoga engage and stimulate the Vagal nerve bundle? Check out these great resources on breathing and Vagal tone (here, here, here).  I’m not an expert by any means but I think the take home message is that when we breathe deep and exhale, Vagal tone increases.  So, any technique that allows us to increase the duration of our exhalation will increase Vagal tone. Now THAT sounds like yoga!

Even more yogic is the way the Vagus nerve is the only nerve in the parasympathetic system that reaches all the way from the colon to the brain.  The fiber is composed mainly of upward (to the brain) pulsing neurons – which sounds a lot like the mystical Kundalini Serpent that arises upwards from within (starting at the root – colon) and ending in the brain.  The picture above – of the Vagus nerve (bright green fiber) – might be what the ancient yogis had in mind?

 

  • Tips to stimulate the vagus nerve

  • Humming: The vagus nerve passes through by the vocal cords and the inner ear and the vibrations of humming is a free and easy way to influence your nervous system states. Simply pick your favorite tune and you’re ready to go. Or if yoga fits your lifestyle you can “OM” your way to wellbeing. Notice and enjoy the sensations in your chest, throat, and head.
  • Conscious Breathing: The breath is one of the fastest ways to influence our nervous system states. The aim is to move the belly and diaphragm with the breath and to slow down your breathing. Vagus nerve stimulation occurs when the breath is slowed from our typical 10-14 breaths per minute to 5-7 breaths per minute. You can achieve this by counting the inhalation to 5, hold briefly, and exhale to a count of 10. You can further stimulate the vagus nerve by creating a slight constriction at the back of the throat and creating an “hhh”. Breathe like you are trying to fog a mirror to create the feeling in the throat but inhale and exhale out of the nose sound (in yoga this is called Ujjayi pranayam).
  • Valsalva Maneuver: This complicated name refers to a process of attempting to exhale against a closed airway. You can do this by keeping your mouth closed and pinching your nose while trying to breathe out. This increases the pressure inside of your chest cavity increasing vagal tone.
  • Diving Reflex: Considered a first rate vagus nerve stimulation technique, splashing cold water on your face from your lips to your scalp line stimulates the diving reflex. You can also achieve the nervous system cooling effects by placing ice cubes in a ziplock and holding the ice against your face and a brief hold of your breath. The diving reflex slows your heart rate, increases blood flow to your brain, reduces anger and relaxes your body. An additional technique that stimulates the diving reflex is to submerge your tongue in liquid. Drink and hold lukewarm water in your mouth sensing the water with your tongue.
  • Connection: Reach out for relationship. Healthy connections to others, whether this occurs in person, over the phone, or even via texts or social media in our modern world, can initiate regulation of our body and mind. Relationships can evoke the spirit of playfulness and creativity or can relax us into a trusting bond into another. Perhaps you engage in a lighthearted texting exchange with a friend. If you are in proximity with another you can try relationship expert, David Snarch’s simple, yet powerful exercise called “hugging until relaxed.” The instructions are to simply “stand on your own two feet, place your arms around your partner, focus on yourself, and to quiet yourself down, way down.”


Because of the pathway of the vagus nerve, long deep breathing is the number one key to activating the vagus nerve.
Breathing can be involuntary (something the vagus nerve does for us when we aren’t paying attention), but it can also be something we do consciously. By bringing awareness to the breath, lengthening and deepening it, you turn on the vagus nerve, giving your body the opportunity to rejuvenate.

So, let’s stop and breathe with awareness for ten minutes:

As you inhale, lift your collarbone.

As you exhale, soften and relax.

As you inhale, expand your ribs out under your arms.

As you exhale, soften and relax.

As you inhale, expand your ribs across your back

As you exhale, soften and relax.

When you sit, close your eyes, and utilize your system’s own action, you enhance your health and wellness.

Here are a number of pathways to the vagus nerve. Choose your favorite:

  • Immerse your face (especially the forehead, eyes, and two-thirds of your cheeks) in cold water for three minutes.
  • Practice restorative yoga and include gentle backbends, forward bends, and twists.
  • Include inversions in your practice like downward dog or legs up the wall.
  • Chant and sing in low resonant tones.
  • Immerse your tongue in saliva while doing long deep breathing.
  • Practice Qigong.
  • Laugh with deep diaphragmatic laughs.

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Fetal alcohol syndrome

fasExposure of fetus to alcohol

Although most nutrients are affected by alcohol intake, specific nutrients noted from numerous studies are thiamin, riboflavin, vitamin B-12, vitamin E, selenium, vitamin A, vitamin C, folic acid, vitamin D, zinc, and a few trace minerals. Alcohol is metabolized within hepatocytes by 1 of the 3 following pathways:

  • Alcohol dehydrogenase pathway (ADH): The first pathway, known as ADH, occurs in the cytosol of the hepatocyte (Fig. 2). ADH metabolizes ethanol to acetaldehyde, which is subsequently converted into acetic acid in mitochondria (20). In the ADH pathway, ethanol competes with vitamin A, or retinol, for metabolism because both substrates are metabolized by the same pathway (this is discussed later). Ultimately, ethanol is oxidized, which leads to the production of acetaldehyde and large amounts of NADH.

Alcohol effects on vitamin A

Alcohol consumption during pregnancy depletes maternal vitamin A stores, which can interrupt normal cell growth of the fetus. The proposed mechanism for this is that when both retinol and alcohol are present, ADH involved in the rate-limiting step of retinol oxidation has a higher affinity to alcohol, therefore preferentially metabolizing alcohol instead of retinol. This results in a deficiency in retinoic acid synthesis (39, 40), which is required to signal and control the cells involved in fetal development, organogenesis, organ homeostasis, cell and neuronal growth and differentiation, development of the CNS, and limb morphogenesis (16, 40).

DHA

DHA is highly important during fetal development because it plays an essential role in cognitive and visual development, as well as the development of the CNS (53, 54). DHA is also a precursor of a potent neurotrophic factor (neuroprotectin D1), which protects the brain and retina against injury-induced oxidative stress and enhances cell survivals in these tissues. Thus, it is recognized as a conditionally essential nutrient for infants. There is no RDA for DHA, but the Adequate Intake (AI) for n–3 FAs for pregnancy is 1.4 g/d (55). DHA is esterified to membrane phospholipids to maintain optimal fluidity and cellular integrity. Among phospholipids, phosphatidylserine has been the most studied in association with CNS development (54, 56, 57). Optimal neuronal development of the fetus is dependent on maternal intake and dietary status of DHA. In humans, the accumulation and integration of DHA into phosphatidylserine and cell membranes occurs from 16 wk to term and continues into the early postnatal development period (53). It is specifically during the last trimester in which DHA is rapidly incorporated into phosphatidylserine synthesis and storage in the hippocampus, because it is during this period in which human brain growth rapidly occurs (57, 58).

Folate (folic acid)

Folic acid, a water-soluble vitamin, has been identified as an essential nutrient that may provide a protective effect against gestational ethanol exposure. For folic acid to become metabolically active, it must be reduced to tetrahydrofolic acid (FH4) as a carrier for single-carbon moieties. FH4 is involved in the biosynthesis of the DNA and RNA precursors thymidylate and purine bases (64). Therefore, adequate maternal folic acid status is integral for optimal fetal growth and development. During pregnancy, the demand for folic acid is increased because it is not only required to support the mother for increased RBC formation but also to support the rapid growth of the fetus, including neural tube formation (65). The RDA for folic acid during pregnancy is 600 μg/d (66), and dietary sources are found in green leafy vegetables, beef, liver, pulses, and foods produced from whole wheat.

Alcohol effects on zinc

Alcohol consumption on a chronic basis itself reduces the availability of zinc because there is decreased intake and absorption and increased urinary excretion. When acute zinc deficiency occurs as a result of ethanol exposure, metallothionein, a low-molecular-weight protein body, sequesters plasma zinc to the liver, resulting in a reduction in plasma zinc. This leads to decreased amounts available for placental transport, resulting in fetal zinc deficiency (81, 82).

Choline

Choline and its metabolites are invaluable in neurotransmission (acetylcholine), structural integrity of cell plasma membranes (phosphatidylcholine and sphingomyelin), and cell signaling and in folate-independent pathways as a methyl donor via its metabolite, betaine (42, 90). This nutrient is the most-studied nutrient related to brain development and memory function and has been classified as an essential nutrient by the Institute of Medicine and National Academy of Sciences in the United States (66).

Choline supplementation in animal models

A recent study looked at the effect of choline supplementation on specific neurons that are altered in FASD (94). Pregnant rat dams were fed an alcohol-containing liquid diet or a control diet during GDs 7 and 21 with or without choline (642 mg/L choline chloride). The results showed that gestational choline supplementation prevented the adverse effects of alcohol on the neurons (Table 1) (94). Previous research from Thomas and colleagues (9599) showed that perinatal choline supplementation can reduce the severity of FASD—specifically, hyperactivity and learning deficits in the rat model. The authors found that choline chloride supplementation (250 mg · kg−1 · d−1 choline chloride) prevented ethanol-induced alterations in tasks that require behavioral flexibility such as spontaneous alternation behavior and memory (Table 1) (98).

Antioxidants

Antioxidants are compounds that are produced to scavenge free radicals and other compounds that threaten cellular oxidation. Cells can neutralize and scavenge reactive oxygen species through the enzymatic activity of SOD, glutathione peroxidase (GPx), and catalase. Nutrients such as folate, vitamin C (ascorbic acid), vitamin E (α-tocopherol), selenium, and zinc are important contributors to antioxidant activity.

Selenium

Selenium is a micronutrient that serves as an important component for the generation of the enzyme GPx. GPx inhibits oxidation because it is involved in scavenging free radicals, specifically hydrogen peroxide, and converting them to harmless products such as water. Selenium-based GPx primarily is active within the cytosol or the mitochondria. The amount of selenium obtained from the diet is based on the amount in the soil or water where the food source was grown. Once consumed, it is predominantly stored in the liver, because alcohol metabolism in the liver produces various reactive oxygen species and free radicals. The RDA for selenium during pregnancy is 60 μg/d (105).

Alcohol effects on selenium.

Typically, selenium deposits and plasma concentratons are low in chronic alcoholics because of decreased dietary intake and increased production of free radicals resulting from alcohol metabolism (107). However, selenium concentrations in the plasma were reported to be increased and were significantly greater in women who drank heavily, defined as >140 g/wk, during their pregnancy in comparison to abstinent women and those who consumed alcohol moderately (108).

http://advances.nutrition.org/content/5/6/675.full#sec-40

Mapping the Brain’s Aging Connections

Summary: Researchers report the brain connections that are key to cognition and complex thinking skills are most effected as we age.

Source: University of Edinburgh.

Impact of ageing on brain connections mapped in major scan study.

Brain connections that play a key role in complex thinking skills show the poorest health with advancing age, new research suggests.

Connections supporting functions such as movement and hearing are relatively well preserved in later life, the findings show.

Scientists carrying out the most comprehensive study to date on ageing and the brain’s connections charted subtle ways in which the brain’s connections weaken with age.

Knowing how and where connections between brain cells – so-called white matter – decline as we age is important in understanding why some people’s brains and thinking skills age better than others.

Worsening brain connections as we age contribute to a decline in thinking skills, such as reasoning, memory and speed of thinking.

Researchers from the University of Edinburgh analysed brain scans from more than 3,500 people aged between 45 and 75 taking part in the UK Biobank study.

Researchers say the data will provide more valuable insights into healthy brain and mental ageing, as well as making contributions to understanding a range of diseases and conditions.

The study was published in Nature Communications journal.

Dr Simon Cox, of the University of Edinburgh’s Centre for Cognitive Ageing and Cognitive Epidemiology (CCACE), who led the study, said: “By precisely mapping which connections of the brain are most sensitive to age, and comparing different ways of measuring them, we hope to provide a reference point for future brain research in health and disease.

“This is only one of the first of many exciting brain imaging results still to come from this important national health resource.”

Professor Ian Deary, Director of CCACE, said: “Until recently, studies of brain scans with this number of people were not possible. Day by day the UK Biobank sample grows, and this will make it possible to look carefully at the environmental and genetic factors that are associated with more or less healthy brains in older age.”

Professor Paul Matthews of Imperial College London, Chair of the UK Biobank Expert Working Group, who was not involved in the study, said: “This report provides an early example of the impact that early opening of the growing UK Biobank Imaging Enhancement database for access by researchers world-wide will have.

Image shows brain scans.

“The large numbers of subjects in the database has enabled the group to rapidly characterise the ways in which the brain changes with age – and to do so with the confidence that large numbers of observations allow.

“This study highlights the feasibility of defining what is typical, to inform the development of quantitative MRI measures for decision making in the clinic.”

ABOUT THIS NEUROSCIENCE RESEARCH ARTICLE

Funding: The University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology receives funding from the Medical Research Council (MRC) and the Biotechnology and Biological Sciences Research Council (BBSRC).

UK Biobank was established by the Wellcome Trust, MRC, Department of Health, Scottish Government and the Northwest Regional Development Agency. It has had funding from the Welsh Assembly Government, British Heart Foundation and Diabetes UK. UK Biobank is hosted by the University of Manchester and supported by the NHS.

Source: Joanne Morrison – University of Edinburgh
Image Source: NeuroscienceNews.com image is adapted from the University of Edinburgh press release.
Original Research: Full open access research for “Ageing and brain white matter structure in 3,513 UK Biobank participants” by Simon R. Cox, Stuart J. Ritchie, Elliot M. Tucker-Drob, David C. Liewald, Saskia P. Hagenaars, Gail Davies, Joanna M. Wardlaw, Catharine R. Gale, Mark E. Bastin & Ian J. Deary in Nature Communications. Published online December 15 2016 doi:10.1038/NCOMMS13629


Abstract

Ageing and brain white matter structure in 3,513 UK Biobank participants

Quantifying the microstructural properties of the human brain’s connections is necessary for understanding normal ageing and disease.

Here we examine brain white matter magnetic resonance imaging (MRI) data in 3,513 generally healthy people aged 44.64–77.12 years from the UK Biobank.

Using conventional water diffusion measures and newer, rarely studied indices from neurite orientation dispersion and density imaging, we document large age associations with white matter microstructure.

Mean diffusivity is the most age-sensitive measure, with negative age associations strongest in the thalamic radiation and association fibres.

White matter microstructure across brain tracts becomes increasingly correlated in older age. This may reflect an age-related aggregation of systemic detrimental effects. We report several other novel results, including age associations with hemisphere and sex, and comparative volumetric MRI analyses.

Results from this unusually large, single-scanner sample provide one of the most extensive characterizations of age associations with major white matter tracts in the human brain.

“Ageing and brain white matter structure in 3,513 UK Biobank participants” by Simon R. Cox, Stuart J. Ritchie, Elliot M. Tucker-Drob, David C. Liewald, Saskia P. Hagenaars, Gail Davies, Joanna M. Wardlaw, Catharine R. Gale, Mark E. Bastin & Ian J. Deary in Nature Communications. Published online December 15 2016 doi:10.1038/NCOMMS13629

Neuroscience of gender differences by Wiki

Neuroscience of sex differences is the study of the characteristics of the brain that separate the male brain and the female brain. Psychological sex differences are thought by some to reflect the interaction of genes, hormones and social learning on brain development throughout the lifespan.

Some evidence from brain morphology and function studies indicates that male and female brains cannot always be assumed to be identical from either a structural or functional perspective, and some brain structures are sexually dimorphic.[1][2]

Experts note that neural sexual dimorphisms in humans exist only as averages, with overlapping variabilities;[3][4] that it is unknown to what extent each is influenced by genetics or environment, even in adulthood;[4][5][6] and that it is impossible to identify whether a given human brain is from an XX or an XY solely by examination of its anatomy.[4]

History

Ideas of differences in the male and female brain circulated during the time of ancient Greek philosophers around 850 B.C. Aristotle claimed that males did not “receive their soul” until 40 days post-gestation and females did not until 80 days. In 1854, Emil Huschke discovered that “the frontal lobe in the male is all of 1% larger than that of the female.”[7] As the 19th century progressed, scientists began researching sexual dimorphisms in the brain significantly more.[8] Until around 21 years ago, scientists knew of several structural sexual dimorphisms of the brain, but they did not think that gender had any impact on how the human brain performs daily tasks. Through fMRI and PET scan studies, a great deal of information regarding the differences between male and female brains and how much they differ in regards to both structure and function has been uncovered.[citation needed]

Evolutionary explanations

Sexual selection

It is thought that male and female differences in learning ability have contributed to sexual selection and mate preference throughout evolution. The hippocampus has even been found to exhibit seasonal activity in some mammals where it is active during breeding periods but inactive during hibernation; this is because spatial learning is more present during the breeding season.[9]

Females show enhanced information recall compared to males. This may be due to the fact that females have a more intricate evaluation of risk-scenario contemplation, based on an prefrontal cortical control of the amygdala. For example, the ability to recall information better than males most likely originated from sexual selective pressures on females during competition with other females in mate selection. Recognition of social cues was an advantageous characteristic because it ultimately maximized offspring and was therefore selected for during evolution.[1]

Oxytocin is a hormone that induces contraction of the uterus and lactation in mammals. It is also a characteristic hormone of nursing mothers. Studies have found that oxytocin improves spatial memory. Through activation of the MAP kinase pathway, oxytocin plays a role in the enhancement of long-term synaptic plasticity, which is a change in strength between two neurons over a synapse that lasts for minutes or longer, and long-term memory. This hormone may have helped mothers remember the location of distant food sources so they could better nurture their offspring.[1]

Male vs. female brain anatomy

Hemisphere differences

Inter- and intrahemispheric connectivities are different between male and female.

A popular theory regarding language functions suggests that women use both hemispheres more equally, whereas men are more strongly lateralized to the left hemisphere.[10] This theory found initial support in a high-profile study of 19 men and 19 women, which found stronger lateralization in men during one of the three language tasks assessed.[11] In 2008, some researchers concluded that further studies have failed to replicate this finding, and a meta-analysis of 29 studies comparing language lateralization in males and females found no overall difference.[12]However, in 2013, researchers at the Perelman School of Medicine at the University of Pennsylvania mapped notable differences in male and female neural wiring. The study used diffusion tensor imaging of 949 individuals aged 8–22 years, and concluded that in all supratentorial regions of the brain inter-hemispheric connectivity was greater in women’s and girls’ brains, whereas intra-hemispheric connectivity was greater in the brains of men and boys. The effect was reversed in cerebellar connections.[13] The detected differences in neural connectivity were negligible up to the age of 13, but became much more prominent in the 14 to 17-year-olds.[13] In terms of the potential effect on behaviour, the authors concluded, “Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes”.[13]

Amygdala

image of Amygdala

The amygdala (red) in a human brain

According to some researchers,[14] “… the research on sex differences in the amygdala has produced conflicting results. Multiple studies report increased amygdala activity during the processing of affective scenes in men relative to women (Schienle et al., 2005; Goldstein et al., 2010), and meta-analysis supports this view, showing larger effect sizes in studies of affective processing including only men compared with those including only women (Sergerie et al., 2008). However several studies using similar stimuli have reported a larger amygdala response in women (Klein et al., 2003; McClure et al., 2004; Hofer et al., 2006; Domes et al., 2010), and others have reported no sex difference at all (Wrase et al., 2003; Caseras et al., 2007; Aleman and Swart, 2008). A possible explanation for these inconsistent results is that sex differences in amygdala response are valence-dependent. Furthermore, according to other researchers,[15] “Correlation analyses revealed that gray matter thickness in left ventromedial PFC was inversely correlated with task-related activation in the amygdala. These data add support to a general role of the ventromedial PFC in regulating activity of the amygdala.”

Research has been done on post-traumatic stress disorder (PTSD), an anxiety disorder found in both sexes, which is particularly common in war veterans, assault victims and women who have experienced abuse. Emotional memory encoding varies in the amygdala on the right and left and occurs equally for both genders: the right triggers unpleasant and fear-related memories, both declarative (conscious) and episodic (nonconcious).[16]

Amygdala volume correlates positively with fearfulness in girls but not in boys.[17]

Hippocampus

Several studies have shown the hippocampi of men and women to differ anatomically, neurochemically, and also in degree of long-term potentiation. Such evidence indicates that sex should influence the role of the hippocampus in learning. One experiment examined the effects of stress on Pavlovian conditioning performance in both sexes and found that males’ performance under stress was enhanced while female performance was impaired. Activation of the hippocampus is more dominant on the left side of hippocampus in females, while it is more dominant on the right side in males. This in turn influences cognitive reasoning; women use more verbal strategies than men when performing a task that requires cognitive thinking.[18] The hippocampus’s relationship with other structures in the brain influences learning and has been found to be sexually dimorphic as well.[1]

Oestradiol has been found to influence hippocampal development. Studies have shown neurogenesis, or the formation of new neurons, to be higher in the male hippocampus than in that of the female. This may be due to the lower levels of estradiol in the male brain compared to the female brain. providing a more optimal environment for neurogenesis.[19]

Frontal lobe

The ventromedial prefrontal cortex (VMPC), plays a key role in social emotional processing. In accordance with the sexual dimorphism of the amygdala, the right VPMC is more dominant in an active limbic system for males while the left is more dominant in females. These differences carry out to a behavioral level. For example, Koscik et al. wrote:

“A man with a unilateral right VMPC lesion, who was well educated and had worked successfully as a minister, was entirely unable to return to any form of gainful employment after his brain damage. He requires supervision for daily tasks and demonstrates severe disturbances in behavior and emotional regulation, including impulsivity and poor judgment. By contrast, a man with a unilateral left VMPC lesion was able to return to his job at a grain elevator and remains successfully employed there. He is remarkably free of disturbances to his social life and emotional functioning”

Orbital prefrontal corte

Positron emission tomography studies have shown that men and women ranging from the ages of 19 to 32 years old metabolize glucose at significantly different rates in the orbital prefrontal cortex. Infant males who exhibited lesions on their orbital prefrontal cortex struggled with object reversal experiments, but females exhibiting such lesions did not have impaired performance in object reversal.[20]

Other regions and not region-specific

There are sex differences in locus coeruleus dendritic structure that allow for an increased reception and processing of limbic information in females compared to males.[17]

Aggressive and defiant behavior is also associated with decreased right anterior cingulate cortex (ACC) volume in boys.[17]

According to the neuroscience journal review series Progress in Brain Research, it has been found that males have larger and longer planum temporale and Sylvian fissure while females have significantly larger proportionate volumes to total brain volume in the superior temporal cortex, Broca’s area, the hippocampus and the caudate.[21] The midsagittal and fiber numbers in the anterior commissure that connect the temporal polesand mass intermedia that connects the thalami is also larger in females.[21]

The journal review also found that male also have larger brain volume which can partly be accounted big bigger male body size. Researchers also found greater cortical thickness, cortical complexity and cortical surface area after adjusting for brain volume.[21] Given that cortical complexity and cortical features are positively correlated with intelligence, researchers postulated that these differences might have evolved for females to compensate for smaller brain size and equalize overall cognitive abilities with males.[21]

White/grey matter

Global and regional grey matter (GM) differs in men and women. Women have larger left orbitofrontal GM volumes and overall cortical thickness than men.[22] Behavioral implications of the greater volume have not yet been discovered. Women have a higher percentage of GM, whereas men have a higher percentage of white matter (WM) and of CSF (cerebrospinal fluid). In men the percentage of GM was higher in the left hemisphere, the percentage of WM was symmetric, and the percentage of CSF was higher in the right. Women showed no asymmetries. Both GM and WM volumes correlated moderately with global, verbal, and spatial performance across groups. However, the regression of cognitive performance and WM volume was significantly steeper in women.[23]

In a 2013 meta-analysis, researchers found on average males had larger grey matter volume in bilateral amygdalae, hippocampi, anterior parahippocampal gyri, posterior cingulate gyri, precuneus, putamen and temporal poles, areas in the left posterior and anterior cingulate gyri, and areas in the cerebellum bilateral VIIb, VIIIa and Crus I lobes, left VI and right Crus II lobes.[24] On the other hand, females on average had larger grey matter volume at the right frontal pole, inferior and middle frontal gyri, pars triangularis, planum temporale/parietal operculum, anterior cingulate gyrus, insular cortex, and Heschl’s gyrus; bilateral thalami and precuneus; the left parahippocampal gyrus and lateral occipital cortex(superior division).[24] The meta-analysis found larger volumes in females were most pronounced in areas in the right hemisphere related to language in addition to several limbic structures such as the right insular cortex and anterior cingulate gyrus.[24]

Amber Ruigrok’s 2013 meta-analysis also found greater grey matter density in the average male left amygdala, hippocampus, insula, pallidum, putamen, claustrum and right cerebellum.[24] The meta-analysis also found greater grey matter density in the average female left frontal pole[24]

Brain networks

A 2014 meta-analysis by researcher Ashley C.Hill found that although men and women commonly used the same brain networks for working memory, specific regions were gender specific.[25] For example, both men and women’s active working memory networks composed of bilateral middle frontal gyri, left cingulate gyrus, right precuneus, left inferior and superior parietal lobes, right claustrum, and left middle temporal gyrus but women also tended have consistent activity in the limbic regions such as the anterior cingulate, bilateral amygdala and right hippocampus while men tended to have a distributed networks spread out among the cerebellum, portions of the superior parietal lobe, the left insula and bilateral thalamus.[25]

Brain differences between homo- and heterosexuals

Brain wiring comparisons of homosexuals and persons of the opposite sex show that homosexuals may be born with a predisposition to be homosexual. Research at the Stockholm Brain Institute in Sweden found that homosexual men and heterosexual women have similar brain characteristics. Specifically, these similarities are in the overall size of the brain and the activity of the amygdala. The same is for heterosexual men and homosexual women. Molecular biologist at the National Institutes of Health, Dean Hamer, says, “this is from a series of observations showing there’s a biological reason for sexual orientation”.[26]

Ivanka Savic – Berglund conducted a study in which MRIs were used to measure the volume and shapes of the brain. She also used PET scans to view blood flow to the amygdala. Savic – Berglund found that in homosexual men and heterosexual women, the blood flowed to areas involved in fear and anxiety, whereas in heterosexual men and homosexual women, it tended to flow to pockets linked to aggression. When looking at hemisphere differences, the right hemisphere was found to be slightly larger than the left in heterosexual men and homosexual women, whereas those of homosexual men and heterosexual women were more symmetrical.[27]

Research has indicated that the corpus callosum is larger in homosexual men than in heterosexual men. This is significant because the corpus callosum is a structure that is developed early. In the Journal Science Simon LeVay showed that the third interstitial nucleus of the hypothalamus has neurons that are packed more together in homosexual men than in heterosexual men.[28] Connections from the amygdala to other parts of the brain are similar between homosexuals and persons of the opposite gender as shown through PET and MRI scans. For example, in homosexual men and heterosexual women, there were more connections from the left amygdala. In homosexual women and heterosexual men, there were more connections from the right amygdala. LeVay’s results were not replicated in other studies. A 2001 study that attempted to replicate the findings concluded that “Although there was a trend for INAH3 to occupy a smaller volume in homosexual men than in heterosexual men, there was no difference in the number of neurons within the nucleus based on sexual orientation.”[29]

Neurochemical differences

Hormones

Steroid hormones have several effects on brain development as well as maintenance of homeostasis throughout adulthood. One effect they exhibit is on the hypothalamus, where they increase synapse formation.[30] Estrogen receptors have been found in the hypothalamus, pituitary gland, hippocampus, and frontal cortex, indicating the estrogen plays a role in brain development. Gonadal hormone receptors have also been found in the basal forebrain nuclei.[31]

Estrogen and the female brain

Estradiol influences cognitive function, specifically by enhancing learning and memory in a dose-sensitive manner. Too much estrogen can have negative effects by weakening performance of learned tasks as well as hindering performance of memory tasks; this can result in females exhibiting poorer performance of such tasks when compared to males.[32]

It has been suggested that during development, estrogen can exhibit both feminizing and defeminizing effects on the human brain; high levels of estrogen induce male neural traits to develop while moderate levels induce female traits. In females, defeminizing effects are resisted because of the presence of α-fetoprotein (AFP), a carrier protein proposed to transport estrogen into brain cells, allowing the female brain to properly develop. The role of AFP is significant at crucial stages of development, however. Prenatally, AFP blocks estrogen. Postnatally, AFP decreases to ineffective levels; therefore, it is probable that estrogen exhibits its effects on female brain development postnatally.[33]

Ovariectomies, surgeries inducing menopause, or natural menopause cause fluctuating and decreased estrogen levels in women. This in turn can “attenuate the effects” of endogenous opioid peptides. Opioid peptides are known to play a role in emotion and motivation. β-endorphin (β-EP), an endogenous opioid peptide, content has been found to decrease (in varying amounts/brain region), post ovariectomy, in female rats within the hypothalamus, hippocampus, and pituitary gland. Such a change in β-EP levels could be the cause of mood swings, behavioral disturbances, and hot flashes in post menopausal women.[31]

Testosterone and the male brain

Testosterone has been found to play a big role during development but may have independent effects on sexually dimorphic brain regions in adulthood. Studies have shown that the medial amygdala of male hamsters exhibits lateralization and sexual dimorphism prior to puberty. Furthermore, organization of this structure during development is influenced by the presence of androgens and testosterone. This is evident when comparing medial amygdala volume of male and female rats, adult male brains have a medial amygdala of greater volume than do adult female brains which is partially due to androgen circulation.[34]

It also heavily influences male development; a study found that perinatal females introduced to elevated testosterone levels exhibited male behavior patterns. In the absence of testosterone, female behavior is retained.[30] Testosterone’s influence on the brain is caused by organizational developmental effects. It has been shown to influence proaptotic proteins so that they increase neuronal cell death in certain brain regions. Another way testosterone affects brain development is by aiding in the construction of the “limbic hypothalamic neural networks”.[30]

Similar to how estrogen enhances memory and learning in women, testosterone has been found to enhance memory recall in men. In a study testing a correlation between memory a recall and testosterone levels in men, “fMRI analysis revealed that higher testosterone levels were related to increased brain activation in the amygdala during encoding of neutral pictures”.[35]

Oxytocin and Vasopressin

Oxytocin is positively correlated with maternal behaviours, social recognition, social contact, sexual behaviour and pair bonding. Oxytocin appears at higher levels in women than in men.[36] Vasopressin on the other hand is more present in men and mediates sexual behavior, aggression and other social functions.[36][37]

Neurotransmitters

Whole level 5-HT serotonin levels are higher in women versus men while men synthesize serotonin significantly faster than women. Healthy women also have higher 5-HT transport availability in the diencephalon and brainstem areas of the brain.[38] Dopamine function is also increased in women especially dopamine transporter which regulates the availability of receptors. Women before the onset of menopause synthesize higher levels of striatal presynaptic dopamine than age-matched men.[38] Other neurotransmitters like μ-opioids show significantly higher binding potential in the cerebellum, amygdala and the thalamus for women than it does so for men.[39] Women are also more dependent on norepinephrine in the formation of long term emotional memories than men are.[39]

Male vs. female brain functionality

Neural masculinization is a developmental process where different sex hormones assist in the expression of male behavior.[40]

Stress

image of stress regions in brain

Regions of the brain associated with stress and fear

Stress has been found to induce an increase in serotonin, norepinephrine, and dopamine levels within the basolateral amygdala of male rats, but not within that of female rats. Furthermore, object recognition is impaired in males as a result of short term stress exposure. Neurochemical levels in the brain can change under the influence of stress exposure, particularly in regions associated with spatial and non-spatial memory, such as the prefrontal cortex and the hippocampus. Dopamine metabolite levels decrease post stress in male rats’ brains, specifically within the CA1 region of the hippocampus.[41]

In female rats, both short term (1 hour) and long term (21 days) stress has been found to actually enhance spatial memory. Under stress, male rats exhibit deleterious effects on spatial memory, however female rats show a degree of resistance to this phenomenon. Stressed female rats’ norepinephrine (NE) levels go up by about 50% in their prefrontal cortex while that of male rats goes down 50%.[41]

Cognitive tasks

It was once thought that sex differences in cognitive task and problem solving did not occur until puberty. However, new evidence now suggests that cognitive and skill differences are present earlier in development. For example, researchers have found that three- and four-year-old boys were better at targeting and at mentally rotating figures within a clock face than girls of the same age were. Prepubescent girls, however, excelled at recalling lists of words. These sex differences in cognition correspond to patterns of ability rather than overall intelligence (although some researchers, such as Richard Lynn of the University of Ulster in Northern Ireland, have argued that there exists a small IQ difference favoring human males). Laboratory settings are used to systematically study the sexual dimorphism in problem solving task performed by adults.[42]

On average, males excel relative to females at certain spatial tasks. Specifically, males have an advantage in tests that require the mental rotationor manipulation of an object.[43] They tend to outperform females in mathematical reasoning and navigation. In a computer simulation of a maze task, males completed the task faster and with fewer errors than their female counterparts. Additionally, males have displayed higher accuracy in tests of targeted motor skills, such as guiding projectiles.[42] Males are also faster on reaction time and finger tapping tests.[44]

On average, females excel relative to males on tests that measure recollection. They have an advantage on processing speed involving letters,digits and rapid naming tasks.[44] Females tend to have better object location memory and verbal memory.[45] They also perform better at verbal learning.[46] Females have better performance at matching items and precision tasks, such as placing pegs into designated holes. In maze and path completion tasks, males learn the goal route in fewer trials than females, but females remember more of the landmarks presented. This shows that females use landmarks in everyday situations to orient themselves more than males. Females are better at remembering whether objects had switched places or not.[42]

Studies using the Iowa gambling task, or Iowa Card Task, have examined cognitive reasoning and decision-making in males and females. A study in which participants of various age groups who were asked to perform the Iowa Card Task produced data showing that males and females differ in their decision making processes on the neurological level. The study suggests that decision-making in females may be guided by avoidance of negativity while decision making in males is mainly guided by assessing the long term outcome of a situation. They also found that males outperformed females in the Iowa Card Task, but there was a negative correlation between elevated testosterone levels and performance in the card task which indicates gonadal hormones influence decision-making.[20]

Depriving Deadly Brain Tumors Of Cholesterol May Be Their Achilles’ Heel

Summary: Depriving glioblastoma brain cancer cells of cholesterol caused tumor regression and prolonged survival in mouse models of the disease, a new study reports.

Source: UCSD.

In mouse models, alternative approach proves promising against hard-to-treat cancer.

Researchers at University of California San Diego School of Medicine, Ludwig Institute for Cancer Research and The Scripps Research Institute, with colleagues in Los Angeles and Japan, report that depriving deadly brain cancer cells of cholesterol, which they import from neighboring healthy cells, specifically kills tumor cells and caused tumor regression and prolonged survival in mouse models.

The findings, published in the online October 13 issue of Cancer Cell, also present a potential alternative method for treating glioblastomas (GBM), the most common and most aggressive form of brain cancer. GBMs are extremely difficult to treat. The median survival rate is just over 14 months, with few treated patients living five years or more past diagnosis.

Adult brain cancers are almost universally fatal, in part because of the biochemical composition of the central nervous system (CNS) and the blood-brain barrier, which selectively and protectively limits the passage of molecules from the body into the brain, but which also blocks most existing chemotherapies, contributing to treatment failure.

This includes blocking small molecule inhibitors that target growth factor receptors, which have not proven to be effective with brain cancers, possibly due to their inability to get past the blood-brain barrier and achieve sufficiently high levels in the central nervous system.

“Researchers have been thinking about ways to deal with this problem,” said senior author Paul S. Mischel, MD, a member of the Ludwig Cancer Research branch at UC San Diego and professor in the UC San Diego School of Medicine Department of Pathology. “We have been challenged by the fact that GBMs are among the most genomically-well characterized forms of cancer, with clear evidence of targetable driver oncogene mutations but this information has yet to benefit patients, at least in part, because the drugs designed to target these oncogenes have difficulty accessing their targets in the brain. We have been trying to find an alternative way to use this information to develop more effective treatments.

“One such approach stems from the observation that oncogenes (mutated genes) can rewire the biochemical pathways of cells in ways that make them dependent on proteins that are not themselves encoded by oncogenes. Targeting these ‘oncogene-induced co-dependencies’ opens up a much broader pharmacopeia, including the use of drugs that aren’t traditionally part of cancer drug pipelines but have better pharmacological properties.”

In previous research, Mischel and others had noted GBM cells cannot synthesize cholesterol, which is vital to cell structure and function, particularly in the brain. Instead, GBM cells derive what they need from brain cells called astrocytes, which produce cholesterol in abundance. Roughly 20 percent of total body cholesterol is found in the brain.

When normal cells have sufficient cholesterol, they convert some of it into molecules called oxysterols, which activate a receptor in the cell’s nucleus — the liver X receptor (LXR) — to shut down the uptake of cholesterol.

“So when normal cells get enough cholesterol, they stop making it, stop taking it up and start pumping it out,” said Mischel. “We found that in GBM cells, this mechanism is completely disrupted. They’re like parasites of the brain’s normal cholesterol system. They steal cholesterol and don’t have an off switch. They just keep gobbling the stuff up.”

Image shows an MRI brain scan of a glioblastoma patient.

GBM cells ensure their cholesterol supply by suppressing the production of oxysterols, the researchers said, ensuring cells’ LXRs remain inactive.

The research team, including Andrew Shaiu and Tim Gahman of Ludwig’s Small Molecule Development team at UC San Diego, identified an experimental metabolic disease drug candidate named LXR-623 that activates LXRs.

In mouse models, LXR-623 easily crossed the blood-brain barrier to bind with LXRs in normal cells, stimulating the production of oxysterols and the reduction of cholesterol. There was no effect upon healthy neurons and other brain cells, the scientists found, but GBM cells were deprived of vital cholesterol, resulting in cell death and tumor regression.

“Disrupting cholesterol import by GBM cells caused dramatic cancer cell death and shrank tumors significantly, prolonging the survival of the mice,” said Mischel. “The strategy worked with every single GBM tumor we looked at and even on other types of tumors that had metastasized to the brain. LXR-623 also had minimal effect on astrocytes or other tissues of the body.”

Mischel suggested the GBM strategy could be implemented in clinical trials using drug-candidates under development or in early trials.

ABOUT THIS NEUROSCIENCE RESEARCH ARTICLE

Co-authors of this paper include: first author Genaro R. Villa, Yuchao Gu, Xin Rong, Cynthia Hong, Timothy F. Cloughesy, UCLA; Jonathan J. Hulce, Kenneth M. Lum, Michael Martini and Benjamin F. Cravatt, TSRI; Ciro Zanca, Junfeng Bi, Shiro Ikegami, Gabrielle L. Cahill, Huijun Yang, Kristen M. Turn, Feng Liu, Gary C. Hon, David Jenkins, Aaron M. Armando, Oswald Quehenberger, Frank B. Furnari, and Webster K. Cavenee, UC San Diego; and Kenta Masui and Peter Tontonoz, Tokyo Women’s Medical University.

Funding: Funding for this research came, in part, from the National Cancer Institute (F31CA186668), the National Institute for Neurological Diseases and Stroke (NS73831, NS080939), the Defeat GBM Program of the National Brain Tumor Society, the Ben and Catherine Ivy Foundation, the Ziering Family Foundation and the National Institutes of Health (CA132630).

Source: Scott LaFee – UCSD
Image Source: NeuroscienceNews.com image is credited A. Christaras.
Original Research: The study will appear in Cancer Cell.

UCSD. “Depriving Deadly Brain Tumors Of Cholesterol May Be Their Achilles’ Heel.” NeuroscienceNews. NeuroscienceNews, 13 October 2016.
<http://neurosciencenews.com/cholesterol-brain-cancer-5294/&gt;.

Music enhances learning through neuroplasticity

Neuroscience research into the neuroscience of music shows that musicians’ brains may be primed to distinguish meaningful sensory information from noise. This ability seems to enhance other cognitive abilities such as learning, language, memory and neuroplasticity of various brain areas.

Scientific review of how music training primes nervous system and boosts learning

Those ubiquitous wires connecting listeners to you-name-the-sounds from invisible MP3 players, whether of Bach, Miles Davis or, more likely today, Lady Gaga, only hint at music’s effect on the soul throughout the ages.

Now a data-driven review by Northwestern University researchers that will be published July 20 in Nature Reviews Neuroscience pulls together converging research from the scientific literature linking musical training to learning that spills over to skills including language, speech, memory, attention and even vocal emotion. The science covered comes from labs all over the world, from scientists of varying scientific philosophies, using a wide range of research methods.

The explosion of research in recent years focusing on the effects of music training on the nervous system, including the studies in the review, have strong implications for education, said Nina Kraus, lead author of the Nature perspective, the Hugh Knowles Professor of Communication Sciences and Neurobiology and director of Northwestern’s Auditory Neuroscience Laboratory. Brain Volts

Scientists use the term neuroplasticity to describe the brain’s ability to adapt and change as a result of training and experience over the course of a person’s life. The studies covered in the Northwestern review offer a model of neuroplasticity, Kraus said. The research strongly suggests that the neural connections made during musical training also prime the brain for other aspects of human communication.

An active engagement with musical sounds not only enhances neuroplasticity, she said, but also enables the nervous system to provide the stable scaffolding of meaningful patterns so important to learning.

“The brain is unable to process all of the available sensory information from second to second, and thus must selectively enhance what is relevant,” Kraus said. Playing an instrument primes the brain to choose what is relevant in a complex process that may involve reading or remembering a score, timing issues and coordination with other musicians.

“A musician’s brain selectively enhances information-bearing elements in sound,” Kraus said. “In a beautiful interrelationship between sensory and cognitive processes, the nervous system makes associations between complex sounds and what they mean.” The efficient sound-to-meaning connections are important not only for music but for other aspects of communication, she said.

The Nature article reviews literature showing, for example, that musicians are more successful than non-musicians in learning to incorporate sound patterns for a new language into words. Children who are musically trained show stronger neural activation to pitch changes in speech and have a better vocabulary and reading ability than children who did not receive music training.

And musicians trained to hear sounds embedded in a rich network of melodies and harmonies are primed to understand speech in a noisy background. They exhibit both enhanced cognitive and sensory abilities that give them a distinct advantage for processing speech in challenging listening environments compared with non-musicians.

Children with learning disorders are particularly vulnerable to the deleterious effects of background noise, according to the article. “Music training seems to strengthen the same neural processes that often are deficient in individuals with developmental dyslexia or who have difficulty hearing speech in noise.”

Currently what is known about the benefits of music training on sensory processing beyond that involved in musical performance is largely derived from studying those who are fortunate enough to afford such training, Kraus said.

The research review, the Northwestern researchers conclude, argues for serious investing of resources in music training in schools accompanied with rigorous examinations of the effects of such instruction on listening, learning, memory, attention and literacy skills.

“The effect of music training suggests that, akin to physical exercise and its impact on body fitness, music is a resource that tones the brain for auditory fitness and thus requires society to re-examine the role of music in shaping individual development, ” the researchers conclude.

“Music training for the development of auditory skills,” by Nina Kraus and Bharath Chandrasekaran, will be published July 20 in the journal Nature Reviews Neuroscience.

Contact: Pat Vaughan Tremmel
Source: Northwestern University

Music on the Brain Neuroplasticity of Music

Neuroscience of music’s influence on neuroplasticity and learning. Music can prime the brain to perform better in many other cognitive abilities. Image: Neuroscience News adapted from NIH brain image