Nurture is every influence from without that affects man after his birth

Summary: A new study reveals a diverse array of genetic changes that occur in the brain following sensory experiences.

Source: Harvard.

“Nature and nurture is a convenient jingle of words, for it separates under two distinct heads the innumerable elements of which personality is composed. Nature is all that a man brings with himself into the world; nurture is every influence from without that affects him after his birth.” – Francis Galton, cousin of Charles Darwin, 1874.

Is it nature or nurture that ultimately shapes a human? Are actions and behaviors a result of genes or environment? Variations of these questions have been explored by countless philosophers and scientists across millennia. Yet, as biologists continue to better understand the mechanisms that underlie brain function, it is increasingly apparent that this long-debated dichotomy may be no dichotomy at all.

In a study published in Nature Neuroscience on Jan. 21, neuroscientists and systems biologists from Harvard Medical School reveal just how inexorably interwoven nature and nurture are in the mouse brain. Using novel technologies developed at HMS, the team looked at how a single sensory experience affects gene expression in the brain by analyzing more than 114,000 individual cells in the mouse visual cortex before and after exposure to light.

Their findings revealed a dramatic and diverse landscape of gene expression changes across all cell types, involving 611 different genes, many linked to neural connectivity and the brain’s ability to rewire itself to learn and adapt.

The results offer insights into how bursts of neuronal activity that last only milliseconds trigger lasting changes in the brain, and open new fields of exploration for efforts to understand how the brain works.

“What we found is, in a sense, amazing. In response to visual stimulation, virtually every cell in the visual cortex is responding in a different way,” said co-senior author Michael Greenberg, the Nathan Marsh Pusey Professor of Neurobiology and chair of the Department of Neurobiology at HMS.

“This in essence addresses the long-asked question about nature and nurture: Is it genes or environment? It’s both, and this is how they come together,” he said.

One out of many

Neuroscientists have known that stimuli–sensory experiences such as touch or sound, metabolic changes, injury and other environmental experiences–can trigger the activation of genetic programs within the brain.

Composed of a vast array of different cells, the brain depends on a complex orchestra of cellular functions to carry out its tasks. Scientists have long sought to understand how individual cells respond to various stimuli. However, due to technological limitations, previous genetic studies largely focused on mixed populations of cells, obscuring critical nuances in cellular behavior.

To build a more comprehensive picture, Greenberg teamed with co-corresponding author Bernardo Sabatini, the Alice and Rodman W. Moorhead III Professor of Neurobiology at HMS, and Allon Klein, assistant professor of systems biology at HMS.

Spearheaded by co-lead authors Sinisa Hrvatin, a postdoctoral fellow in the Greenberg lab, Daniel Hochbaum, a postdoctoral fellow in the Sabatini lab and M. Aurel Nagy, an MD-PhD student in the Greenberg lab, the researchers first housed mice in complete darkness to quiet the visual cortex, the area of the brain that controls vision.

They then exposed the mice to light and studied how it affected genes within the brain. Using technology developed by the Klein lab known as inDrops, they tracked which genes got turned on or off in tens of thousands of individual cells before and after light exposure.

The team found significant changes in gene expression after light exposure in all cell types in the visual cortex–both neurons and, unexpectedly, nonneuronal cells such as astrocytes, macrophages and muscle cells that line blood vessels in the brain.

Roughly 50 to 70 percent of excitatory neurons, for example, exhibited changes regardless of their location or function. Remarkably, the authors said, a large proportion of non-neuronal cells–almost half of all astrocytes, for example–also exhibited changes.

The team identified thousands of genes with altered expression patterns after light exposure, and 611 genes that had at least two-fold increases or decreases.

Many of these genes have been previously linked to structural remodeling in the brain, suggesting that virtually the entire visual cortex, including the vasculature and muscle cell types, may undergo genetically controlled rewiring in response to a sensory experience.

There has been some controversy among neuroscientists over whether gene expression could functionally control plasticity or connectivity between neurons.

“I think our study strongly suggests that this is the case, and that each cell has a unique genetic program that’s tailored to the function of a given cell within a neural circuit,” Greenberg said.

Question goldmine

These findings open a wide range of avenues for further study, the authors said. For example, how genetic programs affect the function of specific cell types, how they vary early or later in life and how dysfunction in these programs might contribute to disease, all of which could help scientists learn more about the fundamental workings of the brain.

“Experience and environmental stimuli appear to almost constantly affect gene expression and function throughout the brain. This may help us to understand how processes such as learning and memory formation, which require long-term changes in the brain, arise from the short bursts of electrical activity through which neurons signal to each other,” Greenberg said.

brainbow of the cerebral cortex

One especially interesting area of inquiry, according to Greenberg, includes the regulatory elements that control the expression of genes in response to sensory experience. In a paper published earlier this year in Molecular Cell, he and his team explored the activity of the FOS/JUN protein complex, which is expressed across many different cell types in the brain but appears to regulate unique programs in each different cell type.

Identifying the regulatory elements that control gene expression is critical because they may account for differences in brain function from one human to another, and may also underlie disorders such as autism, schizophrenia and bipolar disease, the researchers said.

“We’re sitting on a goldmine of questions that can help us better understand how the brain works,” Greenberg said. “And there is a whole field of exploration waiting to be tapped.”

ABOUT THIS NEUROSCIENCE RESEARCH ARTICLE

Additional authors on the study include Marcelo Cicconet, Keiramarie Robertson, Lucas Cheadle, Rapolas Zilionis, Alex Ratner and Rebeca Borges-Monroy.

Funding: This work was supported by the National Institutes of Health (R01NS028829, R01NS046579, T32GM007753, R33CA212697, 5T32AG000222-23), F. Hoffmann-La Roche Ltd., the William F. Milton Fund, a Burroughs Wellcome Fund Career Award and an Edward J. Mallinckrodt Scholarship.

Source: Ekaterina Pesheva – Harvard
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to Lichtman Lab, Harvard University.
Original Research: Abstract in Nature Neuroscience.
DOI:10.1038/s41593-017-0029-5

CITE THIS NEUROSCIENCENEWS.COM ARTICLE
Harvard “Nature, Meet Nurture.” NeuroscienceNews. NeuroscienceNews, 8 February 2018.
<http://neurosciencenews.com/genetic-nature-experience-8455/&gt;.

Abstract

Single-cell analysis of experience-dependent transcriptomic states in the mouse visual cortex

Activity-dependent transcriptional responses shape cortical function. However, a comprehensive understanding of the diversity of these responses across the full range of cortical cell types, and how these changes contribute to neuronal plasticity and disease, is lacking. To investigate the breadth of transcriptional changes that occur across cell types in the mouse visual cortex after exposure to light, we applied high-throughput single-cell RNA sequencing. We identified significant and divergent transcriptional responses to stimulation in each of the 30 cell types characterized, thus revealing 611 stimulus-responsive genes. Excitatory pyramidal neurons exhibited inter- and intralaminar heterogeneity in the induction of stimulus-responsive genes. Non-neuronal cells showed clear transcriptional responses that may regulate experience-dependent changes in neurovascular coupling and myelination. Together, these results reveal the dynamic landscape of the stimulus-dependent transcriptional changes occurring across cell types in the visual cortex; these changes are probably critical for cortical function and may be sites of deregulation in developmental brain disorders.

 


Connie’s comments:

I massaged my babies after birth before each bath and even up to now when they are sick. I train all caregivers to massage home-bound older adults or seniors needing 24/7 care.

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Social skills , touch , nurture and nature

Social skills , touch , nurture and nature

A piglet is shown.

INFECTION IN PREGNANT PIGS LEADS TO ANTISOCIAL PIGLETS

Recent studies have reported on a link between maternal infection and subsequent higher risk of autism in offspring. A new study from ACES reports similar findings in pigs. Mother pigs who develop infection during pregnancy have a higher risk of their piglets developing antisocial problems. READ MORE…

Antisocial personality disorder in 70% of prison inmates

Antisocial personality disorder

Antisocial personality disorder (ASPD), also known as dissocial personality disorder (DPD) and sociopathy, is apersonality disorder, characterized by a pervasive pattern of disregard for, or violation of, the rights of others.

Prisoners

An international team of Finnish, American, British, and Swedish researchers examined data from the Finnish CRIME sample — a database of psychological tests and genetic material from 794 Finnish prisoners taken between 2010-2011.

The findings of this study cannot be implemented for any prediction purposes, or brought into courthouses to be given any legal weight.
Of the 794 prisoners, a full 568 screened positive for ASPD. By comparing that group’s genetic material to a large control sample from the general population, the researchers identified a number of genes that may play a role in at least some ASPD cases.

Hormones and neurotransmitters

Traumatic events can lead to a disruption of the standard development of the central nervous system, which can generate a release of hormones that can change normal patterns of development.[36] Aggressiveness and impulsivity are among the possible symptoms of ASPD. Testosterone is a hormone that plays an important role in aggressiveness in the brain.[37] For instance, criminals who have committed violent crimes tend to have higher levels of testosterone than the average person.[37] The effect of testosterone is counteracted by cortisol which facilitates the cognitive control on impulsive tendencies.[37]

One of the neurotransmitters that have been discussed in individuals with ASPD is serotonin, also known as 5HT.[36] A meta-analysis of 20 studies found significantly lower 5-HIAA levels (indicating lower serotonin levels), especially in those who are younger than 30 years of age.[38]

J.F.W. Deakin of University of Manchester‘s Neuroscience and Psychiatry Unit has discussed additional evidence of a connection between 5HT (serotonin) and ASPD. Deakin suggests that low cerebrospinal fluid concentrations of 5-HIAA, and hormone responses to 5HT, have displayed that the two main ascending 5HT pathways mediate adaptive responses to post and current conditions. He states that impairments in the posterior 5HT cells can lead to low mood functioning, as seen in patients with ASPD. It is important to note that the dysregulated serotonergic function may not be the sole feature that leads to ASPD but it is an aspect of a multifaceted relationship between biological and psychosocial factors.[citation needed]

While it has been shown that lower levels of serotonin may be associated with ASPD, there has also been evidence that decreased serotonin function is highly correlated with impulsiveness and aggression across a number of different experimental paradigms. Impulsivity is not only linked with irregularities in 5HT metabolism but may be the most essential psychopathological aspect linked with such dysfunction.[39] Correspondingly, the DSM classifies “impulsivity or failure to plan ahead” and “irritability and aggressiveness” as two of seven sub-criteria in category A of the diagnostic criteria of ASPD.[19]

Some studies have found a relationship between monoamine oxidase A and antisocial behavior, including conduct disorder and symptoms of adult ASPD, in maltreated children.[citation needed]

Head injuries

Researchers have linked physical head injuries with antisocial behavior.[40][41][42] Since the 1980s, scientists have associated traumatic brain injury, including damage to the prefrontal cortex, with an inability to make morally and socially acceptable decisions.[40][42] Children with early damage in the prefrontal cortex may never fully develop social or moral reasoning and become “psychopathic individuals … characterized by high levels of aggression and antisocial behavior performed without guilt or empathy for their victims.”[40][41] Additionally, damage to the amygdala may impair the ability of the prefrontal cortex to interpret feedback from the limbic system, which could result in uninhibited signals that manifest in violent and aggressive behavior.[40]

Family environment

Some studies suggest that the social and home environment has contributed to the development of antisocial behavior. The parents of these children have been shown to display antisocial behavior, which could be adopted by their children.

Source: Wiki

Cortisol, serotonin and depression: all stressed out?

The fact that patients with major depression exhibit decreased brain serotonin (5-hydroxytryptamine, 5-HT) function and elevated cortisol secretion has reached the status of textbook truism. More recent formulations have suggested that elevated cortisol levels, probably caused by stressful life events, may themselves lower brain 5-HT function and this in turn leads to the manifestation of the depressive state (see Dinan, 1994). This elegant proposal neatly ties abnormalities of cortisol secretion and 5-HT function into a causal chain in which cortisol is the key biological mediator through which life stress lowers brain 5-HT function, thereby causing depression in vulnerable individuals.

The importance, and occasional discomfort, of testing cherished beliefs is shown in a ground-breaking study from the Manchester University Department of Psychiatry published in this issue of the journal (Strickland et al, 2002). In a large group of women the authors found no evidence of increased salivary cortisol levels in those with depression or in the majority of those vulnerable to depression through adverse social or personal circumstances. Moreover, in women with depression, brain 5-HT function (as judged by the prolactin response to the 5-HT releasing agent, d-fenfluramine) was increased rather than diminished. These findings pose serious problems for hypotheses linking hypercortisolaemia with lowered brain 5-HT function and depression.

Source: http://bjp.rcpsych.org/content/180/2/99


Massage therapy on cortisol and serotonin

In this article the positive effects of massage therapy on biochemistry are reviewed including decreased levels of cortisol and increased levels of serotonin and dopamine. The research reviewed includes studies on depression (including sex abuse and eating disorder studies), pain syndrome studies, research on auto-immune conditions (including asthma and chronic fatigue), immune studies (including HIV and breast cancer), and studies on the reduction of stress on the job, the stress of aging, and pregnancy stress. In studies in which cortisol was assayed either in saliva or in urine, significant decreases were noted in cortisol levels (averaging decreases 31%). In studies in which the activating neurotransmitters (serotonin and dopamine) were assayed in urine, an average increase of 28% was noted for serotonin and an average increase of 31% was noted for dopamine. These studies combined suggest the stress-alleviating effects (decreased cortisol) and the activating effects (increased serotonin and dopamine) of massage therapy on a variety of medical conditions and stressful experiences.

http://www.ncbi.nlm.nih.gov/pubmed/16162447

Correlation between cortisol level and serotonin uptake in patients with chronic stress and depression

In a recent study (Tafet, Toister-Achituv, & Shinitzky, 2001), we demonstrated that cortisol induces an increase in the expression of the gene coding for the serotonin transporter, associated with a subsequent elevation in the uptake of serotonin. This stimulatory effect, produced upon incubation with cortisol in vitro, was observed in peripheral blood lymphocytes from normal subjects. In the present work we investigated the cortisol-induced increase in serotonin uptake in lymphocytes from hypercortisolemic patients, including subjects with major depressive disorder (n = 8), and subjects with generalized anxiety disorder (n = 12), in comparison with a control group of normal healthy subjects (n = 8). A significant increase in serotonin uptake (+37% + 14, M + SD) was observed in the control group, whereas neither the generalized anxiety disorder nor the major depression group exhibited changes in serotonin uptake upon incubation with cortisol. It is likely that under chronic stress or depression, the capacity for increase in serotonin transporter has reached its limit due to the chronically elevated blood cortisol level.

http://www.ncbi.nlm.nih.gov/pubmed/12467090


Connie’s comments: A stressed baby can lead to personality disorder in adulthood. Nurture prevents many personality disorders.

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