Divya Mathur, PhD – Brain Blogger http://brainblogger.com Health and Science Blog Covering Brain Topics Wed, 30 May 2018 15:00:03 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.6 Female Teachers’ Math Anxiety Negatively Affects Female Students http://brainblogger.com/2010/06/12/female-teachers-math-anxiety-negatively-affects-female-students/ http://brainblogger.com/2010/06/12/female-teachers-math-anxiety-negatively-affects-female-students/#comments Sat, 12 Jun 2010 14:28:36 +0000 http://brainblogger.com/?p=5090 For a long time it was believed that males have better spatial and numerical abilities resulting in their greater aptitude for mathematics compared to females. But research in cognitive development of human infants and children has failed to support these claims. Instead, scientists now have enough evidence to conclude that the same set of biologically based cognitive capacities is responsible for mathematical and scientific reasoning in both the sexes. However, stereotypes that girls and women lack mathematical ability persist and are still widely held by the society. Gender differences in mathematical performance and ability remain a concern as scientists seek to address the under representation of women at the highest levels of mathematics, physical sciences and engineering fields.

Math anxiety is the unpleasant emotional response to mathematics and to the prospect of performing math related skills. More women than men are affected by it. A new study done on elementary school children suggests that a female teacher’s attitude to mathematics affects the performance of her female students. In the study, the more anxious teachers were about math, the lower the math achievement of female students. Moreover, girls who believed in traditional gender ability beliefs such as “boys are good at math and girls are good at reading,” had significantly lower achievement in math at the end of the school year than girls who did not and boys overall. This relationship between the teachers math anxiety and students performance was absent at the beginning of the school year when teachers did not have ample time with the students to affect their performance. It was evident only at the end of the school year. Thus, teachers with high math anxiety specifically affect girls’ math achievement, by influencing girls’ gender-related beliefs about who is good at math. Research suggests that girls are more socially sensitive than boys in early elementary school, thus, it is possible that even with male teachers, a relation between teacher anxiety and female student achievement might occur.

So why are these results important? More than 90% elementary school teachers in the US are females. Similarly, women constitute the majority of elementary school teachers around most the world. Many teachers entrusted with the task of teaching math to young minds suffer from math anxiety.

Undoubtedly, apart from their current teachers’ anxieties, many other reasons, such as, parents, peers, and siblings who either do or do not model traditional academic gender roles may play an important part in shaping girls’ gender ability beliefs and their math achievement more generally. But considering that elementary school plays a major role in determining a child’s personality, the role of a teacher cannot be downplayed. Currently, even those with a propensity to avoid math can become an elementary school teacher.

Training and education can easily reduce math anxiety. If we expect the next generation of elementary school teachers to teach math effectively, more care needs to be taken to develop positive math attitudes in these educators.

References

Beilock SL, Gunderson EA, Ramirez G, & Levine SC (2010). Female teachers’ math anxiety affects girls’ math achievement. Proceedings of the National Academy of Sciences of the United States of America, 107 (5), 1860-3 PMID: 20133834

Hyde JS, Lindberg SM, Linn MC, Ellis AB, & Williams CC (2008). Diversity. Gender similarities characterize math performance. Science (New York, N.Y.), 321 (5888), 494-5 PMID: 18653867

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Societal Assumptions on Abuse and the Victim’s Perspective http://brainblogger.com/2010/05/01/societal-assumptions-on-abuse-and-the-victims-perspective/ http://brainblogger.com/2010/05/01/societal-assumptions-on-abuse-and-the-victims-perspective/#comments Sat, 01 May 2010 12:00:40 +0000 http://brainblogger.com/?p=4894 Sexual abuse of children is morally revolting and a topic wrought with emotions. In the past few decades, awareness of the prevalence of child abuse and its psychological repercussions has increased. A “trauma model” has been built around sexual abuse that perceives it as being directly traumatic and frightening, and necessarily damaging.

Many psychologists now argue that what hurts most victims is not just the actual experience of abuse itself, but the meaning of the experience. How victims make sense of what happened and how these understandings make them feel about themselves and others have more long term psychological consequences.

Victims who were deeply traumatized by their experience are often angry and don’t feel guilty. However, many victims of childhood sexual abuse know and trust their abuser. They do not fully understand what is being done. Many such victims, in retrospect, reported that they did not initially experience the incidents as traumatic, they weren’t terrified; rather they were ‘uncomfortable and confused’. Any suffering they experienced came later, in the form of shame and guilt that they had somehow “consented” or that they did not experience the abuse as a horrifying trauma that the popular theory dictates they were supposed to have felt.

Victims whose experience was different might feel such because their case does not fit into the ‘trauma model’. When such victims mature and develop the capacity to understand their experience, they are confronted with a rhetoric that classifies sexual abuse as typically traumatic and frightening. They may learn to believe that their experience is abnormal and that there is something wrong with them. This may prevent them from seeking treatment, report the crimes, or worse they may believe that they never actually experienced sexual abuse.

Sometimes, well intentioned health professionals, whose interpretations of abusive experiences are more traumatic than actual events and effects, over emphasize abuse’s violence and fear which may differ from the actual experiences that victims might have had.

There is no doubt that using children for sex is an awful crime and it is also true that victims are often traumatized and need help. However, just as we now accept that “one size does not fit all” in treatment regimes, and that there is a need for personalized medicine, perhaps it is also time to accept these differences that different abuse victims might feel. Are we harming victims of abuse more by expecting them to feel traumatized? There is a danger of survivors being hence “victimized” not only by their abusers but also by the industry dedicated to helping them.

This line of thought is very controversial, going against the grain on an issue as sensitive as this may be misinterpreted by many as being insensitive to or complacent about sexual abuse. Everyone will agree that survivors of abuse need sensitivity and by respecting a victim’s personal perception of the incident is only a step towards achieving that goal.

References

Loftus, E., & Frenda, S. (2010). Bad Theories Can Harm Victims Science, 327 (5971), 1329-1330 DOI: 10.1126/science.1187716

Susan A. Clancy. The Trauma Myth: The Truth About the Sexual Abuse of Children – and Its Aftermath. Basic Books, New York, 2010.

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The Neurobiology of Social Anxiety Disorder http://brainblogger.com/2010/04/22/the-neurobiology-of-social-anxiety-disorder/ http://brainblogger.com/2010/04/22/the-neurobiology-of-social-anxiety-disorder/#comments Thu, 22 Apr 2010 12:00:55 +0000 http://brainblogger.com/?p=3738 Shyness is a unique trait and all of us experience it in various degrees when faced with performance situations or new social surroundings. However, many people go through life dreading such encounters and exposure to the feared social situation provokes anxiety, or possibly a panic attack. Social anxiety disorder (SAD) or social phobia is a common anxiety disorder in which individuals shun all forms of interpersonal contact or undergo extreme physical or mental discomfort in social settings. Until recently, this condition was dismissed as ascribing pathology to a normal variant of human personality in order to sell treatments. However, most psychiatrists now believe that social phobia is not a pathological label for shyness. Shyness neither is a prerequisite for nor can be considered as synonymous with social anxiety disorder.

Patients with SAD crave for company but fear social interactions because they are afraid of being ridiculed and perceived as unlikable, stupid or boring. They suffer from low self esteem and SAD is also associated with an increased risk of comorbid conditions such as depression, bipolar disorder and substance abuse.

Clinically it is not difficult to diagnose SAD but its causes are not yet clearly understood. The cortico-limbic and cortico-striatal circuits are composed of the temporal brain structures such as the amygdala, prefrontal cortex, hippocampus, and striatum. They are responsible for a range of cognitive and affective processes regarding attention, memory, judgment and interpretation about self and others. It is believed that in people suffering from SAD, these circuits send distorted assumptions in response to random images of human faces, suggesting a system sensitive not only to harmful stimuli but also to stimuli that are considered affectively neutral. At a molecular level, patients with SAD exhibit increased glutamate content in the anterior cingulate cortex region of the brain along with some striatal dopamine and serotonin abnormalities when compared to healthy controls.

A number of family, twin and high risk studies have shown a pattern of family aggregation for SAD. The risk for first degree relatives of people suffering from generalized SAD is ten times more than for the general population. Several candidate genes have been associated with traits for social phobia such as the serotonin transporter gene and a functional variant of ß-adrenergic receptor (ADRB1) gene. Association analysis has also implicated the gene encoding regulator of G protein signaling 2 (RGS2), although a clear loci has so far eluded scientists.

Presently, the treatment options for SAD include either psychotherapy, medication, or both. Cognitive behavior therapy that aims at changing the thought patterns and physical reactions to anxiety-inducing situations is found to be effective in treating social phobia. The medications mostly prescribed include antidepressants such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs) and monoamine oxidase inhibitors (MAOIs), beta-blockers and benzodiazepines.

SAD has been described as an “illness of lost opportunities.” Few people with social anxiety disorder seek professional help. For most patients suffering in silence, it remains a pervasive disabling condition that prevents them from leading a fuller, richer life.

References

Stein, M., & Stein, D. (2008). Social anxiety disorder The Lancet, 371 (9618), 1115-1125 DOI: 10.1016/S0140-6736(08)60488-2

Stein MB, & Gorman JM (2001). Unmasking social anxiety disorder. Journal of psychiatry & neuroscience : JPN, 26 (3), 185-9 PMID: 11394188

Shields M. Social anxiety disorder–beyond shyness Health Rep. 2004, 15 Suppl:45-61.

Strug, L., Suresh, R., Fyer, A., Talati, A., Adams, P., Li, W., Hodge, S., Gilliam, T., & Weissman, M. (2008). Panic disorder is associated with the serotonin transporter gene (SLC6A4) but not the promoter region (5-HTTLPR) Molecular Psychiatry, 15 (2), 166-176 DOI: 10.1038/mp.2008.79

Smoller, J., Paulus, M., Fagerness, J., Purcell, S., Yamaki, L., Hirshfeld-Becker, D., Biederman, J., Rosenbaum, J., Gelernter, J., & Stein, M. (2008). Influence of RGS2 on Anxiety-Related Temperament, Personality, and Brain Function Archives of General Psychiatry, 65 (3), 298-308 DOI: 10.1001/archgenpsychiatry.2007.48

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Closing the Window of Fear http://brainblogger.com/2010/04/06/closing-the-window-of-fear/ http://brainblogger.com/2010/04/06/closing-the-window-of-fear/#comments Tue, 06 Apr 2010 14:18:15 +0000 http://brainblogger.com/?p=4028 Excessive fear is the cause of many psychopathologies. Although pharmacological interventions can help in preventing the retrieval of fear memories, they are toxic and involve a lot of side-effects. Till now, non-pharmacological interventions were only effective in suppressing the memory of fear for a short period. A new technique developed by scientists at the Center for Neural Science and New York University has generated a lot of interest in the in the field of psychological therapy.

According to a hypothesis called the reconsolidation theory, fear memories are consolidated every time they are recalled. Following an episode of fear stimuli, it’s memory becomes unstable for some time which allows it to be updated. This window period of reconsolidation has provided scientists with a tool to modify it.

Fear extinction is a well established procedure that involves unlearning of fear associated with a stimuli by repeating it in a safe or non-hazardous manner, so that the fear is dissociated with the stimuli. However, this method does not alleviate the phobia permanently as in most cases the fear comes back. Scientists have now discovered that if this extinction training is given in the window period before reconsolidation of fear memory occurs it can be more effective. For humans, this window period was identified as a period of 6 h within the reminder of the fear stimuli.

In a human experiment, 65 volunteers were shown two differently colored squares, one of which was combined with a shock to the wrist.  The volunteers were divided into three groups, based on whether they were re-exposed 6 h or 10 min before the extinction procedure or not re-exposed to the fear stimuli at all. In the group where this extinction procedure was performed without re-exposure or 6 h after the re-exposure to the stimuli, spontaneous recovery of the fear response occurred on the first re-exposure trial. However, the volunteers who were re-exposed to the stimuli 10 min before extinction procedure showed no fear response to it even a year later.

These effects were highly specific to the stimuli. When two different squares paired with a shock were used, the subjects showed a reduced fear response only to the square of which they had been reminded before the extinction procedure. Interfering with the reconsolidation of one stimulus did not affect the memory of another, similar stimulus. Moreover, this therapy does not tamper with the memory in any way. In the experiment, all subjects distinctly remembered the color of the square paired with the shock stimuli, and only the fear response associated with it was gone.

Thus, introduction of a reminder of fear stimuli before extinction therapy results in a long-lasting blockade of the fear memory compared to extinction therapy alone. The importance of this work lies in its non-invasive technique and its non-dependence on drugs in rewriting the fear memories. Since fear extinction is a critical component of nearly all cognitive and behavior therapies, this study is expected to directly translate into improved treatment procedures for post-traumatic stress disorder and other anxiety conditions. Clinical application of this more naturalistic intervention to erase fear memories should be a significant step in psychotherapy.

References

Schiller, D., Monfils, M., Raio, C., Johnson, D., LeDoux, J., & Phelps, E. (2009). Preventing the return of fear in humans using reconsolidation update mechanisms Nature, 463 (7277), 49-53 DOI: 10.1038/nature08637

Schiller, D., Monfils, M., Raio, C., Johnson, D., LeDoux, J., & Phelps, E. (2009). Preventing the return of fear in humans using reconsolidation update mechanisms Nature, 463 (7277), 49-53 DOI: 10.1038/nature08637

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Coping with Trauma – Lessons from Resilient Individuals http://brainblogger.com/2010/01/18/coping-with-trauma-lessons-from-resilient-individuals/ http://brainblogger.com/2010/01/18/coping-with-trauma-lessons-from-resilient-individuals/#comments Mon, 18 Jan 2010 17:17:19 +0000 http://brainblogger.com/?p=3583 Most individuals at some point of their life experience events that are stressful. While some people seem to crumble to the deleterious effects of stress, others sail through adverse situations. Chronic or acute stress is associated with a wide range of psychosocial disorders. So what are the factors and the possible neurobiological mechanisms associated with resilience?

Scientists have found several factors that maybe responsible for adaptive physical and psychological stress responses in individuals in the face of adversity. These adaptive responses are associated with the degree of behavioral control we have over stress. Resilience to stress is mediated by the changes that alter the functioning of the neural circuits that regulate reward, fear, emotion reactivity and social behavior.

The ability to face one’s fears might be facilitated by stress inoculation (exposure to tolerable levels of stress) during development. This early exposure to manageable stressors might be responsible for adaptations that down regulate negative emotions. Resilient individuals are better at down regulating negative emotions, a process known as ‘cognitive reappraisal’, with a resulting reduction in emotional responses. This is mediated through mechanisms that involve memory suppression, memory consolidation and cognitive control of emotion.

During development, a range of factors can offer potentially protective effects from stress. Research has shown that social competence and openness to social support promote resilience in children and adults. Mutual cooperation can activate the brain reward circuits. The capacity of adaptive systems to resist or recover from marked disturbances is more when they are healthy. Rodent studies have demonstrated that a positive, or more enriched, environment during development makes animals less vulnerable to drug abuse and to stress later in life. In particular, studies have shown that proximity to the primary caregiver is an important modulator of a child’s sense of safety when facing trauma. A close relationship with a caring adult and the capacity for self regulation promote resilience. A sense of purpose and an internal framework of beliefs about right and wrong are characteristics of resilient individuals.

Also, positive emotions might contribute to healthier cognitive responses. Moreover, physical exercise, which can be viewed as a form of active coping, has positive effects on mood, attenuates stress responses and is thought to promote neurogenesis.

So can people be trained to become more resilient? Scientists feel certain forms of psychotherapy to enhance optimism, reappraisal of traumatic events in a more positive light, preserving a person’s sense of purpose in the face of trauma can help maximize resilience. Ongoing research of healthy individuals who have recovered from traumatic experiences may further deepen our understanding of this process.

References

Feder, A., Nestler, E., & Charney, D. (2009). Psychobiology and molecular genetics of resilience Nature Reviews Neuroscience, 10 (6), 446-457 DOI: 10.1038/nrn2649

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Sex, Violence and The Male Warrior Hypothesis http://brainblogger.com/2009/12/21/sex-violence-and-the-male-warrior-hypothesis/ http://brainblogger.com/2009/12/21/sex-violence-and-the-male-warrior-hypothesis/#comments Mon, 21 Dec 2009 16:35:49 +0000 http://brainblogger.com/?p=3434 Throughout the history of human civilization, wars have a common feature of being practiced primarily by males. This group aggression by males is a persistent trait of human behavior, seen across different continents among civilizations that have developed independent of each other.

Also, experimental evidence suggests that compared to females, male behavior and psychology is more inclined to aggression. Men are relatively more aggressive in inter-group games and display stronger ingroup loyalty in the presence of an inter-group threat. This idea is referred to by anthropologists as the male-warrior hypothesis. This general hypothesis leads to the prediction that men “have behavioral propensities to engage in male coalitional violence”. This is perhaps a product of a long evolutionary history, in which males who engaged in such behavior produced more genetic descendants than males without such propensities. Male coalitional violence is also exhibited by our closest living relative, the chimpanzee. Such behavioral propensities did not evolve in females of either species.

Since females in all cultures have greater parental investment than males in their offspring, engaging in openly aggressive acts to acquire resources, either individually or as part of a group, will be physiologically and genetically costlier for women. The mother is more critical to the offspring’s survival than is the father. If a mother wants her children to survive, then she must be equally concerned with her own survival. Because of this, it is believed that women would have evolved a psychology in which the costs of physical danger would have been weighted higher than that of a male.

Recognizing that our biological heritage has produced very different behavioral propensities in human males and females, can also lead to a solution of decreasing violence and warfare in modern times. Although the propensity for violence may be genetically programmed into the human brain, it can be controlled through cultural and social means. Behavioral genetics research on violence shows high heritabilities, suggesting that a substantial amount of genetic variance exists in such behavioral propensities within populations of human males.

By empowering women to be leaders in cultural, social, and political spheres, the violent propensities of men can be restrained, and perhaps men can learn to be less violent themselves. Public investment policies should also recognize that men with poor economic prospects have higher incidence of engaging in violence and being recruited into violent extremism.

Although war is a complex subject and a definitive understanding of coalitional violence is still lacking, women’s empowerment and a greater participation of women in the political arena could be the way for a more peaceful world.

References

Kaplan, H. (2009). Sex, War (and Ecology) Science, 326 (5950), 232-233 DOI: 10.1126/science.1176071

Van Vugt, M., De Cremer, D., & Janssen, D. (2007). Gender Differences in Cooperation and Competition: The Male-Warrior Hypothesis Psychological Science, 18 (1), 19-23 DOI: 10.1111/j.1467-9280.2007.01842.x

Campbell, A. (1999). Staying alive: Evolution, culture, and women’s intrasexual aggression Behavioral and Brain Sciences, 22 (02) DOI: 10.1017/S0140525X99001818

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Religion – A “Natural” Phenomenon? http://brainblogger.com/2009/09/25/religion-a-natural-phenomenon/ http://brainblogger.com/2009/09/25/religion-a-natural-phenomenon/#comments Fri, 25 Sep 2009 13:38:25 +0000 http://brainblogger.com/?p=3308 All human societies have some phenomenon that can be described as religion. It is difficult to understand why religion is so pervasive in human culture. Some theories suggest that religion is a byproduct of evolution. However, no other animal group has anything that even remotely resembles the concept that has been labeled as religion in anthropology. Unlike other social animals, humans are very good at establishing and maintaining relations with agents beyond a physical presence. From childhood, humans are capable of forming enduring, stable and important social relationships with fictional characters, imaginary friends and super heroes. Thus, for humans, it is not difficult to imagine a god who is although invisible and intangible, yet somehow involved with them. Religious thoughts are based on tacit assumptions, when people proclaim their loyalty to a particular faith, they subscribe to claims for which there is no evidence. Unlike conscious beliefs, which differ widely from one tradition to another, such tacit assumptions about religious beliefs are very similar across religions.

The regions of the brain engaged in processing religious knowledge can be studied using modern neuroimaging techniques. Experiments were done to determine the psychological components underlying religious belief and evaluate their neural foundations. These studies support the view that there is no specific domain for religion in the human brain. Religiosity is integrated in our cognitive processes and employs the same brain networks used in social and emotional interactions. Religious understanding probably emerged as a unique combination of several evolutionarily important cognitive processes. Humans are naturally inclined to faith due to these traits. Thus, religious thinking seems to be the path of least resistance for our cognitive systems and is a consequence of having a very ‘human’ type of brain.

By contrast, atheism is harder for the human brain to comprehend. Atheism is generally the result of a deliberate effort against our natural cognitive dispositions and is thus a more difficult ideology to propagate. It is therefore not surprising that despite the appeal of logic and rationality that atheism offers, it has few takers.

Perhaps a capacity for religious thinking — and not specifically religion in its present socio-political context — provided fitness benefits to our ancestors during the course of evolution. Religion can evoke very diverse and strong emotions, which can now be experimentally studied. Neuroscience is trying to provide a pragmatic explanation to the complex phenomenon called religion. Religion continues to dominate both the personal and political aspects of our modern society and it is unlikely that any understanding of the foundations of religious belief in humans will undermine the impact of religion in our lives.

References

Boyer, P. (2008). Being human: Religion: Bound to believe? Nature, 455 (7216), 1038-1039 DOI: 10.1038/4551038a

Kapogiannis, D., Barbey, A., Su, M., Zamboni, G., Krueger, F., & Grafman, J. (2009). Cognitive and neural foundations of religious belief Proceedings of the National Academy of Sciences, 106 (12), 4876-4881 DOI: 10.1073/pnas.0811717106

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Effect of Early Life Stress on Behavior and Cognition http://brainblogger.com/2009/09/16/effect-of-early-life-stress-on-behavior-and-cognition/ http://brainblogger.com/2009/09/16/effect-of-early-life-stress-on-behavior-and-cognition/#comments Wed, 16 Sep 2009 12:00:57 +0000 http://brainblogger.com/?p=3183 The human brain undergoes rapid development from late gestation to early childhood. The brain structures that are developing or undergoing age-related changes are more vulnerable to the effects of stress. Trauma at different time points in an individual’s life might be associated with different outcomes, depending on the brain structure that was affected at the time of exposure to adversity.

The hippocampus, the amygdala and the frontal lobes of the brain are responsible for development of cognitive and emotional functions. Repeated exposure to stress triggers the activation of the hypothalamus-pituitary-adrenal (HPA) axis, resulting in production of glucocorticoids by the adrenal gland. Glucocorticoids are essential for normal brain maturation and its receptors are expressed throughout the brain. Skewed levels of glucocorticoid impair maturation and survival of different brain cells. Hence, expression of glucocorticoids can have long lasting effects on the regions of the brain that regulate their release.

Exposure to stress when these regions of the brain undergo changes may result in long time cognitive and behavioral defects. The effects of stress at different periods of life interact and may manifest after an incubation period.

Maternal depression, intrauterine under-growth and low birth weight are indices of prenatal stress. Low socio-economic status, maltreatment, sexual abuse and war are considered adverse events causing postnatal stress.

Negative effects of stress in the prenatal period may manifest during childhood in the form of behavioral, neurological and cognitive disturbances. These developmental disorders include unsocial and inconsiderate behavior, attention deficit hyperactivity disorder (ADHD), sleep disturbances as well as psychiatric disorders like depressive symptoms, excessive amygdala functioning (fear reaction) and mood and anxiety disorders. However, quality postnatal care often moderates these negative effects.

The hippocampus continues to develop till the age of two years, and so it is extremely vulnerable to the effects of chronic stress. It has been clearly demonstrated that in children who were physically healthy at birth, severe abuse in the early years of life is associated with reduced brain volume. This reduction in volume decreases with increasing age of onset and increases with increased duration of the maltreatment. Children suffering from long hours of neglect are at higher risk of behavioral problems such as novelty-seeking, addictive behaviors and chronic depression later in life.

The frontal cortex undergoes major development during adolescence. Adolescents exposed to early postnatal stress are at a higher risk of developing depression. Also stress during adolescence may result in various psychopathologies such as anxiety and depression.

In adulthood and old age the brain regions that undergo the most rapid decline as a result of aging are highly vulnerable to the effects of stress hormones. Higher stress results in increased glucocorticoid levels. This in turn affects the frontal lobe and hippocampal volume negatively resulting in cognitive impairments.

This research reiterates the importance of rehabilitation of children affected by war, strife and abuse. Better monitoring of state care or orphanages is also needed. Moreover, we require stricter social policies aimed at protecting the most vulnerable section of the society — the children — in the family home from the long term deleterious effects of stress on brain, behavior and cognition.

References

Lupien, S., McEwen, B., Gunnar, M., & Heim, C. (2009). Effects of stress throughout the lifespan on the brain, behaviour and cognition Nature Reviews Neuroscience, 10 (6), 434-445 DOI: 10.1038/nrn2639

McGowan, P., Sasaki, A., D’Alessio, A., Dymov, S., Labonté, B., Szyf, M., Turecki, G., & Meaney, M. (2009). Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse Nature Neuroscience, 12 (3), 342-348 DOI: 10.1038/nn.2270

Charmandari, E., Kino, T., Souvatzoglou, E., & Chrousos, G. (2003). Pediatric Stress: Hormonal Mediators and Human Development Hormone Research, 59 (4), 161-179 DOI: 10.1159/000069325

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The Genetics of Alcoholism http://brainblogger.com/2009/08/02/the-genetics-of-alcoholism/ http://brainblogger.com/2009/08/02/the-genetics-of-alcoholism/#comments Sun, 02 Aug 2009 13:00:50 +0000 http://brainblogger.com/?p=2988 Alcohol consumption is probably as old as human civilization, and so is its abuse. The social and physiological ill effects of alcoholism are well known. What is less clear is why certain individuals are more predisposed to it. Alcohol addiction is a multifactorial phenomenon where personality traits, individual and social influences interact with neurobiology, creating varied clinical results and manifestations. The effect of alcohol on the central nervous system has been established but the exact mechanisms of action remain obscure. Alcoholism has different facets, from habitual intake, to problematic abuse, to addiction resulting in severe physiological damage.

Research now supports the idea that along with other social factors, genetics has an important and critical contribution in the progression of alcoholism.

The comparison of monozygotic and dizygotic twins in different studies has shown a significant correlation between hereditary and alcohol abuse. Children of alcoholic biological parents who were adopted at birth develop alcohol addiction more frequently compared to adopted children with no alcoholic parent. There is a lower genetic risk for alcohol dependence among women.

Candidate gene studies have implicated the genes encoding alcohol metabolising enzymes in the liver like alcohol dehydrogenase (ADH), the microsomal oxidation system (MEOS) and the aldehyde dehydrogenase (ALDH) in the development of alcohol addiction. Genetic studies conducted in various ethnic groups have confirmed that certain allele variations of ADH and ALDH are linked either in development of or in protection from alcohol addiction through a mechanism that is not yet known. The alleles influence the various alcohol addiction syndromes, such as tolerance, sensitivity and dependence. In addition to these genes, neurotransmitter genes have been associated with increased risk for alcohol dependence. Alcohol modifies the neurochemical milieu and acts on many different neuroreceptors although there is no known receptor for alcohol in the brain.

Although the theory that a distinct type of personality leads to alcohol dependency has been rejected, some traits such as low self-esteem and antisocial behavior have been found to be positively correlated to alcoholism. Social modeling and conditioning seem to be significant psychological factors in the development of alcohol addiction. Thus, a complex web of genetic and environmental factors contributes to alcoholism.

Alcoholism is a major economic burden and public health issue. Delineating the genetic components can not only offer information about the risk factors, but also form the theoretical basis for development of therapeutic and educative regimes for its prevention.

References

Moussas, G., Christodoulou, C., & Douzenis, A. (2009). A short review on the aetiology and pathophysiology of alcoholism Annals of General Psychiatry, 8 (1) DOI: 10.1186/1744-859X-8-10

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I Can Read Your Mind! http://brainblogger.com/2009/07/12/i-can-read-your-mind/ http://brainblogger.com/2009/07/12/i-can-read-your-mind/#comments Sun, 12 Jul 2009 20:03:31 +0000 http://brainblogger.com/?p=3037 Neuroscience and Neurology CategoryMind reading or delving into a person’s conscious experience is a concept only science fiction consists of. Though it sounds improbable, recent strides in neuroimaging have made it a reality, at least partially.

Visual stimuli are captured through the eyes and relayed into the brain for perception. Decoding this process involves a systemic mapping between the visual stimuli and brain activity. Scientists have previously used brain activity patterns from functional magnetic resonance imaging (fMRI) technique for reconstruction of images as perceived by the cortex of the brain. The signals were reconstructed through a decoder ‘trained’ by feeding patterns of known images. But, the resolution and accuracy of the reconstructed images was low.

SeeA new method uses sophisticated decoding techniques to improve the quality and scope of the reconstructed images. For the experiment, artificial images, defined entirely by differences in local contrast were used as visual stimulus and presented to experimental subjects while fMRI signals were simultaneously recorded from V1, V2 and V3 areas of the cortex known as the early visual areas. Images were decoded using complicated overlapping regions and multiple scales. Relevant neural signals were automatically identified through the information represented in correlated activity patterns rather than mere use of known functional anatomy. By using this new method for brain decoding, researchers were able to reconstruct a large variety of images using only several hundred random images to train the reconstruction model. Also, almost 100% correct identification of images was achieved which is an impressive improvement from earlier methods.

As of now, none of the published research work claims reconstruction of natural images seen outside the laboratory in our daily life. This is difficult as we have only a rudimentary knowledge of how the higher visual areas of the cortex function.

This generalized procedure can be extended to deal with more complex perceptions consisting of numerous possible states by using multiple decoders. If a perceptual state can be expressed by a combination of elemental features, a modular decoder can be trained for each feature with a small number of data and their combination can accurately predict previously undetermined and novel perceptions.

Brain decoding has many potential applications and can also be used to decode olfactory, motor and sensory stimuli. Thus, a prosthetic device can be controlled by using signals from the motor cortex. It can be further extended to other mental states such as lie detection and even visualization of dreams. Though still in its infancy, this research direction raises uncomfortable questions about ethical issues concerning the privacy of human thought.

References

Kay K, & Gallant J (2009). I can see what you see Nature Neuroscience, 12 (3) DOI: 10.1038/nn0309-245

MIYAWAKI, Y., UCHIDA, H., YAMASHITA, O., SATO, M., MORITO, Y., TANABE, H., SADATO, N., & KAMITANI, Y. (2008). Visual Image Reconstruction from Human Brain Activity using a Combination of Multiscale Local Image Decoders Neuron, 60 (5), 915-929 DOI: 10.1016/j.neuron.2008.11.004

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