Neurogenetics in Depth

Neurogenetics in Depth

Neurogenetics – Genetics of the nervous system

Since a brief explanation of this neuroscience branch was outlined in an alternate entry, the present short essay aims at elucidating some topics that researchers in the field look at in the beginning of 21st century. Thus, the purpose of this text is to review the findings made as regards to neurogenetics and social behaviors (prosocial and antisocial), as well as psychopathology.

(Amazingly, a lot of genetic research applicable to human was done on the Drosophila (fruit fly). When one recalls that the human and mouse genomes are 99% alike, this fact comes as less of a surprise).

As stated elsewhere, neuropeptides oxytocin and vasopressin modulate attachment and sociability. Interestingly, Donaldson and Young (2008) suggest that the individual differences in social and prosocial behaviors may have to do with genetic dissimilarities in the expression of these neurochemicals.

Buckholtz & Meyer-Lindenberg (2008) concentrated on the problem of aggression. The authors explain that while the MAOA gene (transcription rules state that gene names ought to be italicized and capitalized throughout) was most often designated as linked to aggression, the results have been inconsistent across studies. In addition, the scientists overcome methodological obstacles and propose a neurobiological model utilizing gene-environment interactive effects and reconciling irregularities in the literature.

Our nervous system reacts to any external action. Photo by Elena

(The human race exhibits tremendous variety in appearance and other traits. By the same token, geneticists explain that alleles can be either recessive, dominant or, seldom, codominant. For example, the allele (one of two – inherited from both parents – variants for a gene) for blue eyes is recessive to that coding for green, hazel and brown eyes, which means that the characteristic has to be inherited from both sides in order to get phenotypically expressed. Along these lines, genotype refers to the complete genetic makeup passed on, while phenotype denotes only those characteristics which actually undergo expression).

The gene versus environment interaction has been made famous with the nature versus nurture debate. Few continue to rely exclusively on one or the other, with the discipline of behavioral neurogenetics taking into account both sides. Furthermore, Reiss & Dant (2003) show how important are neurogenetics in shedding light on neurodevelopmental disorders. In their paper, the coauthors show how neurogetic methods are applied in attempting to understand the gene-brain-behavior associations in the single gene fragile X syndrome.

By and large, the beginning of genetics is traced back to Mendel, thus the term Mendelian genetics. Gregor Johann Mendel was a monk who performed cross-breeding experiments with peas and derived the main laws of genetics. The same principles are used today to explain why if both parents have blue eyes, the offspring will most likely have blue eyes (e.g. because the allele for blue eyes is recessive to brown, hazel and green, both parents will contribute a blue coding allele, since they both inherited a pair from their progenitors).

Genes determine traits such as as this woman’s black hair and dark blue eyes.

But what about neuroscience? What about the brain? Naturally, neuroscientists are highly interested in genetics. Not only because the two fields often interact, such as when a particular allele variant for serotonin production (a neurotransmitter regulating mood) is passed down genetically, but also because such mental properties as intelligence have been documented as having a significant heritability coefficient (often up to 80 percent!). Therefore, it comes as no surprise that the respective contributions from neuroscience and genetics have formed a new, derivative field of neurogenetics – studying the genetics of the nervous system.

References:

• Buckholtz, J. W. & Meyer-Lindenberg, A. (2008). MAOA and the neurogenetic architecture of human aggression. Trends in Neurosciences, 31 (3): 120-9.
• Donaldson, Z. R. & Young, L. J. (2008). Oxytocin, vasopressin, and the neurogenetics of sociality. Science, 322 (November): 900-4.
• Reiss, A. L. & Dant, C. C. (2003). The behavioral neurogenetics of fragile X syndrome: Analyzing gene-brain-behavior relationships in child developmental psychopathologies. Development & Psychopathology, 15: 927-68.

Copyright © 2011 Megan Jorgensen. All rights reserved.