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Posts Tagged ‘social’

groom

Learning to read emotions and faces is important for our well-being.  For some of us, the act of gazing into another person’s eyes is innately rewarding … especially if they are smiling.  New mothers and their infants can be found locked in each others smiling countenance … thus strengthening the developing neural pathways upon which the infant’s future social skills will grow.

One component of these neural pathways is the CNR1 gene expressed in the striatum and other brain regions that process rewarding and positively-reinforcing stimuli.  For most of us, a happy smiling face is positively rewarding … moreso with certain CNR1 genotypes.

From Drs. Baron-Cohen and Chakrabarti:

“A comparison of these results with those from our earlier fMRI study reveals that for the SNP rs806377, the allelic group (CC) associated with the highest striatal response is also associated with the longest gaze duration for happy faces. For rs806380, the allelic group associated with the highest striatal response (GG) is also associated with the longest gaze duration for happy faces.”

My 23andMe profile shows both the long-gaze CC and GG genotypes for rs806377 and rs806380.  Mmmmkay … I guess this would be a good time to apologize to all the girls I inappropriately stared at in the cafeteria back in college … even though you weren’t usually smiling back at me.  I guess my CNR1 and striatum were pretty overactive.

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rs53576 AA (not GG)

I’m so lonely sometimes, but I never want to go out. I have 2 “A” alleles at rs53576 (link to science).

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Mi iPod con vídeo
Image by juanpol via Flickr

It was a great pleasure to speak with Professor Garet Lahvis from the Department of Behavioral Neuroscience at the Oregon Health and Science University, and learn more about how the biology of empathy and social behaviors in general can be approached with animal models that are suitable for genetic studies.  The podcast is HERE and the post on his lab’s recent paper, “Empathy Is Moderated by Genetic Background in Mice” is HEREThank you again Dr. Lahvis!

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The visual dorsal stream (green) and ventral s...
Image via Wikipedia

One of the longstanding puzzles of brain development is why, in some cases, individuals with developmental disabilities sometimes show enhanced function, rather than a more typical loss of cognitive function.  In the case of Williams Syndrome – which is caused by a hemizygous deletion of a cluster of about 25 genes on 7q11.23 – children show a mild form of mental retardation but also a notable increase in gregarious and social behaviorHow might a genetic deletion lead to a gain of function ? In a recent paper by Sarpal and colleagues [doi:10.1093/cercor/bhn004], they explore the role of the visual cortex and its role in feeding and filtering information to emotional  regions of the brain.

From its receipt of visual information from the eyes – say perhaps, you’re looking at someone’s face, the primary visual cortex parses information into 2 separate streams – a dorsal stream which is good at processing “where” information related to location; and a ventral stream which is good at processing “what”information related to identity and recognition – and moreover, provides inputs to the prefrontal and amygdala (brain regions which are important for social behaviors). What if the genes deleted in Williams Syndrome altered the development of a part of visual cortex that participates in early visual processing to alter the relative balance of dorsal to ventral processing ?  Might it result in a an individual who was better than usual at processing objects (faces) and also showing related emotional traits ? Indeed, this has been a longstanding hypothesis that has since been supported by findings that show relatively intact ventral stream processing but disrupted dorsal stream processing.

In their current paper, Sarpal and colleagues measured brain activity as well as correlations of activity (connectivity) between brain regions as patients with WS passively viewed visual objects (faces and houses).  They report that connections from early visual processing areas (fusiform and parahippocampal gyrus) in WS are actually weaker to the frontal cortex and amygdala.  Since activation of the frontal cortex and amygdala are associated with inhibition and fear, it may be case that the weaker connections from early visual areas to these regions gives rise to the type of gregarious and prosocial (a lack of fear and inhibition) behavior seen in WS.   In further pinpointing where in the brain the genes for WS might be causing a developmental change, the authors point to the ventral lip of the collateral sulcus, an area situated between the fusiform and parahippocampal gyri.  This may be the spot to more closely examine the role of genes such as LIMK1 – a gene that participates in the function of the actin cytoskeleton (an important process in synaptic formation).

This lecture by V.S. Ramachandran covers some of these pathways with respect to Capgras Syndrome.

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