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CCN Brown Bag Series

Wednesday, January 24, 2018,
  • Location: Wilson Hall • 111 21St Ave S • Nashville, TN 37240
  • Room: 115

Ryan Darby, MD

Assistant Professor of Neurology

Vanderbilt University

Disconnection syndromes in brain lesion patients with delusions, criminal behavior, and abnormal free will perception
Neurologists have long hypothesized that the most complex and bizarre symptoms in patients occur not only because of damage to a specific location, but because of dysfunction in connected brain regions, a phenomenon called diaschisis or disconnection syndrome.  We use functional connectivity to study why brain lesions in different locations cause the same bizarre syndromes, hypothesizing that each lesion is functionally connected to the same location or network.  For example, some patients with brain lesions develop Capgras syndromes, the delusional belief that a loved one has been replaced by an identical looking imposter.  It is hypothesized that patients must have two problems: one in familiarity, explaining why a loved one feels unfamiliar, and another deficit in belief monitoring, explaining why this delusional belief is accepted.  We found that lesions causing this syndrome occurred in different locations in the brain, but were all connected to two different brain regions involved in these processes.  We similarly found that patients with criminal behavior had lesions in different locations, but each was connected to regions involved in moral decision-making, and patients with disordered free will perception have lesions in different locations connected to regions involved in agency and volition.  Our approach is a new method for localizing complex behaviors in the brain to specific networks, which can be applied to neuroimaging analysis in healthy subjects and patients with dementia or psychiatric diseases.