Anatomy and Neurochemistry of Major Psychiatric Illnesses
A longstanding focus of our laboratory is examining how pathways through the amygdala are positioned to mediate symptomatology of severe mental illnesses. Over the last decade, multiple human neuroimaging studies show that amygdala dysfunction—its structure, function, or both—is a component of many psychiatric syndromes. Broadly speaking, this is not surprising since the amygdala has long been known to code the salience of external experience. However, the amygdala participates in many diverse and specific functions including fear conditioning and extinction, safety signaling, recognition of emotion in facial expression, and affective responses to primary rewards and punishments. Many of these functions have seemingly opposing goals, raising the question of whether discrete or similar amygdala subregions or cell groups participate in recognizing safety versus reward, or fear learning and extinction. Moreover, the amygdala is a highly heterogeneous structure whose various nuclei have significant differences in structure and connectivity among animal species. Ongoing studies in our laboratory use nonhuman primate models to identify how input/output pathway through the amygdala converge and segregate in order to understand how various types of emotional coding might take place in the human. Because many psychiatric symptoms are brought about by stressful life experiences, we work n collaboration with other nonhuman primate groups, to examine the molecular and cellular features of specific amygdala circuits and subcircuits that are especially important in stress responses. Our work is important in helping to design and interpret outcomes of human neuroimaging work, and we also work with several groups studying manifestations of psychiatric disease in humans.
A new area of study in our laboratory involves models of stress in adolescent rats. Since circuit formation in the amygdala is ongoing during childhood and adolescence, we have several studies investigating the roles of stress on typical amygdala development, and correlated behavioral outcomes.
We invite you to visit our research projects page to see specific projects ongoing in the laboratory.
A word to undergraduates…
We are getting back to our pre-COVID routines, including undergraduate rotations! See details.
Population activity of VLPFC neurons responsive to conspecific expressions is dictated by the identity of the conspecific.
Congratulations to Dr. Keshov Sharma (defending his thesis April 21, 2022). Working with co-mentor Dr. Liz Romanski, Keshov recorded from Macaque VLPFC as animals viewed 3 facial/vocal ‘expressions’ from 3 different conspecifics. Keshov’s unique ‘fireworks plot’ describes the average state of a 285-neuron population responding to each expression from each conspecific over time. Population responses to conspecific expressions start in a central region (light colors) and migrate outward in space (darker colors), over time. However, they do not do so randomly. As evidenced by paths of the same color (representing the identity of the macaque making the expression that was viewed and heard), population responses to the same identity conspecific tend to migrate in the same direction, regardless of the expression being made. This indicates that the group of neurons responding to expressions in the VLPFC respond similarly to the identity of the conspecific. This happens despite the fact that single neurons in this region are not tuned to identity or expression. These findings advance our knowledge of the social role of the VLPFC by specifying a categorical variable of social stimuli, e.g. identity, that is represented in activity of neurons responsive to expressions of another.