“Physiological and Genetic Substrates of Long-Term Habituation”
Robert Calin-Jageman, Dominican University, River Forest, IL 60305

Learning produces long-term changes in behavior, physiology, and gene expression. Although this principle is now well-documented across the animal kingdom, fundamental aspects of learning and memory remain unclear: 1) how physiological and genetic changes supporting long-term memory are integrated across a neural circuit. 2) if forgetting represents the decay of long-term memory processes or an active erasure process, and 3) how individual differences in memory acquisition and retention arise. To address these fundamental issues in learning and memory, we propose a simple set of experiments using long-term habituation of the Aplysia tail-elicited siphon-withdrawal reflex (T-SWR).

Groups of animals will be exposed to long-term habituation training (5 blocks of 30 stimuli applied to one side of the tail, 30s ISI, 90 min between blocks). This training produces a long-lasting and unilateral decrease in T-SWR behavior. To determine the physiological correlates of LTH, trained animals will be anesthetized and reduced to a siphon+tail preparation, enabling physiological recordings from the T-SWR circuit during ongoing behavior. By comparing tail-evoked neural activity from the trained and untrained side of each animal, it will be possible to identify sites of long-term neural plasticity elicited by LTH training. After physiological recordings, sensory and motor neurons from the trained and untrained sides of the T-SWR circuit will be physically isolated. To determine the molecular correlates of LTH, RNA from harvested cells will be extracted, reverse-transcribed, and profiled using microarrays. By repeating this same procedure with animals harvested 1, 7, and 21 days after training, it will be possible to determine physiological and genetic correlates of a memory that is strong (1 day), weak (7 days), and completely decayed (21 days). Individual differences will be examined by exploring for physiological and molecular measures that correlate across time with behavioral LTH measures. Thus, by integrating multiple methodologies, this research will identify a) the initial genetic and physiological responses to LTH training, b) the subsequent changes that occur as LTH fades, and c) the individual genetic and physiological differences that predict LTH acquisition and retention.

Robert Calin-Jageman, Ph.D.
Assistant Professor of Psychology
Dominican University
7900 West Division Street
River Forest, IL 60305
Phone: (708) 524-6581
FAX: (708) 524-5990
Email: rcalinjageman@dom.edu