CELLULAR CODING PROPERTIES OF GOAL DIRECTED BEHAVIOR IN THE MEDIODORSAL AND INTRALAMINAR NUCLEUS OF THE RAT: COMPARISONS TO PREFRONTAL CORTEX

The mediodorsal (MD) and rostral intralaminar (IL) nuclei of central thalamus interact with prefrontal cortex (PFC) through multiple pathways to control goal directed behavior. The initial purpose of this dissertation was to characterize cellular coding properties of these nuclei in central thalamus using electrophysiological measures in awake, behaving rats performing a dynamic delayed non-match to position (DNMTP) task. Two major aims were developed. The first of these was based on the strong reciprocal connections between central thalamus and PFC. Therefore, the current data was compared to data previously collected in prefrontal cortex (Onos et al., 2015). The second was that despite to evaluate the coding properties of MD and IL to elucidate the differences and similarities of cell types found in each thalamic nuclei. Tetrode arrays were implanted and advanced incrementally through MD and IL. A total of 1335 thalamic cells were recorded, 385 (29%) of which were behaviorally correlated (144 in MD and 241 in IL). In general, behaviorally correlated cells fell into one of three broad categories used to define goal-directed behavior (Action, Outcomes, and Action/Outcomes). As expected there was a great deal of overlap in cell types found in central thalamus and PFC as well as many differences. Results suggest that cells within MD are primarily responsible for coding of reinforcement and movement related activity. In addition, cells recorded from IL appear to code for more complex aspects of the task