Differences in neurophysiological indices of associative learning in alcohol-preferring and nonpreferring rats

Alcohol-preferring (P) and -nonpreferring (NP) rats differ in baseline neur ophysiological measures as well as in their neurophysiological responses to ethanol. In the present study, these lines of rats were assessed to determ ine whether they also differ in their neurophysiological responses during a n associative learning paradigm. Male P and NF rats were implanted with ele ctrodes in the frontal cortex, parietal cortex, and amygdala. Both groups w ere then exposed to an associative learning paradigm. During the first five sessions (conditioning phase), an infrequently presented tone was paired w ith the delivery of a food pellet. A second lone was also presented during these sessions, but this tone was never paired with food pellet presentatio n. During the second five sessions (extinction phase), neither of the tones were paired with food pellet presentation. Event-related potentials (ERPs) in response to the tones were recorded during both phases of the experimen t. During the first session, the latency of the N1 and P3 waves from the co rtical lead in response to the food-paired tone was significantly longer in the NP rats than in P rats. In addition, P rats displayed significant incr eases in the latency of the FZ wave component in the cortex and the P3A wav e component in the amygdala in response to changes in the association betwe en food pellet and tone presentation. These data indicate that the P rats w ere more responsive to changes in the association between food pellet deliv ery and tone presentation. They also suggest more enhanced associative lear ning in P rats than in NP rats. This enhanced learning could be an innate t rail of P rats or the result of altered learning due to differences in anxi ety between P and NP rats.