NEURAL CELL-ADHESION MOLECULES, LEARNING, AND MEMORY IN THE DOMESTIC CHICK

The intermediate and medial hyperstriatum ventrale (IMHV) of the chick forebrain is a site of recognition memory for the learning process of imprinting. The results reported here demonstrate that neural cell ad hesion molecules (NCAMs) play a time-dependent role in this recognitio n memory. Dark-reared chicks were trained, tested, and assigned a pref erence score as a measure of learning. Chicks with high preference sco res were designated good learners and those with lower preference scor es, poor learners. Controls were untrained. Tissue was removed, 9.5 hr or 24 hr after training, from the left and right IMHV, hyperstriatum accessorium, and posterior neostriatum. Three major NCAM isoforms (180 , 140, and 120 kDa) were assayed. At 24 hr only, there was in left IMH V significantly more NCAM (for each isoform) in good learners than in the other 2 groups, and also a significant correlation between the amo unts of NCAM and preference scores for all isoforms; the amount predic ted by each regression line at preference score 50 (no learning) did n ot differ significantly from the mean value for untrained controls. Th ere were no learning-related effects in either the hyperstriatum acces sorium or the posterior neostriatum.