Memory systems in the chick: dissociations and neuronal analysis.

Young domestic chicks learn to recognize the visual characteristics of an object to which they are exposed. A restricted part of the forebrain, the intermediate and medial part of the hyperstriatum ventrale (IMHV) is implicated in this process. This form of exposure learning can be dissociated from (i) the ability to learn certain procedures or skills, and (ii) a predisposition to attend to particular types of naturalistic objects. The first of these dissociations is reminiscent of that found in certain human organic amnesias, whilst the second may have its counterpart in the processes involved in face recognition by infants. The right and left IMHV play different roles in the memory that underlies imprinting. The cellular and molecular processes involved in this form of memory are discussed.