ANALOGICAL TRANSFER IS EFFECTIVE IN A SERIAL REACTION-TIME-TASK IN PARKINSONS-DISEASE - EVIDENCE FOR A DISSOCIABLE FORM OF SEQUENCE LEARNING

Several studies of procedural learning in Parkinson's disease (PD) hav e demonstrated that these patients are impaired with respect to age-ma tched control subjects. In order to examine more closely the specific impairment, we considered three dimensions along which a procedural le arning task could vary. These are: (1) implicit vs explicit learning, (2) instance vs rule learning, and (3) learning with internal vs exter nal error correction. We consider two hypotheses that could explain th e impairments observed in PD for different types of explicit motor lea rning: (H1) an impairment related to the acquisition of rules vs speci fic instances, and (H2) an impairment in learning when no explicit err or feedback is provided. In order to examine the condition of rule lea rning with external error feedback, we developed a modified version of the serial reaction time (SRT) protocol that tests analogical transfe r in sequence learning (ATSL). Reaction times are measured for respons es to visual stimuli that appear in several different repeating sequen ces. While these isomorphic sequences are different, they share a comm on rule. Verbatim learning of a sequence would result in negative tran sfer from one sequence to a different one, while rule learning would r esult in positive transfer. Parkinson's patients and age-matched contr ols demonstrate significant acquisition and positive transfer of the r ule between sequences. Our results demonstrate that PD patients are ca pable of learning and transferring rule or schema-based representation s in an explicit learning format, and that this form of learning may b e functionally distinct from learning mechanisms that rely on represen tations of the verbatim or statistical structure of sequences. Copyrig ht (C) 1996 Elsevier Science Ltd.