EYEBLINK CLASSICAL-CONDITIONING IN H M - DELAY AND TRACE PARADIGMS

H.M., a well-known subject with bilateral removal of medial-temporal-l obe structures and profound amnesia, performed eyeblink classical cond itioning (EBCC) for 21 90-trial sessions in the 400-ms delay and 900-m s trace paradigms. A 2nd amnesic subject with temporal lobe lesions an d 2 normal control subjects (NCSs) were also conditioned. Acquisition occurred in both paradigms for all subjects. Acquisition in the delay paradigm was prolonged in H.M. (perhaps because of his cerebellar dege neration in the vermis and hemispheres), but not in the 2nd amnesic su bject. Amnesic subjects and NCSs showed more rapid acquisition in the trace than in the delay paradigm. Two years after initial EBCC, H.M. a ttained learning criterion in the trace paradigm in 1/10th as many tri als. No recollection of the experimenters, apparatus, instructions, or procedure was manifested by H.M. Results suggest that humans can cond ition in the 400-ms delay and 900-ms trace EBCC paradigms with the hip pocampus radically excised.