Evolution of negative and positive SP shifts in cats learning RT tasks

Cortical slow potential (SP) shifts were recorded in freely moving cats while they learned reaction time tasks differing in the duration of the inter-stimulus interval (ISI). ISI durations were either 6 or 4 sec in experiment I; in experiment II, a reaction time paradigm with a 1 sec ISI was compared to a time estimation task. SP shifts of opposite polarity development throughout the experiments. It seems that: (1) positive SP shifts reflect motor processes and mechanisms of proprioceptive feedback related to the cat's preparatory movements for pressing the lever; (2) negative-going shifts peaking at the end of the ISI reflect temporal information processing related to ISI duration. Analogies with potentials found in man and animals in similar paradigms are discussed.