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Biomedical subjects

F Macar

Publications and source records attributed to F Macar.

24 records · Page 2Linked to original sources
PubMed1980

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.

Animals↗
PubMed1979

Contingent negative variation and accuracy of time estimation: a study on cats.

Slow cortical potential shifts, similar to the contingent negative variation (CNV) discovered in man, were analysed in cats submitted to a schedule of temporal conditioning. Two situations were compared, according to information delivered during a 7 sec delay: in the first (A), a fixed visual signal appeared on an oscilloscope screen; in the second (B), the signal moved across with time. In both cases, the cat had to press a lever 5-7 sec after signal onset. The CNV recorded during the delay had different amplitudes according to the cortical site involved. It could be dissociated into two components, which showed similar evolutions as a function of experimental conditions. The characteristics of the CNV as a whole varied with temporal parameters. CNV amplitude and time course were related to the accuracy of the cat's responses; prolonged training in unchanged experimental conditions led to a decline in negativity, which seemed to reflect automation of time estimation processes. These data suggest that CNV may be an index of a phase of information processing aimed at constituting internal time bases congruent with a particular situation.

Animals↗