ISSN:
1432-1106
Keywords:
Sensory transmission
;
Lateral geniculate nucleus
;
Visual cortex
;
Attentive behaviour
;
Vigilance
;
Cat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The behaviour of 6 cats was studied in a vigilance task. Each cat was trained to press a pedal on the floor of a training box. A waiting interval of fixed (FI) or variable (VI) duration then followed, after which a stimulus (S), a spot of light or a tone, was presented for a short period of time. The cat gave a correct response if, during this time, it pressed a panel. The animal was then rewarded with food. When an experiment had been completed using one S the cat was trained to respond to the other. The latency of response following the onset of S was measured for each waiting interval in the VI schedules. It was found that the longer latencies were associated with the shorter waiting intervals; that is, the cats responded more quickly to S as expectancy increased. Between the time the pedal and pand were pressed the optic tract (OT) was shocked not more than once and the response of the LGN and visual cortex recorded. The time at which the shock was delivered varied from 1 trial to the next. The responsiveness of the LGN and visual cortex did not vary during the waiting interval in either of the FI schedules or in the VI schedule in which S was a spot of light. However, in the VI schedule in which S was a tone, the responsiveness of the visual cortex to the thalamocortical input declined as the length of the waiting interval increased. No changes were observed at the LGN or in the presynaptic cortical response. These results contrast with those observed during changes in the level of arousal as assessed by the ECoG. When the ECoG passed from the synchronised to the desynchronised state there was an increase in the amplitude of the postsynaptic LGN response to the OT shock, but no change in the responsiveness of the cortex to the increased thalamocortical input. These changes in transmission in the visual pathways are discussed in relationship to the animal's behaviour and to the inferred state of attention.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234258
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