Lesions of the intermediate medial hyperstriatum ventrale impair sickness-conditioned learning in day-old chicks.
Lesion studies show that the intermediate medial hyperstriatum ventrale (IMHV), a forebrain visual association area in chicks, is involved in learning and memory for one-trial passive avoidance and imprinting. We examined the effects of IMHV lesions in a one-trial, nongustatory, sickness-conditioned learning task. This task is similar to passive avoidance and imprinting because all three tasks require the chick to remember visual cues in order to respond correctly. However, sickness-conditioned learning differs from imprinting and passive avoidance because it uses sickness as the aversive stimulus and there is a longer conditioned stimulus-unconditioned stimulus interval (30-min delay compared to seconds). Bilateral IMHV lesions given 24 h before training impaired the ability of the chicks to avoid a bead associated with sickness produced by lithium chloride injection, as did pretraining unilateral left or right IMHV lesions. Post-training IMHV lesions given 1 h after training did not impair avoidance of the test bead in the sickness-conditioned learning task. However, lesioned chicks showed generalized avoidance of all test beads. The pretraining lesion results are similar to those found in imprinting and passive avoidance learning; however, the effects of unilateral IMHV lesions differed. Post-training lesion effects are similar to those found in passive avoidance learning. We propose that both left and right IMHV are necessary for sickness-conditioned learning and that post-training IMHV lesions impair the ability of the chick to learn or remember the association between the color of the bead and the aversive consequences of LiCl injection.
Barber
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TA
Department of Psychology, Dickinson College, Carlisle, Pennsylvania 17013, USA. barber@dickinson.edu
Howorth
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PD
Klunk
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AM
Cho
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CC
D000367:Age Factors; D000818:Animals; D001245:Association Learning / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D001931:Brain Mapping; D002645:Chickens / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D007173:Imprinting, Psychological / Q000502:physiology; D018021:Lithium Chloride / Q000633:toxicity; D016548:Prosencephalon / Q000502:physiology*; D012153:Retention, Psychology / Q000502:physiology; D013649:Taste / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology
D018021:Lithium Chloride