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1. Defense and the Conditional Reflex
Page 1

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2. Flight, Locomotion and Image Memory
Page 2

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3. Olfactory Familiarity and Imprinting
Page 3

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Neophobia and Object Memory
Page 4

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Learning of "Wildness"
Page 5

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Habituation to Handling
Page 6

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Learning of Visually-Released Boxing
Page 7

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Conclusion
Page 8

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Figure 1
Page 9

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Bibliography
Page 10

We have recently completed a set of studies on the neural mechanisms by which a rat learns to substitute visual stimuli for vibrissal stimuli in the releasing of upright posture and boxing in response to footshock. Although it seems likely that other releasing and directing stimuli may be modified through experience, e. g., the stimuli for ventral rub, flank rub, and full aggressive posture, only in the case of upright posture and boxing has this been securely demonstrated.

The role of learning in visually-released boxing was first demonstrated by Thor and Ghiselli [62]. They showed that animals without prior experience of boxing as a response to footshock were unable to perform the response after anesthesia of the vibrissae and facial hairs. Animals with prior experience, on the other hand, were able to respond despite facial anesthesia. We have shown that this recovery of function is mediated by the visual system, since it is abolished by closure of the eyes.

In our first set of studies [4] we showed that the learned, visually-released boxing was mediated by the visual cortex rather than by the superior colliculus.

In a second set of studies [31] we showed that the ventrobasal thalamus is also necessary for the learned, visually-released boxing. This finding is particularly interesting, because the ventrobasal thalamus is not usually associated with visual behaviors, but is the thalamic relay for tactile sensations. We have interpreted the finding to mean that the visual cortical system, which mediates the learned, visually-released boxing, utilizes the thalamic projection system of tactile sensations in order to replace the disrupted tactile system.

Is the learned aspect of visually-released boxing an example of a more general function of the cerebral cortex? Perhaps it is only one example of the role of the cerebral cortex in synthesizing various afferent systems, as suggested on many occasions by Pavlov, Anokhin, Beritashvili and others. The particular value of the present findings rests in its specificity; we can show that boxing in response to tactile stimuli remains unaffected by the thalamic or cortical lesions, but that the learned behavior in response to visual stimuli is specifically abolished.