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Rats confronted with the onset of a light gradient display a transient increase in locomotion called theactivity response (AR) and a dark preference (Godsil & Fanselow, 2004). These experiments demonstrate that the magnitude of the AR can be blunted
with Pavlovian fear-conditioning procedures via associative and nonassociative fear. Although manifested in decreased locomotion,
the blunted AR effect was not due to increased freezing or immobility behaviors. Instead, rats displayed reduced rearing and
an increase in a class of behaviors calledstationary activity. These results suggest that the lighting differential supplied by the cue influences the topography of defensive behavior
and reduces the expression of freezing. This procedure provides a means by which to examine learned and unlearned defensive
responses to the same stimulus. 相似文献
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Bright light may be a danger signal for rats because they are more vulnerable to predators in bright environments. We examined
the fear-evoking properties of bright light with a novel open-field procedure that confronts a rat with the sudden onset or
termination of a bright light gradient. The rats did not freeze but exhibited a transient increase in locomotion to light
onset and termination, which we call theactivity response (AR). This finding suggests that the AR is an exploratory response geared at investigating stimulus change. The rats also
displayed a preference for dark to the lighting differential that was not due to the novelty or slight heating differential
supplied by the lamps. These experiments demonstrate that the sudden onset of bright light engages preencounter defensive
behavior, as described by the predatory imminence model (Fanselow & Lester, 1988). This task is amenable to studying light-evoked
defensive responses. 相似文献
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