Cognition – Fear Conditioning
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Fear conditioning provides a measure of memory by assessing a memory for the association between an aversive stimulus such as a mild foot shock and a salient environmental cue. The environmental cue is either a discrete stimulus such as a tone (‘cue’) or the test chamber (‘context’). In the fear conditioning test, freezing behavior which is a characteristic fear response in rodents (defined as the complete lack of movement) provides a readout of memory. Animals that show good memory freeze upon re-presentation of the context (contextual fear conditioning) or the tone (cued fear conditioning). Contextual fear conditioning is dependent upon the integrity of the hippocampus while cued fear conditioning is dependent upon the integrity of the basolateral amygdala and also, under certain parameters, the hippocampus.
Contextual fear conditioning in mice: Aged mice (18 months) were treated sub-chronically with either rolipram or vehicle. Mice were tested for contextual fear conditioning 24 hours after the training session. Rolipram-treated mice exhibited significantly higher freezing behavior compared to vehicle-treated mice, indicating enhanced learning and memory.
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Contextual fear conditioning in rats: Galantamine-treated rats exhibited significantly higher freezing behavior compared to vehicle-treated rats upon re-exposure to the training context, suggesting enhanced learning and memory. Asterisks (p<0.05) indicate a significant difference compared to saline.
Cued fear conditioning in rats: Galantamine-treated rats exhibited significantly higher freezing behavior compared to vehicle-treated rats upon re-exposure to the cue in the novel context, suggesting enhanced learning and memory. Asterisks (p<0.05) indicate a significant difference compared to saline.
Contextual fear conditioning in R6/2 mouse, a model of Huntington disease: R6/2 mice with 240 CAG repeats, showed significantly decreased freezing upon re-exposure to the cue in the novel context, indicating a memory deficit in these mice compared to wild-type controls.
