Text

theses

It is becoming increasingly clear that the time-dependent involvement of the hippocampus in the recall of acquired behaviors is more complicated than once thought. Several early studies demonstrated that hippocampal damage attenuates the expression of recent, but not remotely trained tasks. By contrast, an emerging body of evidence has shown that damage to, or inactivation of, the hippocampus impairs recall across a wide range of training-testing intervals. Collectively, these data suggest that the time course of hippocampal involvement in the storage or recall of previously-acquired memories differs according to hippocampal subregion and the particular learning task under consideration. The present study examined the contributions of dorsal (DH) and ventral (VH) hippocampus to the expression of previously-acquired trace fear conditioning, a form of Pavlovian conditioning in which the presentation of an initially neutral cue or cues and a subsequent aversive stimulus is separated by a no-stimulus (trace) interval. Specifically, either the GABA-A agonist muscimol or saline was infused into the DH or VH prior to testing 1, 7, 28, or 42 days after trace fear conditioning. The results revealed a marked dissociation: pre-testing inactivation of DH failed to impair performance at any time-point, while pre-testing inactivation of VH impaired performance at all time-points. Importantly, pre-testing inactivation of VH had no effect on the performance during testing of previously-acquired delay conditioning. Collectively, these data suggest that VH, but not DH, remains a neuroanatomical locus critical to the recall or expression of trace fear conditioning over an extended period of time.

ETD_4482

M.S.

Includes bibliographical references

Includes vita

by David Henry Cox

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000067754

doi:10.7282/T3HM574J

ETD graduate

The author owns the copyright to this work.