Previous research has indicated that the amygdala exerts a modulatory influence on
multiple memory systems. Evidence also indicates that emotional state can influence the
use of multiple memory systems and that this effect is mediated by the amygdala.
Anxiogenic drugs administered during acquisition in a task that can be acquired either
through hippocampus-dependent âÂÂplaceâ learning or caudate dependent âÂÂresponseâÂÂ
learning, resulted in the predominant use of response learning. It is not known whether
inducing anxiety at other behavioral time points will also influence the relative use of
multiple memory systems. In experiment 1, male Long-Evans rats were trained to swim
from the same start point to an escape platform constantly located in a goal arm. Prior to
memory retrieval rats were administered either alpha- two adrenoceptor antagonist RS
79948-197, peripherally (0.03, 0.01, 0.3 mg/kg) or into the basolateral amygdala (0.1 õg),
or saline vehicle. Rats treated with RS 79948-197 prior to memory retrieval exhibited
caudate-dependent response learning.
Previous studies examining the effects of RS 77948-197 on memory were conducted
with rats trained in an anxiogenic state and subsequently probed in a drug free state.
Experiment 2 examined whether state dependency may account for those results.
Animals received peripheral (0.1 mg/kg) or intra-amygdala (0.1 õg) administration of RS 79948-197, prior to both acquisition and memory retrieval. Rats treated with RS 79948-
197 predominantly exhibited response learning.
Finally, experiments 3 and 4 examined whether the use of response learning
produced by RS79948-197 was due to the impairing effect on hippocampus-dependent
memory. Rats that were administered peripheral (0.03 mg/kg) or intra-amygdala (0.1 õg)
injections of RS 79948-197 displayed impaired acquisition of the single solution place
task relative to control animals. This indicates that place learning was impaired.
Over, all the present findings indicate 1) peripheral and intra-amygdala anxiogenic drug
administration results in the use of habit memory at both acquisition and retrieval, 2)
state dependency does not play a role in the influence of RS 799948-197 on memory
system use, 3) the use of response learning produced by peripheral and intra-amygdala
injections of RS 79948-197 may result from an impairing effect of hippocampusdependent
memory.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4302 |
| Date | 30 October 2006 |
| Creators | Elliott, Audrea Elizabeth |
| Contributors | Packard, Mark G. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 347846 bytes, electronic, application/pdf, born digital |
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