Fitz NF, Gibbs RB, Johnson DA (2006) The role of septo-hippocampal cholinergic lesion, place versus response strategy, and acquisition of a delayed matching to position T-maze task. Neuroscience 2006 Abstracts 751.20. Society for Neuroscience, Atlanta, GA.
Summary: Previously we showed that loss of cholinergic input to the hippocampus results in a significant impairment in acquisition of a delayed matching-to-position T-maze task. Further studies suggest that rats adopt different strategies during different stages of acquisition, initially using a response-type strategy or side preference strategy (independent of external cues) and then switching to a more efficient place strategy (reliant on external cues). We hypothesized that animals with lesions of hippocampal cholinergic inputs would have difficulty shifting to a place strategy, resulting in more days using a response-type strategy, and resulting in the deficit in acquisition. Male Sprague-Dawley rats received intraseptal infusions of either artificial cerebrospinal fluid (CSF) or the selective cholinergic immunotoxin, 192 IgG-saporin (SAP; 0.2 μg in 1.0 μl) into the medial septum (MS). Following recovery from surgery, animals were trained in a DMP T-maze task that consisted of learning to return to an arm of the maze that had been explored during a previous trial. Typically, in both treatment groups, rats would initially adopt a strategy of selecting an arm that resulted in a consistent turn (left or right), which was independent of external cues (response-type strategy). Later in training, the animals adopted a strategy that required a turn that was dependent on external cues (place strategy). Compared to controls, SAP animals had a loss of hippocampal cholinergic innervation and an increase in the number of days to reach criterion (21.7 ± 1.6 days vs. 15.9±0.5 days, p < 0.05). For the SAP group, the increased days to criterion was due to a significant increase in the number of days animals used the response-type strategy (14.8 ± 1.8 days vs. 8.1 ± 1.7 days, p < 0.05). There was no significant difference between groups in the number of days animals utilized the place strategy. These data are consistent with the hypothesis that the cause of the learning impairment on the DMP task observed following cholinergic deafferentation of the hippocampus is due to an impairment in the ability to shift from a response-type strategy to a place strategy.
Related Products: 192-IgG-SAP (Cat. #IT-01)