SERIAL PATTERN EXTRAPOLATION IS SPARED DURING A MUSCARINIC CHOLINERGIC CHALLENGE IN RATS

Autor: Miller-Cahill, Megan Elizabeth
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Druh dokumentu: Text
Popis: Rats have the capacity to extrapolate a known sequence of events to anticipate a novel item. We examined whether or not rats can extrapolate a serial pattern during a muscarinic cholinergic challenge. Adult male and female rats learned to nosepoke a sequential pattern of responses in a circular array of 8 receptacles attached one each to the walls of an octagonal chamber. This training pattern consisted of seven 3-element chunks of a rule-based serial pattern, namely, 123-234-345-456-567-678-781. On the day after meeting a high criterion on the training pattern, rats were given i.p. injections of 0.6 mg/kg scopolamine hydrobromide, a muscarinic cholinergic blocker, before encountering patterns consisting of the 7-chunk training pattern plus an added eighth chunk. The added chunk was either consistent with pattern structure (chunk “812”) or contained a terminal element that violated pattern structure (chunk “818”, where the violation element is underlined). Under scopolamine, and even while showing scopolamine-induced impairments of performance throughout the pattern, rats in both groups extrapolated known pattern structure in the novel added chunk, producing approximately 60% rule-consistent “2” responses on the terminal element of both types of chunks. Thus, despite scopolamine exposure, both male and female rats extrapolated well-learned pattern structure to a new chunk. Whereas earlier work showed that muscarinic cholinergic suppression had little effect on rule learning during acquisition of a pattern, the current study demonstrated that intact muscarinic cholinergic neurotransmission is not necessary for extrapolation of a well-learned rule to a novel chunk.
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