Stephen B. Fountain’s research while affiliated with Kent State University and other places

Kundey and Fountain (2011) explored the impact of irrelevant relations on rat serial pattern learning in a circular array. Rats pressed levers according to the same hierarchically-structured serial pattern interleaved with repeating responses on either lever 2, 6, or 8: 122232–223242–324252–425262–526272 (Beginning), 162636–263646–364656–465666–566676 (End), or 182838–283848–384858–485868–586878 (No Irrelevant Relations), where digits indicated the clockwise position of the correct lever. The results indicated that the inclusion of irrelevant relations retarded rats’ learning regardless of their placement within the pattern. Here, we explored the effect of irrelevant relations on performance after a pattern was well learned. In Phase 1, rats learned an interleaved pattern that either did or did not contain irrelevant relations. Subsequently, the interleaved pattern learned in Phase 1 was extended and whether the extension contained irrelevant relations was varied. The results indicated that if the initial pattern was induced in Phase 1 without irrelevant relations, the later inclusion of irrelevant relations when the pattern was extended to double the initial length in Phase 2 was not impairing. However, if irrelevant relations were encountered in Phase 1, performance was disrupted when the pattern was extended. This accords with a similar finding in humans by Hersh (1974), highlighting another similarity of rats’ and humans’ pattern learning and production.

Recombinant DNA technology has facilitated animal models that could be used to investigate candidate gene contributions to acquisition and retention. In practice, researchers focus on genetics or simple behaviors, rarely combining both or investigating genetic contributions to complex behaviors. We investigated inbred C57BL/6 and outbred CF1 mice’s ability to perform single-alternation and double-alternation patterns. C57BL/6 mice performed better, especially on double-alternation patterns. We also observed sex differences in the inbred C57BL/6 strain for the double alternation pattern. This suggests paradigms for investigating complex behaviors can be useful in uncovering strain differences and contributions of candidate genes to learning, retention, and performance.

Many organisms show aptitude for learning and performing patterned sequences. However, we do not yet have a complete account of how they accomplish this. One of the most successful is Restle’s hierarchical model, which supposes organisms represent sequences using the simplest form available through using hierarchies to organize the sequences’ elements. In two experiments, we evaluated if Restle’s model accurately accounted for rats’ patterned sequence learning. First, we compared rats’ learning of a runs pattern with three levels of hierarchical organization with no violations of pattern structure to learning of the same pattern with one violation of pattern structure in the pattern’s second half. Restle’s model predicts rats should have more difficulty learning the violation pattern and that rats learning the pattern with the violation in the second half of the pattern should attempt to reflect that violation to the first half. The results indicated that rats had more difficulty learning the violation pattern and that inserting a violation in the second half of the pattern led rats to make significantly more errors on the second half of the pattern relative to the first half of the pattern. Rats did not insert the violation from the second half of the pattern into the first half of the pattern. In a second experiment, we continued to explore if Restle’s model accurately accounted for rats’ pattern learning using more complex patterns. The present results of both experiments and prior work with humans were inconsistent with Restle’s model, suggesting more work is needed to develop a model that accurately accounts for rats’ learning of complex patterned sequences.

The neural, behavioral, and cognitive processes that convert experiences into neural and cognitive representations of experiences in sensation, perception, conditioning, memory, anticipation, problem solving, language, and related cognitive systems.

Chunking has traditionally referred to cognitive processes that recode multiple separate stimulus events into groups in memory. Chunking has also been referred to as cognitive “recoding,” “grouping,” “sorting,” or “parsing” (e.g., Bower & Springston, 1970; Bower & Winzenz, 1969; Capaldi, Nawrocki, Miller, & Verry, 1986; Fountain & Annau, 1984; Pribram & Tubbs, 1967). Chunking is considered a fundamental process in cognition because it increases memory capacity and efficiency. The idea of chunking was first proposed by Miller (1956) to explain characteristics of human learning, memory, and speech phenomena from a cognitive perspective. Chunking has since been studied widely in a variety of other species by research in the field of comparative cognition (Capaldi et al., 1986; Fountain & Annau, 1984; Hulse, 1978; Hulse, Takeuchi, & Braaten, 1992; Suge & Okanoya, 2010; Terrace, 1987, 1991; Terrace & Chen, 1991a, 1991b).

Numerous investigators have examined the hypothesis that males and females learn or perform differentially on various tasks. However, many of the behavioural investigations with nonhuman animals (e.g., rats) have used paradigms that do not permit the exploration of complex learning and memory between the sexes. To this end, we explored the ability of male versus female mice to learn three different patterns in succession in three separate experiments: single alternation (e.g., right, left, right, left), double alternation (e.g., right, right, left, left), and runs (e.g., 123, 234, 345, 456, 567, 678, 781, 812, where digits represent locations within a circular array in the counterclockwise direction). We hypothesized that sex differences, if they existed, would be most likely to appear as the pattern to be learned became more complex (required more rules to capture how elements relate to one another). The results indicated that mice can learn all three pattern types, but learning was more difficult as pattern complexity increased. Males learned the runs pattern significantly more quickly than females did; no significant differences were found between males and females for acquisition of the single-alternation or double-alternation patterns. These results suggest that sex differences in serial pattern learning within rodents are not unique to rats and are more likely to be seen during acquisition of more complex patterns.

The effects of chronic adolescent fluoxetine (FLX, Prozac®) exposure on adult cognition are largely unknown. We used a serial multiple choice (SMC) task to characterize the effects of adolescent FLX exposure on rat serial pattern learning in adulthood. Male rats were exposed to either 1.0, 2.0, or 4.0 mg/kg/day FLX for five consecutive days each week for five weeks during adolescence, followed by a 35-day drug-free period. As adults, the rats were trained in a task that required them to learn a highly structured sequential pattern of responses in an octagonal chamber for water reinforcement. In a transfer phase, the terminal element of the pattern was replaced by a violation element that was inconsistent with previously learned pattern structure. Results indicated that adolescent FLX exposure caused differential learning deficits for different types of elements in the serial pattern. Adolescent exposure to 1.0 or 4.0 mg/kg/day FLX, but not 2.0 mg/kg/day FLX, impaired chunk-boundary element learning, which is known to be mediated by stimulus-response (S-R) learning. All three doses of FLX impaired violation element learning, which is known to be mediated by multiple-cue learning. FLX did not impair within-chunk element learning, which is known to be mediated by rule-learning mechanisms. The results indicate that adolescent FLX exposure produced multiple cognitive impairments that were detectable in adulthood long after drug exposure ended.