Attentional and learning mechanisms of suppressing behaviourally-irrelevant information in rats

Clara W. Y. Siu, Eve De Rosa

Abstract


Selective attention is the ability to focus on behaviourally-relevant information while suppressing behaviourally-irrelevant information. It has been demonstrated in humans that attention to previously-irrelevant information becomes impaired through both inhibitory attentional processes and learning; this phenomenon is termed ‘learning-to-ignore’. When such attentional suppression to an ignored stimulus occurs across different learning contexts, generalization occurs, resulting in a sustained impairment in subsequently attending to the previously-ignored stimulus. In the present study, acquisition of attentional suppression was translated from the human paradigm to one for rats, to assess whether this inhibitory attentional process in humans is also present in these rodents. If so, then future studies will examine the neural underpinnings for this ability. Twenty Long-Evans rats were trained to associate one of two visual cues simultaneously presented on monitors in touchscreen-equipped operant chambers, such that one cue was ignored or unattended over numerous trials. There were three learning phases: two priming phases and then a test or probe phase. Four experimental conditions were used to assess either stimulus or response inhibition: Learning to Ignore – one context (LI1) and Learning to Ignore – two contexts (LI2) examined the inhibition of an ignored stimulus, while Response Reversal (RR) and Proactive Interference (PI) assessed the inhibition of a prepotent response. The study found that it was significantly more difficult to surmount the suppression of a previously-ignored stimulus (LI1 and LI2) than to surmount a prepotent response (PI). However, in rats, it was also found to be most difficult to successfully surmount both an ignored stimulus and prepotent response (RR). This was a condition that was not included in the previous human work. Therefore, the current study provides evidence that rats utilize similar attentional and learning mechanisms as humans in the learning-to-ignore phenomenon.

Keywords


selective attention; learning to ignore; attention suppression; inhibition; human paradigm; rat; aging; cognitive decline; cognitive impairment; acetylcholine; neocortex

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