Involvement of retrosplenial cortex in forming associations between multiple sensory stimuli.

Abstract

The retrosplenial cortex (RSP) is highly interconnected with medial temporal lobe structures, yet relatively little is known about its specific contributions to learning and memory. One possibility is that RSP is involved in forming associations between multiple sensory stimuli. Indeed, damage to RSP disrupts learning about spatial or contextual cues and also impairs learning about co-occurring conditioned stimuli (CSs). Two experiments were conducted to test this notion more rigorously. In Experiment 1, rats were trained in a serial feature negative discrimination task consisting of reinforced presentations of a tone alone and non-reinforced serial presentations of a light followed by the tone. Thus, in contrast to prior studies, this paradigm involved serial presentation of conditioned stimuli (CS), rather than simultaneous presentation. Rats with damage to RSP failed to acquire the discrimination, indicating that RSP is required for forming associations between sensory stimuli regardless of whether they occur serially or simultaneously. In Experiment 2, a sensory preconditioning task was used to determine if RSP was necessary for forming associations between stimuli even in the absence of reinforcement. During the first phase of this procedure, one auditory stimulus was paired with a light while a second auditory stimulus was presented alone. In the next phase of training, the same light was paired with food. During the final phase of the procedure both auditory stimuli were presented alone during a single session. Control, but not RSP-lesioned rats, exhibited more food cup behavior following presentation of the auditory cue that was previously paired with light compared to the unpaired auditory stimulus, indicating that a stimulus-stimulus association was formed during the first phase of training. These results support the idea that RSP has a fundamental role in forming associations between environmental stimuli.

The retrosplenial cortex is necessary for path integration in the dark

“…This may allow the animal to compensate for motion-dependent error accumulation. This hypothesis is consistent with neuroanatomical and behavioral data that point to a role of the RSC in the integration and association of different types of stimuli, idiothetic and allothetic [16,19]. Accordingly, how to explain why RSC-lesioned rats were not impaired in the light condition?…”

Retrosplenial cortex is required for the retrieval of remote memory for auditory cues

“…Although the RSC has a well-established role in spatial and contextual learning and memory, an emerging literature suggests it also has an important role in processing discrete cues (Gabriel et al 1983;Keene and Bucci 2008b;Robinson et al 2012Robinson et al , 2014. The present experiments extended this work by examining the contribution of the RSC to remote memory retrieval, using a signaled fear conditioning procedure with an auditory cue.…”

“…All rats were trained in a standard fear conditioning task described previously (e.g., Maren et al 1997;Arenos et al 2006;Robinson et al 2012). The training session consisted of three 10-sec presentations of the tone coterminating with the footshock.…”

A novel role for the rat retrosplenial cortex in cognitive control

“…These findings accord with the more general notion that the retrosplenial cortex has a role in switching between representations based on different (Byrne et al 2007;Vann et al 2009). Some additional support for the involvement of the retrosplenial cortex in stimulus evaluation and selection comes from nonspatial tasks; for example, electrolytic retrosplenial cortex lesions disrupt feature-negative discriminations (Keene and Bucci 2008b;Robinson et al 2011), consistent with a role for the retrosplenial cortex in cue competition. Moreover, retrosplenial cortex neurons may encode behaviorally significant cues that predict rewards, or elicit a behavioral response or its omission (e.g., Gabriel et al 1989;Smith et al 2002).…”