Perirhinal cortex involvement in allocentric spatial learning in the rat: Evidence from doubly marked tasks

Abstract

It has recently been suggested that the different cortices of the medial temporal lobe support a mixture of object and spatial processing functions, challenging the anterior model that emphasized a strict functional differentiation between regions. However, for some structures, the perirhinal cortex (Prh) for example, a number of studies using lesion methods have shown a profound deficit exclusively in tasks involving object learning but not allocentric spatial learning. It may be that the learning paradigms used in previous studies have not been sensitive enough to detect a possible allocentric deficit in Prh-lesioned animals. To examine whether Prh lesions critically affect allocentric spatial learning, experimental and control rats were trained in two doubly marked navigation tasks. In experiment 1, the use of either one of two different memory systems, allocentric versus egocentric, made it possible to locate the goal arm in a four-arm radial maze. In experiment 2, rats had to choose between an allocentric versus a S-R/habit strategy, both of which predicted the location of the goal arm. Results showed that both experimental and control animals learned both navigation tasks well, reaching the same level of performance at the end of training. However, a probe test performed 1 day after the learning ended revealed that Prh-damaged animals learned both tasks predominantly using a non-allocentric strategy. Specifically, in lesioned subjects the percentage of egocentric correct responses (experiment 1) and the percentage of habit-based correct responses (experiment 2) was significantly higher than in the control rats. On the other hand, in both experiments, control rats in the probe test presented a significantly higher number of allocentric correct responses than the lesioned subjects. These results clearly suggest that Prh is normally needed for using allocentric strategies in order to solve a navigation problem. © 2017 Wiley Periodicals, Inc.

Involvement of the Postrhinal and Perirhinal Cortices in Microscale and Macroscale Visuospatial Information Encoding

“…Under these circumstances, we detected no changes in Arc mRNA expression in PRC and POR. This experimental design contrasts with approaches used by other scientists where objects were visible from afar and where PRC and POR activation was triggered (Furtak et al, 2012;Barker and Warburton, 2015;Heimer-McGinn et al, 2017;Hernandez et al, 2017;Park et al, 2017;Ramos, 2017). This latter strategy enables that the features of the objects can be detected without a close approach and permits that the animals can predict and interpret their positions respective to the objects.…”

“…Besides these properties, the POR is also reciprocally connected with visual associational cortices (Burwell and Amaral, 1998a;Agster and Burwell, 2009;Agster et al, 2016) and it supports visual object discrimination (Furtak et al, 2012). Thus, the POR is involved in the processing of both spatial and non-spatial information (Furtak et al, 2012;Heimer-McGinn et al, 2017;Ramos, 2017;Burke et al, 2018).…”

“…According to this hypothesis, spatial information is processed in the POR and sent to the hippocampus via the medial entorhinal cortex (MEC), whereas non-spatial information is processed by the PRC via the lateral entorhinal cortex (LEC) before the hippocampus is involved (Burwell et al, 1995(Burwell et al, , 2004Burwell and Amaral, 1998b;Eichenbaum and Lipton, 2008). More recent studies suggest, however, that the functions of the parahippocampal regions do not strictly align to the two-streams hypothesis: both the POR and PRC are involved in different kinds of spatial and non-spatial information processing (Brown and Aggleton, 2001;Ramos, 2002Ramos, , 2008Ramos, , 2013aRamos, ,b, 2017Burwell et al, 2004;Winters et al, 2004;Ramos and Vaquero, 2005;Furtak et al, 2012;Heimer-McGinn et al, 2017;Ramos, 2017;Burke et al, 2018;LaChance et al, 2019).…”

The Importance of Distinguishing Allocentric and Egocentric Search Strategies in Rodent Hippocampal-Dependent Spatial Memory Paradigms: Getting More Out of Your Data

“…This is supported by numerous other studies [7,39,40], which all found significant deficits in traditional spatial memory measurements such as time to platform, distance to platform and time spent in target quadrant (probe trial). Other lesion studies indicate the perirhinal cortex, entorhinal cortex and parietal cortices to be involved in allocentric search navigation [41][42][43]. Maze apparatus that can be utilised to test egocentric search strategies include RAM [44], Cincinnati water maze and Star maze [33].…”

Embarking on discovering the mechanisms of resilience: combining language use analysis with neuroscience.

“…NE effects in many brain regions are [non-linearly] dependent on NE levels. For example, lower NE levels in PFC were reported to promote cortical function (working memory, cognitive flexibility) whereas higher NE levels appear impair prefrontal signaling [106][107][108][109][110][111][112] . NE has been shown to enhance fear conditioning for multi-trial but not single-trial conditioning protocols 89 .…”