The anteromedial extrastriate complex is critical for the use of allocentric visual cues and in the retention of the Lashley III maze task in rats

Marc Leander Zeise,Sergio Espinoza-Cifuentes

doi:10.4067/s0716-97602008000400006

Abstract

The anteromedial extrastriate complex has been proposed to play an essential role in a spatial orientation system in rats. To gain more information about that possible role, in the present work, two questions were addressed: 1. Are allocentric visual cues relevant for acquisition of the orientation task in the Lashley III maze? 2. Is this integration of allocentric inputs in the anteromedial visual complex relevant in the retention of this test? While a control group of rats was trained keeping the maze in the same position, the experimental group was trained with the maze rotated counterclockwise by 144 degrees from session to session. Control rats reached learning criterion significantly earlier and with less errors than the experimental ones (p<.05). After 11 sessions, rats of both groups received stereotaxic injections of ibotenic acid in the anteromedial complex. In the retention test one week after surgery, the control group, which had been able to learn using egocentric and allocentric visual cues, showed a greater deficit than the experimental animals (p<.05). These results confirm the role of the anteromedial complex in the processing of visuospatial orientation tasks and demonstrate the integration of allocentric visual cues in the solution of those tasks.

Highlights

Studies of the visual system have provided valuable insight into the neural processes underlying our capabilities for navigating in our surroundings and recognizing objects in it
The present results show that the AMC is critical for processing allocentic visual inputs in an orientation task
We have shown that distant visual stimuli are used for the orientation task, reducing the number of sessions to reach criterion as well as the number of errors committed during the learning phase

Summary

Introduction

Studies of the visual system have provided valuable insight into the neural processes underlying our capabilities for navigating in our surroundings and recognizing objects in it The interdependence of these tasks has been a matter of intense debate (for example “...it is our contention that, despite the protestations of phenomenology, visual perception and the visual control of action depend on functionally and neurally independent systems” (Milner and Goodale, 2006). In this context, it is interesting that the anteromedial and anterior parts of the rat occipital cortex, the AM complex (AMC), a structure formerly considered an area of purely visual reception and recognition because of its retinotopic organization, turned out to be an integrator of diverse input qualities.

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Conclusion