Anterograde and retrograde influence of vestibular stimulation on spatial working memory

Rats were trained in an eight-arm radial maze to explore the apparatus in search of a food reward. After completion of the training phase, some animals were submitted to a hemicerebellectomy (HCbed group), while others were used as a control group. To study the effects of vestibular stimulation on the recall of ongoing working memory information, both groups were exposed to radial maze sessions: in the first session (no-rotation), animals were confined for 30 s to the fourth arm visited without being further manipulated; in the second session (rotation), the animals were again confined for 30 s to the fourth arm visited, while the apparatus was rotated five times around its vertical axis. The effects of these manipulations on successive visits to complete the task were assessed, as well as the solving time and kinds of errors made. Errors were significantly more frequent in the control animals during the rotation session; HCbed animals were unaffected by confinement alone or by vestibular stimulation, but showed a decreased search speed. It was concluded that vestibular input is required for an adequate functioning of the working memory system devoted to the formation and consolidation of spatial mnesic traces and that the amnesic effect due to vestibular stimulation is both anterograde and retrograde in nature. (C) 2002 Elsevier Science Inc. All rights reserved.