Effect of vibrissae removal on search accuracy in the water maze

In two experiments the vibrissae were clipped on either the left, the right or both sides, and the rats were trained to find a submerged platform in the Morris water maze. In both experiments, animals without vibrissae on both sides or on the left consistently spent significantly more time in the 'counter' area twice the platform diameter in size, surrounding the submerged platform, than intact controls. Counter preference was not as consistent across experiments in rats with right vibrissae removed. These results suggest that the vibrissae are required for proprioceptive location of the platform itself, but not for proximal search accuracy. Since ischaemic damage to hippocampal CA1 pyramidal cells has also been reported to prolong counter search during training, the results support the suggestion that impaired hippocampal processing of proprioceptive information from the vibrissae may contribute to the increased latency to find the platform shown by ischaemic rats.