MOTOR DYSFUNCTION IN A PHOTOTHROMBOTIC FOCAL ISCHEMIA MODEL

The study of behavioural deficits resulting from cerebral infarction i n animal models of stroke has in the past taken second place to histol ogical assessment. This is particularly true of the photothrombotic le sion model. Most tests currently used to measure motor deficits use a scoring system to quantify parameters such as beam walking The present study set out to characterise a simple and objective assessment for m otor impairment in the photothrombotic cortical lesion model. Rats wer e assessed on a number of motor function tests, i.e. gross locomotor a ctivity, rotarod, and grip strength. After the establishment of stable baselines, cortical photothrombotic lesions were induced, after which the animals were re-tested for a further 18 days. The presence of cor tical photothrombotic lesions significantly impaired the rats' perform ance on the rotarod and grip-strength tests. The deficit observed with the grip-strength task appeared 24 h postsurgery, but was much reduce d by day 18 postsurgery. The rotarod test revealed an effect that took longer to establish, but which was more persistent. Gross locomotor a ctivity was not affected. These data suggest that bilateral photothrom botic lesions of the prefrontal cortex produce deficits that can be de tected by rotarod and grip-strength tasks.