Delayed response deficit by cryogenic depression of frontal cortex

Monkeys with chronically implanted cryogenic probes over the surface of the dorsolateral prefrontal cortex were tested in a delayed response task. Performance of this task was reversibly impaired by bilateral cooling and also, to a lesser extent, by unilateral cooling of this cortical area. Cooling to subdural temperatures of 25–30°C was sufficient to produce deficits. These deficits are interpreted as caused by reversible inactivation of the cortex around the sulcus principalis, with the consequent disruption of short-term memory function.