Neurons in the lateral agranular frontal cortex have divided attention correlates in a simultaneous temporal processing task

The frontal cortex is an important brain area for divided attention. Lesions of the lateral agranular frontal cortex in rats disrupt divided attention in a simultaneous temporal processing task. In the present study, the activity of lateral agranular neurons was examined while rats performed a simultaneous temporal processing procedure. Rats were trained to time two stimuli (a light and a tone), each associated with a different fixed interval. Simple trials, in which a single stimulus was presented, and compound trials, in which both stimuli were presented simultaneously, occurred randomly in a session. Rats were able to divide attention between the two stimuli, as assessed by the pattern of lever presses. Approximately 50% of lateral agranular neurons responded to at least one phase of the task with four response patterns observed. The activity of type 1 cells (60%) was altered to compound, but not simple, stimuli. Type 2 cells (10%) responded to both types of simple stimuli and to compound stimuli. Type 3 cells (27%) had changes in firing rate to one type of simple stimulus and to compound stimuli. Type 4 cells (3%) responded to one type of simple stimulus, but were unresponsive to all other stimuli. The large proportion of type 1 cells supports the hypothesis that the lateral agranular cortex is important in divided attention. Previous studies have suggested that the lateral agranular cortex in rats is equivalent to the primary motor cortex. Lf so, the results from the present study provide evidence that the lateral agranular cortex may have some cognitive functions, in addition to being part of the motor system. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.