PREFRONTAL CONTROL OF PREPARATORY ATTENTION AND COORDINATION WITH THE VENTRAL TEGMENTAL AREA

Preparatory attention selects upcoming stimuli that will be used to guide behavior. This cognitive faculty is controlled by the prefrontal cortex (PFC), which primes sensory cortex neurons that represent the stimulus. Lesion studies have implicated multiple PFC regions in the control of attention, including the rat prelimbic cortex (PL) and anterior cingulate cortex (ACC). The first aim of this dissertation was to characterize and compare neural activity in these regions during a preparatory attention task. The second aim was to assess interactions between these regions during preparatory attention. Coordinated activity between the PL and ACC was studied by measuring spike synchrony with local field potential (LFP) oscillations. The third aim was to study neural activity in the ventral tegmental area (VTA), which provides dopamine projections to the PFC that are known to modulate PFC control of attention. The nature of VTA neural activity during attention and its coordination with the PFC has not been characterized.\ud \ud In order to study PFC and VTA neural activity during preparatory attention, we recorded single unit spiking and LFP and primarily focused analysis on the pre-stimulus period, when a preparatory attention control signal is generated by PFC neurons. The rat was trained to orient to a wall of three stimulus ports, expect a brief illumination at one of the ports, and make a response into the illuminated port. While the timing of stimulus onset was predictable, the location varied randomly. These task characteristics resulted in error trials in which the rat responded to an incorrect port. The analyses of pre-stimulus neural activity compared correct and error trials.\ud \ud We observed a sustained change in PFC single unit firing rate during the pre-stimulus period. The sustained firing patterns were predictive of attentional accuracy, in that the sustained activity was reduced during error trials. Furthermore, we demonstrated that the PL and ACC interacted during preparatory attention. We also observed sustained activity in the VTA, which may stabilize sustained PFC activity during preparatory attention. VTA spiking correlated with ACC gamma (40 Hz) oscillations, which may be used to communicate the attention control signal from the PFC to sensory cortex