Two Streams of Attention-Dependent β Activity in the Striate Recipient Zone of Cats Lateral Posterior–Pulvinar Complex

摘要

Local field potentials from different visual cortical areas and subdivisions of the cat's lateral posterior–pulvinar complex of the thalamus (LP-P) were recorded during a behavioral task based on delayed spatial discrimination of visual or auditory stimuli. During visual but not auditory attentive tasks, we observed an increase of β activity (12–25 Hz) as calculated from signals recorded from the caudal part of the lateral zone of the LP-P (LPl-c) as well as from cortical areas 17 and 18 and the complex located at the middle suprasylvian sulcus (MSS). This β activity appeared only in the trials that ended with a successful response, proving its relationship to the mechanism of visual attention. In contrast, no enhanced β activity was observed in the rostral part of the lateral zone of the LP-P and in the pulvinar proper. Two subregions of LPl-c (ventromedial and dorsolateral) were distinguished by visually related, attentional β activity of low (12–18 Hz) and high (18–25 Hz) frequencies, respectively. At the same time, area 17 exhibited attentional activation in the whole β range, and an increase of power in low-frequency β was observed in the medial bank of MSS, whereas cortical area 18 and the lateral bank of the MSS were activated in the high β range. Phase-correlation analysis revealed that two distinct corticothalamic systems were synchronized by the β activity of different frequencies. One comprised of cortical area 17, ventromedial region of LPl-c, and medial MSS, the second involved area 18 and the dorsolateral LPl-c. Our observations suggest that LPl-c belongs to the wide corticothalamic attentional system, which is functionally segregated by distinct streams of β activity.