Abstract
Attention gates the flow of sensory information across brain areas. Mechanistically, attention should depend on a modulation of both feedback (FB) and feedforward (FF) projections, which terminate in distinct laminar compartments and target specific neural populations. We performed simultaneous laminar recordings from macaque V1 and V4 and identified putative fast-spiking (FS) interneurons and excitatory cells. V4 firing rates increased for both excitatory neurons and FS interneurons with attention. This increase was most prominent in superficial layers and preceded the modulations in V1 and Layer-4 of V4 in time, consistent with a FB modulation. We furthermore identified an attentional modulation of FF signaling corresponding to an increase in V1-V4 gamma-synchronization. Surprisingly, in V4, only Layer-4 FS interneurons were phase-locked to the V1 gamma rhythm, suggesting that V1-V4 gamma-synchronization may increase the signal-to-noise ratio rather than the gain of FF information transmission. Consistently, optogenetic tagging experiments in mice showed relatively strong phase-locking of PV+ and narrow-waveform SSt+ interneurons to gamma-rhythmic inputs. These findings reveal two distinct FF and FB pathways for attentional modulation with cell-type and layer-specific physiological effects.
Competing Interest Statement
The authors have declared no competing interest.
