Selective synchronization explains transfer characteristics of attention-dependent routing for broad-band flicker signals to monkey area V4 I Grothe1, D Rotermund2, S D Neitzel3, S Mandon3, U A Ernst2, A K Kreiter3, K Pawelzik2 |
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1Fries lab, Ernst Strüngmann Institute (ESI), Germany |
| Neurons with large receptive fields (RFs) receive inputs representing multiple stimuli and hence require a selection mechanism for processing the relevant signal. Here, we investigate attentional gating of temporally varying visual signals to neurons in areas V1 and V4, and whether differences in synchronization between V4 neurons and their V1 afferent inputs can quantitatively explain selection of the attended stimulus for further processing. To test experimentally whether a local group of neurons can switch processing between different parts of their synaptic inputs, we established a new experimental paradigm. We superimposed behaviorally irrelevant broad-band contrast modulations on two visual objects, both placed within the same V4 RF, while monkeys tracked the changing shape of the cued object. We used a normalized spectral coherence measure to simultaneously characterize the transmission of the superimposed components towards local field potentials recorded in areas V1 and V4. We found strong attention-dependent gating of the visual signals towards V4. Using a minimal model implementing routing by coherence we characterized gating capabilities and transfer characteristics of this mechanism for signals modulated as in the experiment. The model reproduces the experimental findings in detail, supporting gamma-band synchronization as a mechanism subserving gating by attention. |
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