A causal role for the pulvinar in coordinating task‐independent cortico–cortical interactions

Abstract

The pulvinar is the largest nucleus in the primate thalamus and has topographically organized connections with multiple cortical areas, thereby forming extensive cortico-pulvino-cortical input-output loops. Neurophysiological studies have suggested a role for these transthalamic pathways in regulating information transmission between cortical areas. However, evidence for a causal role of the pulvinar in regulating cortico-cortical interactions is sparse and it is not known whether pulvinar's influences on cortical networks are task-dependent or, alternatively, reflect more basic large-scale network properties that maintain functional connectivity across networks regardless of active task demands. In the current study, under passive viewing conditions, we conducted simultaneous electrophysiological recordings from ventral (area V4) and dorsal (lateral intraparietal area [LIP]) nodes of macaque visual system, while reversibly inactivating the dorsal part of the lateral pulvinar (dPL), which shares common anatomical connectivity with V4 and LIP, to probe a causal role of the pulvinar. Our results show a significant reduction in local field potential phase coherence between LIP and V4 in low frequencies (4-15 Hz) following muscimol injection into dPL. At the local level, no significant changes in firing rates or LFP power were observed in LIP or in V4 following dPL inactivation. Synchronization between pulvinar spikes and cortical LFP phase decreased in low frequencies (4-15 Hz) both in LIP and V4, while the low frequency synchronization between LIP spikes and pulvinar phase increased. These results indicate a causal role for pulvinar in synchronizing neural activity between interconnected cortical nodes of a large-scale network, even in the absence of an active task state.

Thalamo-Cortical Interaction for Incremental Binding in Mental Contour-Tracing

“…Second, thalamus provides a good fit to the interfacing role, as thalamus and cortical areas are reciprocally connected in a shallow hierarchy [34]. Third, in line with our lesion studies, the relationship between thalamic and cortical activity is a causal one [46]. And fourth, the featureless, taskdependent representation employed by the proxy nodes of the interfacing module, fits well with the identified role of thalamic function in attentional selection [47,48].…”

Attentional modulation of secondary somatosensory and visual thalamus of mice

“…In nonhuman primates, the lateral pulvinar has been shown to facilitate communication between the visual region V4 and higher order cortical regions. These include the lateral intraparietal area 53 and the temporo-occipital area 54 , regions that are engaged in visual attention tasks. Indeed, there is growing evidence that the secondary nuclei may function as hubs for cortico-cortical communication 23,55,56 .…”

Rhythmic sampling of multiple decision alternatives in the human brain

“…While a decision maker is confronted with the complex task of sampling as much information as possible about each decision alternative and at the same the need to compare different options this conflict is resolved through rhythmicity 14,26 . By oscillating the attention strength, a feature potentially established through cortico-thalamic connections 30,[58][59][60] , reorienting and focusing modes of attention can be temporally multiplexed within each oscillatory cycle. Thus, focused information sampling can alternate with spatial re-allocation of the attentional spotlight without competing for the same cognitive resources.…”