A computational perspective of the role of Thalamus in cognition

TL;DR

This paper reviews recent experimental and theoretical advances that expand the understanding of the thalamus, especially the mediodorsal nucleus, as an active participant in cortical computations and cognitive processes, beyond its traditional relay role.

Contribution

It proposes a new perspective on thalamic function, emphasizing its role in dynamic cortical representation selection through intrinsic computations and output signals.

Findings

Thalamus, particularly the mediodorsal nucleus, influences cortical representations.

Thalamic circuits are more diverse and active than simple relay models suggest.

Coordination of experimental and theoretical work is crucial for understanding thalamic roles in cognition.

Abstract

Thalamus has traditionally been considered as only a relay source of cortical inputs, with hierarchically organized cortical circuits serially transforming thalamic signals to cognitively-relevant representations. Given the absence of local excitatory connections within the thalamus, the notion of thalamic `relay' seemed like a reasonable description over the last several decades. Recent advances in experimental approaches and theory provide a broader perspective on the role of the thalamus in cognitively-relevant cortical computations, and suggest that only a subset of thalamic circuit motifs fit the relay description. Here, we discuss this perspective and highlight the potential role for the thalamus -- and specifically mediodorsal (MD) nucleus -- in dynamic selection of cortical representations through a combination of intrinsic thalamic computations and output signals that change cortical network functional parameters. We suggest that through the contextual modulation of cortical computation, thalamus and cortex jointly optimize the information/cost tradeoff in an emergent fashion. We emphasize that coordinated experimental and theoretical efforts will provide a path to understanding the role of the thalamus in cognition, along with an understanding to augment cognitive capacity in health and disease.