A thalamic bridge from sensory perception to cognition
M. Wolff, S. Morceau, J. Martin-Cortecero, R. Folkard, A. Groh
Neuroscience & Biobehavioral Reviews / Open-Access
https://doi.org/10.1016/j.neubiorev.2020.11.013
Context
This invited review paper is a contribution for an upcoming special issue on the “Cognitive Thalamus”, which is a follow-up of the initial event in 2015. It’s a collaboration between DECAD researchers (Mathieu Wolff and PhD candidate Sarah Morceau) and researchers from Heidelberg university (Alexander Groh, Jesus Martin-Cortecero and Ross Folkard). Mathieu and Alexander have previously organized multiple events around the functional roles of thalamocortical circuits and are now also providing master-level teaching at Bordeaux on the same topic (UE Neural Network). The review paper provides a new look on thalamocortical circuits by combining perspectives from different fields, ranging from sensory processing to cognition.
Twitter thread here: https://twitter.com/wolff_mathieu/status/1333715547096305664
Abstract
The ability to adapt to dynamic environments requires tracking multiple signals with variable sensory salience and fluctuating behavioral relevance. This complex process requires integrative crosstalk between sensory and cognitive brain circuits. Functional interactions between cortical and thalamic regions are now considered essential for both sensory perception and cognition but a clear account of the functional link between sensory and cognitive circuits is currently lacking. This review aims to document how thalamic nuclei may effectively act as a bridge allowing to fuse perceptual and cognitive events into meaningful experiences. After highlighting key aspects of thalamocortical circuits such as the classic first-order/higher-order dichotomy, we consider the role of the thalamic reticular nucleus from directed attention to cognition. We next summarize research relying on Pavlovian learning paradigms, showing that both first-order and higher-order thalamic nuclei contribute to associative learning. Finally, we propose that modulator inputs reaching all thalamic nuclei may be critical for integrative purposes when environmental signals are computed. Altogether, the thalamus appears as the bridge linking perception, cognition and possibly affect.
Schematic drawing of sensory thalamocortical organization. Sensory information from periphery reaches FO nuclei (red box) via driver inputs (blue axons). FO nuclei relay sensory information to cortical layer 4 and TRN (red axons). Subsequently, the cortex relays the processed events to HO nuclei via driver input from layer 5. Finally, HO nuclei relay information to other related cortical areas (green axons). Cortex modulates the activity of FO and HO nuclei via modulator inputs (black axons) and also triggers TRN activity. The TRN is expected to act as a thalamic searchlight to direct attention with possible relevance for cognitive functions.