Cortical neuron expressing inexperienced fluorescent protein, imaged within the dwelling mouse mind utilizing two-photon microscopy. Credit score: Ronan Chéreau
The cerebral cortex processes sensory info through a fancy community of neural connections. How are these alerts modulated to refine notion? A staff from the College of Geneva (UNIGE) has recognized a mechanism by which sure thalamic projections goal neurons and modify their excitability.
The work, revealed in Nature Communications, reveals a beforehand unknown type of communication between two areas of the mind, the thalamus and the somatosensory cortex. It might clarify why the identical sensory stimulus doesn’t at all times elicit the identical sensation and open up new avenues for understanding sure psychological problems.
The identical sensory stimulus could be perceived clearly at instances, and stay obscure at others. This phenomenon could be defined by the way in which the mind integrates stimuli. For instance, touching an object exterior our visual field could also be sufficient to establish it…or not.
These perceptual variations stay poorly understood, however might rely upon elements resembling consideration or the disruptive presence of different stimuli. What is for certain, in line with neuroscientists, is that after we contact one thing, sensory alerts from receptors within the pores and skin are interpreted by a specialised area known as the somatosensory cortex.
On their option to it, the alerts move via a fancy community of neurons, together with a vital construction within the mind known as the thalamus, which serves as a relay station. Nonetheless, the method just isn’t one-way.
A good portion of the thalamus additionally receives suggestions from the cortex, forming a loop of reciprocal communication. However the precise function and functioning of this suggestions loop are nonetheless unclear. Might it play an lively function in how we understand sensory info?
A brand new modulatory pathway
To discover this query, neuroscientists at UNIGE studied a area on the prime of pyramidal neurons of the somatosensory cortex, wealthy in dendrites—extensions that obtain electrical alerts from different neurons.
“Pyramidal neurons have rather strange shapes. They are asymmetrical, both in shape and function. What happens at the top of the neuron is different from what happens at the bottom,” explains Anthony Holtmaat, full professor on the Division of Fundamental Neurosciences (NEUFO) and the Synapsy Middle for Neuroscience Analysis for Psychological Well being at UNIGE’s College of Drugs, and director of the examine.
His staff centered on a pathway wherein the highest of pyramidal neurons in mice receives projections from a particular a part of the thalamus. By stimulating the animal’s whiskers—the equal of contact in people—a exact dialogue between these projections and the dendrites of pyramidal neurons was revealed.
“What is remarkable, unlike the regular thalamic projections known to activate pyramidal neurons, is that the part of the thalamus providing feedback modulates their activity, in particular by making them more sensitive to stimuli,” says Ronan Chéreau, senior researcher at NEUFO and co-author of the examine.
An surprising receptor
Utilizing cutting-edge strategies—imaging, optogenetics, pharmacology and, above all, electrophysiology—the analysis staff was in a position to file {the electrical} exercise of tiny constructions resembling dendrites.
These approaches helped make clear how this modulation works on the synaptic stage. Usually, the neurotransmitter glutamate acts as an activation sign. It helps neurons transmit sensory info by triggering {an electrical} response within the subsequent neuron.
On this newly found mechanism, glutamate launched from thalamic projections binds to an alternate receptor situated in a particular area of the cortical pyramidal neuron.
Slightly than straight thrilling the neuron, this interplay alters its state of responsiveness, successfully priming it for future sensory enter. The neuron then turns into extra simply activated, as if it had been being conditioned to raised reply to a future sensory stimulus.
“This is a previously unknown pathway for modulation. Usually, the modulation of pyramidal neurons is ensured by the balance between excitatory and inhibitory neurons, not by this type of mechanism,” explains Ronan Chéreau.
Implications for notion and problems
By demonstrating {that a} particular suggestions loop between the somatosensory cortex and the thalamus can modulate the excitability of cortical neurons, the examine means that thalamic pathways don’t merely transmit sensory alerts, but in addition act as selective amplifiers of cortical exercise.
“In other words, our perception of touch is not only shaped by incoming sensory data, but also by dynamic interactions within the thalamocortical network,” provides Anthony Holtmaat.
This mechanism might additionally contribute to understanding the perceptual flexibility noticed in states of sleep or wakefulness, when sensory thresholds fluctuate. Its alteration might additionally play a task in sure pathologies, resembling autism spectrum problems.
Extra info:
Federico Brandalise et al, Thalamocortical suggestions selectively controls pyramidal neuron excitability, Nature Communications (2025). DOI: 10.1038/s41467-025-60835-w
Supplied by
College of Geneva
Quotation:
How the mind shapes what we really feel in actual time: A brand new mechanism for modulating sensory alerts (2025, July 30)
retrieved 30 July 2025
from https://medicalxpress.com/information/2025-07-brain-real-mechanism-modulating-sensory.html
This doc is topic to copyright. Other than any honest dealing for the aim of personal examine or analysis, no
half could also be reproduced with out the written permission. The content material is supplied for info functions solely.
