Scientists Create a Model for the Neural Basis of Expectation

Summary: A new theoretical model helps explain how the gustatory cortex mediates the expectation of receiving a taste. The model sheds light on the neural basis of expectation.

Source: Stony Brook University

It is known that sensory stimuli – especially powerful ones like taste – are affected by expectation, which is a trigger to improving stimuli detection, distinction and reaction. Yet, scientists know little about how expectation shapes the cortical processes of sensory information. Now Alfredo Fontanini, PhD, and Giancarlo La Camera, PhD, of the Department of Neurobiology and Behavior in the College of Arts and Sciences and the Renaissance School of Medicine at Stony Brook University, together with their postdoctoral fellow, Luca Mazzucato (now at the University of Oregon), have developed a theoretical model of how the primary gustatory cortex can mediate the expectation of receiving a taste.

In a paper published in Nature Neuroscience, the researchers detail their model which theoretically explains the neural basis of expectation.

The data show experimental evidence that a state of expectation is mediated by an acceleration of the neural activity generated by certain populations of neurons. The authors built a biologically plausible model of this phenomenon based on the modulation of the brain’s own spontaneous activity.

“Neurons in the cortex appear to be continuously active and erratic, giving us a messy sensation of what neurons are doing,” says La Camera. “Our model sheds a potential light on the meaning of such continuous activity and proposes a mechanism through which it could be mediating expectation.”

This shows how the model predicts expectation in a color graph
This color-coded raster plot reveals spiking activity of nine neurons in the gustatory cortex. Every time a color changes neurons become more or less active, which indicate a change in neural states. According to the authors, these states can be altered by expectation. The image is credited to the researchers.

Although the empirical demonstration of the principle was performed in the gustatory cortex, the model may go beyond taste processing as it posits, as a general theory, that expectations can be mediated by a change in the dynamics of certain cortical circuits.

“For this reason”, add the authors, “we do not exclude that other processes such as attention and decision making may be explained by an analogous mechanism.”

Funding: The research was supported in part by grants from National Institute of Health’s National Institute on Deafness and Other Communications Disorders (NIDCD) and the National Science Foundation.

About this neuroscience research article

Source:
Stony Brook University
Media Contacts:
Gregory Filiano – Stony Brook University
Image Source:
The image is credited to the researchers.

Original Research: Open access.
“Expectation-induced modulation of metastable activity underlies faster coding of sensory stimuli”
L. Mazzucato, G. La Camera & A. Fontanini Nature Neuroscience 17(4): e2006421 doi:10.1038/s41593-019-0364-9

Abstract

Expectation-induced modulation of metastable activity underlies faster coding of sensory stimuli

Sensory stimuli can be recognized more rapidly when they are expected. This phenomenon depends on expectation affecting the cortical processing of sensory information. However, the mechanisms responsible for the effects of expectation on sensory circuits remain elusive. In the present study, we report a novel computational mechanism underlying the expectation-dependent acceleration of coding observed in the gustatory cortex of alert rats. We use a recurrent spiking network model with a clustered architecture capturing essential features of cortical activity, such as its intrinsically generated metastable dynamics. Relying on network theory and computer simulations, we propose that expectation exerts its function by modulating the intrinsically generated dynamics preceding taste delivery. Our model’s predictions were confirmed in the experimental data, demonstrating how the modulation of ongoing activity can shape sensory coding. Altogether, these results provide a biologically plausible theory of expectation and ascribe an alternative functional role to intrinsically generated, metastable activity.

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