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Scientists Create a Model for the Neural Basis of Expectation


STONY BROOK, NY, April 12, 2019 – 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.

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.

“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.”

The model also explains how the faster onset of coding states is due to a generic acceleration of the sequences of neural states. The acceleration is caused by the presence of the anticipatory cue (a pure tone) used in the experiments to signal the forthcoming delivery of a taste. The faster speed of the sequence brings forward in time the representation of the taste.

“Presumably, a state of expectation, or ‘readiness’ is mediated by faster or more accurate internal representation of what is happening. Our model says that our internal representations of expected events are formed earlier compared to when the same events are unexpected,” says LaCamera.

Another important contribution of the authors’ model is the explanation of why a generic anticipatory cue can set in motion a faster sequence dynamics. This part of the model can be understood in terms of the mathematical theory of complex dynamical systems.

To understand the brain’s activity during expectation, the researchers relied on a metaphor invented in physics of a motion within a complex landscape of valleys and peaks. Some specific locations in such landscape correspond to the internal representations of the taste stimuli. To reach the relevant locations sometimes a peak must be climbed. According to the model, the effect of the anticipatory cue is to reduce the height of the peaks, so that motion is faster and the relevant representations occur earlier.

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.”

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 Stony Brook University

Stony Brook University, widely regarded as a SUNY flagship, is going beyond the expectations of what today’s public universities can accomplish. Since its founding in 1957, this young university has grown to become one of only four University Center campuses in the State University of New York (SUNY) system with more than 26,000 students, more than 2,700 faculty members and 18 NCAA Division I athletic programs. Our faculty have earned numerous prestigious awards, including the Nobel Prize, Pulitzer Prize, Indianapolis Prize for animal conservation, Abel Prize and the inaugural Breakthrough Prize in Mathematics. The University offers students an elite education with an outstanding return on investment: U.S.News & World Report ranks Stony Brook among the top 40 public universities in the nation. Its membership in the Association of American Universities (AAU) places Stony Brook among the top 62 research institutions in North America. As part of the management team of Brookhaven National Laboratory, the University joins a prestigious group of universities that have a role in running federal R&D labs. Stony Brook University fuels Long island’s economic growth. Its impact on the Long island economy amounts to $7.38 billion in increased output. Our state, country and world demand ambitious ideas, imaginative solutions and exceptional leadership to forge a better future for all. The students, alumni, researchers and faculty of Stony Brook University are prepared to meet this challenge.


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