A new study describes the cerebral cortex as a ‘memory machine’ that continuously searches for novel stimuli to update its predictions of the future. By opting for auditory cortex imaging in mice, researchers uncovered that neurons track sensory inputs through time, forming “echoes,” which aid in the discrimination of new material.
A neural network model reproduced the findings, indicating that novelty detection is simply part of how the brain’s wiring would play out. It’s an important function with respect to perception, learning, and decision-making, and could explain why people with schizophrenia struggle to distinguish new from previously stored information.
The role of the neural networks, as opposed to single neurons, would be apparent in novelty detection. The new research thus represents important progress in understanding both normal brain function and disorders in which predictive processing goes awry.
Neural Echoes: The cortex tracks sensory input with”echoes” of the past stimuli, the use of which aids in the formation of short-term memories; Automatic Novelty Detection: Neural networks, as opposed to individual neurons, sense new stimuli depending on their wiring; Schizophrenia Insight: These findings may account for the reason as to why schizophrenics have difficulty in distinguishing new information from old. (Source: Columbia University)
The cerebral cortex is the largest portion of a mammal’s brain and on certain counts the most significant. In a human particularly, it is where most of the activities occur-perception, thinking, memory storage, decision-making. One of the current hypotheses proposes that forecasting the future is the cortex’s primary purpose, such as identifying and encoding genuinely new information received from the external environment and comparing it with what was expected to occur. A new study, published today in the journal Neuron, makes a major advance toward proving that hypothesis. The first author of the paper is Yuriy Shymkiv, a postdoc in the lab of Professor Rafael Yuste.
Shymkiv explained: “We found that the cortex behaves as a memory machine, encoding new experience and predicting the immediate future.” “This study presents an enormous insight into the roles of the cortex and neurological diseases stemming from dysfunction of the cortex, such as schizophrenia,” Yuste said, noting that the findings also enlighten normal brain function. “Novelty is the difference between the future you predicted and the future actually experienced. The study shows that the cortex is constantly detecting novel stimuli to adjust and predict the nearer future better. Novelty detection is an important function for humans and other animas.”
Read More: Psychology of Novelty: The Appeal of New Experiences
The team thus began their research by designing an experiment that would determine how a mixture of familiar and new sensory stimuli actually works for mice. The main stimulus of the experiment was the presentation of sounds at different pitches. Imaging the auditory cortex, which is the part of the cerebral cortex that deals with sound processing, revealed that groups of neurons responded not only to the characteristic of sounds played, but also to how new the stimulus was. Interestingly, they found that every sound left a trace of neuronal activity, which they called an “echo,” following sensory inputs over time and encoding short-term memories of most recent inputs.
These activity echoes did two amazing things: they ensured that each stimulus led to a wholly consistent response, while, on the other hand, they selected stimuli which were “new,” such that those responses would be much stronger.
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