NextFin news, Researchers from the University of California, Berkeley, in collaboration with the Allen Institute for Brain Science in Seattle, revealed on Monday that the brain actively constructs visual perception through complex neural computations rather than passively receiving sensory input.
The study, published in the journal Nature Neuroscience, identified a specialized group of neurons called IC-encoder neurons in the primary visual cortex of mice. These neurons enable the brain to 'see' illusory contours—edges or shapes that do not physically exist in the sensory input but are perceived due to brain processing.
Lead researcher Dr. Hyeyoung Shin, now at Seoul National University, explained that these IC-encoder neurons receive top-down signals from higher visual areas of the brain, which first interpret the illusion. This feedback instructs the primary visual cortex to complete the missing visual information, effectively causing the perception of shapes like squares or triangles that are not present in the actual stimulus.
The team demonstrated this by showing mice illusory images similar to the Kanizsa triangle and recording brain activity. Using two-photon holographic optogenetics, they stimulated the IC-encoder neurons directly, reproducing the same brain activity patterns even without the illusion present, confirming these neurons' role in constructing visual perception.
Dr. Hillel Adesnik of UC Berkeley and colleagues noted that this discovery overturns the traditional view of vision as a passive process. Instead, perception is an active inference where the brain uses prior knowledge and complex calculations to interpret sensory data.
Jerome Lecoq, associate investigator at the Allen Institute, highlighted the clinical relevance of the findings, noting that abnormal activity in similar neural circuits may underlie perceptual disturbances in conditions such as schizophrenia. Understanding which neurons and brain layers are involved could aid in developing treatments for such disorders.
The research also benefited from the Allen Institute's OpenScope program, which provided advanced tools like Neuropixels probes to record brain-wide electrophysiological activity with millisecond precision, allowing observation of the feedback loops between higher and lower visual areas in real time.
This study, conducted primarily in Seattle and Berkeley, provides new insights into how the brain constructs our visual reality, emphasizing that what we see is a product of active brain computations rather than a direct reflection of the external world.
Source: IT Home (https://www.ithome.com/0/883/189.htm), Neuroscience News (https://neurosciencenews.com/visual-illusion-perception-neurons-29686/), Allen Institute
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