Higher visual areas of the brain influence perception of reality

The research, published in Nature Communications, conducted by the Institute of Neuroscience of the National Research Council of Pisa (Cnr-In), with the collaboration of the Neurofarba Department of the University of Florence, seems to lead to an understanding visual perceptual learning processes, traditionally attributed to the area of ​​the brain known as the “primary visual cortex”. The researchers noted, for the first time at an experimental level, that These processes also involve higher-order cortices, which transmit additional information to that processed by the primary visual cortex, in particular on sensory aspects relating to the behavioral context in which the subject’s activities take place..

The results confirm the existence of a “dialogue” between these two areas, which until now had only been hypothesized.

“It is known that the primary visual cortex – or V1 – is the brain area that allows us to ‘see’ the world, to analyse and recognise shapes and objects as we know them and as they appear to us in everyday life, but also to carry out more complex processes, including the forms of learning known as ‘visual perceptual learning’, that is, the ability to improve the analysis of reality thanks to the experience and stimuli that we constantly receive, to discriminate it, to distinguish increasingly subtle differences”, explains Alessandro Sale, research director of the Cnr-In and coordinator of the study. “Today, our experiments have allowed us to demonstrate that The functional properties of cortical neurons can also be modulated by signals coming from higher-order cortices – in particular from the secondary visual cortex. – with a flow that we can describe as ‘top-down’, and that They carry important information about the context in which we are immersed. This information is added to that obtained with the visual processing of the primary cortex, in an integrated involvement of these two areas.“.

“To study the involvement of higher-order visual areas, we focused our attention on the lateral-medial secondary visual cortex (LM), the homologue of the primate secondary visual cortex (V2): using a combined chemogenetics-based approach (a modern technique in which it is possible to combine knowledge of molecular genetics and chemistry to investigate the role of specific neuronal circuits), Behavioral analysis and multichannel electrophysiological recordingswe have provided very strong evidence for the role of this part of the cortex not only in the acquisition, but also in the retention of visual perceptual learning. By selectively blocking the activity of this area, in fact, we noted a marked impairment of learning abilities, as well as the complete loss of the visual discrimination improvement effects already obtained, when the block was applied after the end of the learning protocol.
“, continue Sale.

The results obtained demonstrate that if the visual processing produced by the primary cortex is not accompanied by the flow of information coming from the higher centers, the perceptual learning effects do not occur: analyzing and constructing reality therefore requires an integrated involvement between lower and higher order visual areas.