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Neural dynamics of visual cognition

Subject Area Human Cognitive and Systems Neuroscience
Cognitive, Systems and Behavioural Neurobiology
Term from 2016 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 278405424
 
Final Report Year 2024

Final Report Abstract

In the blink of an eye we effortlessly recognize everyday objects such as the letters on this page or a coffee cup on a table. The apparent ease of our visual recognition abilities, however, belies its complexity: we correctly identify and classify objects among thousands of alternatives, rapidly within a few hundred milliseconds, and despite huge variation in the retinal image created by changes in viewing conditions. The aim of this project was to shed light on the neural dynamics that makes visual object perception possible. For this we used a combination of non-invasive human brain imaging, computational modelling (deep neural networks), behavioral assessment and multivariate analysis techniques. In particular, we aimed at revealing a) the complex spatiotemporal dynamics enabling object perception (objective 1), b) the way information flows through the underlying neural architecture in feedforward and feedback direction (objective 2), and c) how plastic the underlying architecture is (objective 3). We have obtained the following results. Concerning objective 1, we have a) shed light on the algorithms and representational format of the visual neural processing cascade by demonstrating a spatiotemporal correspondence between human visual brain activity and artificial deep neural networks, b) revealed spatiotemporal dynamics for different visual contents, dimensions and formats, c) identified the subset of activity that is suitably formatted to guide behavior in the effects made visible to the experimenter, d) showed how real-world regularities shape the neural architecture underlying object and scene vision, and e) sharpened analysis methods to make available relevant pieces of empirical information for theory. Concerning objective 2, we have revealed a) that veridical vision (i.e., feed-forward related information flow) and imagery (feedback-related information flow) share neural representations in the alpha frequency band, b) that task goals exhibited late effects on object processing by selectively enhancing task-relevant object features, with limited impact on the overall pattern of object representations, c) that feed-forward and feedback information flow-related activity can be dissociated through rapid serial visual presentation, d) and that alpha frequency feedback orchestrates coherent natural vision. Towards objective 3, we have revealed the spatiotemporal dynamics of the transformation from sensory to perceptual Braille letter perception in the blind, and we have ascertained the behavioral relevance of the representations revealed. Together, our results contribute to the understanding of how the complex spatiotemporal neural dynamics in the visual brain enable our perception of the world and our interaction with it in a meaningful way.

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