Description
- Abstract:
- Saccadic eye movements are an essential component of visual behavior in human and non-human primates, as they move the sensitive portion of the eye’s retina to objects of interest. The hypothesis explored here is that saccades do much more than simply redirect gaze – they are a critical component of an active vision process that uses information from the motor system to optimize visual processing and perception at the start of each fixation. In other words, a corollary discharge signal associated with the eye movement modulates activity in visual cortex and, ultimately, benefits perception. Many labs have investigated active vision, but the work described here is innovative in multiple ways. Unlike most previous studies, it focuses on the activity of neurons at the start of fixations, a critical time for constructing a visual representation. The experiments are the first to simultaneously record from visual cortex while quantifying the effects of saccades on animals’ perceptual sensitivity. To isolate the influence of any corollary discharge signal, a rotating mirror system was used to create simulated saccades that produce the same motion on the retina as actual saccades, but without any eye movement (or corollary discharge). So that both single neuron and network effects of saccades could be assessed, physiological recordings were made from area V1 using arrays of 96-electrodes. Finally, a range of computational approaches were used to quantify neural population coding and dynamics. The data demonstrate that saccades and active vision alter the sensitivity of neurons to different spatial frequencies of the visual input and they have corresponding effects on perceptual sensitivity. As a result, visual processing is shifted toward finer details of behavioral importance. Saccades also modulate cortical networks, altering functional connectivity at the critical time that a new representation is built. Finally, the eye movements have a significant effect on the precise timing and rate of spikes at the beginning of new fixations. These findings provide strong support for the hypothesis that vision is an active process that makes use of corollary discharge to enhance vision at the start of fixations, presumably to serve behavioral goals such as object recognition.
- Notes:
- Thesis (Ph. D.)--Brown University, 2022
Citation
Akers-Campbell, Seth,
"Cortical Dynamics for Active Vision"
(2022).
Neuroscience Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:qmhn92ps/
