Abstract
Visual perception occurs when a set of physical signals emanating from the environment enter the visual system and the brain interprets such signals as a percept. Visual working memory occurs when the brain produces and maintains a mental representation of a percept while the physical signals corresponding to that percept are not available. Early studies in humans and non-human primates demonstrated that lesions of the prefrontal cortex impair performance during visual working memory tasks but not during perceptual tasks. These studies attributed a fundamental role in working memory and a lesser role in visual perception to the prefrontal cortex. Indeed, single cell recording studies have found that neurons in the lateral prefrontal cortex of macaques encode working memory representations via persistent firing, validating the results of lesion studies. However, other studies have reported that neurons in some areas of the parietal and temporal lobe—classically associated with visual perception—similarly encode working memory representations via persistent firing. This prompted a line of enquiry about the role of the prefrontal and other associative cortices in working memory and perception. Here, we review evidence from single neuron studies in macaque monkeys examining working memory representations across different areas of the visual hierarchy and link them to studies examining the role of the same areas in visual perception. We conclude that neurons in early visual areas of both ventral (V1-V2-V4) and dorsal (V1-V3-MT) visual pathways of macaques mainly encode perceptual signals. On the other hand, areas downstream from V4 and MT contain subpopulations of neurons that encode both perceptual and/or working memory signals. Differences in cortical architecture (neuronal types, layer composition, and synaptic density and distribution) may be linked to the differential encoding of perceptual and working memory signals between early visual areas and higher association areas.
Highlights
The animals could perform other perceptual tasks without major difficulty (Jacobsen, 1936). These results suggested that lesions of the prefrontal cortex (PFC) affect mainly working memory while sparing perception
This study extends the observed effects of prefrontal lesions to new world monkeys, with a relatively less expanded PFC than their old world relatives (Passingham and Wise, 2012)
There are populations of neurons that encode both perceptual and working memory signals, with the relative proportion of neurons encoding the latter increasing from early association areas to the PFC
Summary
Visual perception is defined as the ability to interpret the surrounding environment from electromagnetic signals entering the retinas. The distinction between working memory and perceptual functions can be traced to lesions studies conducted more than a century ago in humans and animals They reported that damage to certain brain areas can produce selective deficits of working memory while sparing visual perception (reviewed ). More recent studies have reported co-existence of signal correlates of visual perception and working memory across brain areas and have questioned the segregation of the neural substrates for these two functions in the brain (reviewed in the section “Dissociating Visual Working Memory and Perception: Electrophysiological Studies of Single Neurons Across Brain Areas”) Influential in this latter view, have been findings of functional imaging and EEG/MEG studies in human subjects (Dijkstra et al, 2021). We concentrate on studies that have directly recorded action potentials from neurons or neuronal populations during behavioral tasks that involve visual perception and working memory
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
