Journal Article

Parallel processing strategies of the primate visual system

Callaway, Edward M., Nassi, Jonathan J.

2009

Overview

Key Points Multiple parallel processing strategies, involving over a dozen retinal ganglion cell types, can be found in the retina. Each ganglion cell type tiles the retina to provide a complete representation across the entire visual field of the visual attributes it conveys to the brain. Three retinal ganglion cell types have been particularly well characterized both anatomically and physiologically and project in parallel from the retina, through the lateral geniculate nucleus of the thalamus to the primary visual cortex. The primary visual cortex receives parallel inputs from the thalamus and uses modularity, defined spatially and by cell type-specific connectivity, to recombine these inputs into new parallel outputs. Beyond the primary visual cortex, separate but interacting dorsal and ventral streams perform distinct computations on similar visual information to support distinct behavioural goals. Less is known about the parallel processing strategies that are used in the extrastriate visual cortex. However, there are strong indications that these areas use many of the same strategies that are found in the primary visual cortex. Many of the parallel processing strategies found in the primate visual system are also found in the other sensory processing systems of the mammalian brain. To integrate our visual environment into a unified and coherent perceptual experience, the brain uses multiple processing strategies. Here, Nassi and Callaway review how the primate primary visual cortex integrates parallel inputs and constructs new, parallel outputs to achieve this goal. Incoming sensory information is sent to the brain along modality-specific channels corresponding to the five senses. Each of these channels further parses the incoming signals into parallel streams to provide a compact, efficient input to the brain. Ultimately, these parallel input signals must be elaborated on and integrated in the cortex to provide a unified and coherent percept. Recent studies in the primate visual cortex have greatly contributed to our understanding of how this goal is accomplished. Multiple strategies including retinal tiling, hierarchical and parallel processing and modularity, defined spatially and by cell type-specific connectivity, are used by the visual system to recover the intricate detail of our visual surroundings.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: Animal Genetics and Genomics / Animals / Behavioral psychophysiology / Behavioral Sciences / Biological and medical sciences / Biological Techniques / Biomedical and Life Sciences / Biomedicine / Brain / Electrophysiology / Eye and associated structures. Visual pathways and centers. Vision / Fundamental and applied biological sciences. Psychology / Humans / Models, Biological / Modularity / Neurobiology / Neurosciences / Optic nerve / Photoreceptors / Physiological aspects / Primates / Primates - anatomy & histology / Primates - physiology / Psychology. Psychoanalysis. Psychiatry / Psychology. Psychophysiology / Retina / Retina - physiology / review-article / Sensory Receptor Cells - classification / Sensory Receptor Cells - physiology / Vertebrates: nervous system and sense organs / Vision, Ocular - physiology / Visual Cortex - physiology / Visual Pathways - physiology / Visual perception / Visual Perception - physiology