Brain regions visual cortex

Critical periods are those in which the synaptic circuitry of a given brain region becomes stabilized in a functionally optimized conformation. The cerebral cortex and other brain structures contain functional maps for the activities characteristic of a species. The best example is the ocular dominance columns and other physical and functional characteristics of the circuitry within the visual cortical system that process information derived from the left and right visual fields, producing a map of the visual world. Other internal maps exist for the body (somatosensory, motor corti-... 

A normal observer is able to exchange information between the left and the right hemisphere of the brain through the corpus callosum. A normal observer is therefore able to report on the correct color of the test region if the neutral-density filters are not used. In contrast, the subject with a cut corpus callosum can only report on the visual information processed by the left hemisphere of the brain. His color perception depends on whether a mirror setup is used. Therefore, the visual cortex is also involved in the process of color constancy. 

Figure 6. Mass spectrometry imaging of a capture membrane processed with molecular scanner on a mouse brain (CPu = caudate putamen (striatum) Ml = primary motor cortex VIM = primary visual cortex, monocular region).

When normal subjects were shown film clips that provoked the emotions of happiness, fear, or disgust, oxygen-15 water studies of regional brain blood flow showed increased neuronal blood flow in the primary and secondary visual cortex, as well as in limbic regions [Paradiso et al.. Am. J. Psychiatry 154(3) 384-389,1997]. 

The specialization of regions of the brain can manifest itself in many ways. There is evidence that much of the neocortex is uniform in that locally it has but one kind of circuitry, and the specializations of function derive from specialization of inputs and outputs. In this view, the auditory and visual cortex are structurally the same but differ primarily in the sensory modality of their inputs. 

One of the most successful commercially available implantable microelectrode arrays is the deep-brain stimulator. Deep-brain stimulation (DBS) uses chronically implanted electrodes to treat neurological conditions such as movement disorders. Electrodes deliver high-frequency electrical stimulation to targeted regions of the brain to treat symptoms of Parkinson s disease. Implantable visual prostheses promise to restore vision by providing stimulation at the retina, optic nerve, or visual cortex. Cochlear implants include an electrode array implanted in the inner ear to stimulate the auditory nerve. Other commercially available implantable neural interfaces include neurostimulation systems for treatment of chronic pain or urinary control. 

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