The sensory and motor areas of the cerebral cortex and the pre and postcenter gy

Question

The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed? The sensory and motor areas of the cerebral cortex and the pre and postcenter gyri have been mapped out?how was this performed?

Explanation / Answer

Cortical stimulation mapping or CSM is a type of electrocorticography that involves a physically invasive procedure and aims to localize the function of specific brain regions through direct electrical stimulation of cerebral cortex. The procedure has to be completed during craniotomy. Once the dura mater is peeled back , an electrode is placed on the brain to test motor, sensory, language, visual function at a specific brain site. The electrodes deliver an electric current lasting from 2 to 10 seconds on the surface of the brain causing a reversible lesion in a particular brain location. This lesion can prevent or produce a testable response such as the movement of a limb or an ability to identify an object. The electric current from the electrode stimulates whatever function that site in the brain is responsible for, in essence telling the surgeon or examiner what a specific locale in the brain does.

Motor mapping of CSM includes looking for active movement and inhibition of movement. When the precentral gyrus of the frontal lobe is stimulated, specific muscles in the body will contract based on the location of the brain that receives the electrical signal. Stimulation on one side of the brain will cause a contraction on the contralateral or opposite side of the body. Recent studies using CSM have shown that motor responses occur in the frontal lobe further away from the narrow strip next to the central sulcus.

Somatosensory mapping of CSM involves measuring electrical responses on the surface of the brain as the result of the stimulation of the peripheral nerves, such as mechanoreceptors that respond to pressure on the skin and stimulating the brain directly to map sensory areas. Sensation has been tested in patients through the stimulation of the postcentral gyrus with a drop in amplitude of sensory responses ocurring towards the central sulcus.

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