ch17.pdf - 17 CORTICAL NETWORKS AND DISCONNECTION SYNDROMES Two conclusions from results of imaging studies showing localized activity as different

ch17.pdf - 17 CORTICAL NETWORKS AND DISCONNECTION SYNDROMES...

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17 CORTICAL NETWORKS AND DISCONNECTION SYNDROMES Two conclusions from results of imaging studies showing localized activity as different behavioral tasks are performed : - The anatomically defined cortical lobes each engage in a wide range of cognitive activities - Although the cortical lobes engage in different cognitive activities ,they overlap remarkably in function Disconnection : The cutting of cerebral connections > And the ensuing (opvolgende) behavioral effects are called disconnection syndromes For an animal to display specie-typical responses to a visual stimulus, information must project from the eye to the visual cortex, through the temporal lobes to the amygdala, and from the amygdala to the brainstem and frontal cortex Three major types of neural fiber pathways connect the neocortex : - Associationpathways: connect distant neocortical areas or connect adjacent neocortical areas . - Projection pathways : include ascending fibers from lower brain centers to the neocortex, such as projections from the thalamus, and descending fibers from the neocortex to the brainstem and spinal cord - Commissural pathways : connect the two hemispheres Most of the two frontal lobes have corpus callosum connections, whereas the occipital lobes have almost no connections Callosal connections appear to fall into three general classes : 1. Most callosal projections are topographic ; they connect to homotopic areas - identical points in the two cerebral hemispheres that are related to the body’s midline - presumably to knit the two areas together functionally 2.

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