PSIO 5th Edition Lecture 27Outline of Last Lecture BrainOutline of Current Lecture I. Brain StructureII. Sensory Areas of the BrainIII. AphasiaIV. Cerebral White MatterCurrent LectureBrain Structures and Functions: IObjectives:1. Describe the location and function of the specific functional areas of the cortex as described in lecture2. Describe the general location and function of the basal nuclei3. Describe the location and function of cerebral white matter4. Describe hemispheric lateralizationFour Major Parts of the Brain:1. Cerebrum2. Cerebellum3. Diencephalon- Thalamus- Hypothalamus- Epithalamus4. Brain stem- Midbrain- Pons -Medulla OblongataCerebrum – Functional areas of the cerebral cortex (gray matter)1. Sensory areas2. Motor areas3. Association areas- Primary Somatosensory Area (grey matter)- Primary Motor Area (precentral gyrus)- Broca’s Speech Area- Primary Auditory Area- Brodmann’s Area – Numbered Regions of Cortical tissuePrimary Motor Area :-Location: precentral gyrus in frontal lobe-Function: voluntary activation of skeletal musclesPremotor Area: motor association area-Location: anterior to primary motor area in the frontal lobe- Function- communicates with primary motor area and thalamus to coordinate complex learned movementsPrimary Somatosensory Area:- Location – Postcentral gyrus in parietal lobe- Function – Receives sensory impulses from sensory receptors responding to touch, temperature, and proprioception Sensory and motor inputs and outputs of the cerebral cortex are not equal for all parts of the bodyEntire body can be represented spatially on the primary motor and sensory areas of the cerebral cortexPrimary Visual Area:- Location – medial portion of occipital lobe- Function- nervous signals traveling along the optic nerve provide informationabout color, shape, and movement of visual stimuliVisual Association Area:- Location – occipital lobe, anterior to the primary visual area- Function – receives sensory impulses from the primary visual area for recognition of visual stimuli (visual memory)Primary Auditory Area:- Location- superior portion of temporal lobe- Function- receives impulses arising from the vestibulocochlear nerve which provide information of the basic characteristics of sound (pitch, rhythm, loudness)Auditory Association Area:- Location- temporal lobe, inferior and posterior to the primary auditory area typically found on left temporal lobe only- Function – interpretation and recognition of sound; determines if sound is speck, music, or noiseAuditory Association Area – Wernike’s Area- Location- temporal lobe, posterior to primary auditory area on left lobe- Function- interprets the meaning of speech (translates words to thoughts)Motor Speech Area – Broca’s Area- Location- frontal lobe – usually left side- Function – controls the activity of muscles of the vocal cords to facilitate speechAphasia- Acquired communication disorder that impairs a person’s ability to process language but does not affect intelligence - Most common cause is stroke- Broca’s Aphasia (non-fluent)- Wernicke’s Aphasia (fluent)Basal Nuclei:The basal nuclei are centers of cell bodies deep in the cortex (gray matter)- help initiate and terminate movements - suppress unwanted movements- regulate muscle tone- control subconscious contractions of skeletal muscles Cerebral White Matter:Myelinated axons that are bound into large tractsWhite matter is responsible for communication between cerebral areas and betweencerebral areas and other parts of brainCerebral White Matter:- Association tracts – contain axons that conduct nerve impulses between gyri in the same hemisphere- Commissural tracts- conduct nerve impulses between corresponding gyri from one hemisphere to another - Projection tracts- convey impulses to lower parts of the CNSThe Corpus Callosum is one of the three important groups of commissural tracts – itis a thick band of axons that connects corresponding areas of the two
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