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The three types of functional areas of the Cerebral Cortex are
Motor, Sensory, and Association Areas
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Motor Areas
control voluntary movement
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Sensory areas
conscious awareness of sensation
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association areas
integrate diverse information
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entire cerebtal cortex
conscious behavior
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• Primary (somatic) motor cortex
- • Premotor cortex
- • Broca’s area
- • Frontal eye field
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Primary Motor Cortex
- • Large pyramidal cells of the precentral gyri
- • Long axons → pyramidal (corticospinal) tracts
- • Allows conscious control of precise, skilled, voluntary movements
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Premotor Cortex
- • Anterior to the precentral gyrus
- • Controls learned, repetitious, or patterned motor skills
- • Coordinates simultaneous or sequential actions
- • Involved in the planning of movements that depend on sensory feedback
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* Anterior to the inferior region of the premotor area
- • Present in one hemisphere (usually the left)
- • A motor speech area that directs muscles of the tongue
- • Is active as one prepares to speak
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Frontal Eye Field
- • Anterior to the premotor cortex and superior to Broca’s area
- • Controls voluntary eye movements
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• Primary somatosensory cortex
- • Somatosensory association cortex
- • Visual areas
- • Auditory areas
- • Olfactory cortex
- • Gustatory cortex
- • Visceral sensory area
- • Vestibular cortex
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Primary Somatosensory Cortex
- • In the postcentral gyri
- • Receives sensory information from the skin, skeletal muscles, and joints
- • Capable of spatial discrimination: identification of body region being stimulated
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Somatosensory Association Cortex
- • Posterior to the primary somatosensory cortex
- • Integrates sensory input from primary somatosensory cortex
- • Determines size, texture, and relationship of parts of objects being felt
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Visual Areas
- • Primary visual (striate) cortex
- • Extreme posterior tip of the occipital lobe
- • Most of it is buried in the calcarine sulcus
- • Receives visual information from the retinas
- • Visual association area
- • Surrounds the primary visual cortex
- • Uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
- • Complex processing involves entire posterior half of the hemispheres
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Auditory Areas
- • Primary auditory cortex
- • Superior margin of the temporal lobes
- • Interprets information from inner ear as pitch, loudness, and location
- • Auditory association area
- • Located posterior to the primary auditory cortex
- • Stores memories of sounds and permits perception of sounds
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OIfactory Cortex
- • Medial aspect of temporal lobes (in piriform lobes)
- • Part of the primitive rhinencephalon, along with the olfactory bulbs and tracts
- • (Remainder of the rhinencephalon in humans is part of the limbic system)
- • Region of conscious awareness of odors
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Gustatory Cortex
- • In the insula
- • Involved in the perception of taste
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Visceral Sensory Area
- • Posterior to gustatory cortex
- • Conscious perception of visceral sensations, e.g., upset stomach or full bladder
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Vestibular Cortex
- • Posterior part of the insula and adjacent parietal cortex
- • Responsible for conscious awareness of balance (position of the head in space)
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Multimodal Association Areas
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• Receive inputs from multiple sensory areas
- • Send outputs to multiple areas, including the premotor cortex
- • Allow us to give meaning to information received, store it as memory, compare it to previous
- experience, and decide on action to take
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Multimodal Association Areas
- * Three parts
- • Anterior association area (prefrontal cortex)
- • Posterior association area• Limbic association area
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Anterior Association Area (Prefrontal Cortex)
- • Most complicated cortical region
- • Involved with intellect, cognition, recall, and personality
- • Contains working memory needed for judgment, reasoning, persistence, and conscience
- • Development depends on feedback from social environment
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Posterior Association Area
- • Large region in temporal, parietal, and occipital lobes
- • Plays a role in recognizing patterns and faces and localizing us in space
- • Involved in understanding written and spoken language (Wernicke’s area)
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Limbic Association Area
- • Part of the limbic system
- • Provides emotional impact that helps establish memories
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Cerebral White Matter
- •Myelinated fibers and their tracts
- •Responsible for communication
- •Commissures (in corpus callosum)—connect gray matter of the two hemispheres
- •Association fibers—connect different parts of the same hemisphere
- •Projection fibers—(corona radiata) connect the hemispheres with lower brain or spinal cord
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Functions of Basal Nuclei
- •Though somewhat elusive, the following are thought to be functions of basal nuclei
- •Influence muscular control
- •Help regulate attention and cognition
- •Regulate intensity of slow or stereotyped movements
- •Inhibit antagonistic and unnecessary movements
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Thalamic Function
- •Gateway to the cerebral cortex
- •Sorts, edits, and relays information
- •Afferent impulses from all senses and all parts of the body
- •Impulses from the hypothalamus for regulation of emotion and visceral function
- •Impulses from the cerebellum and basal nuclei to help direct the motor cortices
- •Mediates sensation, motor activities, cortical arousal, learning, and memory
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Hypothalamic Function
- •Autonomic control center for many visceral functions (e.g., blood pressure, rate and force of
- heartbeat, digestive tract motility)
- •Center for emotional response: Involved in perception of pleasure, fear, and rage and in biological
- rhythms and drives
- •Regulates body temperature, food intake, water balance, and thirst
- •Regulates sleep and the sleep cycle
- •Controls release of hormones by the anterior pituitary
- •Produces posterior pituitary hormones
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Epithalamus
- •Most dorsal portion of the diencephalon; forms roof of the third ventricle
- •Pineal gland—extends from the posterior border and secretes melatonin
- •Melatonin—helps regulate sleep-wake cycles
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Brain Stem
- •Three regions
- •Midbrain
- •Pons
- •Medulla oblongata
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Midbrain
- •Located between the diencephalon and the pons
- •Cerebral peduncles
- •Contain pyramidal motor tracts
- •Cerebral aqueduct
- •Channel between third and fourth ventricles
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Midbrain Nuclei
- •Nuclei that control cranial nerves III (oculomotor) and IV (trochlear)
- •Corpora quadrigemina—domelike dorsal protrusions
- •Superior colliculi—visual reflex centers
- •Inferior colliculi—auditory relay centers
- •Substantia nigra—functionally linked to basal nuclei
- •Red nucleus—relay nuclei for some descending motor pathways and part of reticular formation
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Pons
- •Forms part of the anterior wall of the fourth ventricle
- •Connect higher brain centers and the spinal cord
- •Relay impulses between the motor cortex and the cerebellum
- •Origin of cranial nerves V (trigeminal), VI (abducens), and VII (facial)
- •Some nuclei of the reticular formation
- •Nuclei that help maintain normal rhythm of breathing
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Medulla Oblongata
- •Joins spinal cord at foramen magnum
- •Forms part of the ventral wall of the fourth ventricle
- •Contains a choroid plexus of the fourth ventricle
- •Pyramids—two ventral longitudinal ridges formed by pyramidal tracts
- •Decussation of the pyramids—crossover of the corticospinal tracts
- •Inferior olivary nuclei—relay sensory information from muscles and joints to cerebellum
- •Cranial nerves VIII, X, and XII are associated with the medulla
- •Vestibular nuclear complex—mediates responses that maintain equilibrium
- •Several nuclei (e.g., nucleus cuneatus and nucleus gracilis) relay sensory information
- •Autonomic reflex centers
- •Cardiovascular center
- •Cardiac center adjusts force and rate of heart contraction
- •Vasomotor center adjusts blood vessel diameter for blood pressure regulation
- •Respiratory centers
- •Generate respiratory rhythm
- •Control rate and depth of breathing, with pontine centers
- •Additional centers regulate
- •Vomiting, Hiccuping, Swallowing, Coughing, Sneezing
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Cerebellar Processing for Motor Activity
- •Cerebellum receives impulses from the cerebral cortex of the intent to initiate voluntary muscle
- contraction
- •Signals from proprioceptors and visual and equilibrium pathways continuously “inform” the
- cerebellum of the body’s position and momentum
- •Cerebellar cortex calculates the best way to smoothly coordinate a muscle contraction
- •A “blueprint” of coordinated movement is sent to the cerebral motor cortex and to brain stem nuclei
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Cognitive Function of the Cerebellum
- •Recognizes and predicts sequences of events during complex movements
- •Plays a role in nonmotor functions such as word association and puzzle solving
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