Lateralization of Cortical Function Lateralization Division of labor

Lateralization of Cortical Function • Lateralization • Division of labor between hemispheres • Cerebral dominance • Designates the hemisphere dominant for language (left hemisphere in 90% of people) Copyright © 2010 Pearson Education, Inc.

Lateralization of Cortical Function • Left hemisphere • Controls language, math, and logic • Right hemisphere • Insight, visual-spatial skills, intuition, and artistic skills • Left and right hemispheres communicate via fiber tracts in the cerebral white matter Copyright © 2010 Pearson Education, Inc.

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 Copyright © 2010 Pearson Education, Inc.

Longitudinal fissure Lateral ventricle Basal nuclei • Caudate • Putamen • Globus pallidus Thalamus Superior Commissural fibers (corpus callosum) Association fibers Corona radiata Fornix Internal capsule Gray matter Third ventricle White matter Pons Projection fibers Medulla oblongata (a) Copyright © 2010 Pearson Education, Inc. Decussation of pyramids Figure 12. 10 a

Anterior (b) Copyright © 2010 Pearson Education, Inc. Posterior Cerebral cortex Cerebral white matter Corpus callosum Anterior horn of lateral ventricle Caudate nucleus Putamen Lentiform Globus nucleus pallidus Thalamus Tail of caudate nucleus Third ventricle Inferior horn of lateral ventricle Figure 12. 11 b (1 of 2)

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 Copyright © 2010 Pearson Education, Inc.

Thalamus • 80% of diencephalon • Nuclei project and receive fibers from cerebral cortex • Sorts, edits, and relays info • Afferent impulses from all senses and parts of body • Impulses from hypothalamus for regulation of emotion and visceral function • Impulses from the cerebellum and basal nuclei to help direct the motor cortices Copyright © 2010 Pearson Education, Inc.

Hypothalamus • Contains many nuclei • Olfactory relay stations • Infundibulum—stalk that connects to the pituitary gland Copyright © 2010 Pearson Education, Inc.

Paraventricular nucleus Anterior commissure Preoptic nucleus Anterior hypothalamic nucleus Supraoptic nucleus Suprachiasmatic nucleus Fornix Arcuate nucleus Pituitary gland Optic chiasma Infundibulum (stalk of the pituitary gland) (b) The main hypothalamic nuclei. Copyright © 2010 Pearson Education, Inc. Dorsomedial nucleus Posterior hypothalamic nucleus Lateral hypothalamic area Ventromedial nucleus Mammillary body Figure 12. 13 b

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 Copyright © 2010 Pearson Education, Inc.

Hypothalamic Function • Regulates body temp, food intake, water balance, thirst, sleep cycle • Controls release of hormones Copyright © 2010 Pearson Education, Inc.

Epithalamus • Pineal gland secretes melatonin • helps regulate sleep-wake cycles Copyright © 2010 Pearson Education, Inc.

Cerebral hemisphere Septum pellucidum Interthalamic adhesion (intermediate mass of thalamus) Interventricular foramen Anterior commissure Hypothalamus Optic chiasma Pituitary gland Mammillary body Pons Medulla oblongata Corpus callosum Fornix Choroid plexus Thalamus (encloses third ventricle) Posterior commissure Pineal gland (part of epithalamus) Corpora quadrigemina Mid. Cerebral brain aqueduct Arbor vitae (of cerebellum) Fourth ventricle Choroid plexus Cerebellum Spinal cord Copyright © 2010 Pearson Education, Inc. Figure 12. 12

Brain Stem • Controls automatic behaviors necessary for survival • Associated with 10 of 12 pairs of cranial nerves Copyright © 2010 Pearson Education, Inc.

Frontal lobe Olfactory bulb (synapse point of cranial nerve I) Optic chiasma Optic nerve (II) Optic tract Mammillary body Midbrain Pons Temporal lobe Medulla oblongata Cerebellum Spinal cord Copyright © 2010 Pearson Education, Inc. Figure 12. 14

Pons • Fibers: • Connect higher brain centers and spinal cord • Relay impulses between motor cortex and the cerebellum • Nuclei help maintain rhythm of breathing Copyright © 2010 Pearson Education, Inc.

Medulla Oblongata • Joins spinal cord at foramen magnum • Decussation of the pyramids—crossover of corticospinal tracts • Relay sensory info from muscles and joints to cerebellum • Vestibular—maintain equilibrium Copyright © 2010 Pearson Education, Inc.

Medulla Oblongata • Autonomic reflex centers • Cardiovascular center • Respiratory centers • Generate respiratory rhythm • Control rate and depth of breathing, with pons Copyright © 2010 Pearson Education, Inc.

Medulla Oblongata • Additional centers regulate • Vomiting • Hiccuping • Swallowing • Coughing • Sneezing Copyright © 2010 Pearson Education, Inc.

The Cerebellum • 11% of brain mass • Subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction • Two hemispheres connected by vermis • Arbor vitae—distinctive treelike pattern of the cerebellar white matter Copyright © 2010 Pearson Education, Inc.

Anterior lobe Cerebellar cortex Arbor vitae Cerebellar peduncles • Superior • Middle • Inferior Medulla oblongata (b) Copyright © 2010 Pearson Education, Inc. Flocculonodular lobe Posterior lobe Choroid plexus of fourth ventricle Figure 12. 17 b

Anterior lobe Posterior lobe (d) Copyright © 2010 Pearson Education, Inc. Vermis Figure 12. 17 d

Cerebellar Processing for Motor Activity • Receives impulses from cerebral cortex of 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 Copyright © 2010 Pearson Education, Inc.

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 Copyright © 2010 Pearson Education, Inc.