Warm-Up List and describe the 5 elements of a reflex arc. List an example of a reflex. What is the difference between a reflex and a voluntary reaction?

Human Brain

4 Major Regions Cerebral Hemispheres Diencephalon Brain stem Cerebellum

1. Cerebral Hemispheres (Cerebrum) L & R hemispheres Corpus callosum: large fiber tract; connects 2 hemispheres Lobes: major regions (named for cranial bones) Parietal, frontal, occipital, temporal Gyri (gyrus) = elevated ridges of tissue Sulci (sulcus) = shallow grooves Fissures = deeper grooves, separate large regions of brain Motor & sensory function: opposite hemispheres

Cerebral Cortex Grey matter “Executive suite”  conscious mind

Functions of the Major Lobes

Cerebral Hemispheres Surface markings Central sulcus Separates the precentral gyrus of the frontal lobe and the postcentral gyrus of the parietal lobe Longitudinal fissure Separates the two hemispheres Transverse cerebral fissure Separates the cerebrum and the cerebellum

Parieto-occipital sulcus (on medial surface of hemisphere) Precentral gyrus Central sulcus Postcentral gyrus Frontal lobe Parietal lobe Parieto-occipital sulcus (on medial surface of hemisphere) Lateral sulcus Occipital lobe Temporal lobe Transverse cerebral fissure Cerebellum Pons Medulla oblongata Fissure Spinal cord (a deep sulcus) Gyrus Cortex (gray matter) Sulcus White matter (a) Figure 12.6a

Thin (2–4 mm) superficial layer of gray matter Cerebral Cortex Thin (2–4 mm) superficial layer of gray matter 40% of the mass of the brain Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding

Functional Areas of the Cerebral Cortex The three types of functional areas are: Motor areas—control voluntary movement Sensory areas—conscious awareness of sensation Association areas—integrate diverse information Conscious behavior involves the entire cortex

Motor Areas Primary (somatic) motor cortex Premotor cortex Broca’s area Frontal eye field

Sensory areas and related association areas Primary motor cortex Motor areas Central sulcus Sensory areas and related association areas Primary motor cortex Primary somatosensory cortex Premotor cortex Somatic sensation Frontal eye field Somatosensory association cortex Broca’s area (outlined by dashes) Gustatory cortex (in insula) Taste Prefrontal cortex Working memory for spatial tasks Wernicke’s area (outlined by dashes) Executive area for task management Working memory for object-recall tasks Primary visual cortex Visual association area Vision Solving complex, multitask problems Auditory association area Hearing Primary auditory cortex (a) Lateral view, left cerebral hemisphere Primary motor cortex Motor association cortex Primary sensory cortex Sensory association cortex Multimodal association cortex Figure 12.8a

Posterior Motor Motor map in precentral gyrus Anterior Toes Jaw Tongue Primary motor cortex (precentral gyrus) Swallowing Figure 12.9

Sensory Areas Primary somatosensory cortex Somatosensory association cortex Visual areas Auditory areas Olfactory cortex Gustatory cortex Visceral sensory area Vestibular cortex

Sensory areas and related association areas Primary motor cortex Motor areas Central sulcus Sensory areas and related association areas Primary motor cortex Primary somatosensory cortex Premotor cortex Somatic sensation Frontal eye field Somatosensory association cortex Broca’s area (outlined by dashes) Gustatory cortex (in insula) Taste Prefrontal cortex Working memory for spatial tasks Wernicke’s area (outlined by dashes) Executive area for task management Working memory for object-recall tasks Primary visual cortex Visual association area Vision Solving complex, multitask problems Auditory association area Hearing Primary auditory cortex (a) Lateral view, left cerebral hemisphere Primary motor cortex Motor association cortex Primary sensory cortex Sensory association cortex Multimodal association cortex Figure 12.8a

Posterior Sensory Anterior Sensory map in postcentral gyrus Genitals Primary somato- sensory cortex (postcentral gyrus) Intra- abdominal Figure 12.9

Multimodal Association Areas Receive inputs from multiple sensory areas Send outputs to multiple areas Allow us to give meaning to information received, store it as memory, compare it to previous experience, and decide on action to take

Multimodal Association Areas Three parts Anterior association area (prefrontal cortex) Posterior association area Limbic association area

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

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)

Limbic Association Area Part of the limbic system Provides emotional impact that helps establish memories

2. Diencephalon (interbrain) 3 main structures: Thalamus: relay station for incoming info Hypothalamus: Autonomic control center (heart rate, BP, digestion) Emotional response (limbic system) Body temperature regulation Regulate food intake Sleep-wake cycles Control endocrine system  pituitary gland at base Epithalamus: pineal gland (sleep-wake cycle)

Diencephalon

Thalamic Function 80% of diencephalon Gateway to the cerebral cortex Sorts, edits, and relays information Mediates sensation, motor activities, cortical arousal, learning, and memory

(b) The main hypothalamic nuclei. Paraventricular nucleus Anterior commissure Dorsomedial nucleus Fornix Preoptic nucleus Posterior hypothalamic nucleus Anterior hypothalamic nucleus Lateral hypothalamic area Supraoptic nucleus Ventromedial nucleus Supra- chiasmatic nucleus Mammillary body Arcuate nucleus Optic chiasma Pituitary gland Infundibulum (stalk of the pituitary gland) (b) The main hypothalamic nuclei. Figure 12.13b

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

Hypothalamic Function 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 Infundibulum—stalk that connects to the pituitary gland

Pineal gland—extends from the posterior border and secretes melatonin Epithalamus Pineal gland—extends from the posterior border and secretes melatonin Melatonin—helps regulate sleep-wake cycles

3. Brain Stem Programmed, automatic behaviors for survival 3 regions: Midbrain: vision, hearing, reflex Pons: breathing Medulla oblongata: heart rate, BP, breathing, swallowing, vomiting, coughing, sneezing Associated with 10 of the 12 pairs of cranial nerves

Brain Stem

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 Figure 12.14

Oculomotor nerve (III) Trochlear nerve (IV) View (a) Optic chiasma Optic nerve (II) Diencephalon Crus cerebri of cerebral peduncles (midbrain) • Thalamus • Hypothalamus Thalamus Mammillary body Diencephalon Hypothalamus Oculomotor nerve (III) Midbrain Pons Brainstem Trochlear nerve (IV) Medulla oblongata Trigeminal nerve (V) Middle cerebellar peduncle Pons Facial nerve (VII) Abducens nerve (VI) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Hypoglossal nerve (XII) Pyramid Vagus nerve (X) Ventral root of first cervical nerve Accessory nerve (XI) Decussation of pyramids Spinal cord (a) Ventral view Figure 12.15a

Superior cerebellar peduncle Pons Middle cerebellar peduncle Crus cerebri of cerebral peduncles (midbrain) Thalamus View (b) Infundibulum Superior colliculus Pituitary gland Inferior colliculus Trochlear nerve (IV) Trigeminal nerve (V) Superior cerebellar peduncle Pons Middle cerebellar peduncle Facial nerve (VII) Inferior cerebellar peduncle Abducens nerve (VI) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Olive Hypoglossal nerve (XII) Thalamus Vagus nerve (X) Diencephalon Hypothalamus Accessory nerve (XI) Midbrain Pons Brainstem Medulla oblongata (b) Left lateral view Figure 12.15b

Midbrain Nuclei Nuclei (small areas of gray matter) that control cranial nerves III (oculomotor) and IV (trochlear) Visual reflex centers Auditory relay centers

Pons 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) Nuclei that help maintain normal rhythm of breathing

Medulla Oblongata Joins spinal cord at foramen magnum Relay sensory information from muscles and joints to cerebellum Cranial nerves VIII, X, and XII are associated with the medulla Mediates responses that maintain equilibrium

Autonomic reflex centers Cardiovascular center Medulla Oblongata 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

Additional centers regulate Medulla Oblongata Additional centers regulate Vomiting Hiccuping Swallowing Coughing Sneezing

4. Cerebellum Balance, equilibrium, timing of skeletal muscle activity

The Cerebellum 11% of brain mass Dorsal to the pons and medulla precise timing and appropriate patterns of skeletal muscle contraction Sports

Cognitive Function of the Cerebellum sequences of events during complex movements nonmotor functions such as word association and puzzle solving

12 Cranial Nerve Mnemonic: On old Olympus' towering top a Fin and German viewed some hops O: olfactory nerve (CN I) O: optic nerve (CN II) O: oculomotor nerve (CN III) T: trochlear nerve (CN IV) T: trigeminal nerve(CN V) A: abducens nerve (CN VI) F: facial nerve (CN VII) A: auditory (or vestibulocochlear) nerve (CN VIII) G: glossopharyngeal nerve (CN IX) V: vagus nerve (CN X) S: spinal accessory nerve (CN XI) H: hypoglossal nerve (CN XII)

Protection of CNS Meninges: connective tissue covering CNS structures Dura mater (leathery outer), arachnoid mater (web-like middle), pia mater (surface of brain) Meningitis: inflammation of meninges; bacterial or viral infection Cerebrospinal fluid (CSF): watery cushion to protect NS from trauma and provides oxygen, nutrients and vital chemicals to the brain and spinal cord Lumbar (spinal) tap – test for infection, tumors, multiple sclerosis

Meningitis

Symptoms of Meningitis

Treatment for Meningitis Bacterial  antibiotics Herpes meningitis  antiviral meds IV fluids Prevention: vaccines for bacterial infections (HiB)

Blood-Brain Barrier: endothelial cells in capillaries prevent substances from crossing into brain NO: YES: Urea Toxins Proteins White blood cells Bacteria Most drugs Water Glucose Amino acids Gases Fat-soluble substances Some drugs: anesthetics, alcohol, nicotine