THE FUNCTIONS OF THE NERVOUS SYSTEM The Central Nervous System: lower cortex to brain stem.

The cerebral cortex Frontal lobe Parietal lobe Occiptial lobe Temporal lobe

THE parietal lobes Parietal lobes Primary somatosensory cortex Located superior to the lateral fissure Between the central sulcus and the occipital lobe. Primary somatosensory cortex Located on the postcentral gyrus, Processes the skin senses (touch, warmth, cold, and pain), Also senses that inform us about body position and movement.

THE somatosensory homunculus The somatosensory cortex also is organized as a homunculus, size of each area depends on the sensitivity in that part of the body.

THE parietal association areas Contained in each of the lobes carry out further processing beyond what the primary area does often combine information from other senses. Parietal lobe association areas: receive input from the body senses and from vision. Help a person identify objects by touch help determine the location of the limbs Help locate objects in space.

THE parietal association areas Damage to the posterior parietal cortex may produce sensory neglect: a disorder in which the person ignores Objects, People, Activity on the side opposite the damage. Why the opposite side of the damage?

THE temporal lobe Temporal lobes Separated from the frontal and parietal lobe by the lateral fissure Three important areas: Auditory projection area, Visual-auditory association area Wernicke’s Area: Additional language area

THE auditory or temporal cortex Auditory cortex: Receives sound information from the ears Lies on the superior (uppermost) gyrus of the temporal lobe. Wernicke’s area Just posterior to the auditory cortex Interprets language input arriving from the nearby auditory and visual areas. also generates spoken language through Broca’s area and written language by the way of the motor cortex. Inferior temporal cortex Lower part of the lobe (as the name implies) Plays a major role in the visual identification of objects.

THE occipital cortex Occipital lobes Location of the visual cortex, Visual information is processed. Contains a map of visual space because adjacent receptors in the back of the eye (retina) send neurons to adjacent cells in the visual cortex.

Below the cerebral cortex “Older areas of the brain These areas tend to be responsible for Basic functioning of the body Integrating sensory information Coordinating with the cerebral cortex

THE Ventricles Cavities in brain and central canal in spinal cord which form during development Form a hollow interior of the nervous system. Filled with Cerebrospinal Fluid or CSF CSF carries material from the blood vessels to the central nervous system CSF also transports waste materials in the other direction.

Figure 3.14 The cerebral ventricles

THE Midbrain and brainstem Older areas of the brain More “animal-like” in that regulate more basic (noncognitive) functions

Figure 3.12 View of the interior features of the human brain

THE Thalamus Lies deep within the brain Located just below the lateral ventricles Receives information from ALL of the sensory systems EXCEPT olfaction (smell) Relays info to the respective cortical projection areas.

THE hypothalamus Smaller than thalamus Inferior to the thalamus, Plays a major role in controlling emotion and motivated behaviors Controls the 4 F;s: Feeding (eating and drinking) Fighting Fleeing F….sexual activity.

THE hypothalamus Hypothalamus exerts influence largely through its control of the Autonomic Nervous System (ANS) Automatic system ANS composed of two parts: Sympathetic: fear/flight/fight Arousal (but not sexual functions) Uses the neurotransmitter adrenalin (PSN) or norepinephrine (CNS) Parasympathetic: regulatory behavior feeding, sexual behavior Also uses adrenalin and NE, AND hormones!

THE hypothalamus Hypothalamus also influences the body’s hormonal environment E.g., for blood pressure, Angiotensin Slower system but can make more dramatic changes E.g. growth! Controls the Pituitary gland. The pituitary is known as the master gland because it controls other glands in the body. Pituitary regulates other hormone functions in our body

THE pineal gland Posterior to the thalamus Participates with other structures in controlling daily rhythms or circadian rhythm in humans and animals. Secretes melatonin, related to sleep/circadian rhythm Controls seasonal cycles in nonhuman animals

corpus callosum Dense band of fibers that carry information between hemispheres Is found a couple of inches below the brain’s surface where the longitudinal fissure ends Implicated in gender differences in brain function, autism and other developmental disorders

THE midbrain areas Midbrain contains structures that have secondary roles in vision, audition and movement. Superior colliculi: help guide eye movements and fixation of gaze. Inferior colliculi: help locate the direction of sounds. Ventral tegmental area (VTA) plays a huge role in the rewarding effects of food, sex, drugs and so on. This is the area that is “hijacked” in most drug abuse!

Figure 3.15 The brain stem The cerebellum has been removed to reveal other structures.

Corpus Striatum Controls Motor Habits Behaviors you do “without thinking” Walking, writing, proficient or well learned behaviors Located between the cortex and the thalamus Composed of three very large nuclei Caudate nucleus  Putamen  Globus pallidus Collectively- called the striatum

Basal Ganglia and Corpus Striatum  Diffuse system of nuclei Important for coordination of body movement by STOPPING other movements

Basal Ganglia and Corpus Striatum Substantia Nigra One of the structures involved in movement, projects to the basal ganglia to integrate movements. Parkinson's disease, Huntington's chorea both involve damage to these area

Limbic System Amygdala: Hippocampus: Group of interconnected structures Amygdala: Helps regulate states of emotional arousal Hippocampus: Plays important role in the formation of emotional memories

THE hindbrain The hindbrain is composed of The medulla The pons The cerebellum Controls most basic life functions

THE medulla Forms the lower part of the hindbrain. Set of nuclei involved with control of essential life processes Cardiovascular activity Respiration (breathing).

THE pons Means “bridge” in Latin Serves as a major highway Bridges between upper and lower brain areas Serves as a major highway sensory neurons pass through the pons on way to thalamus motor neurons pass through between the cortex and the cerebellum Contains centers related to sleep and arousal Pons is also part of reticular formation.

THE reticular formation Collection of several nuclei Runs through the middle of the hindbrain and the midbrain. Functions: Controls sleep and arousal Contributes to attention Helps modulate aspects of motor activity Reflexes muscle tone Implicated in disorders such as autism, ADHD, narcolepsy

THE CErebellum One of most distinctive appearing brain structure. Perched on the back of the brain stem Wrinkled or striped- Striated Tissue Divided down the middle like the cerebral hemispheres – Name means “little brain.” Critical for refining movements initiated by the motor cortex Controls speed, intensity and direction of movement. It also plays a role in motor learning, and research implicates it in other cognitive processes and in emotion.

THE CErebellum

THE spinal cord Finger-sized cable of neurons Carries commands from the brain to the muscles and organs Efferent branch Carries sensory information into the brain. Afferent branch Composed of bundles of neurons: Nerves and nerve tracts Remember: is living tissue: IF damaged, it must repair itself IF you kill a nerve or nerve tract, it will not come back!

THE spinal cord Dorsal root: Sensory Ventral root: Motor Sensory neurons enter the spinal cord through the of each spinal nerve. Is found along your back side, Ventral root: Motor The axons of the motor neurons pass out of the spinal cord through the of the spinal nerves Is found along your stomach side. Forms the Reflex Pathway: Sensory neurons from the dorsal side connect with motor neurons, either directly or through an interneuron. This pathway produces a simple, automatic movement in response to a sensory stimulus, called a reflex.

Protecting the CENTRAL NERVOUS SYSTEM Meninges: Covers both the brain and spinal cord Protective three-layered membrane called the. Dura Pia mater Arachnoid The space between the meninges and the CNS is filled with cerebrospinal fluid, This cushions the neural tissue from the trauma of blows and sudden movement.

Protecting the CENTRAL NERVOUS SYSTEM Blood-brain barrier: Limits the passage between the bloodstream and the brain Provides constant protection from toxic substances Prevents neurotransmitters from circulating in the blood. Area Postrema: Leaky area at base of brain (medulla) Allows small amount of poison in This results in stimulation of nausea and vomiting

THE PERIPHERAL NERVOUS SYSTEM The peripheral nervous system (PNS) consists of: Cranial nerves that enter and leave the underside of the brain, Spinal nerves that connect to the sides of the spinal cord at each vertebra. The PNS can be divided into the Somatic nervous system: voluntary behavior Autonomic nervous system (ANS): involuntary or automatic behavior

THE somatic nervous SYSTEM Motor neurons operate the skeletal muscles – Neurons that move the body Typically refer to voluntary muscles rather than smooth muscle movement Sensory neurons bring in sensory information bring information into the central nervous system from the body and the outside world. Includes all senses

THE autonomic NERVOUS SYSTEM Regulates general activity levels in the body Controls smooth muscles: Stomach Blood vessels Glands Heart Lungs Other vital and “automatic” organs.

THE ANS has two divisions Sympathetic nervous system Activates the body in ways that help it cope with demands, such as emotional stress and physical emergencies Fear/flight/fight. Arousal (except sexual arousal) Involves norepinephrine and adrenalin Also some hormones Parasympathetic nervous system Slows the activity of most organs to conserve energy, Also activates digestion to renew energy Involves NE and Adrenalin, but also many hormones Question: can you wet your pants when you are afraid?

Figure 3.20 The autonomic nervous system A diagrammatic view of the parasympathetic and sympathetic nerves and their functions. The nerves exit both sides of the brain and spinal cord through the paired cranial and spinal nerves, but are shown on one side for simplicity.

Testing the ANS!