Transcript Chapter 1
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 temporal lobe • Temporal lobes – Separated from the frontal and parietal lobe by the lateral fissure • Three important areas: – Auditory projection area, – visual and auditory association areas – Additional language area: Wernicke’s 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 – Left hemisphere only – 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 send neurons to adjacent cells in the visual cortex. THE Midbrain and brainstem • Older areas of the brain • More “animal-like” in that regulate more basic (noncognitive) functions 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 4F;s: – Feeding (eating and drinking) – Fighting – Fleeing – F….sexual activity. THE hypothalamus • Hypothalamus exerts influence largely through its control of the autonomic nervous system – Automatic system – Sympathetic: fear/flight/fight – Parasympathetic: feeding, sexual behavior • Hypothalamus also influences the body’s hormonal environment – Controls the pituitary gland. – The pituitary is known as the master gland because it controls other glands in the 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 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. 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), which plays a role in the rewarding effects of food, sex, drugs and so on. Mid Brain Motor functions Corpus Striatum • 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 • Basal Ganglia – – Diffuse system of nuclei Important for coordination of body movement • 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 • Group of interconnected structures • Amygdala: – • Helps regulate states of emotional arousal Hippocampus: – Plays important role in the formation of memories The Hindbrain 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 ˉ Bridges between upper and lower brain areas • Serves as a major highway ˉ sensory neurons pass through the pons on way to thalamus ˉ 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. • Major role in sleep and arousal • Contributes to attention • Helps modulate aspects of motor activity – Reflexes – muscle tone • Implicated in disorders such as autism, 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 • Carries sensory information into the brain. • Dorsal root: Sensory – Sensory neurons enter the spinal cord through the of each spinal nerve. • Ventral root: Motor – The axons of the motor neurons pass out of the spinal cord through 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. – 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. • 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. 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 that operate the skeletal muscles – – Neurons that move the body – Typically refer to voluntary muscles rather than smooth muscle movement • Sensory neurons – 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 muscle: – – – – – – 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. • Parasympathetic nervous system – slows the activity of most organs to conserve energy, – also activates digestion to renew energy – Which one modulates sexual behavior? – Question: can you wet your pants when you are afraid? Testing the ANS!