The Nervous System Major division - Central vs. Peripheral Central Nervous System Peripheral Nervous System Major division - Central vs. Peripheral Central or CNS- brain and spinal cord Peripheral- nerves connecting CNS to muscles and organs Author Credit: msu.edu/course/psy/101/jackson/HiAchSum2005 Revised 2010

Peripheral Nervous System 3 kinds of neurons connect CNS to the body sensory motor interneurons Motor - CNS to muscles and organs Sensory - sensory receptors to CNS Interneurons: Connections Within CNS Spinal Cord Brain Nerves key words: peripheral nervous system

Peripheral Nervous System k e l t a ( o m i c ) y p h P r s A u n N v key words: peripheral nervous system; skeletal nervous system; somatic nervous system; autonomic nervous system; sympathetic nervous system; parasympathetic nervous system

Somatic System Nerves to/from spinal cord control muscle movements somatosensory inputs Both Voluntary and reflex movements Skeletal Reflexes simplest is spinal reflex arc Muscle Motor Neuron Interneuron Skin receptors Sensory Brain

Autonomic System Two divisions: Control involuntary functions sympathetic Parasympatheitic Control involuntary functions heartbeat blood pressure respiration perspiration digestion Can be influenced by thought and emotion

Sympathetic “ Fight or flight” response CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney “ Fight or flight” response Release adrenaline and noradrenaline Increases heart rate and blood pressure Increases blood flow to skeletal muscles Inhibits digestive functions keywords: sympathetic nervous system; fighlt or flight response

Parasympathetic “ Rest and digest ” system CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil “ Rest and digest ” system Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure key words: parasympathetic nervous system; rest and digest system

Summary of autonomic differences Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALVATION Increases Perspires SKIN Dries Increases RESPERATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of stress hormones key words: sympathetic nervous system; parasympathetic nervous system

Central Nervous System Spinal Cord Brain Brain and Spinal Cord key words: central nervous system; brain; spinal cord

Brain has 2 Hemispheres Left & Right sides are separate Corpus Callosum : major pathway between hemispheres Some functions are ‘lateralized’ language on left math, music on right Lateralization is never 100% Left Hemisphere Corpus Callosum Right key words: left hemisphere; right hemisphere

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal key words: cerebral cortex; lobes; frontal; parietal; temporal; occipital

Sensory Information sent to opposite hemisphere Left visual field Right visual Optic nerves Corpus Callosum Left Visual Cortex Right Visual Principle is Contralateral Organization Sensory data crosses over in pathways leading to the cortex Visual Crossover left visual field to right hemisphere right field to left Other senses similar key words: left hemisphere; right hemisphere; visual infomation; touch information

Contralateral Motor Control Movements controled by motor area Right hemisphere controls left side of body Left hemisphere controls right side Motor nerves cross sides in spinal cord Somatosensory Cortex Motor Cortex

Corpus Callosum Major ( but not only) pathway between sides Connects comparable structures on each side Permits data received on one side to be processed in both hemispheres Aids motor coordination of left and right side Corpus Callosum Medial surface of right hemisphere Example : You read a geometry problem in a textbook. The words are seen and the visual forms translated into meaning by the language center in the left hemisphere. To solve the problem you have to imagine a cone shaped object. This is accomplished by centers in the right hemisphere. The solution is written down using language generated by the left hemisphere. What would happen in cases like this if the callosum was damaged ?

Corpus Callosum What happens when the corpus callosum is cut? Sensory inputs are still crossed Motor outputs are still crossed Hemispheres can’t exchange data key words: left hemisphere; right hemisphere; corpus callosum; epilepsy One method used to treat severely epileptic patients involves cutting the corpus callosum to prevent the spread of seizures acorss the entire brain. The video clip on this slide shows a man who has had such a surgery. Double click on video to start video clip. This clip discusses the types of information processing deficits associated with cutting the corpus callosum and shows a task often used to assess corpus callosum damage. This task is also represented in drawing form on the following slide as well.

The ‘Split Brain’ studies Surgery for epilepsy : cut the corpus callosum Roger Sperry, 1960’s Special apparatus picture input to just one side of brain screen blocks objects on table from view Nonverbal right hemisphere Verbal left key words: left hemisphere; right hemisphere; corpus callosum; epilepsy This slide is a schematic of the task shown in the video clip on the previous slide

The ‘Split Brain’ studies I saw an apple. “What did you see?” Nonverbal right hemisphere Verbal left Nonverbal right hemisphere Verbal left ?? “What did you see?” “Using your left hand, Pick up what you saw.” Picture to right brain can’t name the object left hand can identify by touch Picture to left brain can name the object left hand cannot identify by touch

Localization of function Frontal Parietal Occipital Temporal key words: cerebral cortex; lobes; frontal; parietal; temporal; occipital

Occipital Lobe Input from Optic nerve Contains primary visual cortex most is on surface inside central fissure Outputs to parietal and temporal lobes Occipital Lobe Visual Lobe

Temporal Lobe Contains primary auditory cortex Inputs are auditory, visual patterns speech recognition face recognition word recognition memory formation Outputs to limbic System, basal Ganglia, and brainstem Temporal Lobe

Parietal Lobe Inputs from multiple senses Somatosensory Cortex contains primary somatosensory cortex borders visual & auditory cortex Outputs to Frontal lobe hand-eye coordination eye movements attention

Frontal Lobe Contains primary motor cortex No direct sensory input Working Memory Motor Cortex Broca’s Area Contains primary motor cortex No direct sensory input Important planning and sequencing areas Broca’s area for speech key words: cerebral cortex; lobes; frontal; motor functions Frontal lobe is not directly involved in sensation or perception. Its functions are related to motor action (behavior). The motor cortex is the start of nerves that run through the spinal cord to the muscles. Broca’s area organizes sequences of speech movements. Damage leads to productive aphasia Dorsolateral Prefrontal Cortex is important in working memory. WM is short term memory for information needed to maintain a context, to prepare for the next step in a sequence of thought, and /or to inhibit irrelevant responses The wisconsin card sorting task illustrates the importance of working memory in maintaining context and inhibiting irrelevant responses Prefrontal area for working memory

The Nervous System: Summary Major structures of the nervous system CNS: Brain & Spinal Cord PNS: Somatic, Autonomic (Sympathetic & Parasympathetic) Two hemispheres & 4 lobes Organization Afferent (sensory) neurons-towards CNS Efferent (motor) neurons-away from CNS Sympathetic-speeds up Parasympathetic-slows down Central Nervous System Peripheral Nervous System

The Nervous System: Summary