The Nervous System Major division Central vs Peripheral

The Nervous System Major division - Central vs. Peripheral Central or CNS- brain and spinal cord Peripheral- nerves connecting CNS to muscles and organs Central Nervous System Peripheral Nervous System

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

Peripheral Nervous System Skeletal (Somatic) Autonomic Sympathetic Parasympathetic

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

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

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

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

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

Central Nervous System Brain and Spinal Cord Brain

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

Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal

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

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 Motor Cortex Somatosensory Cortex

Corpus Callosum Major ( but not only) Medial surface of right hemisphere 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

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

The ‘Split Brain’ studies Surgery for epilepsy : cut the corpus callosum Roger Sperry, 1960’s Special apparatus y picture input to just one side of brain y screen blocks objects on table from view Verbal left hemisphere Nonverbal right hemisphere

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

Localization of function Frontal Parietal Occipital Temporal

Occipital Lobe Input from Optic nerve Contains primary visual cortex ymost 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 y speech recognition y face recognition y word recognition y memory formation Outputs to limbic System, basal Ganglia, and brainstem Auditory Cortex Temporal Lobe

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

Frontal Lobe Contains primary motor cortex No direct sensory input Important planning and sequencing areas Broca’s area for speech Prefrontal area for working memory Frontal Lobe Working Broca’s Memory Area Motor Cortex

Frontal Lobe Disorders Broca’s area yproductive aphasia Prefrontal area ylose track of ongoing context yfail to inhibit inappropriate responses Often measured with the Wisconsin Card Sorting Task

Wisconsin Card Sorting Task Row of 4 example cards set out Patient is given a deck of 64 different cards Told to place each card under the one it best matches Told correct or incorrect after each card Must deduce what the underlying rule is. Correct!

The Nervous System: Summary Major structures of the nervous y CNS, Somatic, Autonomic y Two hemispheres & 4 lobes Organization y contralateral input & output y primary sensory areas y motor areas y Commissure Localization of functions Central Nervous System Peripheral Nervous System