Information from sensory organs Information from CNS to muscles glands In the CNS information from one neuron to another The Neural Control of Behavior Chapter 5 Types of Neurons Sensory neurons Motor neurons Interneurons Parts of the Neuron Cell body Keeps the cell alive Dendrites Axon Receive messages Sends messages Ends in the axon terminal May have myelin sheath The Resting Potential Negatively charged protein molecules A exist only inside the cell and potassium ions K exist mostly inside the cell Sodium Na and chloride Cl ions exist mostly outside the cell The cell membrane is semipermeable to K which can diffuse out resulting in a surplus positive charge outside the cell and a deficit of positive charge inside the cell The resting potential is approximately negative 70mV inside relative to outside the cell Action Potential All or none firing response Can change the rate of impulses to increase strength Depolarization and repolarization Neurotransmitters Synaptic Transmission Fast Neurotransmitters cross the synaptic gap Key and lock Excitatory synapse Na channels are opened up by the neurotransmitter resulting in depolarization and increases the rate of action potentials triggered in the postsynaptic neuron Inhibitory synapse Cl or K channels are opened up by the neurotransmitter resulting in hyperpolarization and decrease the rate of action potentials triggered in the postsynaptic neuron Synaptic Transmission Fast The effects of the excitatory and inhibitory synapses are integrated across the cell membrane Action potentials are triggered when the cell membrane is depolarized a critical value The rate of action potentials in the postsynaptic membrane is a function of integration of depolarizing and hyperpolarizing influences at the excitatory and inhibitory synapses respectively Synaptic Transmission Slow A slow synapse is where neurotransmitters trigger biochemical events that alter the postsynaptic neuron s functioning over a period of time Neuromodulators are neurotransmitters that alter the cell s response to other neurotransmitters Neuromodulators are likely a necessary condition for psychological states e g sleep arousal hunger thirst and learning Studying the Human Brain Observing localized brain damage Transcranial magnetic stimulation TMS Electroencephalogram EEG Positron emission tomography PET Functional magnetic resonance imaging fMRI Studying the Non Human Brain Brain lesions Stimulation Electrical recording Parasympathetic and Sympathetic Nervous Systems Sympathetic nervous system Fight or flight Parasympathetic nervous system Growth promoting energy saving Parasympathetic and Sympathetic Nervous Systems Sensory neurons Spinal Cord Pathway to the brain Organizes simple reflexes Pattern Generation From specialized sensory receptors in sense organs in the head via cranial nerves or body via spinal nerves from skin internal organs muscles tendons Motor neurons final common path Subcortical Structures Medulla Pons Postural reflexes Vital reflexes Sleep waking and arousal Species typical movement patterns Midbrain Thalamus Relays sensory and motor signals Arousal of the brain Subcortical Structures Cerebellum Organizes motor patterns but does not initiate them Rapid coordinated movement Conditioning of quick discrete reflexes Feed forward mechanism movements are planned Basal Ganglia Coordination of slow deliberate movements Feedback mechanism sensory input adjusts movement as it progresses Subcortical Structures Limbic System Amygdala Regulates basic motivational and emotional processes such as fear and aggression Hippocampus Hypothalamus Spatial location Working or short term memory and learning Regulates internal conditions of the body Controls autonomic nervous system Controls release of certain hormones Regulates basic drive and emotional states Hunger thirst sleep waking body temperature Cerebral Cortex Frontal lobe Parietal lobe Temporal lobe Occipital lobe Cerebral Cortex Primary Motor and Sensory Areas The amount of cortex devoted to each part of the body corresponds to the degree of sensory sensitivity or motor fineness Cerebral Cortex Premotor Areas Organize specific movement patterns Receives information from prefrontal cortex planning attention Executes motor patterns by sending information to basal ganglia cerebellum and primary motor cortex Prefrontal Areas Creates action plans Combines information from parietal temporal association areas and limbic system Plans are executed through the premotor area Hemispheric Specialization Left Hemisphere Language Right Hemisphere Non verbal visuospatial information Hemispheric Specialization Half of the axonal projections in the optic nerve cross at the optic chiasma resulting while the other half don t cross Results in the left right visual field projected to the right left occipital lobe The subject below after corpus callosotomy uses the left hand to pick up the pencil but vocally reports seeing an apple Broca s Area and Wernicke s Area Broca s area Broca s aphasia characterized by labored telegraphic speech Possibly responsible for Articulating words sentences fluently Transforming grammatically complex sentences to simpler ones to Wernicke s area extract meaning Wernicke s aphasia characterized by difficulty understanding the meaning of words and finding appropriate words to express and intended meaning Experience and the Brain If you use it it will grow Enriched environments Practice practice practice Neurons that fire together wire together Hebbian synapse Long term potentiation Cortical neurons appear to reorganize restructure and recruitment due not to sensory stimulation but to practice Neuron A is weak and ineffective However if C fires due to neuron B after neuron A releases neurotransmitters the synapse between A and C will grow stronger an effect that can lasts over extended periods of time Hormones and the Brain Hormones molecules secreted in the blood by endocrine glands Hormones versus neurotransmitters Snail mail vs email long term effects E g testosterone and genetic sex linked effects Short term effects Stress Pituitary gland Adrenalin and cortisol Posterior lobe and anterior lobes Neurohormones released by neurons into capillaries and absorbed into the blood Promote secretion of other hormones Drugs and the Brain How drugs get into the brain Blood brain barrier Drugs and synaptic transmission alcohol Fat soluble substances can easily pass through the barrier e g Act on presynaptic neuron