Chapter 3 Neuroscience and Behavior Chronic traumatic encephalopathy CTE to repeated concussions progressive brain damage linked o Associated with inability to concentrate memory loss irritability and depression o Ray Easterling and Dave Duerson Neurons The Origin of Behavior Neurons perform info processing tasks o Composed of 3 parts cells in the nervous system that communicate with one another to 1 Cell Body coordinate info processing and keeps cell alive Largest component of neuron Protein sythesis energy production metabolism Contains nucleus Surrounded by porous cell membrane allowing some molecules to flow in and out of cell houses chromosomes with DNA 2 Dendrites receive info from other neurons and relay it to cell body 3 Axon carries info to other neurons muscles or glads Covered by myelin sheath insulating layer of fatty material i Myelin sheath composed of glial cells support cells found in nervous system Digests parts of dead neurons provide physical and nutritional support for neurons form myelin ii Demyelinating disease deteriorates slowing transmission from 1 neuron to next myelin sheath 3 Major types of neurons 1 Sensory Neurons brain via spinal cord movement Interneurons Neurons by location 2 Motor neurons 3 receive info from external world and convey to carry signals from spinal cord to muscles to produce connect sensory motor or other interneurons type of interneuron that carries info from cerebellum found in cerebral cortex triangular cell body and o Purkinje cells o Pyramidal cells to rest of brain and spinal cord dense bushes single long dendrite among smaller dendrites dendrite o Bipolar cells sensory neuron in retina of eye single axon and single The Electrochemical Actions of Neurons Information Processing movement of electrical signals within neurons from dendrites Conduction Transmission to cell body the throughout axon synapse neuron s cell membrane Action potential axon to synapse Resting potential movement of electrical signals from 1 neuron to another over difference in electric charge between inside and outside of electric signal that is conducted along length of neuron s o All or none electric stimulation below threshold fails to produce but at or above threshold always produces action potential at same magnitude and with the same characteristics o When electric charge is at threshold channels that allow K to flow out shut down and channels that all flow of Na are opened increasing charge inside axon o Membrane channels return to original state and K flows out until resting potential o Ions unbalanced so no action potential causes refractory period time following action potential during which a new action potential cannot be initiated o Myelin sheath facilitates conduction of action potential o Saltatory conduction charge jumps from node to node Terminal buttons knoblike structure that branch out from axon o Filled with tiny vesicles that contain neurotransmitters chemicals that transmit info across synapse to a receiving neuron s dendrites o Receiving dendrite contains receptors parts of cell membrane that receive neurotransmitters and either initiate or prevent a new electric signal Presynaptic neuron sending neuron Postsynaptic neuron receiving neuron Action potential travels down axon to terminal buttons then stimulates release of neurotransmitters Neurotransmitters float across synapse and bind to receptor sites on dendrite Synaptic transmission o Lockk and Key sites on dendrite allows neurons to communicate with one another only some neurotransmitters bind to specific receptor Neurotransmitters leave synapse through 3 processes neurotransmitters reabsorbed by terminal buttons of 1 Reuptake 2 Enzyme deactivation presynaptic neuron s axon neurotransmitters released into synapse and signal neuron to stop 3 Autoreceptors specific enzymes break down specific detect how much of a neurotransmitter has been Types and Functions of neurotransmitters o Acetylcholine Ach functions including voluntary motor control neurotransmitter involved in a number of Found in neurons of brain and synapses where axons connect to muscles and body organs Activates muscles contributes to regulation of attention learning sleeping dreaming and memory Alzheimer s associated with deterioration of Ach o Dopamine pleasure and emotional arousal neurotransmitter regulating motor behavior motivation major excitatory neurotransmitter in brain enhances tends to stop firing of neurons involved in states of vigilance or heightened Plays role in drug addiction High levels linked to Schizophrenia Low levels linked to Parkinson s o Glutamate o GABA gamma aminobutry acid o Norepinephrine transmission of info between neurons awareness of dangers in environment agressive behavior centers of brain o Endorphins o Serotonin involved in regulation of sleep wakefulness eating and chemicals that act within pain pathways and emotion Drugs that mimic neurotransmitters o Agonists o Antagonists drugs that increase action of a neurotransmitter drugs that block function of neurotransmitters The Organization of the Nervous System Nervous system electrochemical info throughout body interacting network of nuerons that conveys o 2 parts 1 Central nervous system composed of brain and spinal cord a Receives sensory info from external world processes and coordinates sunds commands to skeletal and muscluar systems 2 Peripheral nervous system system to body s organs and mucles connects central nervous i Somatic nervous system a 2 parts conveys info between voluntary muscles and central nervous system Concious control Use to perceive think and coordinate set of nerves that behaviors ii Autonomic nervous system that carries involuntary and automatic set of nerves commands that control blood vessels body organs and glands Not under concious control 2 parts 1 Sympathetic nervous system a set of nerves that prepares body for action in challengind or threatening situations helps body return to a normal resting state 2 Parasympathetic nervous system simple pathways in the nervous system that rapidly generate Spinal reflexes muscle contractions Structure of the Brain 3 parts of brain 1 hindbrain spinal cord Simple functions at lower levels and complex functions at higher levels area of the brain the coordinates info coming in and out of a controls basical functions of life respirations alertness and motor b Medulla skills rate circulation and respiration arousal c Reticular formation extension of spinal cord into
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