Autonomic Nervous System A division of the peripheral nervous system that is closely associated with the spinal cord. The individual has very little control over the responses in this division, thus the name, autonomic. Two subdivisions. Peripheral NS and Spinal Cord Peripheral nervous system connects the central nervous system to: the body s organs (autonomic nervous system), involuntary and muscles (somatic nervous system), voluntary Both involuntary and voluntary responses are conducted through the spinal cord. Spinal Cord reflex A reflex is a rapid, automatic response to a stimulus. Organization of automatic reflex behavior at junction of spinal chord Dorsal side (Back) - Afferent (sensory) nerve travels from receptor to spinal cord Ventral side (Front) - Efferent (motor) travels from spinal cord to effector. Spinal Reflexes not under conscious control, but brain has some control. E.g., seizures. A simple sensory-motor (reflex) arc Dorsal Ventral
Brain divided into three parts: Hindbrain, midbrain, forebrain. The most complex three pounds in the universe Forebrain, Midbrain, Hindbrain Hindbrain Brain Brain Forebrain Hind Brain-oldest part of brain Medulla primarily concerned with life support e.g. heart rate, breathing, muscle tone, circulation. Cessation of activity in hind brain required for determination of brain death. It also relays sensory information from the various parts of the body to the brain and sends back motor messages through it. Also Medulla is crossover point of axons to brain. Messages for right side of body go to left side of brain, and vice versa. Reticular Formation receives input from sensory neurons and sends outputs to Thalamus and then to forebrain. Regulates arousal of brain. Controls consciousness, damage leads to coma. Involved in sleep wakefulness cycle and alertness. Cerebellum is important for coordination and timing. It does not initiate action but it is responsible for integrating and smoothing our actions. Damage to cerebellum results in impairments in motor movement and balance. Police test cerebellums on weekends. Pons relays information from the cerebellum to the rest of the brain. Cerebral cortex Subcortical Structures Thalamus relay station for all sensory information going to cerebral cortex. The brain s switch board. Routs sensory messages to the right location. More than switchboard. May also filter important and unimportant information by accentuating it. Hypothalamus responsible for many of the homeostatic functions, such as salt, glucose, and temperature regulation, as well as motivated behaviors. Four F s. Also areas that can be extremely pleasurable. Direct connection with pituitary. Pituitary Gland. Master gland of the endocrine or hormonal system. Receives hormonal and neural instructions from the hypothalamus and then sends hormonal messages to other glands in the body.
Subcortical Structures Limbic System Limbic system important emotional organization. Hypothalamus Important in motivation and emotion. Location of reward centers. Amygdala Active under fear conditions. People with damaged amygdalas find it difficult to avoid dangerous situations, rate their level of fear of lower than normal. Also important in aggressive reactions. Hippocampus Important in establishing memories of important events. Damage to this structure creates lapses of memory or inability to create memories. Brain Forebrain (continued) Cerebrum. Cerebral cortex or outer surface of the brain. Contains the majority of neurons, and 20% of circulating blood although only 2.5% of body weight. Most recently evolved. Hierarchical organization of behavior. In higher animals, cerebrum tends to control lower centers 1/10 inch thick. Wrinkled surface creates more space for neurons in parts you can t see(3/4) 100 Billion neurons, post mitotic, redundancy issue 400 Billion glial cells Importance of stimulation for organization Lobes of the Brain Division of Cerebrum Cerebrum, Two major divisions. Right and left hemispheres, joined by corpus callosum. Each hemisphere further divided into four, parts of which are called projection or primary areas: Frontal lobe-motor area for opposite side of body Parietal lobe-sensory for opposite side of body Occipital lobe-visual, right occipital lobe = left visual field and vice versa Temporal lobe-auditory Use, is an important principle in normal brain development Size = function
Phantom Limbs Studying the brain Case study of brain damaged patients-damage often not restricted in location to give accurate assessment and depends on naturally occurring events Electroencephalograph (EEG)-Gross measure of neural activity Electrical stimulation of the brain (ESB) limited use in human patients, more in animal Positron-emission Tomography, PET scan Volunteers injected with a low dose of a radioactive sugar. Detectors around the person s head pick up the release of gamma rays from the sugar concentrated in active brain areas. Shows activity of brain indicated by uptake of radioactive nutrients Magnetic Resonance Imaging (MRI) Computer builds three dimensional surface of brain by measuring changes in magnetic fields Functional Magnetic Resonance Imaging (fmri) monitors blood and oxygen changes in brain to show changes in activity and in what areas of the brain Brain Phineas Gage Association Areas Unlike projection areas there is no direct input or output from outside the brain. Eighty percent of brain is association areas. Prefrontal cortex - The story of Phineas Gage Early evidence for the importance of association areas for higher functions. Changes in Phineas Capricious, perseverative, lack of foresight, disorganized, tactless, profane, lacking social conventions, and dishonest. No longer the same old Phineas. Evidence suggests involvement of prefrontal cortex in the monitoring, organizing and direction of our thought processes. Perseveration
RED YELLOW RED BLUE GREEN RED YELLOW RED BLUE Lobotomy GREEN RED RED YELLOW BLUE YELLOW GREEN GREEN BLUE YELLOW RED RED GREEN RED GREEN YELLOW RED BLUE GREEN YELLOW BLUE Other Association Areas of the Brain Variety of Cortical Association areas of the brain accomplish tasks to create coherent world Prosopagnosia (lack of face recognition)- Typically underside right temporal lobe. Can t recognize faces of strangers or friends. Damage in temporal/parietal areas can lead to sensory neglect. Association Areas Some functions such as language show lateralization. Expressive aphasia - Broca s area(left Frontal) Tan s Brain. Inability to speak, trouble putting thoughts into the motor movements that create words Broca s area close to motor area for jaw, tongue, lips, larynx so on Receptive aphasia - Wernicke's area(left Parietal-temporal) Inability to understand speech but talks freely and fast but make little sense e.g. I was over the other one, and then after they had been in the department, I was in this one. Difficulty is understanding the meaning of words needed to express what they intend to say. Recovery from aphasia depends on age at which damage occurred.
Split - Brain Patients Split brain -- Began as an attempt to alleviate the effects of severe seizures Corpus callosum cut to prevent seizures Patients show little change in behavior Effects can be observed in tests which are designed to send different information to each hemisphere Brings up the issues of the seat of consciousness and whether there is an executive agent in the brain Figure 6.10 Testing the divided brain Myers: Psychology, Ninth Edition in Modules Copyright 2010 by Worth Publishers Figure 6.11 Try this! Myers: Psychology, Ninth Edition in Modules Copyright 2010 by Worth Publishers
Integrator Demonstration Three Types of Neurons Sensory neurons carry information from sense organs to the central nervous system. Motor neurons carry messages from the central nervous system to muscles, glands and organs. Interneurons, connecting neuron Excitatory and Inhibitory Influences Components of the Neuron Neurons are a unique type of cell that can receive and transmit information electrochemically. Dendrites: receive information from other neurons Cell body: creates transmitter molecules Axon Terminal buttons of the axon contain synaptic vesicles that release neurotransmitters into a space called the synapse Axon Hillock, the point at which chemical transmission begins Neuron Neuronal Communication Resting potential base charge of neuron 70 millivolts. - - Negative charge maintained by sodium/potasium pump. Sodium(NA) outside Potassium(K) inside. Threshhold around -60
The Action Potential(AP) During the AP, NA+ ions flow into the cell raising the membrane potential to +40 mv, producing the spike The restoration of the membrane potential to -70 mv is produced by an opening of channels to Potassium K+ Why is all or none important? Overview of the Action Potential Saltatory Conduction NA ions in K ions out Myelin, fatty material that insulates the nerve cell, speeds up conduction of nerve messages The action potential occurs in nodes of ranvier rather than each individual segment, like an express bus. Multiple sclerosis is a disease breakdown of myelin 2004 John Wiley & Sons, Inc. Details of the Synapse Synaptic Transmission Neurotransmitter binding Autoreceptor Enzyme deactivation Reuptake
Neuronal Communication Disruption of Neuronal communication Novocaine blocks pain by blocking sodium ions Korsakoff's Syndrome Vitamin B-1 deficiency Lou Gherig s Disease Breakdown of Myelin Sheath Communcation between neurons Binding of receptors by neurotransmitter based on "Lock and Key What is the advantage of a Lock and Key system? Neurotransmitters (Cont.) Implications of Lock and key transmission of Neurotransmitters in use of drugs Agonist - chemical that mimics the action of neurotransmitter Antagonist - chemical that opposes the action of neurotransmitter Endorphins Show decrease sensitivity to pain, increased arousal, tendency to persist in ongoing activities. Runner s high. Morphine and Heroin (agonists) Uses same sites as endorphins Naloxone (antagonist) blocks effects Neurotransmitters Acetylcholine Motor neurons for skeletal muscles Involved in attention, and memory, Alzheimer's Monoamines Serotonin - Sleep and mood changes, hunger and arousal Deficit related to aggressive behavior, sleeplessness, and depression Dopamine Emotional arousal and pleasure, voluntary movement, Deficit-Parkinson's disease Excess-Schizophrenia, Epinephrine, Norepinephrine-Alertness and Autonomic Arousal Deficit can lead to depressed mood GABA (Gamma Amino Butyric Acid) - Major inhibitory transmitter Why does the brain have inhibitory transmitters? Huntington's Chorea The five key processes involved in communication at synapses are (1) synthesis and storage, (2) release, (3) binding, (4) inactivation or removal, and (5) reuptake of neurotransmitters.
Drugs Endocrine System Drug Effects: Alters the amount of neurotransmitter in synaptic cleft Black Widow venom increases release of acetylcholine Botulinus toxin prevents release acetylcholine Amphetamines increase amount of norepineprhine available at synapse Mimics neurotransmitter to create similar effects Nicotine stimulates acetylcholine sites Heroin and morphine binds with neurotransmitter site for pain Blocks receptor site so neurotransmitter cannot bind Curare, cobra venom occupies binding site for acetylcholine Halperidol, occupies dopamine sites, psychoactive drugs Prevents reuptake of neurotransmitter Cocaine blocks reuptake of norepinephrine, serotonin, dopamine Prozac blocks reuptake of serotonin Ecstacy stimulates release of dopamine and blocks reuptake of serotonin Endocrine System Not part of the nervous system, but releases hormones into blood stream which affect body organs. Hypothalamus-Nervous system control center for the Pituitary or master Gland Pituitary Growth Hormone Pituitary Dwarf, Giant, acromegaly. Gonads Sex Hormones, androgens (testosterone) and estrogens (estradiol) Adrenal Glands Stress Hormones Acromegaly