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Myers’ PSYCHOLOGY (7th Ed) Chapter 2 Neuroscience, Genetics and Behavior James A. McCubbin, PhD Clemson University Worth Publishers Everything psychological is simultaneously biological! Your every idea, mood or urge is a biological happening!!!! Without your body, you are nobody! Chapter 2-Neuroscience-explains how our biology underlies our mental & behavior processes. Biological Psychologists study the links between biological activity and psychological events. PHRENOLOGY Invented by Franz Gall in the early 1800’s. A theory that claimed that bumps on the skull could reveal our mental abilities and character traits. Phrenology focused the attention that various regions of the brain have particular, specific functions. Neuron a nerve cell the basic building block of the nervous system -our bodies information system is built from 100 billion of interconnected cells called neurons. -many different types of neurons, but all are composed in the same way. Glial Cells cells in the nervous system that support, nourish, and protect neurons Dendrites (Greek for tree) Are the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body. They receive information from other nerve cells and send it through the soma or cell body to the: Axon (Greek for axle) the extension of a neuron, (long fiber) ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands (senders). At the end of the axon are thousands of terminal buttons. Vesicles and Neurotransmitters The area where the axon ends, in the terminal buttons just before the synapse, is filled with small containers that look like bubbles..called vesicles. Inside the vesicles are thousands of chemical messengers called neurotransmitters. Myelin Sheath Myelin [MY-uh-lin] Sheath a layer of fatty cells segmentally encasing the fibers of many neurons (insulating the axons) enables vastly greater transmission speed of neural impulses Multiple Sclerosis, a disease in which the myelin sheath degenerates, which results in a slowing of communication to the muscles and loss of muscle control. Synapse [SIN-aps] (means junction point) The space between the axon tip of the sending neuron and the dendrite of the receiving neuron tiny gap at this junction is called the synaptic gap or cleft Neurons work by electricity. Electricity will not go over a space, so it stops. Structure of a Neuron Neural Communication Neurotransmitters chemical messengers that traverse the synaptic gaps between neurons when released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse If the message is for arm movement, the vesicles only release neurotransmitters involved in the movement circuit. There are dozens of different neurotransmitters. Neurotransmitters Neurotransmitters Acetylcholine [ah-seat-el-KO-leen] (Ach) most common, best understood a neurotransmitter that, among its functions, triggers muscle contraction is involved in memory (a shortage of causes Alzheimer’s Disease) Endorphins [en-DOR-fins] “morphine within” natural, opiate like neurotransmitters linked to pain control and to pleasure Neurotransmitters DopamineInvolved in the control of bodily movements, learning, attention, & emotion. Shortage causes Parkinson’s disease Excessive dopamine linked with schizophrenia Seratonin Affects mood, hunger, sleep and arousal Addiction – the result of suppressing the brain’s production of its own opiates If indeed the endorphins lessen pain and boost mood, why not flood the brain with artificial opiates, thereby intensifying the brain’s own “feel-good” chemistry? One problem is that when flooded with opiate drugs such as heroin and morphine, the brain may stop producing its own natural opiates. When the drug is withdrawn, the brain may then be deprived of any form of opiate. For a drug addict, the result is discomfort that persists until the brain resumes production of its natural opiates or receives more artificial opiates. Mood altering drugs, from alcohol to nicotine to heroin, share a common effect: The trigger unpleasant, lingering aftereffects. Lithium Lithium is used to treat and prevent episodes of mania (frenzied, abnormally excited mood) in people with bipolar disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Lithium is in a class of medications called antimanic agents. It works by decreasing abnormal activity in the brain. Lithium acts on a person's central nervous system (brain and spinal cord). Doctors don't know exactly how lithium works to stabilize a person's mood, but it is thought to help strengthen nerve cell connections in brain regions that are involved in regulating mood, thinking and behavior. Bipolar Disorder Neural Communication Serotonin Pathways Dopamine Pathways Neural Communication Neural communication refers to how the neurons relay messages to each other. It is referred to an electrochemical reaction. Neurons are surrounded by fluid. The fluid inside a neuron contains negative charged atoms, called ions, ( - ) from the fluid located outside the neuron, which has positive charged ions (+). Ions The neural membrane only allows certain ions through the membrane. Positively charged sodium and potassium ions and negatively charged chloride ions flow back and forth across the cell membrane, but they do not cross at the same rate. The difference in the flow leads to a higher concentration of negatively charged ions inside the cell. Electrical and Resting Potential Positive ions will flow into the neuron if not stopped or pumped out by the membrane. This is called the electrical potential, which is measured in millivolts. The resting potential is the neuron’s usual charge, which is –70 millivolts. When the resting potential has changed enough, about +10mv, the membrane changes and this is called the action potential. A neuron fires an impulse, when it receives signals from sense receptors…the impulse is called Action Potential a neural impulse; a brief electrical charge that travels down an axon, each tripping the next (depolarization) generated by the movement of positively charged ions (atoms) in and out of channels in the axon’s membrane. The speed at which an action potential travels the axon ranges from 2 to 250 mph. Refractory Period- a resting pause, when the neuron pumps the positively charged ions back outside…then it can fire again. Excitatory-signal to send the message Inhibitory-signal to stop the message Threshold -the level of stimulation required to trigger a neural impulse Agonist-excite by mimicking particular neurotransmitters or block their reuptake. Antagonists-inhibit a neurotransmitter’s release or block its effect. All or nothing neural reaction The neuron’s reaction is an “all or none response.” Neurons either fire or they don’t. (like a gun) HW Assignment: How is the action potential neuron like flushing a toilet? or like using a camera? Neural Communication Cell body end of axon Direction of neural impulse: toward axon terminals The Nervous System Nervous System the body’s speedy, electrochemical communication system consists of all the nerve cells of the peripheral and central nervous systems Central Nervous System (CNS) the brain and spinal cord Peripheral Nervous System (PNS) the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body The Nervous System Nervous system Central (brain and spinal cord) Peripheral Autonomic (controls self-regulated action of internal organs and glands) Somatic or Skeletal (controls voluntary movements of skeletal muscles) Sympathetic (arousing) Parasympathetic (calming) Three Types of Neurons that carry information throughout the nervous system: Sensory Neurons (Afferent) neurons that carry incoming information from the sense receptors to the brain & spinal cord (CNS) Interneurons CNS neurons that internally communicate and intervene between the sensory inputs and motor outputs Motor Neurons (Efferent) carry outgoing information from the CNS to muscles and glands The sensory & motor axons carrying the PNS information are bundled into electrical cables called: Nerves neural “cables” containing many axons part of the peripheral nervous system connect the central nervous system with muscles, glands, and sense organs The Peripheral Nervous System Somatic Nervous System the division of the peripheral nervous system that controls the body’s skeletal muscles, composed of sensory & motor nerves. Controls our voluntary movements & reflexes. The Nervous System Autonomic Nervous System the autonomic control system of the body (the peripheral nervous system) It regulates breathing, heartbeat & digestion. It sometimes can be overridden by the brain. It is a dual system composed of: Sympathetic Nervous System division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations, slows digestion. Raises blood sugar & pressure, heart rate, dilates eyes. Gets body ready for “fight or flight” Parasympathetic Nervous System division of the autonomic nervous system that calms the body, conserving its energy It decreases your heartbeat, lowers your blood sugar and pressure. These two systems work together to keep us in balance. The Nervous System The Nervous System The Nervous System Reflex a simple, automatic, inborn response to a sensory stimulus Brain Sensory neuron (incoming information) Muscle Skin receptors Motor neuron (outgoing information) Interneuron Spinal cord The Nervous System Neurons in the brain connect with one another to form networks Inputs The brain learns by modifying certain connections in response to feedback Neural Networks interconnected neural cells with experience, networks can learn, as feedback strengthens or inhibits connections Outputs that produce certain results computer simulations of neural networks show analogous learning Methods Used in Studying The Brain 1. Accidents In 1848, a railroad worker named Phineas Gage was involved in an accident that damaged the front part of his brain. Gage’s doctor took detailed notes documenting the brain damage and about Gage’s behavior & personality changes. Before the accident, Gage was a nice guy, after the accident he was highly emotional and impulsive. 2. Lesion is the removal or destruction of part of the brain. a brain lesion is a naturally or experimentally caused destruction of brain tissue Frontal lobotomies 3. Electroencephalogram (EEG) an amplified recording of the waves of electrical activity that sweep across the brain’s surface these waves are measured by electrodes placed on the scalp CT (computed tomography) Scan a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body; also called CAT scan It creates a 3-D image of brain’s structure. Does not show function or activity. PET (positron emission tomography) Scan a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task MRI (magnetic resonance imaging) a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain, not function MRI Scan PET Scan The Cerebral Cortex Functional MRI scan shows the visual cortex activated as the subject looks at faces Three regions of the brain 1. the forebrain -most recently evolved section 2. the midbrain -contains the upper part of the brain stem 3. the hindbrain -consists of structures in top part of the spinal cord, most of the brain stem. The Hindbrain Brainstem the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull responsible for automatic survival functions Medulla [muh-DUL-uh] base of the brainstem, attaches to spinal cord controls heartbeat and breathing The Brain Reticular Formation (Reticular Activating System) a nerve network in the brainstem that plays an important role in controlling arousal & sleep. Involved in controlling muscle reflexes, breathing & perception. The Brain The Brain Cerebellum [sehruh-BELL-um] the “little brain” attached to the rear of the brainstem it helps coordinate voluntary movement and balance The Midbrain A segment of the brainstem located between the hindbrain & forebrain, containing the reticular formationregulating sleep & arousal. The Forebrain Thalamus [THAL-uh-muss] the brain’s sensory switchboard, located on top of the brainstem it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla The Forebrain Limbic System a doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres associated with emotions such as fear and aggression and drives such as those for food and sex, regulates emotion, memory & motivation includes the hippocampus, amygdala, and hypothalamus. Amygdala [ah-MIG-dah-la] two almond-shaped neural clusters that are components of the limbic system and are linked to emotion, aggression & fear The Forebrain Hypothalamus neural structure lying below (hypo) the thalamus; directs several maintenance activities eating drinking body temperature helps govern the endocrine system via the pituitary gland is linked to emotion The Limbic System The Cerebrum Is the largest & most complex part of the human brain. It includes the brain areas that are responsible for the most complex mental activities: learning, rememebering, thinking & consciousness itself. The Cerebral Cortex Cerebral Cortex Is the convoluted outer layers of the cerebrum. The cortex is folded & bent & divided into 2 hemispheres. The hemispheres are the left & right halves of the cerebrum. the intricate fabric of interconnected neural cells that covers the cerebral hemispheres the body’s ultimate control and information processing center The Cerebral Cortex Frontal Lobes involved in speaking and muscle movements and in making plans and judgments Parietal Lobes includes the sensory cortex, registers body sensations Occipital Lobes include the visual areas Temporal Lobes includes the auditory areas, processes hearing & speech The Cerebral Cortex The Cerebral Cortex The Cerebral Cortex Motor Cortex area at the rear of the frontal lobes that controls voluntary movements Sensory Cortex area at the front of the parietal lobes that registers and processes body sensations Brain Structures and their Functions Visual and Auditory Cortex The Cerebral Cortex Aphasia impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) Broca’s Area an area of the left frontal lobe that directs the muscle movements involved in speech Wernicke’s Area an area of the left temporal lobe involved in language comprehension and expression Specialization and Integration Specialization and Integration Brain activity when hearing, seeing, and speaking words Association Areas More intelligent animals have increased “uncommitted” or association areas of the cortex Brain Reorganization Plasticity the brain’s capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development Our Divided Brain Corpus callosum Corpus Callosum large band of neural fibers connects the two brain hemispheres carries messages between the hemispheres Split Brain a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them The Endocrine System Endocrine System the body’s “slow” chemical communication system a set of glands that secrete hormones into the bloodstream Neural and Hormonal Systems Hormones chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another. They work the same as neurotransmitters Pituitary Gland under the influence of the hypothalamus, the 1)pituitary regulates growth and 2)controls other endocrine glands, “Master Gland” small bean shaped unit, located in base of the brain The Thyroid Gland -the pituitary gland signals the thyroid, its job is to control metabolism. -It is located inside the neck and looks like a bow tie. Adrenal [ah-DREEN-el] Glands a pair of endocrine glands just above the kidneys secrete the hormones epinephrine (adrenaline) and norepinephrine (nonadrenaline), which help to arouse the body in times of stress The Gonads are sex glands that make the sperm or eggs. Male sex hormones are androgen & testosterone Female hormones is estrogen We have both hormones in our body