Psychology Textbook PDF

Chapter 3 The brain consists of two types of cells: Neurons and Glia Neurons: Individuals cells in the nervous system that receive, integrate, and transmit information. Glial Cells Glial: Cells found throughout the nervous system and they provide various types of support for neutrons. - Some...

Chapter 3 The brain consists of two types of cells: Neurons and Glia Neurons: Individuals cells in the nervous system that receive, integrate, and transmit information. Glial Cells Glial: Cells found throughout the nervous system and they provide various types of support for neutrons. - Some act like parents, providing nutrition, healing, protection, and physical support for the neutrons. - Some act like cleaners, removing debris from the brain. - Some devour dead and damaged cells - They produce cerebrospinal fluid. Cerebrospinal fluid (CSF): Colorless fluid surrounding the brain and spinal cord. It has several functions, including serving to cushion the brain during an impact. Neurons Synapse: A junction where information is transmitted from one neuron to the next. Cell body (Soma): Contains the nucleus and acts like a tiny factory where proteins and neurotransmitters are manufactured. Dendrites: Which gather much of the incoming information from other cells. Axon: Long, thin fiber that transmits signals away from the soma to other neurons or to muscles or glands. Axon terminals (button terminals): Where chemicals are released by the neuron to influence the activity of other neurons. Myelin Sheath: Insulating material, derived from specialized glial cells. - If an axon’s myelin sheath deteriorates, its signals may not be transmitted effectively. The loss of muscle control resulting from multiple sclerosis is due to a degeneration of myelin sheaths. - Speeds up the transmission of signals that move along axons.  - The quickly processed pain is a message carried from your toe to your brain via myelinated axons (the fast ones). Multiple Sclerosis: Disease where the immune system malfunctions and attacks the glial cells that insulate the neurons in the brain and spinal cord. Resting Potential: Its stable, negative charge when the cell is inactive. Action Potential: Very brief shift in a neuron’s electrical charge that travels along an axon. All-or-none: Either the cell fires or it does not. Synaptic Transmission Synaptic Transmission: Primary way that neurons communicate with other neurons. - Basically, each neuron makes a chemical and stores it in the terminal buttons. When a neuron is sufficiently stimulated, an action potential causes the chemical to be released into very tiny gaps between the neuron and adjacent neurons. These gaps are called the synaptic clefts. - The first neuron is called the presynaptic neuron because it occurs before the synapse (the tiny gaps that separates neurons) - The adjacent neuron is called the postsynaptic neuron because it occurs after the synapse. Neurotransmitters: Transmit information from one neuron to another. 1. Transportation and storage - Transported from the cell body to the axon terminal where they are stored. Stored in synaptic vesicles. 2. Release - When an action potential reaches the axon terminal, the neurotransmitter is released into synapse. 3. Binding - Neurotransmitters float across the gap and some bind with the membrane of the cell after the synapse. Molecules bind to receptors. A specific neurotransmitter can bind only to receptor sites that its molecular structure will fit into. 4. Deactivation - One type of neurotransmitter can be destroyed by an enzyme in the synapse. 5. Autoreceptor activation - Autoreceptors only respond to neurotransmitters that have been released by the same neuron on which it is situated. 6. Reuptake  - Leftover and excess neurotransmitter can be brought back into the presynaptic region of the cell Graded Potentials Inhibitory Postsynaptic: They inhibit or decrease the chance of an action potential Excitatory Postsynaptic Potentials: They increase the chance of an action potential Integrating Signals: Patterns of Neural Activity Synaptic Pruning: Elimination of old or less-active synapses. Key process in the formation and strengthening of the neural networks. Hebbian learning rule: When a neuron stimulates another neuron repeatedly, this produces changes in the synapse between them. Neurotransmitters and Behavior Neurotransmitter: Molecules that are released from the presynaptic region to allow one neuron to influence the firing rate of another neuron. They are like chemical couriers that allow for the communication of information between neurons. Facts - They are synthesized in the neuron - They are stored in the synaptic terminals - They are released when the neuron has an action potential - They are deactivated or removed from the synapse when they have completed their task They either increase the chance of the postsynaptic cell firing (excitatory) or they decrease the chance of the postsynaptic firing (inhibitory), it depends on the receptor they bind to. A transmitter has to fit into a receptor site for binding to occur. Acetylcholine (ACh) - Released by motor neurons controlling skeletal muscles - Contributes to the regulation of attention, arousal, and memory - Some ACh receptors stimulated by nicotine - Alzeimer’s disease Dopamine (DA) - Contributes to control of voluntary movement - Cocaine and amphetamines elevate activity at DA synapses - Dopamine circuits in medial forebrain bundle characterized as “reward pathway” - Parkinsonism, Schizophrenic disorders, Addictive disorders Norepinephrine (NE) - Contributes to modulation of mood and arousal - Cocaine and amphetamines elevate activity at NE synapses - Depressive disorders Serotonin - Involved in regulation of sleep and wakefulness, eating, aggression - Prozac and similar antidepressant drugs affect serotonin circuits - Depressive disorders, Obsessive-compulsive disorders - Eating disorders GABA - Serves as widely distributed inhibitory transmitter, contributing to regulation of anxiety and sleep/arousal - Valium and similar anti anxiety drugs work at GABA synapses - Anxiety disorders Endorphins - Resemble opiate drugs in structure and effects - Play role in pain relief and response to stress - Contribute to regulations of eating disorders Monoamines: Dopamine, norepinephrine, serotonin Agonist: chemical that mimics the action of a neurotransmitter Antagonist: chemical that opposes the action of a neurotransmitter The Peripheral Nervous System Peripheral Nervous System: made up of all the nerves that lie outside the brain and spinal cord. Nerves are bundles of neuron fibers (axons) that are routed together in the peripheral nervous system. Subdivided into the somatic nervous system and the autonomic nervous system The Somatic Nervous System Somatic Nervous System: made up of nerves that connect to voluntary skeletal muscles and to sensory receptors. Afferent nerve fibers: axons that carry information inward to the central nervous system from the periphery of the body. Efferent nerve fibers: axons that carry information outward from the central nervous system to the periphery of the body. The Autonomic Nervous System Autonomic Nervous System: Made up of nerves that connect to the heart, blood vessels, smooth muscles, and glands. - Controls automatic, involuntary, visceral functions that people don’t normally think about, such as heart rate digestion, and perspiration. Divided into sympathetic and parasympathetic Sympathetic division: mobilizes the body’s resources for emergencies - Fight-or-flight response - Slows digestive processes and shunts blood toward the periphery (to the muscles) to prepare for physical activity - Breathing and heart rate quicken - When anxious, mouth dry and sweat Parasympathetic division: conserves bodily resources - Allow the body to save and store energy - Slow heart rate, reduce blood pressure and promote digestion - After relaxing - Pupils small Research Methods Lesioning: involves destroying a piece of the brain - Done by inserting an electrode into a brain structure and passing a high frequency electric current through it to burn the tissue and disable the structure Electrical stimulation of the brain (ESB): where a weak electric current is sent into a brain structure to stimulate (activate) it. CT(computerized tomography) scan: computer enhanced x ray of brain structure. X rays are taken from many angles, and the computer combines these images to create vivid pictures of cross sections of the brain. MRI(magnetic resonance imaging): uses magnetic fields, radio waves, and computerized enhancement to map out brain structures with more detail than a CT scan. - Three dimensional Electroencephalograph (EEG): device that monitors the electrical activity of the brain over time to show the functioning of the brain. PET(positron emission tomography): radioactive markers to map chemicals in the brain over time. Provides color coded maps indicating which areas of the brain are active when people do an action. Functional Magnetic Resonance Imaging (fMRI): It can map actual activity in the brain over time. Vastly greater precision. The Hindbrain Hindbrain: Includes the cerebellum and two structures found in the lower part of the brain-stem: the medulla and the pons. Medulla: In charge of largely unconscious but vital functions, including circulating blood, breathing, maintaining muscle tone, and regulating reflexes such as sneezing, coughing, and salivating. The Pons: Connects the brainstem with the cerebellum. Contains several clusters of cell bodies involved with sleep and arousal. Cerebellum (“little brain”): Large and deeply folded structure next to the back surface of the brain stem. Involved in coordinating movement and is critical for our sense of equilibrium, or physical balance. Plays a role in sensing the position of our limbs. The Midbrain Midbrain: Segment of the brainstem located between the hindbrain and the forebrain. Contains a region that integrates sensory processes, including vision and hearing. Reticular Formation: Helps with the modulation of muscle reflexes, breathing, and pain reception. It is best known for its role in the regulation of sleep and arousal. The Forebrain Forebrain: Largest and most complex region of the brain, encompassing a variety of structures, including the thalamus, hypothalamus, limbic system, and cerebrum. Thalamus: All sensory information must pass to get to the cerebral cortex. Hypothalamus: Involved in the regulation of basic biological needs. Hippocampus: Role in memory processes. Responsible for consolidation of memories for factual information and perhaps other types of memories. Consolidation involves the conversion of information into durable memories. Amygdala: Learning of fear responses and the processing of other basic emotional responses. The Cerebrum Cerebral Cortex: Convoluted outer layer of the cerebrum. The Cerebral hemispheres: Right and left halves of the cerebrum. The corpus callosum: Connects the two cerebral hemispheres. The occipital lobe: Where most visual signals are sent and visual processing is begun. The parietal lobe: includes the area that registers the sense of touch called the primary somatosensory cortex. The temporal lobe: Devoted to auditory processing called the primary auditory cortex. Damage to an area in the temporal can impair the comprehension of speech and language. The frontal lobe: Control the movement of muscles, the primary motor cortex. There is also the prefrontal cortex which is thought to organize and direct thought processes. Broca’s area: Important in the production of speech. Wernicke’s area: Important for the comprehension of speech and language. The Plasticity of the brain Brain plasticity: “the brain's ability to change structure and function”. Experience stimulates brain plasticity, including changes in dendritic length, synapse formation, and altered metabolic activity. - Experience can sculpt features of brain structure - Damage to incoming sensory pathways or the destruction of brain tissue can lead to neural reorganization. - Brain’s plasticity declines with age. Neurogenesis: The formation of new neurons. Stressful experiences suppress the rate of neurogenesis, whereas physical exercise enhances neurogenesis.