Chapters 2 and 3 notes
Chapters 2 and 3 notes Psychology 100
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Date Created: 02/22/16
Overview of the Neuron • The nervous system has two types of cells o Neurons are nerve cells that receive, integrate, and transmit information § The basic building blocks of the nervous system, messages are transmitted through the nervous system § Each neuron is a single cell consisting of a soma, axon, and dendrites § A neuron is not the same thing as a nerve, a nerve is a bundle of axons from different neurons o Glial cells are like glue, they help nourish neurons and hold them together, among other functions § Support the neurons by supplying them with nutrients and removing waste material in the human brain § More numerous than neurons; come in a variety of forms • Dendrites: the parts of the neuron that are specialized to receive information; docking station o Tree like structures projecting from the soma • Soma: cell body; contains the cell nucleus and much of the chemical machinery common to most cells o Houses the nucleus and carries out metabolic (life sustaining) functions • Axons: specialized structures that transmit information to other neurons or to muscles of glands o Can be a few thousandths of an inch long or a few feet long o The action potential either fires or it doesn’t fire, it’s all or nothing • Myelin Sheath: a white, fatty substance that serves as an insulator around the axon and speeds the transmission of signals o Formed by the glial cells • Nodes of Ranvier: gaps in the myelin sheath creating noninsulated areas on the axon • Terminal buttons: knob endings of an axon that transmit messages to other neurons o Stores neurotransmitters and releases them into the synapse • Synapse: a junction where information is transmitted from one neuron to another o Synaptic vesicles are small sacs within the terminal buttons in which neurotransmitters are stored o Tiny fluid filled gap between neurons • Three types of neurons are in the nervous system o Sensory neurons (afferent): receive signals from outside the nervous system and send them to the spinal chord and brain; also carry information from the muscles and inner organs and send them to the spinal chord and brain o Motor neurons (efferent): carry messages from the central nervous system to the muscles that move the body; convey messages to the glands causing them to release hormones o Interneuron (associative): neurons that communicate with other neurons; most common type of neuron, process information and control higher mental functions How Neurons Communicate § Inside and outside the neuron are electrically charged atoms and molecules called ions o Either positive or negative o Two most important ions are positively charged, sodium and potassium o Move through the cell membrane: controlled by a series of tiny doors that open to allow ions in and close to shut them out § Resting potential: the electrical potential across the cell membrane of a neuron in its resting state o Cells must be stimulated in order to “fire” § Depolarization: a positive shift in the electrical charge in the neuron’s resting potential, making it less negatively charged § Action potential: an abrupt change from a negative to a positive charge of a nerve cell; also called a neural impulse o All or nothing: neurons will only fire when a change in the level of excitation occurs that is sufficient to produce action potential o When the neural impulse reaches the axon’s terminal buttons, it triggers the release of chemicals that either increase or decrease the likelihood that neighboring cells will fire § Refractory period: a temporary state in which a neuron is unable to fire in response to continued stimulation o Neurons can reload hundreds of times per second Neurotransmitters • Neurotransmitters are chemicals that transmit information from one neuron to another • Reuptake of neurotransmitters: a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane o Storage of neurotransmitter molecules in synaptic vesicles o Release of neurotransmitter molecules into synaptic cleft o Reuptake of neurotransmitters absorbed by the presynaptic neuron o Inactivation (by enzymes) or removal (drifting away) of neurotransmitters o Binding of neurotransmitters at receptor sites on postsynaptic membrane • Types of neurotransmitters Related disorders o Dopamine Parkinson’s disease, schizophrenia o Norepinephrine depressive disorders o Serotonin depressive disorders, OCD, eating disorders o GABA anxiety disorders The Nervous System • Central nervous system: CNS is the body’s master control unit o Spinal chord: a column of nerves between the brain and peripheral nervous system, controls simple reflexes § A spinal reflex is controlled at the level of the spinal chord, allowing you to respond more quickly than you would if the signal had to be transmitted to the brain for processing § The knee jerk reflex: the patellar tendon’s nerves connect to the spinal chord § The withdrawal reflex (burning your hand): sensory signals sent up the arm and into the spinal chord o Brain: divided into 3 major parts; the lower part (hindbrain), the midbrain, and the forebrain • Peripheral nervous system: PNS o The somatic nervous system: carries information from sensory organs to the central nervous system and relays motor commands to muscles o The autonomic nervous system: regulates involuntary bodily processes, including heart rate, respiration, digestion, and pupil contraction; operates automatically without conscious direction § Sympathetic nervous system: mobilizes bodily resources in response to threat by speeding up heart rate and respiration and drawing stored energy from bodily reserves • Arouses: fight or flight § Parasympathetic nervous system: replenishes bodily resources by promoting digestion and slowing down other bodily processes • Calms: rest and digest Genes § Genes influence many patterns of behavior (selective breeding of animals) § Genetic factors create a predisposition § Genotype: an organisms genetic code § Phenotype: the physical expression of their genotype § Polygenic: traits influenced by one or more genes § Heredity: transmission of physical and psychological characteristics from parents to their children through genes § Genes: specific areas on a strand of DNA that carry hereditary information o Dominant: the gene’s feature will appear each time the gene is present o Recessive: the gene’s feature will appear only if it is paired with another recessive gene § Familial association studies, twin studies, and adoption studies assess the impact of heredity on behavior o Familial association studies and twin studies focus on genetic relatedness and how it affects various traits in order to study the influence of nature on behavior o Adoption studies are able to assess the influence of both nature and nurture, as adopted children’s traits can be evaluated in relation to both their biological and adoptive parents The Brain • The Hindbrain o Medulla: controls vital bodily processes such as heart rate, breathing, and reflexes like swallowing, coughing, and sneezing o Pons: helps regulate states of wakefulness and sleep o Cerebellum: controls balance and coordination of basic body movements o Reticular Formation: best known for its role in the regulation of processes of attention, alertness, and arousal • Midbrain: mostly concerned with relaying sensory information to the forebrain • Forebrain: the largest and most complex region of the brain, involving the thalamus, hypothalamus, limbic system, and cerebrum o Thalamus: relays messages between lower brain centers and cerebral cortex o Hypothalamus: controls maintenance functions such as eating, helps govern endocrine system (linked to emotion and reward) o The Limbic System: § Amygdala: a set of almond shaped structures believed to play an important part in aggression, rage, and fear (linked to emotion) § Hippocampus: involved in memory formation (linked to memory) • The Endocrine System: the body’s slow chemical communication system, communication is carried out by hormones; serves as a second communication system in the body, messages are conveyed through blood vessels using hormones that regulate bodily processes and maintains homeostasis o Hormones: chemicals synthesized by the endocrine glands that are secreted in the bloodstream o Hypothalamus: brain region controlling the pituitary gland; connects with the pituitary gland o Thyroid gland: involved in regulating metabolic functions and physical growth; related to metabolism, anxiety, and irritability o Adrenal glands: inner part helps trigger flight or fight response; secretes stress hormones (epinephrine and norepinephrine) and produces cortical steroids that promote muscle development o Pineal glands: releases melatonin which helps regulate the sleep-wake cycle o Gonads: sex glands that produce hormones and germ cells (sperm and egg cells) § Testis: secretes male sex hormones § Ovary: secretes female sex hormones o Pancreas: regulates the level of sugar in the blood o Parathyroid: help regulate the level of calcium in the blood o Pituitary gland: secretes many different hormones, some of which affect other glands; master endocrine gland • The Cerebral Cortex: the thin outer layer that covers the cerebral hemispheres, it is the body’s ultimate control and information processing center o Corpus callosum: thick, tough nerve fibers connecting two cerebral hemispheres o Lobes of the Cerebral Cortex § Frontal lobe is the executive center of the brain: problem solving, decision making, calculating, planning, accessing/acting on stored memories, thinking and reasoning, and motor response § Parietal lobe controls body sensations of touch, pressure, temperature, pain, and body movement § Temporal lobe is responsible for hearing, giving rise to sensations of sound § Occipital lobe is responsible for vision, giving rise to sensations of vision • Experimental Methods o Lesioning o Electrical recording o Electrical stimulation • Recording and Imaging Techniques o EEG: electroencephalograph § An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp o CT scan: computed tomography scan (CAT scan) § Provides a 3D x-ray image of bodily structures, can revel structural abnormalities in the brain that may be associated with blood clots, tumors, or psychological disorders like schizophrenia o PET scan: positron emission tomography scan § A visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task o MRI: magnetic resonance imaging § Uses magnetic fields and radio waves to produce computer generated images that distinguish among different types of brain tissue o fMRI: functioning MRI § A newer form of MRI that takes snapshots of the brain in action, it is used to assess both the function and structures of the brain • Broca’s Area: an area that directs the muscle movements involved in speech • Wernicke’s Area: an area involved in language comprehension and expression • Plasticity: ability of the brain to adapt and reorganize itself following trauma or surgical alteration (the curious case of Phineas Gage- had a pole go through his brain and survived) • The Divided Brain o People are not left brained or right brained, information passes back and forth along the corpus callosum o Left hemisphere: language abilities, logical reasoning, and problem solving § Language dominance is associated with handedness o Right Hemisphere: nonverbal processing Stimulus in Left Stimulus in Right Half of Visual Field Half of Visual Field Fixation Point Left Eye Right Eye Right Hemisphere (Control of Right Hand) (Control of Light Hand) Optic Nerves Severed Corpus Callosum Information Delivered Information Delivered to Right Visual to Left Visual Processing Area Processing Area Verbal Nonverbal Processing Processing Sensation • Sensation: the process by which stimulation of the sense organs is transformed into neural impulses the brain can use to produce sensations of vision, hearing, touch, and so on o The process by which we receive, transform, and process stimuli into neural impulses • Perception: the process by which the brain integrates, organizes, and interprets sensory impressions to create representations of the world o Sorts out the important from the unimportant • Sensory receptors: specialized cells in our sensory organs that detect different forms of stimulation from the outside world and convert them into neural impulses • The study of sensation and perception is called psychophysics o The study of relationships between features of physical stimuli and the sensation we experience in response to these stimuli • Transduction: the process of converting raw sensory information into neural impulses • Absolute threshold: the smallest amount of stimulus a person can reliably detect • Difference threshold: just noticeable difference; the minimum difference or change in a stimulus that can be detected • Weber’s law states that the amount of change in a stimulus needed to occur for that difference to be detected is given by a constant ratio of the original stimulus • Signal detection theory: the threshold for detecting a given event depends not only on the features of that event, but on other factors as well o Factors: background stimulation (noise) and biological and psychological characteristics of the receiver • Sensory adaptation: sensory systems become less sensitive to constant or unchanging stimuli Vision • Cornea: a transparent covering on the eye’s surface through which light enters • Iris: circular muscle in the eye • Pupil: the black opening inside the iris that allows light to enter the eye • Lens: structure in the eye that focuses light rays on the retina • Accommodation: process by which the lens changes its shape to focus images more clearly on the retina • Optic nerve: nerve that carries neural impulses to the brain • Blind spot: area in the retina where the optic nerve leaves the eye receptor calls • Fovea: the center of focus for clearest vision • Retina: the neural tissue lining the inside back surface of the eye o It absorbs light, processes images, and sends visual information to the brain o Sensory receptors in vision § Rods: play a key role in night vision because they are more sensitive than cones to dim light § Cones: play a key role in daylight vision and color vision • The visual cortex o Feature detectors: specialized neurons in the visual cortex that respond only to particular features of visual stimuli, such as horizontal or vertical lines § Neurons that respond to specific features of a visual stimulus § The cells in the visual cortex respond to lines, edges, and more complicated stimuli, rather than to small spots of light o All visual input eventually reaches the occipital lobe of the cortex • Theories of color vision o Trichromatic theory: the human eye has three types of receptors sensitive to the specific wavelengths associated with red, green, and blue-violet o Opponent process theory: our ability to perceive color is controlled by three receptor complexes with opposing actions § The red-green complex, the blue-yellow complex and the black-white complex § Only one of the two colors can be perceived at the same time o Afterimages: visual image of a stimulus that remains after the stimulus is removed • Color blindness o Trichromats: normal color vision o Monochromats: no color vision (1/40000 people) o Dichromats: can see some colors but not others (8% of men and 1% of women) Hearing • Two types of deafness o Conduction: form of deafness, usually involving damage to the middle ear, in which there is a loss of conduction of sound vibrations through the ear o Nerve: deafness associated with nerve damage, usually involving damage to the hair cells or to the auditory nerve itself Chemical, Skin, and Body Senses • Smell • Touch • Gate control theory of pain o Neutral gate: mechanism in spinal chord controls pain messages o Bottleneck at the gate may block pain o Endorphins also help close the pain gate • Kinesthesia: body sense that provides information about movement of body parts and relative position of body parts to each other o Receptors located in joints, ligaments, tendons, skin, and muscles o This sense makes it possible to us to touch our nose with our finger without looking • Vestibular sense: allows us to maintain our balance and equilibrium o Receptors are the hair cells located in the inner ear Principles of Perception • Process by which sensations are turned into meaningful representations of the world o It is an active process o Perceptions may not accurately reflect external reality • Perception: the process by which the brain integrates, organizes, and interprets sensory impressions to create representations of the world • Selective attention: process by which we attend to meaningful stimuli and filter out irrelevant or extraneous stimuli o Influenced by factors like motivational states (hunger and thirst) and repeated exposure (may increase attention to particular stimuli or we become accustomed to it) • Inattentional blindness: the inability to see an object or a person in our midst • Perceptual set: the tendency for one’s perceptions to be influenced by expectations or preconceptions • The way we perceive visual information o Bottom-up processing: the brain recognizes meaningful patterns by piecing together bits and pieces of sensory information o Top-down processing: the brain identifies patterns as meaningful wholes rather than as piecemeal constructions • Gestalt Principles o Maintain that the whole can be greater than the sum of its parts o Figure and ground: the organization of the visual field into objects (figures) that stand out from their surroundings (ground) o Laws of grouping: • Perceptual constancies: tendency to perceive an object as remaining the same even when the retinal image changes o Shape constancy: the tendency to perceive an object as having the same shape despite differences in the images it casts on the retina as the viewer’s perspective changes o Size constancy: the tendency to perceive an object as having the same size despite changes in the images it casts on the retina as the viewing distance changes o Color constancy: the tendency to perceive an object as having the same color despite changes in lighting conditions o Brightness constancy: (lightness constancy) the tendency to perceive objects as retaining their brightness even when they are viewed in dim light • Perceiving depth or distance o Depth perception: enables us to judge distances o Binocular cues: depth cues that depend on the use of two eyes § Retinal disparity § convergence o Monocular cues: depth cues available to either eye alone § Relative size § Interposition § Relative clarity § Texture gradient § Shadowing § Linear perspective: perception of parallel lines converging as they recede into the distance • Motion perception: path of image as it crosses the retina, the changing size of the object o Phi phenomenon: the illusion of movement created when two or more adjacent lights blink on and off in quick concession o Stroboscopic movement: a type of apparent movement based on the rapid succession of still images, as in motion pictures § The motion in motion pictures is a perceptual feature of the viewer, not the projector • Controversies in perception o Subliminal perception: perception of stimuli that are presented below the threshold of conscious awareness o Extrasensory perception: perception that occurs without benefit of the known senses o Parapsychology: the study of phenomenon that cannot be explained by physical, psychological, or biological mechanisms • Paranormal phenomena—research data does not support the existence of any of these phenomena o Telepathy: communication of thoughts from one mind to another that occurs without using the known senses o Clairvoyance: the perception of events that are not available to the senses o Precognition: the ability to foretell the future o Psychokinesis: (telekinesis) the ability to move objects by mental effort alone
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