PSY 3031 Week One Notes
PSY 3031 Week One Notes PSY 3031
U of M
Popular in Introduction to Sensation and Perception
Popular in Psychology
This 13 page Class Notes was uploaded by Naomi Terpening on Sunday September 11, 2016. The Class Notes belongs to PSY 3031 at University of Minnesota taught by Dr. Stephen Engel in Fall 2016. Since its upload, it has received 52 views. For similar materials see Introduction to Sensation and Perception in Psychology at University of Minnesota.
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Date Created: 09/11/16
PSY 3031 Week One Notes (Note: This week my notes only contain information from the required readings. In future weeks, I will try to include summarized information from the slides as well) (Additional Note: Most of the information could be described as vocabulary. I will underline key terms. I suggest flashcards. If I have time I will post my flashcards on Study Soup as well.) Sensation sensory receptors: neurons that respond to specific stimuli o sensation happens when these neurons are stimulated o message regarding the sensation is relayed to the central nervous system in the form of action potentials transduction: conversion of sensory stimulus energy into an action potential senses: vision, audition, olfaction, gustation, somatosensation, the vestibular sense, proprioception and kinesthesia, nociception, and thermoception absolute threshold: the smallest amount of stimulus energy that must be present in order for it to be detected by the body half of the time subliminal messages: messages that don’t meet the absolute threshold that are received by the brain without a person having conscious awareness of it just noticeable difference (JND): the smallest change in stimuli that can be detected as a difference o dependent on the intensity of the stimulus o Weber’s Law: the difference threshold is a constant fraction of the original stimulus Perception Perception: how sensory information is organized, interpreted, and consciously experienced o Happens after sensation o Bottomup processing: perceptions are built from sensory input o Topdown processing: how we understand sensory information depends on our available knowledge, experiences, and thoughts Sensory adaptation: when a stimulus is no longer perceived because it has been present and constant over a prolonged period of time How much attention is being given to a particular stimulus can change what is being perceived o Example: being very focused on a television program to the point that you don’t hear your mother call for you from another room Inattentional blindness: not noticing something that you obviously can notice due to a lack of attention Motivation also affects perception o Thinking you heard a sound you want to hear even though it didn’t happen o Signal detection theory: ability to notice and identify a stimulus despite distraction background noise covering it up Perception can be influenced based on your experiences and your culture o MullerLyer illusion: an illusion in which lines of the same length seem to be different due to surrounding aspects of the image; Westerner are more likely to experience the illusion Basic Structure and Function of the Nervous System Brain: nervous tissue within the cranium Spinal cord: extension of nervous tissue that is in the vertebral column Nervous system is much more complex than it seems The Central and Peripheral Nervous Systems Two major regions of the nervous system: central and peripheral Central nervous system (CNS): brain and spinal cord Peripheral nervous system (PNS): all the nerves in the rest of the body o These definitions are oversimplified but are a good place to start Two types of cells make up nervous tissue: glial cells and neurons o Glial cell: provides framework and support for neurons and their activities o Neuron: main role of generating and spreading electrical signals through the nervous system and into other parts of the body Structure of a neuron: o Soma: cell body o Process: extension of the neuron cell o Axon: fiber that connects the neuron to another cell o Dendrite: process responsible for receiving information from surrounding neurons o Gray matter: region of the nervous system that is mostly composed of cell bodies and dendrites o White matter: region of the nervous system mainly composed of axons o Myelin: lipidrich substance that insulates axons o Nucleus: group of neuron cell bodies in the CNS o Ganglion: group of neuron cell bodies in the PNS o Tract: group of axons in the CNS o Nerve: group of axons in the PNS Name for certain axons can depend on which part of the axon you are referring to and where that part is located in the nervous system Optic nerve and optic tract refer to the same bundle of axons but different parts of the bundle Functional Divisions of the Nervous System Functional divisions can be split into basic functions or somatic and autonomic regions Basic Functions o Sensation: sensory functions o Response: motor functions o Integration: process combining sensory perceptions with higher cognitive functions in order to produce a response Sensation First major function of the nervous system Stimulus: a change from homeostasis or an event in the environment Chemical substances for taste and smell, physical or mechanical stimuli for touch, light for sight, and sound (physical) for hearing Main five senses are the ones that receive input from outside the body and are consciously perceived Response Response is based on information gathered through sensation Refers to contraction of all three types of muscle tissue as well as control of glands Voluntary vs. involuntary o Voluntary: contraction of skeletal muscle; somatic nervous system o Involuntary: contraction of smooth and cardiac muscle and control of glands; autonomic nervous system Integration Communication of sensory information to the CNS for processing Integration leads to a specific response Controlling the Body Two parts of the nervous system based on functional differences in response Somatic nervous system (SNS): the part of the nervous system that is involved in conscious perception and voluntary motor responses o Includes reflexes Autonomic nervous system (ANS): the part of the nervous system that is involved in involuntary control of the body o Maintaining homeostasis o Input from inside and outside the body o Output to smooth and cardiac muscle and glands Enteric nervous system (ENS): the part of the nervous system involved in controlling the digestive system o Large part of the PNS; not dependent on CNS o Part of the ANS because it regulates digestion, an involuntary process Nervous Tissue Neurons Basis of nervous tissue Transfer information throughout the body through electrical signals o These signals produce movement and promote thought processes Parts of a Neuron Synapses: specialized areas of contact from which dendrites receive information from other neurons Neurons are polar; information can only flow in one direction Axon hillock: tapered region where the axon emerges from the soma Axoplasm: solution within the axon that is changed from cytoplasm in the axon hillock Node of Ranvier: gap in the myelin that influences how an electrical signal moves through the axon Axon segment: length of an axon between the nodes of Ranvier Axon terminal: area at the end of the axon where it branches off to extend toward the target or synapse Synoptic end bulb: enlargement at each end of the branches at the axon terminal that makes the connection at a synapse Types of Neurons Neurons can be classified based on number of processes o Names refer to polarity Unipolar neurons: only on process o True unipolar neurons only found in invertebrates In vertebrates, the axon splits to cover longer distances o Sensory neurons o Dendrites receive sensory information o Cell bodies always in ganglia because sensation is a PNS function Bipolar neurons: two processes that extend in opposite directions o One process is dendrites and the other is the axon o Not common o Found in the olfactory epithelium and the retina Multipolar neurons: anything that isn’t unipolar or bipolar o One axon and two or more dendrites Neurons can also be classified according to many other factors such as what they do, who discovered them, or the chemicals they interact with Glial Cells Supporting cells with the role of helping neurons 6 types: 4 found in the CNS and 2 in the PNS Glial Cells of the CNS Astrocyte: supporting cells in the CNS with many processes o Examples of support: maintain homeostasis in extracellular space, remove extra signaling molecules, react to damage, contribute to BBB o Bloodbrain barrier (BBB): physiological barrier that keeps various circulating fluids out of the CNS Only certain molecules can enter the CNS Oligodendrocyte: glial cell that insulates axons within the CNS o A few processes that surround an axon Microglia: small glial cells that ingest and digest diseased or damaged cells and pathogens within the CNS o May develop from macrophages during early development Ependymal cell: filters the blood to make fluid that flows through the CNS o Cerebrospinal fluid (CSF): fluid that circulates through the CNS Glial Cells of the PNS Satellite cell: glial cells of the PNS that surround cell bodies of neurons o Similar role as astrocytes Schwann cell: glial cell of the PNS that insulates axons o Surrounds one axon segment rather than many as oligodendrocytes do in the CNS Myelin Myelin sheath: sheath of the lipidrich myelin that helps with the transmission of impulses through an axon Myelin is the membrane of glial cells plus proteins Little to no cytoplasm resides between glial cell layers in myelin The Function of Nervous Tissue Thermoreceptor: sensory receptor that is sensitive to temperature Graded potential: amount of change in the voltage of a sensory receptor’s cell membrane is dependent on how intense the stimulus is o If the stimulus is strong enough, an electrical impulse relays the message Threshold: voltage necessary for a signal to be created Action potential: the electrical signal that travels through the axon Propagation: the process of an action potential travelling through an axon o Axon >axon hillock >axon terminals >synaptic end bulbs Neurotransmitters: signaling molecules that diffuse across a synapse to be picked up by a target neuron o Process that allows action potential to travel through more than one neuron Thalamus: part of the CNS and brain that relays sensory information Cerebral cortex: outermost layer of gray matter in the brain where conscious perception begins o Then sends out messages about what to regarding the sensory information The Action Potential Electrically Active Cell Membranes By controlling what can pass through the cell membrane, ion channels are instrumental in determining if an action potential is generated The Membrane Potential Membrane potential: distribution of charge across the cell membrane o Compare inside relative to outside Slight difference in charge (from the net neutral charge) occurs at the membrane surface o Allows for action potential to be generated Resting membrane potential: difference in charge is 70 mV The Action Potential Membrane potential must change from resting for an action potential to be generated Depolarization: when the membrane potential becomes closer to zero Two major steps o Step 1: channel allowing sodium ions to enter the cell opens Sodium ions continue to enter the cell after membrane potential is 0 mV, making the voltage around the channel positive, about +30 mV o Step 2: channels allowing potassium ions to leave the cell open Repolarization occurs: membrane voltage moves toward resting potential Continues until 70 mV is past, making the charge more negative o This change of 100 mV is the action potential Process begins when either a neurotransmitter or sensory stimulus causes the sodium channels to open The threshold is at 55 mV If this is reached, action potential is generated; if not, no action potential is generated Stronger stimuli do not result in a stronger action potential; rather they are stimulated more quickly o Refractory period: period of time in which an action potential cannot be generated because another one is already in progress Propagation of the Action Potential Because sodium channels go through a refractory period, the action potential cannot travel backwards, forcing it to move through the axon Myelin allows this spread to occur at an ideal speed by forcing sodium ions to enter and leave the cell at specific points along the axon Continuous conduction: propagation of an action potential along an unmyelinated axon Salutatory conduction: propagation of an action potential along a myelinated axon Communication Between Neurons Graded Potentials Graded potentials: local changes in membrane potential o Can be depolarizing or hyperpolarizing o Depolarizing occurs when sodium or calcium ions enter the cell o Hyperpolarizing occurs when potassium leaves the cell or chlorine enters the cell Types of Graded Potentials o Generator potential: when a graded potential develops in the dendrites that have an effect on the action potential of a unipolar cell o Receptor potential: graded potential that causes a release of neurotransmitters o Postsynaptic potential (PSP): graded potential in dendrites of a cell that receives neurotransmitters from synapses Excitatory postsynaptic potential (EPSP): depolarization in a PSP Membrane potential becomes closer to the threshold Inhibitory postsynaptic potential (IPSP): hyperpolarization in a PSP Membrane potential becomes farther away from the threshold Summation Summation occurs when charges generated from graded potentials add together o Total change may reach the threshold Synapses Chemical synapse: neurotransmitter is released from one cell and affects another Electrical synapse: ions pass directly through cells that are connected Common characteristics of synapses: o Presynaptic element o Neurotransmitter o Synaptic cleft o Receptor proteins o Postsynaptic element o Neurotransmitter elimination or reuptake Neurotransmitter Systems Cholinergic system: based on acetylcholine o ANS and brain o Nicotinic receptor: receptor of the cholinergic system found in the neuromuscular junction and other synapses o Muscarinic receptor: receptor of the cholinergic system Both named for drugs that also interact with them besides acetylcholine Amino acids o Glutamate, GABA, and glycine o Each have their own system; do not interact with each other o Eliminated from synapses by reuptake Biogenic amine: group of neurotransmitters enzymatically made from amino acids o Examples: serotonin, dopamine, norepinephrine, epinephrine Neuropeptide: neurotransmitter consisting of chains of amino acids connected by peptide bonds There must be a receptor protein in the postsynaptic element in order for neurotransmitters to have any effect Ionotropic receptors: ligandgated ion channels that bind to certain neurotransmitters Metabotropic receptors: complexes of proteins that when bonded with certain neurotransmitters cause metabolic changes in the cell The Cerebrum Cerebrum: the easily recognized gray mantle of the brain o Seems to make up most of the brain Cerebral cortex: wrinkled, outer part of the cerebrum Longitudinal fissure: separation between the two hemispheres of the brain Cerebral hemisphere: one side of the cerebrum; left and right Corpus callosum: white matter structure within the cerebrum that allows for messages to be passed between the two hemispheres Responsible for many higher neurological functions o Memory, emotion, consciousness, etc. Made up of the cortex and deep nuclei o Basal nuclei: portion of the cerebrum responsible for cognitive processing o Basal forebrain: part of the cerebrum containing nuclei in charge of learning and memory o Limbic cortex: part of the cerebrum that is a part of the limbic system o Limbic system: structures involved in emotion, memory, and behavior Cerebral Cortex Gyrus: ridge of a wrinkle in the cerebral cortex Sulcus: groove between two gyri o Folding of the gray matter (wrinkles) allows more to fit inside the skull o Also allows for mapping of different regions on the cerebral cortex Lateral sulcus: separates the temporal lobe from other regions Central sulcus: separates parietal lobe and frontal lobe Parietaloccipital sulcus: separates parietal lobe and occipital lobe Temporal lobe: involved in auditory sensation and memory Occipital lobe: involved in visual perception Brodmann’s areas: classification system of numbered parts of the brain based on anatomical differences that align with functional differences Parietal lobe: involved in sensation within the body Somatosensation: general sensations related to the body o Tactile sense, proprioception, kinesthesia Postcentral gyrus: gyrus within the parietal lobe that functions as the primary somatosensory cortex o Brodmann’s areas 1, 2, and 3 Frontal lobe: involved in motor functions Precentral gyrus: gyrus within the frontal lobe that functions as the primary motor cortex Premotor area: area within the frontal lobe responsible for thinking of movements that will be made Frontal eye fields: control eye movements and attend to visual stimuli Broca’s area: area located on the left side of the frontal that is important in producing language and controlling speech Prefrontal lobe: involved in personality, shortterm memory, and consciousness Subcortical Structures Subcortical nuclei: sets of nuclei beneath the cerebral cortex involved in bettering cortical processes Hippocampus and amygdala: mediallobe structures related to longterm memory and emotion Basal nuclei: compare cortical processing to how active the nervous system is to determine how likely it is for a movement to occur Caudate, putamen, and globus pallidus: major structures of the basal nuclei that are in charge of controlling movement Striatum: the caudate and putamen together Basal nuclei combined with some nuclei in the brain stem create a motor pathway that can either inhibit the thalamus through an indirect pathway or disinhibit the thalamus through a direct pathway The Diencephalon Diencephalon: connection between the cerebrum and the rest of the nervous system for all senses but olfaction o If “thalamus” is in the name, the structure is in the diencephalon Thalamus o Thalamus: group of nuclei that pass messages between the cerebral cortex and the PNS, spinal cord, or brain stem o All sensory information (except for olfaction) goes through the thalamus before being processed by the cerebral cortex Some processing occurs within the thalamus regarding importance of stimuli and what receives attention o Information sent from the cerebral cortex to the thalamus is about motor commands Hypothalamus o Hypothalamus: group of nuclei that regulate homeostasis In charge of the ANS and the endocrine system o Also functions in memory and emotion Part of the limbic system Brain Stem Brain stem: structure that connects the brain to the spinal cord o Contains the midbrain and hindbrain o Attached to cerebellum Hindbrain is composed of the pons and the medulla Midbrain Midbrain: region of the brain that contains the tectum and tegmentum and is located between the thalamus and the pons Colliculi are four small bumps on the tectum o Inferior colliculus: part fo the auditory brain stem pathway o Superior colliculus: combines sensory information about visual, auditory, and somatosensory space in order to orient the eyes toward a nonvisual stimulus Pons Pons: main connection between cerebellum and the brain stem o White matter surrounding gray matter that is a continuation of the tegmentum Medulla Region of white matter surrounding further continued gray matter from the rest of the brain stem Reticular formation: gray matter in brain stem related to sleep and wakefulness The Cerebellum Cerebellum: region of the brain similar to the cerebrum that is in charge of the comparison of information from the cerebrum to sensory information from the PNS o Connected to the pons o Sends corrective commands to compensate for differences between the two sources of information The Spinal Cord Anterior median fissure: marks anterior midline Posterior median sulcus: marks posterior midline Posterior nerve root: where axons enter the posterior side of the spinal cord Anterior nerve root: where axons leave the anterior side of the spinal cord o Posterior: sensory functions; anterior: motor functions Divided into regions that align with regions of the spine Gray Horns Gray matter of the spinal cord divided into regions called horns Posterior horn: responsible for sensory processing Anterior horn: responsible for sending motor signals to skeletal muscles Lateral horn: important part of the sympathetic division of the ANS; only in the thoracic, upper lumbar, and sacral regions of the spinal cord White Columns White matter of the spinal cord Ascending tracts bring sensory information to the brain and descending tracts bring motor commands to the body Posterior columns: bands of white matter between the two posterior horns Anterior columns: bands of white matter between the two anterior horns Lateral columns: bands of white matter on either side of the spinal cord Posterior columns are made of only ascending tracts Anterior and lateral columns are a mix of ascending and descending tracts Ganglia Ganglion: cluster of neural cell bodies in the PNS o Either sensory or autonomic Dorsal root ganglion: most common type of sensory ganglion; cell bodies of neurons with axons that are sensory endings and extend into the CNS through the dorsal nerve root Cranial nerve ganglion: same as the dorsal root ganglion except it is connection to a cranial nerve o Roots within cranium and ganglia outside skull Sympathetic chain ganglia: row of ganglia along vertebral column; receive input from lateral horn of thoracic and upper lumbar spinal cord Paravertebral ganglia: three ganglia in the cervical region Prevertebral ganglia: three ganglia outside the chain of ganglia along the vertebral column that perform similar functions o Chain, paravertebral, and prevertebral ganglia regulate the sympathetic aspect of homeostasis Terminal ganglia: group of autonomic ganglia that regulate parasympathetic aspect of homeostasis Generally, an organ is connected to both terminal and chain ganglia in order for overall function to be regulated Plexus: network of fibers or vessels that connect to the wall of a target organ Nerves Bundles of axons in the PNS o Combined with connective tissues and blood vessels Epineurium: layer of fibrous connective tissue on the outside of a nerve Fascicles: bundles of axons within a nerve Perineurium: layer of fibrous connective tissue on the outside of a fascicle Endoneurium: connective tissue on the outside of individual axons Cranial Nerves Nerves attached to the brain that control sensory and motor functions for the head and neck Twelve; labeled CNI through CNXII Can be sensory, motor, or both Olfactory nerve: responsible for smell Optic nerve: responsible for vision Oculomotor nerve: responsible for eye movements o Trochlear nerve and abducens nerve also control eye movements Trigeminal nerve: responsible for sensations from the skin of the face and for chewing Facial nerve: responsible for facial expression, gustation, and the production of saliva Vestibulocochlear nerve: responsible for hearing and balance Glossopharyngeal nerve: responsible for muscles in the mouth and upper throat, part of gustation and olfaction, and the production of saliva Vagus nerve: responsible for homeostasis in organs of the thoracic and upper abdominal cavities Spinal accessory nerve: responsible for neck muscles and cervical spinal nerves Hypoglossal nerve: responsible for muscles of the lower throat and tongue Spinal Nerves Nerves connected to the spinal cord o All are a mix of sensory and motor axons that separate into two nerve roots o Sensory axons enter spinal cord; motor axons leave spinal cord 31 spinal nerves named for where they leave the spinal cord Systemic nerve: where axons from different spinal nerves come together o Occurs at four places call nerve plexuses Cervical plexus: axons from spinal nerves C1 through C5 Brachial plexus: axons from spinal nerves C4 through T1 Lumbar plexus: axons from all lumbar spinal nerves Sacral plexus: axons from L4, L5, and S1 to S4 Intercostal nerves: nerves in the thoracic region that are not part of the plexuses
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