Cognitive Psychology (PSYC 365) Lecture Notes PDF

COGNITIVE PSYCHOLOGY PSYC 365 Cognitive Neuroscience 1  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Descr...

COGNITIVE PSYCHOLOGY PSYC 365 Cognitive Neuroscience 1  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 2  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 3  What are neurons? neurons = nerve cells function = creates and transmits information characteristics of neurons o I send and receive electrical signals o interconnected in the form of networks o on average 10,000 connections per neuron 3.5lb structure building blocks of the brain 4  Three Components of a Neuron Dendrites o receive messages from other neurons Cell Body (aka soma) o combines and processes all incoming signals from dendrites o contains vital cell structures (e.g. nucleus, DNA) Axons o sends out signals (electrical impulses) to other neurons, muscles or glands receiving processing sending 5  Three Components of a Neuron receiving processing & sending Synapse receiving 6 www.kenhub.com ↑ now electrical Signal from one neuron goes from one toanother  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 7  Neural Representation Principle of Neural Representation o everything we experience is based not on direct contact with stimuli, but on representations of that stimuli in the nervous system o sight à light o sound à sound waves energy triggers an action potential ~ o taste/smell à chemicals 8 8  Neural Representation Principle of Neural Representation o e.g. when you see a tree, sensory neurons are detecting light reflected off the tree, and sending action potentials to the brain o e.g. close your eyes and imagine a tree. That mental image you see is also caused by neural circuits firing numerous regions of the brain work together to represent an object o beyond primary cortical areas ↳ beyond occipital lobe 9 9 Theories of Neural Representation How does the brain represent complex stimuli? Specificity Coding Population Coding Sparse Coding 10 10  Theories of Neural Representation Specificity Coding = every stimulus is represented by the firing of a very specialized neuron There is a neuron in the brain · o often called Grandmother Cells that will fire when we see certain in ppl. o Problems o Not enough neurons for every object in the world o Lack of evidence from single-cell recordings o What about new objects? 11 11  Theories of Neural Representation Population Coding = every stimulus is represented by the pattern of firing across many neurons o i.e. use combination of firing patterns of 10 neurons to code many different objects o reliable evidence for Population Coding in sensations and cognitive functions o Problems o Not all functions need all neurons 12 12  Theories of Neural Representation Sparse Coding = every stimulus is represented by the pattern of firing across a small number of neurons i.e. while many neurons may be involved in recognizing an object, not all of them are involved in recognizing every object (many don’t respond for a given object) o reliable evidence for Sparse Coding in vision, hearing and smell · most reliable Do * subset different of neurons of levels activity 13 13  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 14  Major Techniques to Study the Brain Localization of Function = specific cognitive functions are supported by specific areas of the brain Destruction & Stimulation Brain Structure Brain Activity 15 15  S Destruction Animal Studies o Ablation = remove portion of the brain (animal studies) o Lesion = focused damage in specific area o Usually use tiny electrodes à focused damage (animals) o Damage produced by heat/cold/electricity/chemical Human Studies o Accident/disease can produce lesions (e.g. brain injury, stroke) o Surgical-elicited lesions (e.g. epilepsy patients may require removal of parts of brain tissues to control for seizures) 16  Destruction neuropsychology = study of brain-behavior relationships in humans neuropsych tests = test verbal and non-verbal functions affected by brain damage o assess simple to complex functions o determines which functions are impaired o determines severity of impairments (used to infer the extent of the brain damage) o standardized typically used in clinical/medical evaluations o e.g. a patient who suffers from a brain damage due to an accident 17  Destruction example neuropsych test – working memory How items hold in you memory ? can many your Digit Span 18. 2 Stimulation Stimulation of brain areas through mild electric current o Can enhance or disrupt cognitive functions associated with brain area o Wilder Penfield o stimulated brain of awake patient during brain surgery (invasive) o no pain receptors in CNS (so local anesthetic is fine) o patients describe their sensations, and surgeons note changes in behavior o some places, stimulation caused movement of limbs, or the report of feeling a light touch, hearing a melody, or the smell of a rose o non-invasive methods exist but results in less focal stimulation 19 Major Techniques to Study the Brain Destruction & Stimulation Brain Structure Brain Activity 20 20  CAT / CT computerized (axial) tomography (CAT/CT): take images of slices of brain, then piece slices together to create a 3D image of the brain o similar to very powerful x-ray utility: reveals localized brain tumors and lesions Advantages ~ o instantaneous o non-invasive Disadvantages X o exposure to radiation o poor spatial resolution 21  MRI magnetic resonance imaging (MRI): large magnet that reveals brain structures by taking “images” of the brain utility: reveals soft tissue abnormalities in the brain Advantages o great spatial resolution o non-invasive o mostly low risk* Disadvantages mppict o contraindications o low accessibility 22 Major Techniques to Study the Brain Destruction & Stimulation Brain Structure Brain Activity 23 23  EEG Electroencephalogram (EEG): records electrical activity of large group of neurons in the brain o micro electrodes: record activity of single neuron * utility: direct measure of neural activity Advantages o excellent temporal resolution (msecs) o non-invasive, low risk Disadvantages: o poor spatial resolution o sensitive to movement 24  fMRI If means functional DifferentMist functional magnetic resonance imaging (fMRI): measures blood flow via from changes in oxygen in hemoglobin during task ↑ o more activity à more oxygen required à more oxyhemoglobin utility: indirect measure of brain activity; changes in oxygen usage are interpreted as brain areas involved during cognitive functions o we infer that areas with higher oxygen usage are more active Advantages o same as MRI Disadvantages o same as MRI 25  fMRI: Connectivity brain areas are interconnected – they work together to support cognitive functions o interconnectedness can be structural or functional neural networks = distributed brain areas that consistently communicate with each other to facilitate complex functions o extension of distributed/sparse coding color coded neural networks 26 Yeo. J Neurophys. 2011  fMRI: Brain Networks default network = brain areas that are active when we are ”at rest” o also active during mind wandering, thinking about past/future/self/others 27 neuroscientificallychallenged.com  Exercise: Name that Method An investigator seeks to understand the relationship between the amygdala and hippocampus during the processing of emotional information. Participants in this study are shown emotionally charged videos obtained from the internet. What method should they use? · fMRI would be best ! 28  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 29  Cerebral Cortex Left Hemisphere - 30  Cerebral Cortex wrinkly exterior layer of the brain cortex contains ~80% of neurons in entire brain o our ratio of cortex-to-brain size is what differentiates us from animals 31 brainmuseum.org  Cerebral Cortex functional categorization = we can define cortical areas based on what they do o some functions take up only a small portion of an anatomical area o some functions involve several different anatomical areas o many complex functions involve simultaneous activity in multiple areas of brain 32  Major Functions of Four Lobes Parietal Lobe - somatosensory processes - high level visual processes Frontal Lobe - many functions! /sensation of heat) and cold Occipital Lobe - visual processes (color, form, spatial) Temporal Lobe - auditory processes - high level visual processes - memory functions 33  Major Functions of Frontal Cortex Broca’s area: speech production motor cortex: muscle movements prefrontal cortex: executive functions o setting goals and making plans o emotion regulation o self-awareness if prefrontal cortex is damaged o unable to carry out sequences of actions o unable to predict what will happen o problems with impulse control o lack of empathy 34 radiopaedia.org  Primary Areas of Four Lobes primary areas = sensory processing of information o Frontal: primary olfactory and motor cortex (first point of contact) o Temporal: primary auditory cortex o Parietal: primary somatosensory cortex o Occipital: primary visual cortex 35  Primary Areas of Four Lobes Primary Somatosensory Parietal Lobe Primary Motor Cortex Cortex Frontal Lobe Broca’s Area Primary Visual Occipital Cortex Lobe Primary Auditory Cortex Temporal Lobe Wernicke’s Area 36  Association Areas of Four Lobes association cortex = areas not directly involved in receiving sensory information or producing voluntary movement exists in all four lobes of brain, takes up ~ 75% of human cortex combines multiple inputs from sensory systems (and motor) involved in higher mental cognitive processes o e.g. language, problem solving 37  Association Areas of Four Lobes Example: Broca’s Area (frontal lobe) o function: speech production (i.e. articulate words, grammar) o damage: difficulty speaking, and articulating o it does not impact speech comprehension Example: Wernicke’s Area (temporal lobe) o function: speech comprehension (i.e. understand spoken/written words) o damage: difficulty understanding (and thus cannot respond appropriately) o it does not impact speech production 38  Objectives 1. Define neurons and identify its components. 2. Describe the role of neurons in representation. 3. Elaborate on the techniques for studying the brain. 4. Describe the structures of the cortex, and their corresponding functions. 5. Compare and contrast functions of the two hemispheres. 39  Left Brain vs Right Brain Layperson Perspective What functions come to mind when you hear left vs right brain? verywellmind.org 40 psychologytoday.com  Left Brain vs Right Brain left and right hemispheres are connected by the corpus callosum (bundle a of o allows the two hemispheres to work together for most tasks some activities do use one side of the brain more than the other o especially pronounced in males & right-handed people LEFT HEMISPHERE RIGHT HEMISPHERE language facial recognition math spatial navigation music *Both hemispheres have the capacity to perform a given function. 41  Control of Contralateral Side (opposite) Left Hemisphere Right Hemisphere controls right side of controls left side of face/body face/body sensory + motor auditory 42  Control of Contralateral Side – Exception * vision is an exception to the rule * o each hemisphere processes both visual fields o BUT whatever is in the left field of view is “seen” by right side of brain first, then passed onto left side via corpus callosum (and vice versa) optic chiasm 43  Corpus Callosum nerve fiber connecting left and right hemispheres function: carry information between the two hemispheres 44  Commissurotomy commissurotomy = cutting of corpus callosum to disconnect the two hemispheres to prevent the spread of seizure split brain patients: patients with commissurotomy (severe epilepsy) o allow us to study hemispheric organization and corpus callosum function by limiting information to one hemisphere 45  Split Brain Phenomenon in split brain patients, hemispheres cannot communicate o so whatever is in the left visual field is only seen by the right side of brain (vice versa) To get info · from one side to the other have you , to shift your eyes ladjust visual) field optic chiasm 46 Split Brain Patients – Task Performance * visual field is key o could name or describe o could NOT name or object describe object o could pick up matching o could pick up matching object with right hand nu object with left hand - 47  Split Brain Patients Michael Gazzaniga’s work on split brain patients. 48 https://www.youtube.com/watch?v=ZMLzP1VCANo  Lessons from Split Brain Phenomenon cerebral cortex has the capacity to act as two separate entities, each able to learn independently. caution: split brain patient phenomenon is interesting, but findings are sometime exaggerated o not always replicated in subsequent studies (depends on years since lesion) keep in mind: in neurologically healthy individuals (with intact corpus callosum), both hemispheres contribute to most (if not all) functions 49  Objectives ✔ 1. Define neurons and identify its components. ✔ 2. Describe the role of neurons in representation. ✔ 3. Elaborate on the techniques for studying the brain. ✔ 4. Describe the structures of forebrain, and their corresponding functions. ✔ 5. Compare and contrast functions of the two hemispheres. 50