CSD 303 / Psych 365 Exam1
CSD 303 / Psych 365 Exam1 Psych 365
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This 11 page Study Guide was uploaded by Michelle Lee on Sunday April 24, 2016. The Study Guide belongs to Psych 365 at Northwestern University taught by Sazzad Nasir in Spring 2016. Since its upload, it has received 10 views. For similar materials see Brain and Cognition in Psychlogy at Northwestern University.
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Date Created: 04/24/16
Introduction ➢ Cognitive neuroscience approach ○ Provide brainbased account of cognitive processes ○ Possible through technological advances ○ Cognition mental action/process of understanding through thought ➢ History ○ Mindbody problem:how physical substance (brain) can give rise to our sensations/thoughts/emotions (mind) ○ Dualism: mind and body are separate substances (Decartes) ○ Dualaspect theorythe belief that mind & brain are two levels of description to the same thing (Spinoza) ○ Reductionism: mind is explained soley in terms of physical or biological theory ● Cognition → Biology ○ Phrenology: different parts of cortex serve different functions ● Personality traits differ due to cortical size/bumps on skull ○ Functional specializatidifferent regions of the brain specialize for different functions ● Broca’s observations thru empirical methods ascertain diff functions ■ Patient with frontal lesion couldn’t speak but had cognitive ability ■ Inference that there are two independent language faculties in brain made ○ Made without knowing where in brain located → Cognitive neuropsychology ○ Cognitive neuroscience: minds with brains ● 1970: CT, MRI enabled precise images of brain (structural imaging) ● 1980: PET scan adapted to models of cognition ● 1985: TMS first used (noninvasive), study of virtual lesions ● 1990: fMRI used level of oxygen in blood used to measure cog function ➢ Brain structures ○ Gray matteneuron cells bodies on cortical surface ● Handles perception, attention, and language ○ White matteaxons, myelin, glia cells ● Between cortical & subcortical regions ● Compose commissures (corpus callosum), connecting hemispheres ○ Cerebral cortex ● Gyri/gyru raised folds of the cortex ● Sulci/sulcburied grooves of the cortex ● Brodmann’s arearegions of cortex defined by distribution of cell types across cortical layers ○ Subcortex ● Basal gangliregions of gray matter involved in motor control and skill learning ● Limbic systeregion involved in relating organism to environment ● Thalamus:major relay center for sensory organs (minus smell) ● Hypothalamusspecialized for different functions concerned with body regulation ○ Midbrain and hindbrain ● Superior collinucleus forms a part of subcortical sensory pathway ● Inferior collnucleus that forms part of a subcortical auditory pathway ● Cerebellumthe “little brain” in charge of dexterity/smooth movement and execution ● Pons: link between cerebellum and cerebrum ● Medulla oblongaregulates vital functions (breathing, etc) Methods ➢ Electrophysiological methods ○ Based on concept that neurons generate electrical signals ○ Representations ● Mental sense of properties of outside world copied by cognition ■ i.e. colors, objects ■ issues with mapping ● Neuralthe way properties of outside world manifest themselves into neural signals ■ How stimulus is represented → different spiking rates for different stimuli ○ Singlecell record measure responsiveness of a neuron to a given stimulus ● Action potential is directly measured by implanting small electrode into neuron or outside of membrane ● Count number of action potentials for one neuron ● Best resolution, but impractical w/ regards to time ● Grandmother celneuron that responds only to a stimulus ● PROS: good spatial and temporal resolution ● CONS: invasive (openbrain surgery) ○ Electroencephalography (EEGmeasure rate of change electric signals generated by brain ● Use electrodes placed on different points on scalp ● Measured instantaneously, useful for measuring relative timing of neural activity ● Compare voltage between 2+ sites of voltages (reference & test) ○ Eventrelated potential (averagemount of change in voltage at scalp linked to timing of events ● Based on EEG recordings, relates neural and electrical activity ● Records the peaks of pos/neg series ■ Timing and amplitude spatial bad, temporal good ■ i.e. stimulus → response ● PROS: instantaneously records electrical activity ● CONS: not possible to derive where sources are in scalp (inverse problem) ■ Solved bydipole modeli assume how many dipoles contribute to signal recorded ○ Face Recognition Using ERP ● N170: neg peak in ERP specialized for faces ● Associative primi reaction times are faster to X after being presented to Y if X and Y were previously associated together ● Exogenous components:related to stimulus properties ● Endogenous components:related to task properties ○ Magnetoencephalography (MEG)noninvasive method for recording magnetic fields generated by the brain at the scalp ● Signal unaffected by skull, meninges, etc ● Poor at detecting deeper dipoles, sensitive to sulci ● Good temporal res and potentially good spatial res ● Expensive and limited availability ➢ Brain Imaging ○ Structural imagimeasures spatial configuration of diff types of brain tissue ● CT scans:related to xray absorption ● MRI: no radiation (safer), provides a better spatial res than CT ■ Better gray/white matter discrimination ○ Functional imagi measures temporary changes in brain physio (fMRIs) ● Voxelbased morphometry (VBMtechnique for segregating & measuring differences in white/gray matter ● Diffusion tensor imaging use MRI to measure white matter connectivity btwn regions ● PET scans: measures blood flow in region ■ Poor temporal but good spatial res for whole brain ● fMRI: measure blood oxygenation (BOLD) ■ Changes in BOLD over time (HRF) ■ Also poor temporal but good spatial res ■ Some brain regions are hard to image ○ Subtraction methodology ● Experimental design in which activity in a control task is subtracted from activity in experimental task ○ Functional integrat the way different regions communicate with each other ● Resting state paradigmeasures functional connectivity where correlations between regions are assessed while subject is resting ● Default mode networkset of brain regions that is more active in bloodflow during rest than during tasks ● Block designstimuli from a given condition are present together ● Eventrelated desigstimuli from two or more conditions are presented randomly/interleaved ● Data interpretation: ■ Inhibitireduction/suppression of activity of brain region, triggered by activity in another region ■ Excitatio increase of activity of brain region, triggered by activity in another region ■ Activatioincrease in physiological processing in one condition compared to others ■ Deactivatiodecrease in physio processing ■ Can only tell when neurons are active, don’t know if they’re inhibiting/exciting ➢ Lesioned Brain ○ Infer the function of a region by removing it and measuring system effect ○ Damage of brain function comes through strokes, tumors, TMS ● TMS: noninvasive stimulation of brain caused by rapidly changing the current, creating a magnetic field and disrupting cognitive function during that point in time ● Single dissociatidissociating and associating lesion with effect ■ If lesion in region 1 disrupts task A but not task B, assume task A and B are managed by diff regions ● Double Dissociationsderived from 2+ single cases Vision ➢ A constructive process 1. Light enters eye, triggers photochemical reaction in rods & cones at the back of retina 2. Activates bipolar cells 3. Bipolar cells activate ganglion cells, where their axons converge to form the optic nerve 4. Nerve transmits info to the visual cortex in brain’s occipital lobe ➢ Anatomy of the eye ○ Retina: internal surface of eyes consisting of multiple layers, containing photoreceptors form the outermost layer, farthest from lens ➢ Images on retina are inverted and reversed ○ Rods: function in dim lighting ○ Cones: use spatial detail and color ○ Fovea: has the highest visual acuity ○ Receptive fielregion of space that elicits response from neuron ○ Blind spot point which the optic nerve leads the eye, no rods/cones ➢ Mapping of visual field ○ Two optic nerves partially form an ‘X’ in the optic chiasm ○ Nasal half of each retina cross in optic chiasm; temporal half of each retina don’t cross ● Depth perception ➢ Perception and control ○ Reflexive: retinal projection go directly to superior colliculus ● Receives 10% of axons via superior colliculus ● Orienting response (neck/head movement, etc) ○ Perception: main route terminates in V1 ● Called the “geniculostriate pathway” ➢ Pathways ○ Magnocellularlarge visual field areas; respond to motion ● Faster than pcells ○ Parvocellula respond to smaller detail and color ● Slower than mcells ➢ Lateral geniculate nucleus (LGN) ○ Divided by right & left sides, as well as subdivision of layers ○ Cells have entersurroundeceptive field, respond to different light presence in receptive field ○ Mpathways: first two layers are magnocellular, sensitive to motion and contrast ○ Ppathways: last four layers are parvocellular, sensitive to form and color ○ Retinotopy organization of LGN cells mimics the retinal cells ● Each location in LGN maps location on retina ➢ Primary visual cortex (V first stage of visual processing, retains the spatial relationships found on the retina and combines simple ○ Transforms info from LGN into processing codes ○ Extracts basic info from visual scene (edges, orientations, wavelengths of light) ○ Used later by stages of processing to extract info about shape, color, movement ● Simple cell cells that respond to light in particular orientation ■ On center / off surround ■ Orientation selective ● Complex cellcells that respond to light in a particular orientation but not to single points of light ■ Combination of simple cells ○ Spatial arrangement (BA 17) ● Retinotopic organizatspatial arrangement of light on retina retained in V1 response properties ○ Cortical blindness ● Damage to V1 areas result in blindness for corresponding region of space ● Blindsighdamage to geniculostriate route ● impairs conscious vision; patients cannot see stimuli in particular region but can still perform visual discriminations accurately ■ Other routes can act unconsciously ○ Functional specialization beyond V1 ● Ventral strea pathway extending from occipital to temporal lobe, involved in object recognition & memory ■ “What” pathways (parvocellular) ● Dorsal strea pathway extending from occipital to parietal lobe, involved in visually guided action and attention ■ “Where” pathways (magnocellular) ● V4: main color center of brain ■ Color constanccolor of surface perceived constant even when in different lighting ■ Damage to V4 see world in black & white (achromatopsia) ● V5/MT: main movement center of brain ■ Do not respond to color, only movement directions ■ Damage to V5 see world in series of still frames (akinetopsia) ➢ Recognizing Objects 1. Early visual processing 2. Grouping of visual elements (Gestalt principles) 3. Structural description: matching visual description to representation from brain 4. Semantic memory: attaching meaning to object ● Agnosiadisorders in recognition ■ Apperceptive failure to understand meaning of objects due to lackbject perception ■ Associative failure to understand meaning of objects due to lackemantic memory ○ Figureground segregatisegmenting visual displays into objects, not background surfaces ● Law of proximity: elements close together are grouped ● Law of similarity: elements sharing visual attribute are grouped ● Law of good continuation: edges grouped together to avoid changes or interruptions ● Law of closure: missing parts are filled in ● Law of common fate: elements that move together are grouped ➢ Face Recognition ○ Fusiform face area (FF in the inferior temporal lobe, responds to faces and processes facial identity ○ Prosopagnosia: impairments of face processing = inability to recognize faces ○ Why faces are special ● Task difficulty ● Holistic processing ● Visual expertise ● Domainspecificity Attention ➢ The process by which certain info is selected for further processing, others discarded ○ Inattentional blindnfailure to be aware of a visual stimulus b/c attention is directed away from it ○ Change blindnessfailure to notice the appearance/disappearance of objects between two alternating images ○ Feature attentibind together different aspects of conscious perception ➢ Spatial and Nonspatial Attention ○ Salien an aspect of stimulus that stands out from the rest (spotlight metaphor) ● Orientinmovement of attention from location to another ■ Covert:orientation w/o moving the eyes/body ■ Overt: orientation by movement of eyes/body ■ Exogenous: attention that is guided by stimulus ■ Endogenous: attention guided by perceiver’s goal ○ Inhibition of re slowing the reaction time associated with going back to previously attended location ○ Visual searc task of detecting the presence/absence of target object in array ➢ Topdown/Bottomup processing ○ Topdown processingholding target in mind, endogenously driving orientation ○ Bottomup stimulus driven and perceptual identification of objects and features ○ Voluntary attenti intentionally attending to something, goal driven ○ Reflexive attentbottomup, stimulusdriven process where sensory event (i.e. loud bang, flash of light, etc.) captures our attention ○ Early selecti info selected according to perceptual attributes ● Limitedcapacity stages: bottleneck ○ Late selecti info processed to semantic level before selected for processing ➢ Feature Attention: Feature Integration Theory ○ Model of how attention selects perceptual objects and binds different features of objects ○ Visual search paradigm ● Popout: ability to detect an object among distractor objects ■ Top array ● Negative primingan ignored object suddenly becomes attended object, they will process it slower ■ Bottom array ○ Make salience map: spatial layout emphasizing most of the behaviorally relevant stimuli in environment ○ Evidence againsFIT: ● Negative priming ● Semantic info required, causes processing beforehand to distract ● FIT works better for bottom up (stimulus driven) ➢ Cortical Areas for Selective Attention ○ Frontal eye fields (F posterior portion of midfrontal gyrus ● Responsible for voluntary eye movements (planning) ● “Activates” in preparation for shift in attention ○ Superior parietal lobule (Sfrontalinferior temporal gyrus of Broca’s ● Involved in planning and/or reorientation of attention
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