Psychology Week 3 PDF

METHOD IS COG NEURO Carefully designed experiment > mental processes involved in the task (linking to the > Various cognitive functions) > behavioural dependent variable Neurophysiology: Single cell recording: - What individual neurons are responding to - Using electrodes to measure brain a...

METHOD IS COG NEURO Carefully designed experiment > mental processes involved in the task (linking to the > Various cognitive functions) > behavioural dependent variable Neurophysiology: Single cell recording: - What individual neurons are responding to - Using electrodes to measure brain activity - Cell is responsive when a stimulus is presented in its receptive field - Cue > Delay > Response - Spike happens in delay Lesion Studies: - Experimentally induce a damage or site of lesion in the brain that is very specific - Gives us better insight on which part of the brain is responsible for (usually for brain injuries) Cognitive Neuroimaging Medical uses / Clinical - Identifying cause of impairment (pathophysiology) - Localizing anatomical and/or functional disruptions Basic Reseal Uses / Basic research uses - Examining healthy and impaired brain topography (structural analyses) - Examining healthy and impaired brain functioning (functional analyses) Computerized Axial Tomography (CT/CAT) - Linked to a computer - Looks at brain from top-down - Scans slices of body (tomography) - 3-D x-ray - Rotates around the body, Can be used on any part of the body - Different parts of the body absorb radiation different: Bone = white, Fluid = Black (white for blood) - Pros: Safe for most people, Quick and noninvasive - Limits: not as sharp image for the brain, exposing one to radiation Structural Magnetic Resonance Imaging (sMRI) - Looks at structure of the body - Not radiation-based, but magnetic - The signal given off a body signal through an MRI - Picture of the body/brain  1. In normal state, the orientation of spinning protons is randomly distributed 2. Exposure to the magnetic field of the MRI scanner algins the orientation of the protons 3. When the radio frequency pulse is applied, the axes of the protons are shifted in a predictable manner and put the protons on an elevated energy state (resonance) 4. When the pulse is turned off, the protons release their energy as they spin back to the orientation of the magnetic field a. Different tissues in the body have different resonance properties b. Fluids = protons go further, bone = protons are shallow - More resolution than CT/CAT - Non-invasive - Repeatable (not radiation) - Correlating Brain Structure with behaviour - Brain space in voxels - Specifying the size of the brain lesion using voxels - Correlating brain lesion size to neurobehavioural phenomena - Lesion overlap method: common impairment, common damage Diffusion tensor imaging (DTI) (still MRI) - Uses Brwonian motion of water molecules to provide data for images - Quantifying fractional anisotropy on a voxel-by-voxel basis - Enables observation of the maturation process of white matter structures Electroencephalography (EEG) - measure electrical activity in the brain - Electrodes place on multiple areas of the scalp - Each electrode creates a recording channel - More electrode, more recording channel - Solid temporal resolution (but weaker spatial resolution) - Good at telling time - Not good where - Computing event-related potentials (ERPs) for EEG data - Crucial important of many trails-trail average - Exploring ERP signal properties - Electrocorticography (ECoG) - EEG directly on the brain - Increases spatial resolution - Only on small part Functional magnetic Resonance Imaging (fMRI) - Same brain scan but just looking at function - Neurovascular coupling: the magnetic properties of oxygenated and deoxygenated haemoglobin differ - Nuero and blood changes happen together  - The BOLD signal: Blood Oxygenation Level Dependent - BOLD changes are mapped on to an sMRI template brain for reference - Visualising activation and deactivation - Solid spatial resolution, weaker temporal resolution (every one second) Challenge of Interpreting Brain Data Subtraction method Stimulus State - Control State = Activity due to Stimulus fMRI - a causation and correlation technique - Single and double associations - Single dissociation occurs when damage to a brain area impairs performance on one task (task A) but not on another (task B). For example, damage to Broca’s area affects speech fluency but not comprehension. However, this doesn’t necessarily mean the tasks use completely different brain areas; task A might just require more resources from the same area. This makes single dissociations somewhat limited in drawing conclusions about cognitive functions. - Double dissociation addresses these limitations by showing that damage to one brain area (area X) impairs task A but not task B, while damage to a different area (area Y) impairs task B but not task A. For example, while Broca’s area affects speech, damage to Wernicke’s area impairs comprehension but not speech fluency. This complementary relationship demonstrates that the two tasks are independent, offering stronger evidence for the distinct roles of different brain regions - Simulating Brain Dysfunction: Transcranial Magnetic Stimulation (TMS) - Knowledge of pre-injured state - Temporary induction of dysfunction, repeatable - Can increase/decrease brain activity with magnetic stimulation Synesthesia - One sensory experience is automatically crosses aith another sensory experience - Not transitory; how you were born - Females > males > left-handers > right-handers - Prevalence estimates vary widely - Letter to colour - People have stronger connections between colour and letter area of the brain - Sound to colour - See numbers in space - Auditory-tactile - Mirror-touch synesthesia The McGurk Effect - Illusion hoe perceivers merge information for speech sounds across the senses