Lecture 2: Research Methods

Main Assumption

psychological processes might be asw distinct patterns of neural activity; ex. Orange

Pop Encoding

diff neurons active during diff processes; LBD/brain injuries

Pop Weakness

1) not economical, neurons not re-used; 2) certain neurons are always active, tonic (reward)

Rate Encoding

diff rates of activity in diff processes; economical but neurons have situation specific activity

Firing Rate

as signal exposure continues, FR changes; 1) stimuli processing 2) lack of conscious awareness

Integrated Solution

both types are key; Halle Berry; set of neurons respond strongly to HB, the concept;

Halle Berry Study

not just one pic, but the concept of HB; applies to objects and the object in diff angles

Neural Rep

rep of info in the NS; multiple forms → pop. encoding, rate encoding, activity-silent

Presentational Drift

neural reps are not constant, info + behaviour last but can change → false mem/misinfo

PD Reasons

cell death (reconfigure), synaptic turnover (prune), new connections w/new info (interference)

Brain Decoding

repeat word → record brain (good temp/spat); neural dictionary; predict words from activity

Decode Advan

communication w/non-verbal + restoration of movement in individuals with paralysis

Decode Disadva

health, ethic (privacy, discrimination, equity), logistics (output, reliability, info, maintenance)

Lesion Study

damage to specific brain region, impairs specific behavior → region may contribute to behavior

Phineas Gage

frontal lobe damage, became a diff person; language, social interaction, impulsivity issues

Dissociation

naming living/non-living things seen in diff patients → could be separate functions

Lesion Limits

1) misinterpret, verify post-mortem, 2) large lesions, cannot as single area with an impairment, 3) not all behaviours measured, cannot as area with single impairment, 4) n = 1 observe, general

Contrecoup Effects

impact on one side of the brain → causes damage to the other side due to brain mvmt

Lesion Problems

measure brain after injury, need to examine healthy brain; microprocessor example

BB Relation

process asw activation of brain region; then brain region may contribute to that process; ex. music

Spatial Resolution

ability to tell apart brain regions

Temporal Resolution

changes in the brain activity over time; ex. how active the cells were

Coverage/Mobility

1) how much of the brain you can measure 2) can the tool be moved around

ERD

event-related design; good temp (EEG, MEG, fMRI), measure signals during brief processing events

BD

block design; bad temp (PET), average signals over an extended period; expectation + adaptation effects;

EEG

electrical activity in specific BR; good temp (quick), poor spatial; arousal, epilepsy, consciousness

EEG Mechanism

electrodes over specific BRs on skull → measure activity; only observe cells near surface

ECoG

electrocorticography; right on the cortex, invasive, rare; great temp, great spatial

EEG Signal

potential diff (voltage) over time; voltage varies (peaks/valleys); voltage variation = frequency

EEG - Consciousness

read out → waves → diff states of consciousness; mediation → beta/theta frequencies

ERP

neural activity related to brief mental process; measured using EEG; take many reads → average

ERP - Language Processing

notice semantic (meaning) diff in N400, notice syntax (grammar) affects P600

EEG/ECoG Advan

good temp; millisecond; rapid changes in arousal/consciousness + cognitive processes

EEG/ECoG Disadvan

1) cannot determine specific area that’s active 2) deeper brain areas not measured

MEG

electrical currents generate magnetic fields in perpendicular direction; approximate neural activity; huge

MEG - Face Processing

field strength over time during processing of face; M170 → type of signal + time

MEG Advan/Dis

good temp, good spatial (magnetic signals attenuate less); expensive, inconvenient, rare

PET/FDG

positron emission tomography; FDG (fluorodeoxyglucose) acts like glucose (active neurons)

PET Mechanism

synthetic radiotracer taken → reacts with brain tissue → signal generates; signal diff btw BRs reflects diff in glucose demands (neuronal activity)

PET Advan/Dis

decent spatial, poor temp (long time + long lasting); characterizing substances, diagnosis

MRI

gray matter, structural; strong field, spin alignment of atoms, radio freq → OT, signal reflects tissue, pic

DTI

white matter, structural; diffusion tensor imaging; reduced tract growth asw poor verbal performance

MRI/DTI Measures

not all same, changes vary and why; more gray matter = synapses, not neurons

fMRI

activity; active neurons use G + O; blood delivers O → deoxygenated; blood change in BR → activity

fMRI Signal

oxygenated + deoxygenated blood have diff magnetic properties → measure; temporal lag

BOLD

blood oxygen-level dependent; assumes neurovascular coupling → blood O correlated w activity

Subtractive Method

signal in context - control stimulus, background; ex. Teddy Bear

fMRI CP

brain activity patterns vary by task; areas shown are changes in activity, not actual activity

fMRI/Connectivity

activity in diff BR → areas with high correlated activity → interconnected → map

rsMRI

activity → at rest, pattern; cognitive abilities; connectivity → plastic, modify; changes w/experience

Connectivity Changes

brain stimulation influences connectivity → plastic, modifiable

fMRI Adva/Dis

great spatial, decent temporal (lag), most popular

Forward/Reverse Inference

forward, aggression → amygdala active; reverse, amygdala active → aggression

fMRI Limits

reverse inference (insula), device/uncomfortable, expense/expertise, NC, data, reliability

Data Problem

lack of standardization in analysis, error correction, low n, power concerns, false positives

Dead Salmon Study

fMRI of dead salmon; areas showed above chance activity although dead

FNIR

func. near infrared spectroscopy; measure BOLD signal based on light absorption;

FNIR Advan/Disadvan

mobility, limited coverage (mostly frontal), less precise (poor spatial)

BCIs

brain-computer interfaces; neuralink, implant in brain, measure activity; synchron → stent, non-invasive

Single-Cell Recording

surgery, implant electrode, measure neuron func.; invasive, good temp, good spatial

Physiological

GSR (galvanic skin resistance); arousal, emotion process, conscious; polygraphs (lie detectors)

Skin Conductance/Fear

amygdala lesion; aware of CS-UCS (blue box-shock), express UCR to UCS (shock → SC), could not acquire CR to CS (no blue-box to SC)

Foreign Lullabies

foreign lullabies have similar effects, don’t need to understand words; arousal → HR, PD

Brain Stimulation

manipulate brain activity using magnetic + electrical stimulation; multiple sites at once → mental process may involve simultaneous excitation + inhibition of different brain areas

TMS

magnetic; TMS of brain area changes behaviour → brain area contributes to behavior;

TMS Therapeutics

treatment for depression + in frontal lobe affects cognition/memory in AD

TDCS

electric; transcranial direct current stimulation

TMS/TDCS Advan

non-invasive, well-tolerated, fast, reversible

TMS/TDCS Disadvan

unclear of stimulation parameters, difficulties targeting deep brain areas, new

EBS

electric brain stimulation; Penfield’s brain mapping → invasive, rare

DBS

deep brain stimulation; invasive, implant, rare; therapies for Parkinson’s Disease