Chapter 3 - Methods of Cognitive Neuroscience

Structural MRI

measures brain anatomy (gray matter

Why would a researcher use structural MRI instead of fMRI?

To study physical brain structure rather than activity such as damage or volume differences.

Functional MRI (fMRI)

measures brain activity using BOLD signal (blood oxygen level changes)

What does an increase in BOLD signal indicate about a brain region?

That the region is more active and consuming more oxygen.

BOLD signal

indirect measure of neural activity based on oxygenated vs deoxygenated blood

Why is the BOLD signal considered indirect?

Because it measures blood flow changes rather than neurons firing directly.

Event-related design

measures brain response to individual stimuli or trials

When is an event-related design better than a block design?

When you want to isolate responses to specific stimuli or trial types.

Block design

groups similar stimuli together to measure sustained activity

Why does block design produce stronger signals than event-related design?

Because repeated similar stimuli amplify the signal over time.

Multivoxel pattern analysis (MVPA)

analyzes patterns across voxels to decode information

How is MVPA different from traditional fMRI analysis?

It focuses on patterns of activation rather than overall activity levels.

EEG

measures electrical activity of the brain with high temporal resolution

What is the main advantage of EEG over fMRI?

It captures rapid changes in brain activity (milliseconds).

ERP (event-related potential)

averaged EEG response to a specific stimulus

Why do researchers average ERP signals across trials?

To reduce noise and isolate the true brain response.

MEG

measures magnetic fields produced by neural activity

How is MEG similar to EEG?

Both measure fast neural activity with high temporal resolution.

TMS (transcranial magnetic stimulation)

temporarily disrupts brain activity using magnetic pulses

Why is TMS useful for studying causation?

Because it can directly interfere with a brain region and observe behavioral effects.

Lesion method

studies effects of brain damage on behavior

What is a limitation of lesion studies?

Damage is not controlled and often affects multiple regions.

Connectivity

relationship between activity in different brain regions

What does strong connectivity between two regions suggest?

That they are functionally interacting or part of the same network.

Structural connectivity

physical connections between brain regions (white matter tracts)

What technique is used to measure structural connectivity?

Diffusion tensor imaging (DTI).

Functional connectivity

correlation of activity between brain regions over time

Can two regions be functionally connected without being directly physically connected?

Yes

Connectome

complete map of brain connections

Why is the connectome important for neuroscience?

It shows how brain regions interact as a network.

Node

a brain region in a connectivity network

In a connectivity map

what does a node represent?

Edge

connection between nodes in a network

What does the strength of an edge represent?

The strength of connectivity between two regions.

Resting-state fMRI

measures brain activity when a person is not performing a task

Why is resting-state fMRI important?

It reveals intrinsic brain networks without task influence.

Default mode network (DMN)

active during rest and internal thought

When is the DMN typically less active?

During goal-directed tasks.

Frontoparietal network

involved in cognitive control and executive function

When is the frontoparietal network most active?

During difficult or attention-demanding tasks.

Salience network

detects important stimuli and switches attention

What is the role of the salience network in behavior?

It helps prioritize relevant information.

Network flexibility

ability of brain networks to reconfigure across tasks

Why is flexibility important for cognition?

It allows adaptation to different demands.

Brain fingerprinting

idea that individuals have unique connectivity patterns

How can connectivity patterns identify individuals?

Each person’s network organization is distinct.

Computational model

simplified simulation of brain processes

Why are models useful in neuroscience?

They allow testing of theories and predictions.

Artificial neural network (ANN)

computational system inspired by brain neurons

What do connections (weights) represent in ANNs?

The strength of influence between units.

Deep learning

neural networks with many layers that learn complex patterns

Why are deep networks powerful?

They can extract hierarchical features from data.

Representation

how information is encoded in a model or brain

What does it mean for a concept to have a “representation”?

It is stored as a pattern of activity.

Parallel processing

multiple computations happening simultaneously

Why is parallel processing important in neural systems?

It allows efficient and fast information processing.

Hippocampus

brain region critical for forming new memories

What happens if the hippocampus is damaged?

New memories cannot be formed (anterograde amnesia).

Memory consolidation

process of stabilizing memories over time

Where are long-term memories stored after consolidation?

In the neocortex.

Classification (machine learning)

sorting data into categories

Give a neuroscience example of classification.

Predicting whether someone has a disorder based on brain data.

Regression (machine learning)

predicting continuous outcomes

Example of regression in neuroscience?

Predicting intelligence score from connectivity.

Clustering

grouping data based on similarity without labels

When is clustering useful?

When categories are not predefined.

Converging methods

combining multiple techniques to study the brain

Why are converging methods powerful?

They provide stronger and more reliable conclusions.

Correlation vs causation

relationship vs direct effect

Which method provides causation: fMRI or TMS?

TMS.

fMRI limitation

shows correlation but not causation

Why can’t fMRI prove a brain region causes behavior?

It only shows activity

TMS advantage

allows causal testing of brain function

What happens if TMS disrupts a region and behavior changes?

The region is necessary for that behavior.

Temporal resolution

ability to track timing of brain activity

Which has better temporal resolution: EEG or fMRI?

EEG.

Spatial resolution

ability to locate activity in the brain

Which has better spatial resolution: fMRI or EEG?

fMRI.

Double dissociation

two brain regions affect different functions

Why is double dissociation strong evidence?

It shows functions are independent.

TMS timing studies

applying stimulation at different time points

What does it mean if TMS only disrupts behavior at 180 ms?

That’s when the brain region is involved.

Gene–brain–behavior relationship

genetic variation affects brain and behavior

Example from lecture of gene-brain-behavior relationship?

COMT gene affecting dopamine and decision-making.

Connectivity vs lesion prediction

connectivity often predicts complex behavior better

Why might connectivity outperform lesion location?

Because behavior depends on networks