Cognitive Neuroscience Methods: MRI, fMRI, TMS, and TDCS

Flashcards covering the main topics in the cognitive neuroscience methods lecture, including structural and functional MRI, fNIRS, PET, lesion patients, TMS, and TDCS.

What does MRI stand for?

Magnetic Resonance Imaging

What type of images are produced by basic MRI?

Structural images (static images in 3D)

What are the three planes in MRI?

Sagittal, horizontal/axial, and coronal

What is the key principle behind how MRI works?

Contrast between different tissue types

What molecule is the physics of MR based on?

Water (H2O)

What part of the water molecule is important for MRI?

Hydrogen atoms, specifically the protons within those atoms

What happens to the protons when placed in an MR scanner?

They align with the magnetic field.

What is the purpose of the radio frequency (RF) pulse in MRI?

To knock the protons perpendicular to the magnetic field.

What does fMRI stand for?

Functional Magnetic Resonance Imaging

What is the technique used to understand active brain regions in fMRI?

Cognitive subtraction (comparing a baseline task to an experimental task)

What is the 'ongoing myth' dispelled by fMRI?

That we only use a certain proportion of our brain; all of our brain receives a constant supply of blood.

What is being measured in fMRI?

BOLD signal (Blood Oxygen Level Dependent signal)

Is BOLD signal a direct or indirect measure of neural activity?

Indirect

What is the basic concept of the BOLD signal?

Neural activity consumes oxygen, leading to more blood flow to the active region.

According to the lecture, approximately how long after initial activity does the peak of the hemodynamic response function occur?

Six to eight seconds

In fMRI images, what name is given to the 3D equivalent of pixels?

Voxels

What does FNIRS stand for?

Functional Near Infrared Spectroscopy

How does FNIRS measure brain activity?

By sending out near-infrared light and measuring blood oxygen levels in the brain.

What does PET stand for?

Positron Emission Tomography

How are PET images created?

By injecting someone with radioactive tracers that accumulate in different tissues based on activity.

What are some reasons for lesions occuring in the brain that the lecture mentions?

Disease, stroke, or brain injury

What are the names of the two conditions involved in lesion studies?

Single dissociation and double dissociation

According to the lecture, which of the two dissociation conditions is best for functional specialization?

Double dissociation

What does TMS stand for?

Transcranial Magnetic Stimulation

What does the TMS coil do?

Carries an electric current, producing a small magnetic field.

What effect does TMS have on the targeted area of the brain?

Temporarily induces a current in nearby neurons, causing them to fire and interfering with normal processing.

What are some weaknesses to using TMS to perform this interruption, according to the lecture?

Requires regulation due to ethical guidlines, some discomfort for participants, cannot use on those with epilepsy, can't simulate some brain regions.

What does TDCS stand for?

Transcranial Direct Current Stimulation

How does TDCS work?

Applies a weak electrical current between two electrodes (anodal and cathodal)

In TDCS, how can the two electrodes be thought of?

Anodal is positive, cathodal is negative.

Generally in TDCS, how can one expect the electrodes to affect performance?

The cathodal electrode typically decreases performance and the anodal electrode typically increases performance.

What is the general operation TDCS based on?

How neurotransmitters excite or inhibit neurons. Anodal electrode promotes excitation and cathodal promotes inhibition