Behavioral Neuroscience: Neuroimaging Methods and Brain Stimulation

A set of vocabulary flashcards covering key concepts in neuroimaging techniques (EEG, MEG, CT, MRI, fMRI, DTI, PET), seizure classifications, and brain stimulation methods (TMS, Optogenetics).

Magnetoencephalography (MEG)

A functional neuroimaging method that measures the tiny magnetic fields given off by active neurons, requiring a large helmet apparatus to keep magnetic detectors cool.

Electroencephalogram (EEG)

A common neuroimaging method that records summed post-synaptic electrical potentials (coordinated extracellular electrical activity) from thousands of neurons to indicate states of sleep, consciousness, and seizure activity.

Seizure

A symptom of epilepsy characterized by a synchronization of electrical activity in the brain, often caused by excess glutamate and/or inadequate GABA overexciting the central nervous system.

Generalized Seizures

A main class of seizures that affects both hemispheres of the brain simultaneously.

Focal Seizures

A main class of seizures (formerly called partial seizures) that affects a specific area or 'focus' within one hemisphere of the brain.

Simple Partial Seizures

A type of focal seizure (focal aware) in which consciousness is retained during the episode.

Complex Partial Seizures

A type of focal seizure (focal impaired awareness) characterized by a loss of consciousness.

Tonic-Clonic Seizure

A generalized seizure (grand mal) in which nerve cells fire in high-frequency bursts, leading to muscle stiffening ('tonic') followed by jerking or twitching ('clonic').

Absence Seizure

A generalized seizure (petit mal) characterized by brief episodes of altered consciousness involving staring, unresponsiveness, and subtle motor movements, most common in children.

Event-Related Potentials (ERPs)

Large potential shifts caused by discrete stimuli, generated by averaging together many trials of EEG data.

Exogenous Factors (ERP)

Factors directly related to discrete stimuli that drive early responses in event-related potentials.

Endogenous Factors (ERP)

Internal factors, particularly emotions, that drive late responses ($500\,\text{ms}+$) in event-related potentials.

Computerized Axial Tomography (CT or CAT)

A noninvasive structural neuroimaging technique that measures X-ray absorption at several positions around the head to map tissue density.

Hyperdense vs. Hypodense Lesions

Appearance of tissues on CT scans where hyperdense lesions appear abnormally bright and hypodense lesions appear dark based on density.

Magnetic Resonance Imaging (MRI)

A noninvasive structural neuroimaging method that uses strong magnetic fields and radio frequency energy to align atomic protons and record their energy signatures upon relaxation.

Functional MRI (fMRI)

A neuroimaging method that detects small changes in neural oxygen use in active brain regions by measuring the blood-oxygen-level-dependent (BOLD) response.

Blood-Oxygen-Level-Dependent (BOLD) Response

The metabolic signal evaluated in fMRI based on variations between oxygenated hemoglobin (which has no unpaired electrons and is not attracted to magnetic fields) and deoxygenated blood.

Diffusion Tensor Imaging (DTI)

A structural neuroimaging method utilizing MRI technology to study white matter tracts by assessing the directional movement of water molecules.

Fractional Anisotropy (FA)

A metric derived from DTI where high FA signifies healthy, well-myelinated axonal tracts, and low FA indicates axonal damage such as demyelination.

Isotropic vs. Anisotropic Diffusion

Isotropic diffusion is unrestricted water movement equally in all directions, whereas anisotropic diffusion is restricted water movement along specific spatial orientations such as axons.

Diffusion Tensor

A $3 \times 3$ matrix that reflects water diffusion rates across different directions in tissue.

Positron Emission Tomography (PET)

An invasive metabolic imaging technique that directly measures brain metabolic activity through the uptake of an injected radioactive tracer.

Difference Image

A color-coded visual representation of brain activity computed by subtracting scans taken during a control condition from scans taken during an experimental stimulus or task.

Transcranial Magnetic Stimulation (TMS)

A brain stimulation technique that uses magnetic pulses to briefly stimulate discrete cortical regions, exciting underlying neurons at the surface of the cortex.

Optogenetics

A neurostimulation approach using genetic tools to express light-sensitive ion channels (opsins) in target neurons, allowing selective excitation or inhibition using light delivered via fiber-optic cables.