Chapter 2: Methods of Cognitive Neuroscience Flashcards
agonist
neuropharmacological agent that mimics the action of a neurotransmitter
antagonist
neuropharmacological agent that opposes or interferes with the action of a neurotransmitter
blocked design
task design used in PET studies and sometimes in fMRI studies where multiple trials of the same type are grouped together in blocks. The brain activity is then analyzed by comparing neural activity across the entire block against blocks containing another type of trials, or with a different cognitive condition
blood oxygenation level-dependent (BOLD)
measurement of brain activity using fMRI that is based on the local variations in deoxygenated hemoglobin that result from the changes in blood flow induced by neural activity
coactivation
areas of the brain are said to be coactivated if they both show higher activity in a specific task. Statistically, coactivation is reflected by a positive correlation of activity between two areas
computerized tomography (CT)
imaging method in which X-rays acquired at multiple angles are used to build a three-dimensional structural image of biological tissue
dendritic field potentials
electrical potential induced in the dendritic tree of a neuron by input from the axons of other neurons; this electrical activity can often also be detected at the scalp as an EEG or ERP response
diaschisis
disruption of the function of one brain area caused by focal damage to another, distant part of the brain. Often, the proper functioning of a brain area relies upon receiving input and stimulation from other, distant areas, so that if a distant area is damaged, the “down-stream” area can be affected as well
diffusion tensor imaging (DTI)
method of MRI that can show the preferred directions of diffusion within tissue; useful for the imaging of fiber tracts of the brain
dopamine system
refers to the circuits in the brain that include neurons that release the neurotransmitter dopamine. The dopaminergic neurons, which are mostly located in the ventral tegmental area of the midbrain, the substantia nigra pars compacta, and the hypothalamus, have been particularly associated with reward
double dissociation
functional relationship in which one area of the brain is experimentally shown to be associated with a particular task or cognitive function and not with another task or function, whereas another area is shown to be involved in the second task or function but not the first. This demonstration thus distinguishes the cognitive roles of different regions in a more rigorous way than does simply showing that the two regions in question respond differently
dynamic causal modelling
successor to structural equation modelling which testsdirectionalmodels of functional connectivity against brain data to determine the relative likelihood of the activity in one area of the brain causing the activity in others
event-related design
task design used in fMRI studies in which trials or events of different types may follow one another in randomized order and the neural responses from the different events can be extracted from the measured signals. Analogous to the extraction of event-related potentials (ERPs) from ongoing EEG and to the construction of peristimulus histograms from single-neuron recordings
event-related optical signals (EROS)
noninvasive optical imaging approach based on the fact that when brain tissue is illuminated, even through the skull, the amount of transmitted versus scattered light varies as a function of whether the neuronal tissue is electrically active
event-related potential (ERP)
voltage fluctuations in an ongoing brain EEG that are triggered by sensory and/or cognitive events; the changes reflect the summed electrical activity of neuronal populations specifically responding to those events and are extracted from the ongoing EEG by time-locked averaging
extracellular recording
recording the electrical potentials in the extracellular space near active neurons
fiber tract
bundles of axons in the brain that carry neuronal signals between brain areas
fMRI adaptation
one way of using repetition suppression within an fMRI paradigm that uses pairs of similar stimuli. If the second stimulus induces less activity than the first stimulus (or prime) in a particular brain area, then it can be inferred that the region in some way supports a process common to the two stimuli
fractional anisotropy (FA)
degree to which water diffuses in a preferred direction within tissue. Higher levels of fractional anisotropy are thought to reflect greater amounts of white-matter (i.e., fiber tract) integrity
frequency bands
specific frequency range within a spectrum, usually referring to oscillatory electrical brain activity
functional connectivity
how the activity of one brain region varies with the activity in other brain regions
functional magnetic resonance imaging (fMRI)
non-invasive method for imaging brain activity that uses imaging pulse sequences generated by a magnetic resonance scanner; the signal measured is caused by hemoglobin-based changes in blood oxygenation and blood flow that are induced by local neural activity
homunculus
“little man” (Greek), often used in referring to the shape of a primary sensory or motor cortical map. Also used to refer (often negatively) to the dualist notion of a non-neurally based “self”
intracellular recording
recording the potential between the inside and outside of a neuron with a microelectrode
local field potentials (LFP)
dendritic field potentialthat is recorded intracranially close to the dendritic source (i.e., locally)
magnetic resonance imaging (MRI)
noninvasive imaging method based on the behavior of atomic nuclei (particularly hydrogen) within a strong magnetic field; provides excellent soft-tissue contrast of brain anatomy, and can also be used to measure functional brain activity noninvasively
magnetoencephalography (MEG)
method of measuring at the scalp the electrical currents in the brain based on the detection of the magnetic fields produced by those currents. Like EEG, MEG activity is thought to reflect mainly the electrical currents produced in the dendritic trees of the large pyramidal cells in cortex
multivoxel pattern analysis (MVPA)
technique that analyzes patterns of activation across voxels in a particular brain region that consistently correspond to certain stimulus or event types, rather than the overall increase or decrease in activation of the entire region
neuroimaging genomics
method of relating differences in fMRI activity between people to specific genetic variations. This method can provide accounts of how genetics can influence brain structure and function, and thus in turn cognitive processes
optogenetics
method in which genes that code for light-sensitive ion channels or light-sensitive ion transporters are introduced into neurons. Once these genes are expressed, and the channels or transporters are integrated into the cell membrane, the neuron’s activity may be controlled by stimulation with light
peristimulus time histogram (PSTH)
graph that plots neuronal activity, typically firing rate or number of spikes, as a function of the time of stimulus presentation
positron emission tomography (PET)
method of noninvasive, hemodynamically based brain imaging that uses radioactively labeled molecules injected into the bloodstream that are taken up to a greater degree by active neurons
psychophysiological interaction (PPI) analysis
fMRI analysis technique that uses the time courses of activity in different brain areas to analyze how interactions between them differ as a function of the cognitive task being performed. For example, it analyzes whether the correlation in activity between two areas, rather than activity itself, differs in one task versus another
repetition suppression/ neural priming
phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli
repetitive TMS
method in which the brain is stimulated with a repeated sequence of magnetic field pulses, ranging from less than 1 per second up to 30 Hz or more
resting-state connectivity
patterns of functional connectivity of the brain while a person is awake but not engaged in any specific task or activity
somatotopic
refers to a representation of the body mapped on to the cortex of the brain in a topgraphically preserved way, meaning that adjacent locations on the surface of the body have adjacent representations in the cortex, even if perhaps stretched or distorted. The primary motor cortex and the somatosensory area of the brain are two somatotopically organized areas
structural equation modeling
mathematical method of analyzing fMRI data by which two or more models of functional connectivity may be tested against brain data. The method aims at determining the relative likelihood of one model over another given the observed data
transcranial magnetic stimulation (TMS)
method in which a rapidly changing, strong magnetic field is generated next to the skull, thereby delivering transient electrical stimulation to the underlying cortex; the electrical stimulation typically disrupts the local cortical activity, thereby enabling inferences concerning the cognitive function(s) in which that brain area is involved
trial
single occurrence of an experimental event in a study
tuning curve
function obtained when a neuron’s receptive field is tested with stimuli at different orientations; its peak defines the maximum sensitivity of the neuron in question
