Chapter 2 Flashcards
diaschisis
a 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 affect as well
agonists
a neuropharmacological agent that mimics the action of a neurotransmitter. Compare antagonist.
antagonists
a neuropharmacological agent that opposes or interferes with the actions of a neurotransmitter. Compare agonist
transcranial magnetic stimulation (TMS)
A 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 typical disrupts the local cortical activity, thereby enabling inferences concerning the cognitive function(s) in which that brain area is involved
repetitive TMS (rTMS)
A method in which the brain is stimulated by with a repeated sequence of magnetic field pulses, ranging from less than 1 per second up to 30 Hz or more.
optogenetics
A 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.
extracellular recording
recording the electrical potentials in the extracellular space near the active neurons. Compare (intracellular recording)
intracellular recording
Recording the potential between the inside and outside of a neuron with a microelectrode
peristimulus time histogram (PSTH)
A graph that plots neuronal activity, typically firing rate or number of spikes, as a unction of the time of stimulus presentation.
trial
A single occurrence of an experimental event in a study.
tuning curves
The 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.
dendritic field potentials
An electrical potential induced in the dendritic tree of a neuron by input from the axons of the at the scalp as an EEG or ERP response. Compare local field potentials
local field potentials (LFPs)
A dendritic field potential that is recorded intercranially close to the dendritic source.
frequency bands
A specific frequency range within a spectrum, usually referring to oscillatory electrical brain activity.
event related potentials (ERPs)
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.
magnetoencephalography (MEG)
A method of measuring at the scalp the electrical currents in the brain based on the detecting of the magnetic fields produced by those currents. Like EEG, MEG activity is thought to reflect mainly the electrical currents produced by dendritic trees of the large pyramidal cells in the cortex.
positron emission tomography (PET)
A 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.
blocked design
A 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 again blocks containing another type of trials, or with different cognitive condition. (Compare event related design)
functional magnetic resonance imaging (fMRI)
A 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.
blood oxygenation level-dependent (BOLD)
A measurement of brain activity using fMRI that is based on the local variations in deoxygenated hemoglobin that result form the changes in blood flow induced by neuronal activity.
event-related design
A 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 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. Compare block design.
multivoxel pattern analysis (MVPA)
A technique that analyzes patterns of activation across voxels in a particular brain region that consistently correspond to a certain stimulus or event types, rather than the overall increase or decrease in activation of the entire region.
repetition suppression
Also called neuronal priming. A phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli. Compare repetition enhancement.
fMRI adaptation
A non-invasive method for imaging brain activity that use imaging pulse sequence 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 neuronal activity.
