Glossary Terms  Home

 

 

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Action potential

A wave of depolarization that travels down a neuronal axon (6,15)

 

Adaptation

A change in the response to a stimulus following its repeated presentation

 

Adenosine triphosphate(ATP)

A nucleotide containing three phosphate groups that is the primary energy source for cells in the human body.

 

Aerobiy glycolysis

The process, consisting of glycolysis, the TCA cycle, and the electron transport chain, that breaks down glucose in teh presence of oxygen, resulting in a gain of 36 ATP.

 

Aliasing

The sampling of a signal at a rate insufficient to resolve the highest frequencies that are present. The energy at those frequencies becomes artifactually expressed at lower frequencies, distorting the measure signal.

 

Alpha Value

An a priori probabiblity (e.g., .001) choses as the threshold for statistical significance. If the probability that the data would be obtained under the null hypothesis is less than the alpha value, the data are considered to be statistically significant.

 

Alternating design

A blocked design in which two conditions are presented one after another for the duration of the experimental run.

 

Anaerobic Glycolysis

The conversion of glucose to lactate in the absence of oxygen.

 

Anatomical ROI

Region of interest that is chosen based on anatomical criteria.

 

Angular momentum (J)

A quantity given by multiplying the mass of a spinning body by its angular velocity

 

Anisotropic

Having different properties in different directions; often referenced in the context of anisotropic diffusion, where molecules tend to diffuse along one axis but not others.

 

Anode

a source of positive charge or ions, and an attractor for free electrons.

 

 Antiparallel State

The high-energy state in which an atomic spin precesses around an axis that is antiparallel (opposite) to that of the main magnetic field.

 

Apical Dendrites

The dendrites that are distant from the neuronal cell body. For typical pyramidal cells in the cortex, the apical dendrites extend to the superficial layers of the cortex, while teh cell bodies are located in deeper layers.

 

Apparent difusion coefficient

The quantification of diffusivity assuming isotropic diffusion.

 

Arachnoid

The middle membrame covering the brain; its name comes from its weblike appearing.

 

Arterial spin labeling (ASL)

A family of perfusion imaging techniques thta measure blood flow by labeling spins with excitation pulses and then waiting for the labeled spins to enter the imaging plane before data acquisition

 

Arteries

Blood vessels that carry oxygenated blood from the heart to the rest of the body

 

Arterioles

Small arteries.

 

Ascending/descending slice acquisition

The collection of data in consecuting order, so that slices are acquired from bottom to top of from top to bottom

 

Astrocyte

A type of glial cell that regulates the extracellular environment.

 

Autoradiography

An invasive imaging technique that labels molecules using radioactive isotopes and then measures the concentration of those molecules by exposing slices of tissue to photographic emulsions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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