Summary: Methods in Neuroscience

CHAPTER 2: CELLS AND STRUCTURES

Brain-imaging techniques reveal structure and function of brain

Computerized Axial Tomography (CAT or CT): non-invasive technique to examine brain structure through computer analysis of x-ray absorption at several positions around the head, x-ray energy is used to generate medium-resolution images useful for problems like stroke, tumours or cortical shrinkage

Magnetic Resonance Imagining (MRI): non-invasive brain imaging technology using magnetism and radiofrequency energy to create images, higher-resolution images than CT

-magnet causes protons in brain’s tissues and fluids to line up parallel , knocked over by powerful pulse of radio waves, then pulse turned off to let protons relax back to original configuration, emitting radio waves as they do so

-measure these radio waves that emit differently for tissues of different density

-reveals subtle changes in brain like loss of myelin

Diffusion Tensor Imaging (DTI): modified form of MRI where diffusion of water in confined space is exploited to produce images of axonal fiber tracks

Functional MRI (fMRI): magnetic resonance imaging that detects changes in blood flow and therefore identifies regions of the brain that are particularly active during task

-generates images of brains activity rather than details of its structure

-not photographic; created by metabolic and structural assumptions, may be misleading

Positron Emission Tomography (PET): tracks metabolism of injected radioactive substances in the brain to map brain activity

-depicts brains activity during behavioral tasks

-not as detailed as fMRI but is faster and tracks quick changes in brain activity

Transcranial Magnetic Stimulation (TMS): non-invasive technique to examine brain function, applies strong magnetic fields to stimulate cortical neurons in order to identify discrete areas of the brain particularly active during specific behaviors

Magnetoencephalography (MEG): non-invasive, creates maps of brain activity during cognitive tasks by measuring tiny magnetic fields produced by active neurons

-since it tracks quick moment-by-moment changes in brain activity, excellent for studying rapidly shifting patterns of brain activity in cortical circuits that fMRI is too slow to track


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