5.12 Tools to Examine Brain Structure and Function

Structural brain imaging

Structural techniques show brain anatomy but not activity. A CT (computed tomography) scan uses X-rays to create cross-sectional images, useful for detecting tumors or damage. An MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce detailed, high-resolution images of soft tissue, revealing structural abnormalities like lesions with greater clarity than CT scans.

Functional brain imaging

Functional techniques show brain activity in real time. An fMRI (functional MRI) tracks blood flow and oxygen use to show which brain areas are active during tasks. A PET (positron emission tomography) scan uses radioactive glucose to reveal metabolic activity and neurotransmitter function. An EEG (electroencephalogram) records electrical activity via scalp electrodes, offering excellent timing precision but poor spatial detail.

Lesioning and stimulation methods

Researchers also study the brain by manipulating it directly. Lesioning destroys or damages specific brain tissue to observe resulting deficits, revealing that area's function. TMS (transcranial magnetic stimulation) uses magnetic pulses to temporarily activate or disrupt specific brain regions, helping researchers infer function without permanent damage.

Key terms

CT scan

Uses X-rays to create cross-sectional structural images of the brain.

MRI

Uses magnetic fields and radio waves to produce detailed structural images of soft brain tissue.

fMRI

Tracks blood flow and oxygen use to show real-time brain activity during tasks.

PET scan

Uses radioactive glucose to measure metabolic activity and neurotransmitter function in the brain.

TMS

Transcranial magnetic stimulation; uses magnetic pulses to temporarily activate or disrupt specific brain regions.

Try an AP-style question

Which tool is best?

1. EEG
2. PET
3. CT
4. Structural MRI