1.9 Tools for Examining Brain Structure and Function

Older techniques: damage and electrical activity

Before modern imaging, scientists studied lesioning (destroying tissue to see resulting deficits) and case studies of accidental brain damage (e.g., Phineas Gage). The EEG (electroencephalogram) records electrical activity via scalp electrodes, showing brain waves useful for studying sleep stages and seizures, but with poor spatial precision.

Structural imaging tools

CT (computed tomography) scans use X-rays to create cross-sectional images of brain structure. MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce detailed structural images without radiation, revealing tumors, damage, or structural abnormalities in soft tissue.

Functional imaging tools

fMRI (functional MRI) tracks blood oxygen/flow to show brain activity in real time, linking structure to function. PET (positron emission tomography) scans use a radioactive tracer to reveal metabolic activity, highlighting which brain areas are most active during specific tasks.

Key terms

EEG

Electroencephalogram; records electrical brain activity via scalp electrodes, useful for studying sleep and seizures.

Lesioning

Deliberately damaging brain tissue (often in animals) to study resulting behavioral or functional deficits.

CT scan

Computed tomography; uses X-rays to produce cross-sectional structural images of the brain.

MRI

Magnetic resonance imaging; uses magnetic fields and radio waves to create detailed structural images without radiation.

fMRI vs. PET

fMRI tracks blood oxygen/flow to show real-time brain activity; PET uses a radioactive tracer to show metabolic activity.

Try an AP-style question

Which tool is best?

1. Structural MRI
2. CT scan
3. Lesioning
4. fMRI