Overview of Brain Study Methods

Introduction

Various methods exist for studying the brain.
Methods are divided into two main categories:
- Structural methods (brain structure)
- Functional methods (brain function)

CAT Scans (CT Scans)
- Full Form: Computerized Axial Tomography
- Mechanism: Uses X-rays to create brain images.
- Uses: Detects tumors, swelling, or bleeding.
- Limitations: Does not show brain activity.
Magnetic Resonance Imaging (MRI)
- Mechanism: Utilizes radio waves and strong magnetic fields.
- Process:
  - Person’s head is exposed to a magnetic field.
  - Atoms align directionally; radio waves disrupt this alignment.
  - As atoms realign, they emit signals.
  - Different atoms emit distinct signals, creating detailed brain images.
- Limitations: Like CT, it does not provide functional information.

Electroencephalography (EEG)
- Mechanism: Measures electrical activity of neurons using scalp electrodes.
- Properties:
  - Electrodes placed externally (non-invasive).
  - Records cumulative electrical fields from the brain.
- Outputs: Wavy lines indicating states like wakefulness, seizures, cognitive engagement.
Magnetoencephalography (MEG)
- Mechanism: Records magnetic fields from brain’s electrical currents.
- Equipment: Uses SQUIDs (Superconductive Quantum Interface Devices).
- Resolution: Better than EEG.
- Limitations: Requires large machinery and special room shielding.

Functional Magnetic Resonance Imaging (FMRI)
- Combines MRI’s structural image with functional activity.
- Mechanism:
  - Active neurons require more oxygen.
  - Measures oxygenated vs. deoxygenated blood to track brain activity.
  - Can identify active brain regions during specific tasks.
Positron Emission Tomography (PET Scans)
- Combines with other structural techniques like MRI.
- Mechanism:
  - Injects radioactive glucose.
  - Active cells (using more glucose) are visualized.
- Limitations: More invasive due to injection requirements.