Chapter 13: Measuring Brain Activity

Chapter 13: Measuring Brain Activity

Module 13.14: Brain Activity Monitoring

• Brain activity can be monitored using external electrodes.

• The recorded activity is referred to as an Electroencephalogram (EEG).

Electrical Activity of the Brain

• Neural function is dependent on electrical events, which involve charge changes in the membrane of neurons.

• The electrical activity generated by all neurons in the brain creates an electrical field that can be measured using electrodes placed on the scalp.

• The printed report of the brain's electrical activity is called an electroencephalogram (EEG).

• The various electrical patterns observed in an EEG are referred to as brain waves.

Types of Brain Waves

Alpha Waves

• Occurrence:

  • Present in healthy, awake adults while they are resting with their eyes closed.

  • Disappear during sleep and when there is a concentration on a specific task.

Beta Waves

• Characteristics:

  • Have a higher frequency than alpha waves.

  • Manifest in individuals who are concentrating on tasks, under stress, or experiencing psychological tension.

Theta Waves

• Occurrence:

  • Appear transiently during sleep in normal adults.

  • Typically observed in children and intensely frustrated adults.

  • Presence under other circumstances may indicate potential brain disorders.

Delta Waves

• Characteristics:

  • Large-amplitude and low-frequency waves.

  • Normally seen during deep sleep across all ages.

  • Also noted in the brains of infants due to incomplete cortical development.

  • Can be observed in awake adults if there are issues such as tumors, vascular blocks, or inflammation affecting brain areas.

Abnormal Brain Activity

• The electrical activity in the cerebral hemispheres is typically synchronized by a "pacemaker" mechanism that involves the thalamus.

• Asynchrony (lack of synchronization) of brain activity may indicate localized brain damage or abnormalities.

  • Example: Presence of a tumor or injury can disrupt the normal pattern in one hemisphere, resulting in a loss of alignment between the hemispheres.

Seizures

• Definition:

  • A seizure is defined as a temporary cerebral disorder characterized by unusual neural activity resulting in various movements, sensations, or behaviors.

  • Seizures are marked by a change in the pattern of electrical activity within the brain.

• Clinical Conditions:

  • Epilepsies, or seizure disorders, are clinical conditions identified by the occurrence of seizures intermittently over time.