Introduction to Symmetry and Asymmetry in EEG

Questions and Answers

What does asymmetrical refer to in EEG patterns?

A change in appearance of a rhythm on one side (correct)

Patterns that occur at regular time intervals

Equal activity across both hemispheres

Patterns that are uninterrupted

Which term describes a waveform that occurs at regular intervals of time?

Reactivity

Periodic (correct)

Discontinuous

Intermittent

How is unilateral activity defined in the context of EEG recordings?

Activity that is focused in one hemisphere only (correct)

Random activity without distinct patterns

Patterns that occur equally over left and right hemispheres

Activity that involves both hemispheres simultaneously

What is the definition of reactivity in EEG patterns?

Patterns that change with environmental stimuli Signup and view all the answers

What characterizes multifocal spike discharges?

Multiple independent foci of activity Signup and view all the answers

Which term indicates patterns that occur occasionally and are not synchronized?

Discontinuous Signup and view all the answers

Study Notes

Symmetry and Asymmetry

Symmetry refers to the uniformity of patterns or rhythms on both hemispheres of the brain.
Symmetry can relate to frequency (how often a wave occurs) and amplitude (height of the wave).
Asymmetrical activity shows a variance in rhythm appearance on one side, often due to added or suppressed brain activity on that side.

Key Terms in Wave Characteristics

Periodicity: Describes the regular time intervals between occurrences of waves or patterns; periodic waveforms demonstrate consistent timing.
Reactivity: Identifies patterns that change with specific stimuli, such as eye opening, which can lead to attenuation of alpha waves in occipital leads.

Wave Presence and Distribution

Continuous: Waves are present without any interruptions throughout the recording.
Discontinuous: Waves occur at intervals but are not consistent or constant; interrupted patterns are observed.
Intermittent: Waves appear sporadically and do not follow a defined periodic pattern.

Lateralization in EEG

Lateralized: Activities or patterns present exclusively in one hemisphere of the brain.
Bilateral: Activities evident in both hemispheres of the brain during EEG readings.
Unilateral: Activities confined to one hemisphere, indicating localized effects.

Contralateral and Ipsilateral Activity

Contralateral: Refers to activities or symptoms affecting the opposite side of the body or head in relation to brain activities.
Ipsilateral: Activities occurring on the same side as the source of stimulation or effect.

Focal, Multifocal, and Generalized Activity

Focal: Activity concentrated in a specific, clearly defined brain area, such as temporal spikes or slowing.
Multifocal: Involves multiple independent focal activities, such as multifocal paroxysmal spike discharges.
Generalized: Spread of activity across all electrodes, can be:
- Primarily generalized: Discharges that are generalized from the start.
- Secondarily generalized: Discharges that begin as focal and subsequently expand to a generalized state.

Description

This quiz explores the concepts of symmetry and asymmetry as they relate to EEG patterns. Understand the significance of periodicity and how it affects the representation of brain activity on both sides. Test your knowledge on waveforms and their characteristics in neurological contexts.