Glossary
Neural oscillations
What are neural oscillations?
Neural oscillations are rhythmic changes in neural electrical activity. They can arise from properties of individual neurons and interactions within networks. Frequency bands such as delta, theta, alpha, beta and gamma describe aspects of these rhythms; their meaning depends on where and how the activity is measured. The familiar term brain waves usually refers to oscillatory patterns seen in scalp EEG. Neural oscillations are the broader concept.
How it works
Researchers use frequency labels such as delta, theta, alpha, beta and gamma to describe oscillatory activity. Theta waves and other bands can occur in different regions and conditions. Their functions are not determined by frequency alone, and several rhythms may coexist.
Frequency is measured in hertz (Hz): one hertz is one cycle per second. The following are approximate conventions, not fixed biological boundaries; studies and recording methods use somewhat different cutoffs.
| Band | Approximate frequency |
|---|---|
| Delta | 0.5–4 Hz |
| Theta | 4–8 Hz |
| Alpha | 8–13 Hz |
| Beta | 13–30 Hz |
| Gamma | Above about 30 Hz; upper limits vary |
Applied example
Slow activity is prominent during slow-wave sleep. During wakefulness, closing the eyes commonly strengthens alpha activity over posterior scalp regions. Beta activity in motor systems often falls around voluntary movement and returns afterward. These are observations tied to particular regions and conditions: a frequency band alone does not identify a specific thought or mental state.
Why it matters
Oscillations provide a way to study timing and coordination in neural populations. Proposed functions include organizing inputs and supporting plasticity, but no single rhythm accounts for all cognition or consciousness.
Research: Buzsáki and Draguhn (2004) review network functions of oscillations rather than a one-to-one code for mental states.
Buzsáki, Logothetis and Singer (2013), supplementary discussion describes these sleep, posterior-alpha and motor-beta examples.