What is Local Field Potential?

A low-frequency electrical signal recorded by an intracortical or ECoG electrode that reflects the aggregate synaptic activity of a local neural population.

What category does Local Field Potential belong to in BCI?

Local Field Potential is a Signal Types concept in brain-computer interface science.

Local Field Potential — BCI Glossary

The local field potential (LFP) is a broadband low-frequency neural signal (typically 1–300 Hz) recorded by an electrode in or on brain tissue. Unlike single-unit action potentials, which reflect the activity of individual neurons, the LFP reflects the summed synaptic currents flowing in neurons within a roughly 250 µm radius of the recording electrode.

What LFPs Represent

LFPs are dominated by postsynaptic potentials (EPSPs and IPSPs) from large populations of neurons whose dendrites are oriented similarly. They reflect the "input" to a cortical region — the aggregate synaptic drive from local and long-range connections — rather than the output (spikes).

Key LFP frequency bands and their significance:

Delta (1–4 Hz): Deep sleep, general anesthesia
Theta (4–8 Hz): Hippocampal navigation, working memory
Alpha (8–12 Hz): Idling/inhibition, sensory gating
Beta (13–30 Hz): Motor cortex "idling"; excessive beta is a biomarker of Parkinson's motor symptoms
Gamma (30–80 Hz): Active processing, attention
High-gamma (70–150 Hz): Local cortical activation; strong BCI decoding signal in ECoG recordings

Clinical Relevance in BCI

LFPs play a critical role in two major clinical BCI applications:

DBS Sensing (Parkinson's/Tremor): Medtronic's Percept PC BrainSense technology records subthalamic nucleus LFPs to detect pathological beta oscillations (13-30 Hz) associated with Parkinson's motor symptoms. This enables adaptive, closed-loop DBS that adjusts stimulation amplitude in response to beta power — a major advance over constant stimulation.
Endovascular BCI: Synchron's Stentrode, implanted in blood vessels adjacent to motor cortex, records LFPs (not single-unit spikes) through the vessel wall. Motor-band LFP modulation is sufficient to decode intended movement for device control.

LFP vs. Spikes for BCI

LFPs are generally more stable over time than single-unit recordings — they remain interpretable even as individual electrode recordings degrade due to glial scarring. This makes LFP-based decoding particularly attractive for chronic implanted BCIs. The tradeoff is lower information content per channel compared to single-unit spike recordings.