Ephaptic

Part of speech: adjective

Definitions

1. Relating to electrical interactions between adjacent nerve or muscle fibers not involving synapses but through direct field effects ; describing a type of communication between cells via extracellular electric fields rather than chemical signals ; pertaining to the transfer of impulses due to close proximity of excitable membranes without conventional synaptic connections
2. Concerning non-synaptic electrical influence between cells occurring from electric field effects across nearby membranes ; referring to direct electrical coupling between neurons or muscle fibers outside of traditional synapses ; involving the transmission of impulses due to electrical interactions between adjacent excitable tissues without neurotransmitter release
3. Denoting a mode of cellular communication where electrical signals pass through local field effects rather than synaptic gaps ; characterizing interactions between closely positioned nerve or muscle cells mediated by electric current rather than chemical means ; relating to the phenomenon where neural or muscular activity affects neighboring cells through electrical coupling without synaptic junctions

Etymology: "Ephaptic" describes nerve impulses that pass from one fibre to a neighbouring one not through a synapse but through the electric field that the active fibre generates. The word is a learned coinage built from Ancient Greek parts: "eph-", meaning "on" or "upon", and "hapsis", meaning "touching" or "contact" (the same root that gives English "haptic"). Literally, then, an ephaptic effect is one that happens by touching across a distance without physical contact. The word is a modern technical term, borrowed in the scientific style of classical compounds rather than used by the ancient Greeks, who had no concept of nerve fields. It is a clean example of how physiologists reached back to classical vocabulary to name a phenomenon that had no existing English word.