Large irregular activity

Large (amplitude) irregular activity (LIA), refers to one of two local field states that have been observed in the hippocampus. The other field state is that of the theta rhythm. The theta state is characterised by a steady slow oscillation of around 6-7 Hz. LIA has a predominantly lower oscillation frequency but contains some sharp spikes (called sharp waves by Buzsa´ki, 1986) of a higher frequency than that of theta. LIA accompanies the small irregular activity state to which the term LIA has been used to describe overall (termed by Vanderwolf, 1969).