title: Increased mesiotemporal delta activity characterizes virtual navigation in humans.
abstract: Hippocampal theta or rhythmic slow activity (RSA) occurring during exploratory behaviors and rapid-eye-movement (REM) sleep is a characteristic and well-identifiable oscillatory rhythm in animals. In contrast, controversy surrounds the existence and electrophysiological correlates of this activity in humans. Some argue that the human hippocampal theta occurs in short and phasic bursts. On the contrary, our earlier studies provide evidence that REM-dependent mesiotemporal RSA is continuous like in animals but instead of the theta it falls in the delta frequency range. Here we used a virtual navigation task in 24 epilepsy patients implanted with foramen ovale electrodes. EEG was analyzed for 1-Hz wide frequency bins up to 10 Hz according to four conditions: resting, non-learning route-following, acquisition and recall. We found progressively increasing spectral power in frequency bins up the 4 Hz across these conditions. No spectral power increase relative to resting was revealed within the traditional theta band and above in any of the navigation conditions. Thus the affected frequency bins were below the theta band and were similar to those characterizing REM sleep in our previous studies providing further indication that it is delta rather than theta that should be regarded as a human analog of the animal RSA.
authors.affiliation: National Institute of Neuroscience, Amerikai út 57, H-1145 Budapest, Hungary. clemenszsofia@gmail.com
authors.forename: Zsófia
authors.initials: Z
authors.lastname: Clemens
authors.forename: Csaba
authors.initials: C
authors.lastname: Borbély
authors.forename: Béla
authors.initials: B
authors.lastname: Weiss
authors.forename: Loránd
authors.initials: L
authors.lastname: Erőss
authors.forename: Anna
authors.initials: A
authors.lastname: Szűcs
authors.forename: Anna
authors.initials: A
authors.lastname: Kelemen
authors.forename: Dániel
authors.initials: D
authors.lastname: Fabó
authors.forename: György
authors.initials: G
authors.lastname: Rásonyi
authors.forename: József
authors.initials: J
authors.lastname: Janszky
authors.forename: Péter
authors.initials: P
authors.lastname: Halász
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D012895:Sleep, REM / Q000502:physiology*; D014584:User-Computer Interface; D055815:Young Adult