Theta power and theta-gamma coupling support spatial memory retrieval

Abstract

23Hippocampal theta oscillations have been implicated in spatial memory function in both 24 rodents and humans. What is less clear is how hippocampal theta interacts with higher 25 frequency oscillations during spatial memory function, and how this relates to subsequent 26 behaviour. Here we asked ten human epilepsy patients undergoing intracranial EEG 27 recording to perform a desk-top virtual reality spatial memory task, and found that increased 28 theta power in two discrete bands ('low' 2-5Hz and 'high' 6-9Hz) during cued retrieval was 29 associated with improved task performance. Similarly, increased coupling between 'low' 30 theta phase and gamma amplitude during the same period was associated with improved 31 task performance. These results support a role of theta oscillations and theta-gamma phase-32 amplitude coupling in human spatial memory function. 33 34

Theta rhythmicity governs the timing of behavioral and hippocampal responses in humans specifically during memory-dependent tasks

“…PPC increases were also visible in the raw data (Figure S4B) and appeared as theta oscillations in event-related potentials of correct trials (Figure S4D), confirming that these effects were not caused by changes in the baseline. The increases in PPC were accompanied by increased power for retrieval trials, but not for encoding and catch questions (see Figure S4C), in line with (Vivekananda et al, 2019), suggesting that power and phase were modulated independently.…”

Dissociable oscillatory theta signatures of memory formation in the developing brain

“…These results establish that two theta oscillations are present in cortical sites of the developing MTL and PFC. In addition to extending findings from adults [49][50][51][52] to children and adolescents, these results demonstrate that the phenomenon of two theta oscillations is not specific to the hippocampus but extends to frontotemporal networks.…”

“…Based on our finding of power subsequent memory effects across lower and higher theta frequency ranges, and motivated by burgeoning reports in adults, [49][50][51][52] we next tested for the presence of two theta oscillations in our pediatric sample. Results establish two theta oscillations in cortical sites of the developing MTL and PFC, thus extending the phenomenon from adults to children and adolescents, and from the hippocampus to frontotemporal networks.…”

“…25 Recent studies in adults converge on the finding that two distinct oscillations at the ends of the theta band, centered $2 and $8 Hz, support hippocampal processes during memory and navigation. [49][50][51][52] Jointly motivated by this literature and the observed spectral signatures of memory formation, we next examined the prevalence of two theta oscillations in cortical sites of the developing brain in a 3-fold procedure. First, visual inspection of study trials (all attended scenes) suggested periodic fluctuations of the ECoG signal in MTL electrodes (Figure 3A, left).…”

“…Peak detection was performed on the oscillatory residuals using a threshold of 4.5 Hz to distinguish slow from fast theta. [49][50][51][52] Inter-regional amplitude coupling Study data segments were zero-padded and bandpass filtered per-electrode at the theta peaks (1/3 fractional bandwidth) following removal of the ERP. [87][88][89]91 The filtered data were epoched from -0.45 to +3.5 s from scene onset and z-scored per trial in the time domain to control for differences in voltage between hit and miss trials.…”