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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: Neuropsychologia. 2015 Mar 20;76:108–124. doi: 10.1016/j.neuropsychologia.2015.03.021

Figure 3. Entorhinal (ER) theta generation and modulation.

Figure 3

A. Yellow arrow indicates the entorhinal cortex (ER) laminar probe location on a sagittal MRI taken with the probes in situ (Patient 3). Laminar tip is in the medial aspect of the left parahippocampal g., adjacent to the cisterna ambiens (Insausti and Amaral, 2004) (coordinates −23, −17, −25).

B. iERSP evoked in the WR task. Initially, words evoke strong wideband (~2-200Hz) increases in spectral power (↓). The increase is present in both superficial and deep layers, to both new and old stimuli, but is strongest in superficial layers to old words (↓↓). In most frequencies, the broadband increase appears to begin at ~300ms after word onset. Significant old> new differences are present in all frequency bands from ~400-600ms after word onset, mainly in superficial layers. This broadband increase is followed by a theta band increase, from ~500-1100ms in upper layers, new (↑) greater than old (↑↑). At still longer latencies, after 1100ms, theta is larger to old stimuli in both superficial (⇑) and deep layers (Δ). Although the first burst of high frequency activity is mainly to old words and over by ~600ms, high frequency activity continues, especially to new words, until ~2000ms (^).

C. Phase-locking between superficial and deep CSD. Phase locking increases mainly in gamma frequencies to new words (⇓), and mainly in theta and delta bands to old words (↓).

D. PG waveforms from individual trials of WR, aligned on stimulus onset and superimposed. Single trials show an initial component with duration of ~400ms peaking at ~300ms (⇓), followed by a slower components with peaks at ~750ms (⇑) and 1700ms (↓).

E. Inter-Trial Coherence of PG in putative deep ER layer. ITC in low theta and delta frequencies increases relative to baseline until ~900ms after stimulus onset (⇑).

F. Event-related averaged PG during WR. Phase-synchronization of low frequency PG waveforms allows them to contribute to the cross-trial average.

G. Depth profile of the theta CSD. Broadband CSD was averaged to theta peaks found in the band-passed data. Distinct profiles are observed for theta triggered to peaks in the superficial (red traces) versus deep (black traces) layers. In both cases, there are two spatially separated sinks, one deep (Δ) and one superficial (^), with each sink surrounded by its own current sources.