Contribution to Published Research
From: Control of Working Memory by Phase Amplitude Coupling of Human Hippocampal Neurons: co-authorship* Daume et al., Nature, 2024
To determine the influence of theta waveform shape on PAC, we tested for differences in theta waveform peak-to-trough as well as rise-to-decay asymmetries between the two load conditions, which could potentially cause differences in TG-PAC. To extract and characterize each theta cycle during the delay period in all significant hippocampal PAC channels, we used the bycycle toolbox in Python. We averaged estimates for peak-to-trough as well as rise-to-decay asymmetries across cycles during the maintenance period from the same trials used for our PAC analysis within each load and tested the estimates between the conditions.
Additional Results:
Simultaneous Analysis of Hippocampal Single Unit Activity and Local Field Potential (LFP)
neuron firing rate compared to LFP from same channel
neuron firing rate compared to LFP from all other channels
Finding: Greater waveform asymmetry in local theta oscillations significantly correlates with faster firing of single neurons in the hippocampus.
MATLAB-Python Codebase: here
Complete Analysis Results: here
Developing a Signal Processing Pipeline for Human Intracranial EEG
General Research Overview
Nonsinusoidal neuronal oscillations: bug or feature? Lozano-Soldevilla, J Neurophysiology, 2018
Coupled neural activity controls working memory in humans: Ziv Williams, Nature News & Views, 2024
Control of Working Memory by Phase-Amplitude Coupling of Human Hippocampal Neurons: co-authorship* Daume et al., Nature, 2024
Analysis Rationale:
Filters: When, Why, and How (Not) to Use Them Cheveigne and Nelken, Neuron, 2019
Waveform shape assumptions can produce artifactual cross-frequency-coupling results. Control analysis required to establish stronger basis for attributing TG-PAC differences to conditioned memory load.
Methodology: Theta Burst Detection and Waveform Shape Characterization
Cycle-by-cycle analysis of neural oscillations: Cole & Voytek, J. Neurophysiology 2019
Visual Intro to Fourier Transform: here
Published Results:
Extended Data Fig. 3c: Theta-high gamma PAC control analyses in the hippocampus.