Reliability of early cortical auditory gamma-band responses

Abstract

Objective To evaluate the test-retest reliability of event-related power changes in the 30–150 Hz gamma frequency range occurring in the first 150 ms after presentation of an auditory stimulus. Methods Repeat intracranial electrocorticographic (ECoG) recordings were performed with 12 epilepsy patients, at ≥ 1-day intervals, using a passive odd-ball paradigm with steady-state tones. Time-frequency matching pursuit analysis was used to quantify changes in gamma-band power relative to pre-stimulus baseline. Test-retest reliability was estimated based on within-subject comparisons (paired t-test, McNemar’s test) and correlations (Spearman rank correlations, intra-class correlations) across sessions, adjusting for within-session variability. Reliability estimates of gamma-band response robustness, spatial concordance, and reproducibility were compared with corresponding measurements from concurrent auditory evoked N1 responses. Results All patients showed increases in gamma-band power, 50–120 ms post-stimulus onset, that were highly robust across recordings, comparable to the evoked N1 responses. Gamma-band responses occurred regardless of patients’ performance on behavioral tests of auditory processing, medication changes, seizure focus, or duration of test-retest interval. Test-retest reproducibility was greatest for the timing of peak power changes in the high-gamma range (65–150 Hz). Reliability of low-gamma responses and evoked N1 responses improved at higher signal-to-noise levels. Conclusions Early cortical auditory gamma-band responses are robust, spatially concordant, and reproducible over time. Significance These test-retest ECoG results confirm the reliability of auditory gamma-band responses, supporting their utility as objective measures of cortical processing in clinical and research studies.

The importance of individual frequencies of endogenous brain oscillations for auditory cognition – A short review

“…The peak in the spectrum (the frequency for which the amplitude is largest in the time frequency analysis) is highly variable across individuals, but at the same time, relatively constant within individuals (Fründ et al, 2007). Cervenka et al (2013) found early cortical auditory eGBRs to be test-retest reliable, regardless of general individual auditory performance. The same stability has been revealed for the preferred frequency of the auditory cortex (Baltus and Herrmann, 2015).…”

Ictal propagation of high frequency activity is recapitulated in interictal recordings: Effective connectivity of epileptogenic networks recorded with intracranial EEG

“…We computed the time-frequency energy distribution of ictal activity in all recorded channels using a matching pursuit (MP) algorithm (Mallat and Zhang, 1993), which has been previously successfully used for detection of epileptic activity (Jouny et al, 2007a; Jouny et al, 2003), as well as functional activity (Boatman-Reich et al, 2010; Cervenka et al, 2011a; Cervenka et al, 2013a; Cervenka et al, 2013b; Cervenka et al, 2011b). MP is an iterative procedure that decomposes signal x(t) into a linear combination of members of a specified set of functions.…”

A Dynamic Directional Model for Effective Brain Connectivity Using Electrocorticographic (ECoG) Time Series

“…ECoG recordings are characterized by high signal-to-noise ratios and excellent temporal (1-2 ms) and spatial (10 mm) resolution. ECoG recordings from the human auditory cortex have been shown recently to be highly reliable and reproducible (Cervenka et al , 2013). Resting on the unique properties of the ECoG, below we propose a new dynamic directional model (DDM) with a simple formulation to evaluate the effective connectivity between many brain components.…”

“…Event-related ECoG recordings were acquired simultaneously from all electrodes using an established 300-trial passive auditory oddball paradigm (Sinai et al , 2009; Cervenka et al , 2013). Two 50 ms duration single-frequency tones were presented: a frequently repeated 1000 Hz tone ( N =246 trials) and an infrequently and pseudo-randomly presented (no consecutive repetitions) 1200 Hz tone ( N =54 trials).…”

“…Tone stimuli were presented binaurally at a comfortable listening level through insert earphones at inter-stimulus intervals of 1450 ms. To reduce attention effects, the patient watched an animated movie with no sound. The continuous ECoG signal was amplified (5×1000) and recorded digitally using a referential montage, 1000 Hz A/D sampling and a bandwidth of 0.1-300 Hz, as previously described (Cervenka et al , 2013). Two electrodes (channels 47 and 48) in the top corner of the array, outside perisylvian cortex, were assigned as the reference and ground electrodes.…”