A quantitative study of gamma‐band activity in human intracranial recordings triggered by visual stimuli
- 1 July 2000
- journal article
- research article
- Published by Wiley in European Journal of Neuroscience
- Vol. 12 (7), 2608-2622
- https://doi.org/10.1046/j.1460-9568.2000.00163.x
Abstract
This paper studies gamma‐band responses from two implanted epileptic patients during a simple visual discrimination task. Our main aim was to ascertain, in a reliable manner, whether evoked (stimulus‐locked) and induced (triggered by, but not locked to, stimuli) responses are present in intracranial recordings. For this purpose, we introduce new methods adapted to detect the presence of gamma responses at this level of recording, intermediary between EEG‐scalp and unicellular responses. The analysis relies on a trial‐by‐trial time–frequency analysis and on the use of surrogate data for statistical testing. We report that visual stimulation reliably elicits evoked and induced responses in human intracranial recordings. Induced intracranial gamma activity is significantly present in short oscillatory bursts (a few cycles) following visual stimulation. These responses are highly variable from trial to trial, beginning after 200 ms and lasting up to 500 ms. In contrast, intracranial‐evoked gamma responses concentrate around 100 ms latencies corresponding to evoked responses observed on the scalp. We discuss our results in relation to scalp gamma response in a similar protocol [Tallon‐Baudry et al. (1996) J. Neurosci., 16, 4240–4249] and draw some conclusions for bridging the gap between gamma oscillations observed on the scalp surface and their possible cortical sources.Keywords
This publication has 37 references indexed in Scilit:
- Oscillatory gamma activity in humans and its role in object representationTrends in Cognitive Sciences, 1999
- Is Neural Noise Just a Nuisance?Science, 1996
- Synchronization of neuronal responses in the optic tectum of awake pigeonsVisual Neuroscience, 1996
- Evoked and induced gamma-band activity of the human cortexBrain Topography, 1995
- Improving the readability of time-frequency and time-scale representations by the reassignment methodIEEE Transactions on Signal Processing, 1995
- Visual Feature Integration and the Temporal Correlation HypothesisAnnual Review of Neuroscience, 1995
- Episodic multiregional cortical coherence at multiple frequencies during visual task performanceNature, 1993
- Visually Triggered Neuronal Oscillations in the Pigeon: An Autocorrelation Study of Tectal ActivityEuropean Journal of Neuroscience, 1993
- Fast (beta) rhythms in the hippocampus: A reviewHippocampus, 1992
- Electrical activity of the cingulate cortex. I. Generating mechanisms and relations to behaviorBrain Research, 1987