Phase/amplitude reset and theta-gamma interaction in the human medial temporal lobe during a continuous word recognition memory task.

@article{citeulike:2939322, abstract = {We analyzed intracranial electroencephalographic (EEG) recordings from the medial temporal lobes of 12 epilepsy patients during a continuous word recognition paradigm, contrasting trials of correctly recognized repeated words (hits) and correctly identified new words (correct rejections). Using a wavelet-based analysis, we investigated how power changes and phase clustering in different frequency bands contribute to the averaged event-related potentials (ERPs). In addition, we analyzed the actual mean phases of the different oscillations. Our analyses yielded the following results: (1) power changes contributed significantly only to the late components of the ERPs (>400 ms) (2) earlier ERP components were produced by a stimulus-related broad-band phase and amplitude reset of ongoing oscillatory activity about 190 ms after stimulus onset that involved not only the theta band, but also covered alpha and lower beta band frequencies (3) phase and amplitude reset occurred during an epoch of increased phase entrainment over time that lasted for about two oscillation periods for all involved frequencies and was more pronounced for correct rejections than for hits. The broad-band phase and amplitude reset was observed for both hits and correct rejections, and therefore, did not appear to support a specific cognitive function, but rather to act as a general facilitating factor for the processes involved in this memory task. Further analyses of synchronization between oscillations and power changes in different frequency bands revealed a task-dependent modulation of gamma activity by the entrained theta cycle, a mechanism potentially related to memory encoding and retrieval in the rhinal cortex and hippocampus, respectively.}, address = {Department of Epileptology, University of Bonn, Germany. florian.mormann@ukb.uni-bonn.de}, author = {Mormann, F. and Fell, J. and Axmacher, N. and Weber, B. and Lehnertz, K. and Elger, C. E. and Fern\'{a}ndez, G. }, citeulike-article-id = {2939322}, doi = {http://dx.doi.org/10.1002/hipo.20117}, issn = {1050-9631}, journal = {Hippocampus}, keywords = {gamma, human, lfp, oscillation, theta}, number = {7}, pages = {890--900}, posted-at = {2008-06-28 17:28:24}, priority = {2}, title = {Phase/amplitude reset and theta-gamma interaction in the human medial temporal lobe during a continuous word recognition memory task.}, url = {http://dx.doi.org/10.1002/hipo.20117}, volume = {15}, year = {2005} }

TY - JOUR ID - citeulike:2939322 L3 - citeulike-article-id:2939322 TI - Phase/amplitude reset and theta-gamma interaction in the human medial temporal lobe during a continuous word recognition memory task. JF - Hippocampus VL - 15 IS - 7 SP - 890 EP - 900 AD - Department of Epileptology, University of Bonn, Germany. florian.mormann@ukb.uni-bonn.de SN - 1050-9631 N2 - We analyzed intracranial electroencephalographic (EEG) recordings from the medial temporal lobes of 12 epilepsy patients during a continuous word recognition paradigm, contrasting trials of correctly recognized repeated words (hits) and correctly identified new words (correct rejections). Using a wavelet-based analysis, we investigated how power changes and phase clustering in different frequency bands contribute to the averaged event-related potentials (ERPs). In addition, we analyzed the actual mean phases of the different oscillations. Our analyses yielded the following results: (1) power changes contributed significantly only to the late components of the ERPs (>400 ms) (2) earlier ERP components were produced by a stimulus-related broad-band phase and amplitude reset of ongoing oscillatory activity about 190 ms after stimulus onset that involved not only the theta band, but also covered alpha and lower beta band frequencies (3) phase and amplitude reset occurred during an epoch of increased phase entrainment over time that lasted for about two oscillation periods for all involved frequencies and was more pronounced for correct rejections than for hits. The broad-band phase and amplitude reset was observed for both hits and correct rejections, and therefore, did not appear to support a specific cognitive function, but rather to act as a general facilitating factor for the processes involved in this memory task. Further analyses of synchronization between oscillations and power changes in different frequency bands revealed a task-dependent modulation of gamma activity by the entrained theta cycle, a mechanism potentially related to memory encoding and retrieval in the rhinal cortex and hippocampus, respectively. KW - gamma KW - human KW - lfp KW - oscillation KW - theta AU - Mormann, F AU - Fell, J AU - Axmacher, N AU - Weber, B AU - Lehnertz, K AU - Elger, CE AU - Fernández, G PY - 2005/// UR - http://dx.doi.org/10.1002/hipo.20117 ER -