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Cortical inhibition of distinct mechanisms in the dorsolateral prefrontal cortex is related to working memory performance: a TMS-EEG study.
Cortex 2015; 64:68-77C

Abstract

Paired-pulse transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) is a method for studying cortical inhibition from the dorsolateral prefrontal cortex (DLPFC). However, little is known about the mechanisms underlying TMS-evoked cortical potentials (TEPs) from this region, let alone inhibition of these components. The aim of this study was to assess cortical inhibition of distinct TEPs and oscillations in the DLPFC using TMS-EEG and to investigate the relationship of these mechanisms to working memory. 30 healthy volunteers received single and paired (interstimulus interval = 100 msec) TMS to the left DLPFC. Variations in long-interval cortical inhibition (LICI) of different TEP peaks (N40, P60, N100) and different TMS-evoked oscillations (alpha, lower beta, upper beta, gamma) were compared between individuals. Variation in N100 slope following single pulse TMS, another putative marker of inhibition, was also compared with LICI of each measure. Finally, these measures were correlated with performance of a working memory task. LICI resulted in significant suppression of all TEP peaks and TMS-evoked oscillations (all p < .05). There were no significant correlations between LICI of different TEP peaks or TMS-evoked oscillations with the exception of P60 and N100. Variation in N100 slope correlated with LICI of N40 and beta oscillations. In addition, LICI of P60 and N100 were differentially correlated with working memory performance. The results suggest that both the LICI paradigm and N100 following single pulse TMS reflect complementary methods for assessing GABAB-mediated cortical inhibition in the DLPFC. Furthermore, these measures demonstrate the importance of prefrontal GABAB-mediated inhibitory control for working memory performance.

Authors+Show Affiliations

Monash Alfred Psychiatry Research Centre, Central Clinical School, The Alfred and Monash University, Melbourne, Australia; Monash Clinical and Imaging Neuroscience, School of Psychological Science and Monash Biomedical Imaging, Monash University, Melbourne, Australia. Electronic address: nigel.rogasch@monash.edu.Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, University of Toronto, Toronto, Canada.Monash Alfred Psychiatry Research Centre, Central Clinical School, The Alfred and Monash University, Melbourne, Australia.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25461708

Citation

Rogasch, Nigel C., et al. "Cortical Inhibition of Distinct Mechanisms in the Dorsolateral Prefrontal Cortex Is Related to Working Memory Performance: a TMS-EEG Study." Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, vol. 64, 2015, pp. 68-77.
Rogasch NC, Daskalakis ZJ, Fitzgerald PB. Cortical inhibition of distinct mechanisms in the dorsolateral prefrontal cortex is related to working memory performance: a TMS-EEG study. Cortex. 2015;64:68-77.
Rogasch, N. C., Daskalakis, Z. J., & Fitzgerald, P. B. (2015). Cortical inhibition of distinct mechanisms in the dorsolateral prefrontal cortex is related to working memory performance: a TMS-EEG study. Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 64, pp. 68-77. doi:10.1016/j.cortex.2014.10.003.
Rogasch NC, Daskalakis ZJ, Fitzgerald PB. Cortical Inhibition of Distinct Mechanisms in the Dorsolateral Prefrontal Cortex Is Related to Working Memory Performance: a TMS-EEG Study. Cortex. 2015;64:68-77. PubMed PMID: 25461708.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cortical inhibition of distinct mechanisms in the dorsolateral prefrontal cortex is related to working memory performance: a TMS-EEG study. AU - Rogasch,Nigel C, AU - Daskalakis,Zafiris J, AU - Fitzgerald,Paul B, Y1 - 2014/10/22/ PY - 2014/05/19/received PY - 2014/08/23/revised PY - 2014/10/07/accepted PY - 2014/12/3/entrez PY - 2014/12/3/pubmed PY - 2015/12/15/medline KW - Cortical inhibition KW - Dorsolateral prefrontal cortex KW - Electroencephalography KW - Transcranial magnetic stimulation KW - Working memory SP - 68 EP - 77 JF - Cortex; a journal devoted to the study of the nervous system and behavior JO - Cortex VL - 64 N2 - Paired-pulse transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) is a method for studying cortical inhibition from the dorsolateral prefrontal cortex (DLPFC). However, little is known about the mechanisms underlying TMS-evoked cortical potentials (TEPs) from this region, let alone inhibition of these components. The aim of this study was to assess cortical inhibition of distinct TEPs and oscillations in the DLPFC using TMS-EEG and to investigate the relationship of these mechanisms to working memory. 30 healthy volunteers received single and paired (interstimulus interval = 100 msec) TMS to the left DLPFC. Variations in long-interval cortical inhibition (LICI) of different TEP peaks (N40, P60, N100) and different TMS-evoked oscillations (alpha, lower beta, upper beta, gamma) were compared between individuals. Variation in N100 slope following single pulse TMS, another putative marker of inhibition, was also compared with LICI of each measure. Finally, these measures were correlated with performance of a working memory task. LICI resulted in significant suppression of all TEP peaks and TMS-evoked oscillations (all p < .05). There were no significant correlations between LICI of different TEP peaks or TMS-evoked oscillations with the exception of P60 and N100. Variation in N100 slope correlated with LICI of N40 and beta oscillations. In addition, LICI of P60 and N100 were differentially correlated with working memory performance. The results suggest that both the LICI paradigm and N100 following single pulse TMS reflect complementary methods for assessing GABAB-mediated cortical inhibition in the DLPFC. Furthermore, these measures demonstrate the importance of prefrontal GABAB-mediated inhibitory control for working memory performance. SN - 1973-8102 UR - https://www.unboundmedicine.com/medline/citation/25461708/Cortical_inhibition_of_distinct_mechanisms_in_the_dorsolateral_prefrontal_cortex_is_related_to_working_memory_performance:_a_TMS_EEG_study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0010-9452(14)00316-5 DB - PRIME DP - Unbound Medicine ER -