Blood oxygenation changes resulting from trains of low frequency transcranial magnetic stimulation

Richard H. Thomson; Jerome J. Maller; Zafiris J. Daskalakis; Paul B. Fitzgerald

doi:10.1016/j.cortex.2011.04.028

Blood oxygenation changes resulting from trains of low frequency transcranial magnetic stimulation

Richard H. Thomson, Jerome J. Maller, Zafiris J. Daskalakis, Paul B. Fitzgerald^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

23 Citations (Scopus)

Abstract

The evoked responses to transcranial magnetic stimulation (TMS) have been previously demonstrated to be on average greater at the beginning of a session; however the physiological reason for this remains uncertain. In order to investigate a possible hemodynamic mechanism for this phenomenon, changes in oxy-hemoglobin (HbO) following trains of single pulse TMS was investigated using near infra-red spectroscopy (NIRS). TMS was delivered in trains of two and four pulses to left pre-frontal cortex (PFC) at a typical intensity and frequency (2Hz) used in neuroscience research. Both trains resulted in significant drops of HbO that remained after the cessation of TMS. The changes observed imply that arterial supply drops following suprathreshold TMS and oxygen consumption outstrips supply, resulting in a net drop of HbO. This study provides evidence that at typical TMS delivery frequencies, local HbO levels remain at a sustained lower level than at the beginning of the session, potentially explaining changes in sensitivity to stimulation with repeated TMS pulses.

Original language	English
Pages (from-to)	487-491
Number of pages	5
Journal	Cortex
Volume	48
Issue number	4
DOIs	https://doi.org/10.1016/j.cortex.2011.04.028
Publication status	Published - Apr 2012
Externally published	Yes

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10.1016/j.cortex.2011.04.028

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title = "Blood oxygenation changes resulting from trains of low frequency transcranial magnetic stimulation",

abstract = "The evoked responses to transcranial magnetic stimulation (TMS) have been previously demonstrated to be on average greater at the beginning of a session; however the physiological reason for this remains uncertain. In order to investigate a possible hemodynamic mechanism for this phenomenon, changes in oxy-hemoglobin (HbO) following trains of single pulse TMS was investigated using near infra-red spectroscopy (NIRS). TMS was delivered in trains of two and four pulses to left pre-frontal cortex (PFC) at a typical intensity and frequency (2Hz) used in neuroscience research. Both trains resulted in significant drops of HbO that remained after the cessation of TMS. The changes observed imply that arterial supply drops following suprathreshold TMS and oxygen consumption outstrips supply, resulting in a net drop of HbO. This study provides evidence that at typical TMS delivery frequencies, local HbO levels remain at a sustained lower level than at the beginning of the session, potentially explaining changes in sensitivity to stimulation with repeated TMS pulses.",

keywords = "Brain stimulation, Cortical blood flow, Cortical inhibition, Oxygenated hemoglobin, Paired pulse, Pre-frontal cortex, Transcranial magnetic stimulation",

author = "Thomson, {Richard H.} and Maller, {Jerome J.} and Daskalakis, {Zafiris J.} and Fitzgerald, {Paul B.}",

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AU - Thomson, Richard H.

AU - Maller, Jerome J.

AU - Daskalakis, Zafiris J.

AU - Fitzgerald, Paul B.

PY - 2012/4

Y1 - 2012/4

N2 - The evoked responses to transcranial magnetic stimulation (TMS) have been previously demonstrated to be on average greater at the beginning of a session; however the physiological reason for this remains uncertain. In order to investigate a possible hemodynamic mechanism for this phenomenon, changes in oxy-hemoglobin (HbO) following trains of single pulse TMS was investigated using near infra-red spectroscopy (NIRS). TMS was delivered in trains of two and four pulses to left pre-frontal cortex (PFC) at a typical intensity and frequency (2Hz) used in neuroscience research. Both trains resulted in significant drops of HbO that remained after the cessation of TMS. The changes observed imply that arterial supply drops following suprathreshold TMS and oxygen consumption outstrips supply, resulting in a net drop of HbO. This study provides evidence that at typical TMS delivery frequencies, local HbO levels remain at a sustained lower level than at the beginning of the session, potentially explaining changes in sensitivity to stimulation with repeated TMS pulses.

AB - The evoked responses to transcranial magnetic stimulation (TMS) have been previously demonstrated to be on average greater at the beginning of a session; however the physiological reason for this remains uncertain. In order to investigate a possible hemodynamic mechanism for this phenomenon, changes in oxy-hemoglobin (HbO) following trains of single pulse TMS was investigated using near infra-red spectroscopy (NIRS). TMS was delivered in trains of two and four pulses to left pre-frontal cortex (PFC) at a typical intensity and frequency (2Hz) used in neuroscience research. Both trains resulted in significant drops of HbO that remained after the cessation of TMS. The changes observed imply that arterial supply drops following suprathreshold TMS and oxygen consumption outstrips supply, resulting in a net drop of HbO. This study provides evidence that at typical TMS delivery frequencies, local HbO levels remain at a sustained lower level than at the beginning of the session, potentially explaining changes in sensitivity to stimulation with repeated TMS pulses.

KW - Brain stimulation

KW - Cortical blood flow

KW - Cortical inhibition

KW - Oxygenated hemoglobin

KW - Paired pulse

KW - Pre-frontal cortex

KW - Transcranial magnetic stimulation

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DO - 10.1016/j.cortex.2011.04.028

M3 - Article

SN - 0010-9452

VL - 48

SP - 487

EP - 491

JO - Cortex

JF - Cortex

IS - 4

ER -

Blood oxygenation changes resulting from trains of low frequency transcranial magnetic stimulation

Abstract

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