Limits...
Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS.

Sowman PF, Dueholm SS, Rasmussen JH, Mrachacz-Kersting N - Front Hum Neurosci (2014)

Bottom Line: Acoustic stimuli can cause a transient increase in the excitability of the motor cortex.We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation.This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Science, Macquarie University Sydney, NSW, Australia ; Perception and Action Research Centre (PARC), Faculty of Human Sciences, Macquarie University Sydney, NSW, Australia ; Australian Research Council Centre of Excellence in Cognition and its Disorders (CCD), Macquarie University Sydney, NSW, Australia.

ABSTRACT
Acoustic stimuli can cause a transient increase in the excitability of the motor cortex. The current study leverages this phenomenon to develop a method for testing the integrity of auditorimotor integration and the capacity for auditorimotor plasticity. We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation. This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli. We propose that the method developed here might provide a useful tool for future studies that measure auditory-motor connectivity in communication disorders.

No MeSH data available.


Related in: MedlinePlus

Two sounds used as auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise version of (A). Frequency spectra of the two auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise (white noise) version of (A).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4042887&req=5

Figure 1: Two sounds used as auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise version of (A). Frequency spectra of the two auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise (white noise) version of (A).

Mentions: Resting motor threshold (MT) was determined by finding the lowest stimulation intensity of the motor hotspot for the right FDI needed in order to obtain an MEP with a peak-to-peak amplitude of 50 µV in 5 out of 10 consecutive stimulations. The TMS test intensity was then set at 120% of resting MT. Eight different TMS conditions were tested. These consisted of seven auditory-stimulation/TMS pairs and one TMS condition without associated auditory stimulation (baseline). The auditory-stimulation/TMS pairs consisted of a test TMS pulse applied at one of seven different intervals (25, 50, 100, 150, 200, 250 and 300 ms) after the onset of the auditory stimulus. The auditory stimulus consisted of a male voice pronouncing the word “Hey!” played back at 80 dB SPL via Etymotic ER-1 insert tube-phones. We chose to use a speech sounds because previous research suggests that speech sounds strongly activate the motor cortex e.g., Flöel et al. (2003). However, other evidence suggests that the motor cortex might be also activated by non speech sounds (Watkins et al., 2003; Alibiglou and Mackinnon, 2012) so we also included a condition in which the auditory stimulus matched the amplitude envelope of the speech stimulus but consisted entirely of white noise (Pulvermüller et al., 2006). This signal-correlated noise (SCN) stimulus was created using Praat (Boersma and Weenink, 2013). Time and frequency domain comparisons of the two signals are displayed in Figure 1.


Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS.

Sowman PF, Dueholm SS, Rasmussen JH, Mrachacz-Kersting N - Front Hum Neurosci (2014)

Two sounds used as auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise version of (A). Frequency spectra of the two auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise (white noise) version of (A).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4042887&req=5

Figure 1: Two sounds used as auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise version of (A). Frequency spectra of the two auditory stimuli. (A) The word “Hey!” and (B) signal correlated noise (white noise) version of (A).
Mentions: Resting motor threshold (MT) was determined by finding the lowest stimulation intensity of the motor hotspot for the right FDI needed in order to obtain an MEP with a peak-to-peak amplitude of 50 µV in 5 out of 10 consecutive stimulations. The TMS test intensity was then set at 120% of resting MT. Eight different TMS conditions were tested. These consisted of seven auditory-stimulation/TMS pairs and one TMS condition without associated auditory stimulation (baseline). The auditory-stimulation/TMS pairs consisted of a test TMS pulse applied at one of seven different intervals (25, 50, 100, 150, 200, 250 and 300 ms) after the onset of the auditory stimulus. The auditory stimulus consisted of a male voice pronouncing the word “Hey!” played back at 80 dB SPL via Etymotic ER-1 insert tube-phones. We chose to use a speech sounds because previous research suggests that speech sounds strongly activate the motor cortex e.g., Flöel et al. (2003). However, other evidence suggests that the motor cortex might be also activated by non speech sounds (Watkins et al., 2003; Alibiglou and Mackinnon, 2012) so we also included a condition in which the auditory stimulus matched the amplitude envelope of the speech stimulus but consisted entirely of white noise (Pulvermüller et al., 2006). This signal-correlated noise (SCN) stimulus was created using Praat (Boersma and Weenink, 2013). Time and frequency domain comparisons of the two signals are displayed in Figure 1.

Bottom Line: Acoustic stimuli can cause a transient increase in the excitability of the motor cortex.We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation.This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Cognitive Science, Macquarie University Sydney, NSW, Australia ; Perception and Action Research Centre (PARC), Faculty of Human Sciences, Macquarie University Sydney, NSW, Australia ; Australian Research Council Centre of Excellence in Cognition and its Disorders (CCD), Macquarie University Sydney, NSW, Australia.

ABSTRACT
Acoustic stimuli can cause a transient increase in the excitability of the motor cortex. The current study leverages this phenomenon to develop a method for testing the integrity of auditorimotor integration and the capacity for auditorimotor plasticity. We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation. This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli. We propose that the method developed here might provide a useful tool for future studies that measure auditory-motor connectivity in communication disorders.

No MeSH data available.


Related in: MedlinePlus