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Interhemispheric interactions between the human primary somatosensory cortices.

Ragert P, Nierhaus T, Cohen LG, Villringer A - PLoS ONE (2011)

Bottom Line: Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms.Additionally, the subcortically generated P14 response in left S1 was also not affected.These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20-25 ms after median nerve stimulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. ragert@cbs.mpg.de

ABSTRACT
In the somatosensory domain it is still unclear at which processing stage information reaches the opposite hemispheres. Due to dense transcallosal connections, the secondary somatosensory cortex (S2) has been proposed to be the key candidate for interhemispheric information transfer. However, recent animal studies showed that the primary somatosensory cortex (S1) might as well account for interhemispheric information transfer. Using paired median nerve somatosensory evoked potential recordings in humans we tested the hypothesis that interhemispheric inhibitory interactions in the somatosensory system occur already in an early cortical processing stage such as S1. Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms. No such changes were observed for later cortical components such as the N20/P25, N30, P40 and N60 amplitude. Additionally, the subcortically generated P14 response in left S1 was also not affected. These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20-25 ms after median nerve stimulation.

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Example traces of a single subject PMNSEP response at electrode CP3 for all CS+TS conditions (5–30ms, red trace) relative to TS alone (blue trace).Please note that the PMNSEPs for all CS+TS conditions are superimposed (shifted) on the N20 onset of the TS alone condition for display purpose only. For average group data please see Table 1.
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pone-0016150-g002: Example traces of a single subject PMNSEP response at electrode CP3 for all CS+TS conditions (5–30ms, red trace) relative to TS alone (blue trace).Please note that the PMNSEPs for all CS+TS conditions are superimposed (shifted) on the N20 onset of the TS alone condition for display purpose only. For average group data please see Table 1.

Mentions: Conditioning the right S1 by electrical median nerve stimulation of the left MN (CS) resulted in a significant reduction of the N20 response to right MN stimulation in the target (left) S1 (one-way ANOVARM with factor ISI (TS alone, 5–30ms): F(6,66) = 3.951; p = 0.031, see Figures 2 and 3). No such changes could be observed for the other amplitudes tested (N20/P25: F(6,66) = 2.380; p = 0.085; N30: F(6,66) = 0.847; p = 0.458; P40: F(6,66) = 0.920; p = 0.463; N60: F(6,66) = 2.691; p = 0.066).


Interhemispheric interactions between the human primary somatosensory cortices.

Ragert P, Nierhaus T, Cohen LG, Villringer A - PLoS ONE (2011)

Example traces of a single subject PMNSEP response at electrode CP3 for all CS+TS conditions (5–30ms, red trace) relative to TS alone (blue trace).Please note that the PMNSEPs for all CS+TS conditions are superimposed (shifted) on the N20 onset of the TS alone condition for display purpose only. For average group data please see Table 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037378&req=5

pone-0016150-g002: Example traces of a single subject PMNSEP response at electrode CP3 for all CS+TS conditions (5–30ms, red trace) relative to TS alone (blue trace).Please note that the PMNSEPs for all CS+TS conditions are superimposed (shifted) on the N20 onset of the TS alone condition for display purpose only. For average group data please see Table 1.
Mentions: Conditioning the right S1 by electrical median nerve stimulation of the left MN (CS) resulted in a significant reduction of the N20 response to right MN stimulation in the target (left) S1 (one-way ANOVARM with factor ISI (TS alone, 5–30ms): F(6,66) = 3.951; p = 0.031, see Figures 2 and 3). No such changes could be observed for the other amplitudes tested (N20/P25: F(6,66) = 2.380; p = 0.085; N30: F(6,66) = 0.847; p = 0.458; P40: F(6,66) = 0.920; p = 0.463; N60: F(6,66) = 2.691; p = 0.066).

Bottom Line: Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms.Additionally, the subcortically generated P14 response in left S1 was also not affected.These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20-25 ms after median nerve stimulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. ragert@cbs.mpg.de

ABSTRACT
In the somatosensory domain it is still unclear at which processing stage information reaches the opposite hemispheres. Due to dense transcallosal connections, the secondary somatosensory cortex (S2) has been proposed to be the key candidate for interhemispheric information transfer. However, recent animal studies showed that the primary somatosensory cortex (S1) might as well account for interhemispheric information transfer. Using paired median nerve somatosensory evoked potential recordings in humans we tested the hypothesis that interhemispheric inhibitory interactions in the somatosensory system occur already in an early cortical processing stage such as S1. Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms. No such changes were observed for later cortical components such as the N20/P25, N30, P40 and N60 amplitude. Additionally, the subcortically generated P14 response in left S1 was also not affected. These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20-25 ms after median nerve stimulation.

Show MeSH