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Distinct Somatic Discrimination Reflected by Laser-Evoked Potentials Using Scalp EEG Leads

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ABSTRACT

Discrimination is an important function in pain processing of the somatic cortex. The involvement of the somatic cortex has been studied using equivalent dipole analysis and neuroimaging, but the results are inconsistent. Scalp electroencephalography (EEG) can reflect functional changes of particular brain regions underneath a lead. However, the responses of EEG leads close to the somatic cortex in response to pain have not been systematically evaluated. The present study applied CO2 laser stimulation to the dorsum of the left hand. Laser-evoked potentials (LEPs) of C4, T3, and T4 leads and pain ratings in response to four stimulus intensities were analyzed. LEPs started earlier at the C4 and T4 leads. The onset latency and peak latency of LEPs for C4 and T4 leads were the same. Only 10 of 22 subjects (45 %) presented equivalent current dipoles within the primary somatosensory or motor cortices. LEP amplitudes of these leads increased as stimulation intensity increased. The stimulus–response pattern of the C4 lead was highly correlated with pain rating. In contrast, an S-shaped stimulus–response curve was obtained for the T3 and T4 leads. The present study provides supporting evidence that particular scalp channels are able to reflect the functional characteristics of their underlying cortical areas. Our data strengthen the clinical application of somatic-cortex-related leads for pain discrimination.

No MeSH data available.


Grand averaged LEPs for four stimulus intensities in (A) C4, (B) T4, and (C) T3 leads. Maximal negative peak and positive peak of LEPs are labeled N2 and P2, respectively. No clear response is observed under 1-W stimulus intensity
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Fig1: Grand averaged LEPs for four stimulus intensities in (A) C4, (B) T4, and (C) T3 leads. Maximal negative peak and positive peak of LEPs are labeled N2 and P2, respectively. No clear response is observed under 1-W stimulus intensity

Mentions: For averaged LEPs, the largest and mostly negative peak was defined as N2, and the largest subsequent positive peak was defined as P2 (Fig. 1). In general, time windows of ±60 ms with respect to the N2 or P2 peak of the 4-W LEP were accepted for identifying cortical responses. The N2–P2 peak-to-peak amplitudes of three-channel LEPs in response to the four laser intensities were calculated. Both the peak latency and onset latency of LEPs for the C4, T4, and T3 leads were measured. The grand average of LEPs across all subjects was calculated.Fig. 1


Distinct Somatic Discrimination Reflected by Laser-Evoked Potentials Using Scalp EEG Leads
Grand averaged LEPs for four stimulus intensities in (A) C4, (B) T4, and (C) T3 leads. Maximal negative peak and positive peak of LEPs are labeled N2 and P2, respectively. No clear response is observed under 1-W stimulus intensity
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016541&req=5

Fig1: Grand averaged LEPs for four stimulus intensities in (A) C4, (B) T4, and (C) T3 leads. Maximal negative peak and positive peak of LEPs are labeled N2 and P2, respectively. No clear response is observed under 1-W stimulus intensity
Mentions: For averaged LEPs, the largest and mostly negative peak was defined as N2, and the largest subsequent positive peak was defined as P2 (Fig. 1). In general, time windows of ±60 ms with respect to the N2 or P2 peak of the 4-W LEP were accepted for identifying cortical responses. The N2–P2 peak-to-peak amplitudes of three-channel LEPs in response to the four laser intensities were calculated. Both the peak latency and onset latency of LEPs for the C4, T4, and T3 leads were measured. The grand average of LEPs across all subjects was calculated.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Discrimination is an important function in pain processing of the somatic cortex. The involvement of the somatic cortex has been studied using equivalent dipole analysis and neuroimaging, but the results are inconsistent. Scalp electroencephalography (EEG) can reflect functional changes of particular brain regions underneath a lead. However, the responses of EEG leads close to the somatic cortex in response to pain have not been systematically evaluated. The present study applied CO2 laser stimulation to the dorsum of the left hand. Laser-evoked potentials (LEPs) of C4, T3, and T4 leads and pain ratings in response to four stimulus intensities were analyzed. LEPs started earlier at the C4 and T4 leads. The onset latency and peak latency of LEPs for C4 and T4 leads were the same. Only 10 of 22 subjects (45 %) presented equivalent current dipoles within the primary somatosensory or motor cortices. LEP amplitudes of these leads increased as stimulation intensity increased. The stimulus–response pattern of the C4 lead was highly correlated with pain rating. In contrast, an S-shaped stimulus–response curve was obtained for the T3 and T4 leads. The present study provides supporting evidence that particular scalp channels are able to reflect the functional characteristics of their underlying cortical areas. Our data strengthen the clinical application of somatic-cortex-related leads for pain discrimination.

No MeSH data available.