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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.


Distribution of all equivalent current dipoles of 4-W LEPs. S2/insula or neighborhood areas are characterized by red dots. Midline cortical dipoles, including anterior and middle cingulate gyri, are characterized by green dots. Contralateral dipoles within dorsal sensorimotor cortex, including primary somatosensory cortex and primary motor cortex, are characterized by blue dots
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Fig3: Distribution of all equivalent current dipoles of 4-W LEPs. S2/insula or neighborhood areas are characterized by red dots. Midline cortical dipoles, including anterior and middle cingulate gyri, are characterized by green dots. Contralateral dipoles within dorsal sensorimotor cortex, including primary somatosensory cortex and primary motor cortex, are characterized by blue dots

Mentions: In addition to the scalp maps of LEPs, the equivalent current dipoles of 4-W LEPs were calculated using the spatiotemporal source model with four dipoles. In the present study, residual variance for dipole approximation was 6.47 ± 0.33 %. The dipoles are primarily located within the contralateral sensorimotor area, cingulate cortex, and bilateral S2 or insula (Fig. 3). The detailed coordinates and distribution of the dipoles are summarized in Table 2. All participants showed dipoles in the medial cortical region (64 % in the anterior cingulate cortex, 36 % in the middle cingulate cortex). 82 % of the equivalent current dipoles were located in the contralateral parasylvian region (50 % in S2, 32 % in the insula). Similar results were obtained for the ipsilateral parasylvian region (50 % in S2, 32 % in the insula). In contrast, the fourth equivalent current dipole was more widespread. In contrast to the highly consistent dipole locations for the previous three equivalent current sources, only 45 % of the fourth equivalent current dipoles were located in the sensorimotor region [27 % in S1, 18 % in the primary motor cortex (M1)]. Because of diverse distribution of sensory-cortex-related dipoles, the present study used LEP amplitudes of selected channels for further analysis instead of dipole strengths.Fig. 3


Distinct Somatic Discrimination Reflected by Laser-Evoked Potentials Using Scalp EEG Leads
Distribution of all equivalent current dipoles of 4-W LEPs. S2/insula or neighborhood areas are characterized by red dots. Midline cortical dipoles, including anterior and middle cingulate gyri, are characterized by green dots. Contralateral dipoles within dorsal sensorimotor cortex, including primary somatosensory cortex and primary motor cortex, are characterized by blue dots
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5016541&req=5

Fig3: Distribution of all equivalent current dipoles of 4-W LEPs. S2/insula or neighborhood areas are characterized by red dots. Midline cortical dipoles, including anterior and middle cingulate gyri, are characterized by green dots. Contralateral dipoles within dorsal sensorimotor cortex, including primary somatosensory cortex and primary motor cortex, are characterized by blue dots
Mentions: In addition to the scalp maps of LEPs, the equivalent current dipoles of 4-W LEPs were calculated using the spatiotemporal source model with four dipoles. In the present study, residual variance for dipole approximation was 6.47 ± 0.33 %. The dipoles are primarily located within the contralateral sensorimotor area, cingulate cortex, and bilateral S2 or insula (Fig. 3). The detailed coordinates and distribution of the dipoles are summarized in Table 2. All participants showed dipoles in the medial cortical region (64 % in the anterior cingulate cortex, 36 % in the middle cingulate cortex). 82 % of the equivalent current dipoles were located in the contralateral parasylvian region (50 % in S2, 32 % in the insula). Similar results were obtained for the ipsilateral parasylvian region (50 % in S2, 32 % in the insula). In contrast, the fourth equivalent current dipole was more widespread. In contrast to the highly consistent dipole locations for the previous three equivalent current sources, only 45 % of the fourth equivalent current dipoles were located in the sensorimotor region [27 % in S1, 18 % in the primary motor cortex (M1)]. Because of diverse distribution of sensory-cortex-related dipoles, the present study used LEP amplitudes of selected channels for further analysis instead of dipole strengths.Fig. 3

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.