Hyperactivity of the medial thalamus in patients with photophobia-associated migraine.

OBJECTIVE: To examine cerebral functional alterations associated with sensory processing in patients with migraine and constant photophobia. BACKGROUND: Migraine is a common headache disorder that presents with photophobia in many patients during attacks. Furthermore, some patients with migraine experience constant photophobia, even during headache-free intervals, leading to a compromised quality of life. METHODS: This prospective, case-control study included 40 patients with migraine (18 male and 22 female) who were recruited at an eye hospital and eye clinic. The patients were divided into two groups: migraine with photophobia group, consisting of 22 patients (10 male and 12 female) with constant photophobia, and migraine without photophobia group, consisting of 18 patients (eight male and 10 female) without constant photophobia. We used 18F-fluorodeoxyglucose and positron emission tomography to compare cerebral glucose metabolism between the two patient groups and 42 healthy participants (16 men and 26 women). RESULTS: Compared with the healthy group, both the migraine with photophobia and migraine without photophobia groups showed cerebral glucose hypermetabolism in the bilateral thalamus (p < 0.05, family-wise error-corrected). Moreover, the contrast of migraine with photophobia minus migraine without photophobia patients showed glucose hypermetabolism in the bilateral medial thalamus (p < 0.05, family-wise error-corrected). CONCLUSIONS: The medial thalamus may be associated with the development of continuous photophobia in patients with migraine.

Improvement of Glucose Metabolism in the Visual Cortex Accompanies Visual Field Recovery in a Patient with Hemianopia.

Damage to the visual cortex or the geniculostriatal pathways could cause homonymous visual field (VF) defects at the contralateral side of the lesion. In clinical practice, it is known that the VF defects are gradually recovered over months on the cases. We report a case with recovered homonymous hemianopia following an infarction in the visual cortex by positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) and (11)C-flumazenil (FMZ). A 58-year-old man experienced defect of left VF, and magnetic resonance imaging (MRI) revealed a localized infarction in the right occipital lobe. Goldmann VF perimetry revealed left homonymous hemianopia, but central VF was intact. Three months after the onset of infarction, we measured cerebral glucose metabolism with FDG and FMZ binding using PET. FMZ binding reflects the density of surviving neurons. Moreover, eight months after the onset, FDG-PET scan was performed. Goldmann VF perimetry was also performed at the same times of PET examinations. Decrease of cerebral glucose metabolism in the right anterior striate cortex was observed at three months after onset, while FMZ binding in the same area did not decrease in the patient. At eight months after onset, we observed recovery of VF and improvement of cerebral glucose metabolism in the anterior striate cortex. We presented change of cerebral glucose metabolism using PET accompanying improvement of VF. Evaluation of cerebral glucose metabolism and FMZ binding in the striate cortex is useful for estimating the prognosis of hemianopia caused by organic brain damage.

Cerebral Functional Response during Eyelid Opening/Closing with Bell's Phenomenon and Volitional Vertical Eye Movements in Humans.

Bell's phenomenon is a physiological phenomenon wherein the eye ball involuntarily rolls upward during eyelid closing. Although this phenomenon occurs in healthy individuals, the neural mechanism related to Bell's phenomenon has not yet been identified. We aimed to investigate the brain regions relevant to Bell's phenomenon and volitional eye movement using [15O] H2O and positron emission tomography (PET). We measured regional cerebral blood flow (rCBF) in 8 normal subjects under 3 conditions: at rest with eyes closed, during opening and closing of the eyelids in response to sound stimuli (lid opening/closing), and during vertical movement of the eyes with lids closed in response to sound stimuli (volitional eye movement). The supplementary motor area (SMA) proper, right superior temporal gyrus, right insular cortex and left angular gyrus were activated during lid opening/closing. The right frontal eye field (FEF), pre-SMA, left primary motor area, right angular gyrus, and SMA proper were activated during volitional eye movement. The SMA proper was active during both tasks, while the FEF and pre-SMA were active during volitional eye movement, but not during eyelid opening/closing. A comparison of activation during volitional eye movements and lid opening/closing tasks revealed a relative increase in rCBF in the FEF. There were no areas that are activated in relation to Bell's phenomenon. In conclusion, activation in the FEF mainly occurs during volitional eye movement. Since Bell's phenomenon is a reflexive eye movement, the FEF is scarcely concerned in Bell's phenomenon.

Cerebral glucose metabolism in the striate cortex positively correlates with fractional anisotropy values of the optic radiation in patients with glaucoma.

BACKGROUND: It has recently become clear that glaucoma is not only an ocular disease, but involves central visual pathways as well. The purpose of this study was to examine functional and structural alterations in the brains of glaucoma patients. DESIGN: Case-control study in a hospital. PARTICIPANTS: A total of 32 glaucoma patients and 19 healthy controls. METHODS: All participants underwent positron emission tomography with (18)F-fluorodeoxyglucose, diffusion-tensor magnetic resonance imaging, and the 30-2 program of the Humphrey Visual Field Analyzer. MAIN OUTCOME MEASURES: Fractional anisotropy values of the optic radiation were compared between the two groups by defining regions of interests. Cerebral glucose metabolism was compared using statistical parametric mapping software. The correlation coefficients were calculated between the average of the total deviation of hemivisual fields of both eyes, fractional anisotropy values of the contralateral optic radiation and glucose metabolism in the contralateral striate cortex. RESULTS: Fractional anisotropy values in the bilateral optic radiations were significantly lower in patients with glaucoma. A significant glucose hypometabolism in the bilateral striate cortex was also observed in the glaucoma group. Regression analyses for glaucoma patients demonstrated that the average of the total deviation of hemivisual fields significantly correlated with both fractional anisotropy value of the contralateral optic radiation and glucose metabolism in the contralateral striate cortex. Moreover, there were significant correlations between fractional anisotropy values of the optic radiation and ipsilateral striatal glucose metabolism. CONCLUSION: We observed structural alterations in the bilateral optic radiations and glucose hypometabolism in the bilateral striate cortex of glaucoma patients.

Measurement of Cerebral Glucose Metabolism in the Visual Cortex Predicts the Prognosis of Hemianopia.

BACKGROUND AND OBJECTIVE: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction. METHODS: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio. RESULTS: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices. CONCLUSION: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.

Relationship between Diabetic Nephropathy and Development of Diabetic Macular Edema in Addition to Diabetic Retinopathy.

This study aimed to examine the relationship between diabetic retinopathy (DR) and systemic factors. We evaluated 261 patients (143 men, 118 women, aged 70.1 ± 10.1 years) with type 2 diabetes. All participants underwent a fundus examination, fundus photography using spectral domain optical coherence tomography (SD-OCT), and blood tests. For glycated hemoglobin (HbA1c) levels, the average and highest values in the past were used. We observed DR in 127 (70 men and 57 women) of 261 patients. Logistic regression analyses revealed a significant correlation between DR development and the duration of diabetes (OR = 2.40; 95% CI: 1.50), average HbA1c level (OR = 5.57; 95% CI: 1.27, 24.4), highest HbA1c level (OR = 2.46; 95% CI: 1.12, 5.38), and grade of diabetic nephropathy (DN) (OR = 6.23; 95% CI: 2.70, 14.4). Regression analyses revealed a significant correlation between the severity of DR and duration of diabetes (t = -6.66; 95% CI: 0.21, 0.39), average HbA1c level (t = 2.59; 95% CI: 0.14, 1.02), and severity of DN (t = 6.10; 95% CI: 0.49, 0.97). Logistic regression analyses revealed a significant correlation between diabetic macular edema (DME) development and DN grade (OR = 2.22; 95% CI: 1.33, 3.69). DN grade correlates with the development of DR and DME, and decreased renal function predicts the onset of DR.

In vivo genotoxicity of high-intensity intermediate frequency magnetic fields in somatic cells and germ cells.

Intermediate frequency magnetic fields (IF-MFs) at ~85 kHz are one of the components of wireless power transfer (WPT) systems. However, the available data needed for the assessment of the safety of organisms from IF-MF exposure are scarce. Thus, there is an imminent need to accumulate evidence-based assessment data. In particular, if humans are exposed to IF-MF due to an accident or trouble, they are at increased risk of being exposed to high-intensity IF-MF within a short period. The already existing exposure system was improved to a system that could intermittently expose animals at 3 s intervals. This system allows the exposure of a mouse to high-intensity IF-MF (frequency: 82.3 kHz; induced electric field: 87 V/m, which was 3.8 times the basic restriction level for occupational exposure in the ICNIRP guideline), while regulating the heat generated by the coil. In vivo genotoxicity after IF-MF exposure was assessed using micronucleus (MN) test, Pig-a assay, and gpt assay. The results of MN test and Pig-a assay in hematopoietic cells revealed that neither the reticulocytes nor the mature erythrocytes exhibited significant increases in the IF-MF-exposed group compared with that in the sham-exposed group. In germ cells, MN test and gpt assay outcomes showed that IF-MF exposure did not cause any genetic or chromosomal abnormality. Based on these data, there was no genotoxic effect of our set IF-MF exposure on somatic and germ cells. These findings can contribute to the widespread use of WPT systems as effective data of IF-MF safety assessment.

Glucose hypermetabolism in the thalamus of patients with hemifacial spasm.

The purpose of this study was investigate functional alteration in the brains of patients with hemifacial spasm using positron emission tomography (PET). We studied cerebral glucose metabolism using PET with (18) F-fluorodeoxyglucose in 13 patients with right lateral hemifacial spasm and 13 with left lateral hemifacial spasm. All patients underwent 2 PET scans before treatment (active state) and after treatment (suppressive state) with the botulinum neurotoxin type A. At the time of the PET scans, the severity of the spasm was rated according to the Jankovic Disability Rating Scale. We also used magnetic resonance imaging to evaluate the grade of neurovascular compression in each patient using scores of 1 to 3 (1 = mild, 3 = severe). Fifty-two normal volunteers were examined as controls. Compared with controls, patients with right and left hemifacial spasm showed bilateral cerebral glucose hypermetabolism in the thalamus in both the active and suppressive states. However, thalamic glucose metabolism after the suppressive state was significantly reduced compared with that in the active state using region of interest analysis. There was a positive correlation between the severity of the spasm in the active state and the score of neurovascular compression (rs = 0.65) that was estimated using Spearman order correlation coefficient. We observed bilateral cerebral glucose hypermetabolism in the thalamus of patients with hemifacial spasm. The thalamic glucose hypermetabolism may be attributed to multiple sources, including afferent input from the skin and muscle spindle, antidromic conduction of the facial nerve, and secondary alteration in the central nervous system.

Cardiac Hypertrophy May Be a Risk Factor for the Development and Severity of Glaucoma.

The purpose of this study was to examine the relationship between glaucoma and cardiac abnormalities. We evaluated 581 patients with open-angle glaucoma (285 men and 296 women) and 595 individuals without glaucoma (273 men and 322 women). All of the participants underwent visual field testing using a Humphrey Visual Field Analyzer (30-2 program), an electrocardiogram (ECG), and blood pressure measurement. We examined the ECG abnormalities and other factors (age, intraocular pressure (IOP) and systemic hypertension) involved in the development and severity of glaucoma. Logistic regression analyses revealed significant correlations of glaucoma with IOP (OR = 1.43; 95% CI: 1.36−1.51; p < 0.00001), atrial fibrillation (OR = 2.02; 95% CI: 1.01−4.04; p = 0.04), left ventricular hypertrophy (LVH) (OR = 2.21; 95% CI: 1.15−4.25; p = 0.02), and bradycardia (OR = 2.19; 95% CI: 1.25−4.70; p = 0.02). Regression analyses revealed significant correlations of the mean deviation of the visual field with age (t = −6.22; 95% CI: −0.15, −0.08; p < 0.00001), IOP (t = −6.47; 95% CI: −0.42, −0.23; p < 0.00001), and LVH (t = −2.15; 95% CI: −3.36, −0.29; p = 0.02). Atrial fibrillation, LVH and bradycardia may decrease the cerebral blood flow, and may also affect the ocular blood flow. Cardiac abnormalities may be associated with the development and severity of glaucoma.

Measurement and Exposure Assessment of Intermediate Frequency Magnetic Fields From Electronic Article Surveillance (EAS) Gates in Libraries.

Exposure to magnetic fields from the electronic article surveillance (EAS) gate was evaluated in consideration of the application to epidemiological studies of library workers who are exposed continually to intermediate frequency magnetic fields from the EAS gate. Two types of exposures were investigated. One was transient exposure due to passing through or beside the gate and another was chronic exposure in the room. We measured magnetic fields from five EAS gate models which were commonly used in libraries in Japan. Detailed measurements were performed for two of them in consideration of the phase difference of vector components of magnetic flux density. The polarization of the magnetic field in the gate was investigated with the index of ellipticity. The induced electric field in a human body was numerically calculated for exposures to magnetic fields of the two gate models. The results provide a quantitative understanding of exposures during passing through or by the EAS gate. Magnetic field distribution was measured in a large room for one gate model to quantify the chronic exposure of library workers during the work at the desk. It was found that the magnetic field was distributed as a function of the horizontal distance to the nearest gatepost. The 45-point average value BIEC defined by the IEC standard was suggested to be a useful quantity to characterize the magnitude of the magnetic field from the EAS gate. Exposures to different EAS gates are expected to be compared through this quantity without detailed measurements. These results are expected to provide useful means for exposure assessment of epidemiological studies on the association between the IF-EMF exposure and possible health outcomes.

Gray matter density increase in the primary sensorimotor cortex in long-term essential blepharospasm.

In this study, we investigated gray matter density in essential blepharospasm (EB) patients, focusing on the duration of disease and severity of symptoms. We studied 32 patients (10 males and 22 females; age, 55.0 ± 6.5years) with EB and 48 controls (15 males and 33 females; age, 54.4 ± 10.3years) by using 3D T1-weighted magnetic resonance imaging and voxel-based morphometry. We defined an activity index (AI) that reflects the severity and duration of EB symptoms in each patient. The difference between the 2 groups was examined by statistical parametric mapping software (SPM8). After controlling for age, gray matter density increased in the bilateral primary sensorimotor cortex (S1M1) and cingulate gyrus. The gray matter density in the bilateral S1M1 was found to have a significant positive correlation with the duration of disease and a more robust correlation with AI. The correlation coefficients, after correcting for age, in the S1M1 and left cingulate gyrus were as follows: with duration, right S1M1, 0.72 (P<0.00001); left S1M1, 0.72 (P<0.00001); and left cingulate gyrus, 0.33 (not significant); and with AI, right S1M1, 0.81 (P<10(-7)); left S1M1, 0.74 (P<0.00001); and left cingulate gyrus, 0.43 (P<0.05). The increase in gray matter density in the S1M1 and cingulate gyrus might be a secondary effect caused by long-term hyperactivity in these areas instead of a predisposing factor.

Visual Acuity in Glaucomatous Eyes Correlates Better with Visual Field Parameters than with OCT Parameters.

The visual acuity is very important for glaucoma patients in their lives. The purpose of this study was to examine about the correlation of visual acuity and visual field (VF) parameters or optical coherence tomography (OCT) parameters in patients with glaucoma. We evaluated 210 eyes of 210 patients (110 men and 100 women; mean age, 69.6 ± 9.6 years) with open-angle glaucoma and 68 eyes of healthy controls. In glaucomatous eyes including healthy eyes, correlation between visual acuity and each of the VF parameters or each of the OCT parameters was estimated using regression analyses. The average visual acuity of control group was - 0.08, and that of glaucoma group was - 0.06 (early stage), - 0.03 (moderate stage), and 0.08 (severe stage), respectively. Regression analyses including healthy eyes and glaucomatous eyes revealed significant correlations between visual acuity and mean deviation (MD) of 30-2 Humphrey VF (rs = - 0.44), MD of 10-2 VF (rs = - 0.45), total deviation in central 10-2 VF (rs = - 0.42), ganglion cell complex thickness (macula, rs = - 0.33; superior, rs = - 0.33; inferior, rs = - 0.35; and global, rs = - 0.34), and circumpapillary retinal nerve fiber layer (rs = - 0.38). The visual acuity of glaucomatous eyes correlated with VF parameters and OCT parameters. The visual acuity decreased as glaucoma progressed.

No evidence for genotoxicity in mice due to exposure to intermediate-frequency magnetic fields used for wireless power-transfer systems.

Time varying magnetic fields (MFs) are used for the wireless power-transfer (WPT) technology. Especially, 85 kHz band MFs, which are included in the intermediate frequency (IF) band (300 Hz - 10 MHz), are commonly used WPT system for charging electric vehicles. Those applications of WPT technology have elicited public concern about health effects of IF-MF. However, existing data from health risk assessments are insufficient and additional data are needed. We assessed the genotoxic effects of IF-MF exposure on erythroid differentiation in mice. A high-intensity IF-MF mouse exposure system was constructed to induce an average whole-body electric field of 54.1 V/m. Blood samples were obtained from male mice before and after a 2-week IF-MF exposure (1 h/day, total: 10 h); X-irradiated mice were used as positive controls. We analyzed the blood samples with the micronucleus (MN) test and the Pig-a mutation assay. No significant differences were seen between IF-MF-exposed and sham-exposed mice in the frequencies of either MN or Pig-a mutations in mature erythrocytes and reticulocytes. IF-MF exposure did not induce genotoxicity in vivo under the study conditions (2.36× the basic restriction for occupational exposure, 22.9 V/m, in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines). The absence of significant biological effects due to IF-MF exposure supports the practical application of this technology.

Cataract Formation by Near-infrared Radiation in Rabbits.

Surveys and epidemiological studies have shown an increased prevalence of cataracts in workers in the glass and steel industries. These cataracts are associated with exposure to intense infrared radiation (IR) emitted from heated materials and industrial furnaces. Thermal model calculations predicted that near and far IR would cause cataract with different mechanisms. The present study investigated cataract formation by near IR. Eyes of pigmented rabbits were exposed to IR at a wavelength of 808 nm. Morphological changes in the anterior segment of the eye were assessed by slit-lamp microscopy, and temperature distributions in the anterior chamber of the eye were observed during IR exposure using microencapsulated thermochromic liquid crystals. Cortical cataract appeared below the exposed area of the iris in eyes that had been exposed for 6 min to an irradiance of 1.27 W cm-2 or higher. The monitored temperature in the anterior chamber began to increase in the region adjacent to the exposed area of the iris with the onset of IR exposure. These results demonstrate that 808-nm IR is absorbed and converted to heat within the iris, which is then conducted to the lens and produce a cataract, as Goldmann theory states.

Dielectric property measurements of corneal tissues for computational dosimetry of the eye in terahertz band in vivo and in vitro.

The dielectric constant of the normal corneal tissue of a rabbit eye was obtained in vitro in the range from approximately 0.1 to 1 THz, and the drying process on the eye surface exposed to high-power terahertz waves was investigated by in vivo reflectance measurement using terahertz time-domain spectroscopy. When the rabbit eye was exposed to terahertz waves at 162 GHz for 6 min with an irradiation power of 360 or 480 mW/cm2, the reflectance temporally increased and then decreased with a temperature increase. Based on multiple-reflection calculation using the dielectric constant and anterior segment optical coherence tomography images, those changes in reflectance were attributed to drying of the tear and epithelium of the cornea, respectively. Furthermore, the drying progressed over a temperature increase of around 5°C under our exposure conditions. These findings suggest that the possibility of eye damage increases with the progress of drying and that the setting of the eye surface conditions can be a cause of disagreement between computational and experimental data of absorbed energy under high-level irradiation because reflectance is related to terahertz wave penetration in the eye tissue. The time-domain spectroscopic measurements were useful for the acquisition of the dielectric constant as well as for the real-time monitoring of the eye conditions during exposure measurement.

Photophobia in essential blepharospasm--a positron emission tomographic study.

To localize regional alterations in cerebral glucose metabolism in essential blepharospasm (EB) patients with photophobia. We have studied 22 EB patients by performing positron emission tomography and [(18)F]-fluorodeoxyglucose analysis. The patients were classified into two subgroups, namely, EB with photophobia (P group) and EB without photophobia (NP group), and compared with a healthy control group (n = 44). There were no significant differences between the two patient groups with respect to the severity of motor symptoms or the duration for which the condition persisted. The FDG-PET images were analyzed using the statistical parametric mapping software. As compared to the control group, the P group exhibited significant hypermetabolism in the thalamus (P = 0.002), while the NP group exhibited significant hypometabolism in the dorsal midbrain, especially, in the superior colliculus (P = 0.005). The P group exhibited significant hypermetabolism in the thalamus and the dorsal midbrain as compared to the NP group (P < 0.001). These findings suggest that photophobia in EB patients may be associated with abnormal hyperactivity in the thalamus. Either hyperactivity of the thalamus or hypoactivity of the superior colliculus, or both may be associated with excessive blinking in these patients.

The pre-supplementary and primary motor areas generate rhythm for voluntary eye opening and closing movements.

Blinking and opening/closing of the eyelid are considered to be different movements with independent control mechanisms. Apraxia of lid opening (ALO) is a clinical syndrome in which patients experience difficulty in opening their eyes voluntarily. Our previous study with fluorodeoxyglucose and positron emission tomography (PET) has suggested that functional impairments in the supplementary motor area (SMA) and the anterior cingulate gyrus may be involved in the pathophysiology of ALO. The aim of this study was to explore the physiological mechanisms for voluntary eyelid opening/closing and the difference between self-initiated and triggered movements, using [(15)O]H(2)O and PET. We measured the regional cerebral blood flow in 8 healthy subjects under 3 conditions: [A] at rest with eyes closed, [B] with self-paced lid opening/closing, and [C] with triggered lid opening/closing. All tasks were done with a blindfold to exclude the influence of visual input. The SMA proper and the angular gyrus were activated during self-paced and triggered lid opening/closing movements; however, the pre-SMA and the primary motor area (M1) were activated only during self-paced movements. The anterior cingulate gyrus and the cerebellum were activated during self-paced condition over triggered condition. The roles of SMA, M1 and cerebellum were assumed in eyelid opening/closing movements: the preparation and processing of movements in SMA, execution of movements in M1, and rhythmic generation in pre-SMA, M1 and cerebellum. We suggest that the activation in pre-SMA, anterior cingulate gyrus, and cerebellum may be responsible for the self-initiated eyelid opening/closing movements.

The response of the neuronal activity in the somatosensory cortex after high-intensity intermediate-frequency magnetic field exposure to the spinal cord in rats under anesthesia and waking states.

Novel technologies using the intermediate-frequency magnetic field (IF-MF) in living environments are becoming popular with the advance in electricity utilization. However, the biological effects induced by the high-intensity and burst-type IF-MF exposure used in the wireless power transfer technologies for electric vehicles or medical devices, such as the magnetic stimulation techniques, are not well understood. Here, we developed an experimental platform using rats, that combined an 18 kHz, high-intensity (Max. 88 mT), Gaussian-shaped burst IF-MF exposure system with an in vivo extracellular recording system. In this paper, we aimed to report the qualitative differences in stimulus responses in the regions of the somatosensory cortex and peripheral nerve fibers that were induced by the IF-MF exposure to the rat spinal cord. We also report the modulation of the stimulus responses in the somatosensory cortex under anesthesia or waking states. Using this experimental platform, we succeeded in the detection of the motor evoked potentials or the neuronal activity in the somatosensory cortex that was induced by the IF-MF exposure to the spinal cord in rats. Compared to the state of anesthesia, the neuronal activities in the somatosensory cortex was enhanced during the waking state. On the other hand, these neuronal responses could not be confirmed by the IF-MF exposure-related coil sound only. Our experimental results indicated the basic knowledge of the biological responses and excitation mechanisms of the spinal cord stimulation by the IF-MF exposure.