• The Korean Journal of Physiology and Pharmacology
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• v.5 no.1
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• pp.27-32
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• 2001

We have characterized the aftereffects of impulse activities on the transmission of afferent sensory to the primary somatosensory (SI) cortex of the anesthetized rats (n=22). Following conditioning stimulation (CS, 10 sec, either 5 Hz or 200 Hz) to the receptive field (RF), quantitative determination of the changes of afferent sensory transmission was done by generating post-stimulus time histogram of unit response to the testing stimulation (TS, at 0.5 Hz) to the RF center (RFC) for 60 min. In one group of experiments, CS was delivered to the RF center (RFC). In another group of experiments, CSs were simultaneously given to both RFC and RF outside (RFO, either forepaw or hindpaw). CS of 5 Hz to RFC exerted irreversible facilitation of sensory transmissions evoked by TS. Simultaneous CSs of 5 Hz to RFC and hindpaw RFO exerted reversible suppression of afferent transmission. However, CSs of 5 Hz to RFC and forepaw RFO did not significantly altered afferent sensory transmission to SI cortex neurons. CS of 200 Hz to RFC exerted irreversible suppression of sensory transmissions up to 60 min of experimental period. Simultaneous CSs of 200 Hz to RFC and RFO did not significantly altered afferent sensory transmission to SI cortex neurons. The profiles of CS-induced modulation of afferent sensory transmission were significantly different between two CS conditions. Thus, this study suggests that activity-dependent modulation of afferent transmission from a RF center to the SI cortex may be significantly altered when remote body part was simultaneously activated.

• Progress in Medical Physics
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• v.17 no.3
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• pp.159-166
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• 2006

The nonlinearity of hemodynamic response in the somatosensory cortex was investigated with vibrotactile stimulation. The stimuli consisted of a train of 25 Hz, each tasting five different duration periods, 2 s, 4 s, 8 s 12 s, or 16 s with 20 sec periods of no vibration in a pseudo-random order. In order to understand the linearity on the change of stimulus duration for somatosensory cortex, two different tests- checking the linearity of system and finding the impulse response function from gamma-variate function were applied to analyze the hemodynamic response functions. They have produced nearly same results. The BOLD response in the somatosensory cortex Is nonlinear for stimuli of less than 8 seconds, but nearly linear for stimuli greater than 8 seconds. The amplitude, area, TTP, and FWHM as functions of the stimulus duration were calculated and showed a significant downward trend with Increasing stimulus duration for the amplitude and the area. It supports the ranges of nonlinearity are less than 8 seconds.

• Journal of Acupuncture Research
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• v.17 no.4
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• pp.41-50
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• 2000

Objectives : Acupuncture is expected to have somewhat like the efficacy parallel increasing activity of immune system in Western modem medicine. There, already, are many animal researches on activating effect of acupuncture for the immune system in peripheral organs. So, we carried out this experiment to see whether acupuncture has controlling effect on interleukin-6(IL-6) activity in rat's brain. Methods and Results : We had topical application of IL-6(1U=lpg, $10{\mu}l$) on brain of rat. It reduced afferent sensory transmission to the primary somatosensory(SI) cortex from periphery. Whereas, electrical stimulation(ES, 2Hz, 1.5V, 15min) of ST36(足三里) with application of IL-6 prominently activated afferent sensory transmission. ES of non-acupoint(proximal tail) with IL-6 showed suppression of afferent transmission. ES of ST36 without IL-6 application also exerted facilitation of afferent transmission to the SI cortex. Conclusions : Electoacupuncture(EA) on ST36 has noticeable influences on modulating activation of IL-6 in central nervous system, which do major role in immune system.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.521-528
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• 2009

This study is about to evaluation of postural stability according to characteristics of electrical stimulation on the ankle muscles. We measured body sway(center of pressure, COP) when various parameters of electrical stimulation was applied to ankle muscles in stable and unstable posture. Subjects consisted of 10 young adults, and electrical stimulation was delivered on right and left of tibialis anterior and Achilles tendon. The body sway was measured during electrical stimulation of three duty cycle and frequencies in stable posture and three amplitudes of sensory threshold in unstable posture. Consequently, the COP Shift is higher during electrical stimulation of 1/30(duty ratio) and 100Hz(frequency) in stable posture. In unstable posture, 100% amplitude of sensory threshold induced postural stability. These findings are important for the rehabilitation system of postural stability and the use of electrical stimulation as somatosensory information.

• Annals of Clinical Neurophysiology
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• v.12 no.2
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• pp.35-46
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• 2010

Various electrophysiological tests have provided a large body of valuable information on neuronal responses to a presented stimulus. The special and general somatic sensory pathways are main targets of evoked potentials. Two types of evoked potentials, exogenous and endogenous, are commonly used. Exogenous evoked potentials of general and special somatic sensory systems will be reviewed. One of general somatic sensory functional pathways, proprioception, can be evaluated by general somatosensory evoked potentials with electrical stimulation on nerves. The special somatosensory functional pathways, including vision, and audition, can be evaluated by visual evoked potentials and auditory evoked potentials. Also laser-evoked potentials are newly developed for pain pathway, including lateral spinothalamic pathway, and vestibular myogenic evoked potentials for sacculocollic pathways. The evoked potentials of sensory system have maximal clinical utility in evaluating functional deficits along the sensory pathways. They are used for evaluating comatose patients, hysterical patients, premature infants, patients with suspected demyelinating diseases or neoplasms, and research. We discuss the neurophysiologic tests of sensory systems in views of practical points. The organized evaluation of sensory electrophysiologic tests can be helpful in detecting and estimating the abnormalities in neurological diseases.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.3
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• pp.129-132
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• 2004

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.481-488
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• 1994

In this paper a study of neuro-pathway estimation based on visual and somatosensory evoked potential is given. The evoked potentials which are caused by visual and somatosensory stimulation are detected by an average method. The forward problem that is estimating a scalp potential from a given electrical source in the brain is solved by using a triple concentric spherical shell model of the head and a single current dipole model of the neuron activity. The inverse problem which calculates a source position is solved by a least square fit between the model predicted potential and a given evoked potential measurement. The similarities between estimated sensory neuro-pathways and physiological brain function regions are verified.

• Physical Therapy Korea
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• v.12 no.2
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• pp.73-80
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• 2005

We investigated the activation of the cerebral cortex during active movement, passive movement, and functional electrical stimulation (FES), which was provided on wrist extensor muscles. A functional magnetic resonance imaging study was performed on 5 healthy volunteers. Tasks were the extension of right wrist by active movement, passive movement, and FES at the rate of .5 Hz. The regions of interest were measured in primary motor cortex (M1), primary somatosensory cortex (SI), secondary somatosensory cortex (SII), and supplementary motor area (SMA). We found that the contralateral SI and SII were significantly activated by all of three tasks. The additional activation was shown in the areas of ipsilateral S1 (n=2), and contralateral (n=1) or ipsilateral (n=2) SII, and bilateral SMA (n=3) by FES. Ipsilateral M1 (n=1), and contralateral (n=1) or ipsilateral SII (n=1), and contralateral SMA (n=1) were activated by active movement. Also, Contralateral SMA (n=3) was activated by passive movement. The number of activated pixels on SM1 by FES ($12{\pm}4$ pixels) was smaller than that by active movement ($18{\pm}4$ pixels) and nearly the same as that by passive movement ($13{\pm}4$ pixels). Findings reveal that active movement, passive movement, and FES had a direct effect on cerebral cortex. It suggests that above modalities may have the potential to facilitate brain plasticity, if applied with the refined-specific therapeutic intervention for brain-injured patients.

• Annals of Clinical Neurophysiology
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• v.8 no.2
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• pp.158-162
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• 2006

Background: It has been proposed that proprioceptive input can modulate neural excitability in both primary motor cortices (M1) simultaneously, although direct evidence for this is still lacking. Previous studies showed that proprioceptive accuracy of one hand is reduced after the application of one-Hz repetitive transcranial magnetic stimulation (rTMS) for 15 minutes over the contralateral somatosensory cortex. The aim of this study was to investigate the effect of rTMS-induced central proprioceptive deafferentation to excitability of both M1 as reflected in ipsilateral and contralateral motor evoked potentials (MEP). Methods: MEPs of both abductor pollicis bravis (APB) muscles were recorded using single-pulse TMS over right M1 in seven healthy subjects. Immediately after one-Hz rTMS was applied for 15 minutes over the right somatosensory cortex, the MEP measurement was repeated. The proprioceptive function of the left thumb was assessed, before and after rTMS, using a position-matching task. Results: There was an increase in ipsilateral MEP after the rTMS: whereas no MEPs were recorded on the ipsilateral hand before the rTMS, MEPs were recorded in both ipsilateral and contralateral hand in three of seven subjects. At the same time, the mean log amplitude was reduced and the mean latency was prolonged in the contralateral MEP. Conclusions: rTMS-induced central proprioceptive deafferentation reduces the MEP generation in the contralateral hand, and fascilitates that in the ipsilateral hand. A further study with a larger sample seems warranted to confirm this finding and to elucidate the neurophysiology underlying it.

• Journal of Acupuncture Research
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• v.20 no.4
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• pp.145-156
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• 2003

Objective : This study is to investigate the effect of electro-acupuncture ST36 on altered transmission of afferent somatosensory information caused by amyloid-${\beta}$(A-${\beta}$) that caused Alzheimer's disease. Methods : The effects of topical application of A-${\beta}$, A-${\beta}$ with ST36, aggregated A-${\beta}$(aA-${\beta}$), aA-${\beta}$ with ST36 and ST36 on the afferent sensory transmission to the neurons in the primary somatosensory(SI) cortex was observed in anesthetized rats. Quantitative determination of the effects of A-${\beta}$, A-${\beta}$ with ST36, aA-${\beta}$, aA-${\beta}$ with ST36 and ST36 was made by generating poststimulus time histogram of evoked response of individual cortical neuron by electrical stimulation of the receptive located in peripheral area(forepaw) Results : The results obtained in present study were summerized as follow : 1. Application of physiological concentrative 0.5 nM A-${\beta}$ caused afferent sensory transmission of SI cortex facilitated. 0.5 nM A-${\beta}$ with ST36 exerted much stronger effects than 0.5 nM A-${\beta}$ alone. 2. Application of $10{\mu}M$ A-${\beta}$ caused afferent sensory transmission of SI cortex unchangeable. But $10{\mu}M$ A-${\beta}$ with ST36 is facilitated at 30 min of post-drug period 3. Application of $10{\mu}M$ aA-${\beta}$ caused afferent sensory transmission of SI cortex diminished. $10{\mu}M$ aA-${\beta}$ with ST36 is diminished after 15min of post-drug period but is facilitated after 75min.