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Biomedical subjects

R Sumino

Publications and source records attributed to R Sumino.

7 recordsLinked to original sources
PubMed1991

Comparisons of the sensation perceived and intradental nerve activity following temperature changes in human teeth.

The relationship between the intradental nerve responses and subjective sensory ratings evoked by thermal stimulation of the teeth was studied in man. Recordings were taken from a total of 12 thermally sensitive units from the inferior dental nerve following thermal tooth stimulation, of which seven responded to both heating and cooling, two were exclusively cold-sensitive and three exclusively heat-sensitive. The early and late sensory responses following both cold and heat stimulation of the tooth were observed. The late sensory responses were more unstable than the early sensory responses. The mean threshold of the early sensory responses to tooth cooling was 13.6 +/- 1.9 degrees C (n = 9) and that to heat stimulation was 48.4 +/- 4.8 degrees C (n = 10). The firing frequency of the heat-sensitive, but not the cold-sensitive, units increased linearly in proportion to the increase in magnitude of the early sensory ratings.

Adult↗
PubMed1991

Fifth somatosensory cortex (SV) representation of the whole body surface in the medial bank of the anterior suprasylvian sulcus of the cat.

The physiological properties of neurons in the medial bank of the anterior suprasylvian sulcus (ASSS-m) of the cat's cortex were studied using unit recording techniques. Receptive fields (RFs) on the face are represented in the most rostral aspects of the ASSS-m. Of these neurons, 84% responded to light touch of the skin on the contralateral region of the face and 12% responded to mechanical stimulation of facial hair. In addition, 4% of the neurons responded to light touch to the skin or mechanical stimulation of the hair on the contralateral face and also to visual stimuli. The RFs of neurons responsive to the hindlimb and tail are located in the most caudal aspects of the ASSS-m. 22% of these neurons responded to the light touch to the skin and 78% responded to movement of hair. The RFs of neurons responsive to the trunk area in the ASSS-m are located between the facial and hindlimb regions. Of these neurons, 2% responded to light touch of the skin and 98% responded to movements of hair. Some neurons which responded to stimulation of hair or skin on the trunk included forelimb and/or hindlimb areas. In addition, some neurons had RFs on both sides of the trunk including the shoulder area. These regions were in area 5a. Various features of representation in ASSS-m distinguish this region from other somatosensory areas. We designate the ASSS-m as the fifth somatosensory cortex (SV).

Animals↗
PubMed1991

Cortical potentials associated with voluntary biting movement in humans.

We compared the distribution of Bereitschaftspotentials (BPs) on both sides of the scalp preceding jaw biting movements in order to identify the relationship between the cortical regions and the activation of the masseter muscle in 10 healthy subjects. The BPs were recorded from the midline-central, central and temporal areas of the scalp according to the international 10-20 system, preceding self-paced biting on one side. The cortical negative potentials began 1.0 approximately 1.5 s before the EMG onset of the masseter muscle. All of these negative potentials could be considered to be BPs, and the additional negative slope component (NS) occurred 70 approximately 80 ms before the EMG onset of the masseter muscle. The BPs were detected from all the recorded regions of the scalp, while the NS was observed only from the bilateral temporal area. The amplitudes of BPs and NSs were largest in the temporal areas (T3 and T4) that were ipsilateral to the biting. The rates of occurrence of NS at T3 and T4 ipsilateral temporal areas were 80% and 60%, respectively. These results suggest that unilateral biting movements may be controlled mainly from the ipsilateral hemisphere.

Adult↗
PubMed1991

[Somatosensory evoked potentials by mechanical stimulation of tooth in humans].

We examined topographical analysis of the PM-SEP (periodontal mechanoreceptor-sensory evoked potential) inducing by mechanical stimulation of the tooth in eight subjects. Sensory evoked potential were recorded from various regions of the scalp by the mechanical stimulation of the normal tooth. Eleven electrodes were placed according to the International 10-20 system (T3, T4, C3, C4, T5, T6, F7, F8, Fz, Cz, Oz). The mechanical stimulation was applied to the right upper first incisor tooth. PM-SEPs were averaged 100 times following the mechanical stimulation of the tooth produced six waves of SEP at the ipsilateral temporal area (T4), but did not evoked any potential from the other regions. PM-SEP included I, II, III, IV, V and VI. The earliest latency (I wave) was approximately 11ms and latest latency (VI wave) was approximately 40 ms. These PM-SEP observed by intensity with 3 times of the threshold. In addition, the all components were abolished after local anesthesia of the periodontal ligament. These data suggests that the six waves of the PM -SEP were evoked the ipsilateral temporal region following mechanical stimulation of the tooth, and these regions were projected by afferent impulse from the periodontal mechanoreceptor.

Adult↗
PubMed1975

A peripheral "cold" fiber population responsive to innocuous and noxious thermal stimuli applied to monkey's face.

The activity of 134 cold fibers innervating the hairy skin of the face was recorded from fine dissected strands of the infraorbital nerve in rhesus monkeys anesthetized with sodium pentobarbital. A precisely controlled contact thermode was used to produce rapid temperature shifts of approximately 10 degrees C/s in the cooling and warming directions with a 20-60 degrees C range. Cold fiber receptive fields usually were single spots less than 300 mum in diameter. The mean conduction velocity of 94 cold fibers determined by electrical stimulation of the receptive field was 9.0 m/s, with a range indicating an almost exclusive A-delta population. Rapid cooling shifts of 1-10 degrees C produced an initial transient period of high-frequency discharges, which decayed rapidly and was followed by a period of slow adaptation. Intensity functions were linear for cooling shifts up to 6-8 degrees C, and the slope of the intensity function was independent on the base-line temperature over a 30-40 degree C range. Rapid warming shifts produced a transient suppression of cold fiber activity. Previous cooling stimuli also influenced cold fiber responses, and these effects were dependent on the intensity of the previous stimulus as well as the stimulus interval. The average maximum discharge frequency of cold fibers to constant or steady-strate temperatures occurred at 30 degrees C, but varied over a 20-35 degrees C range for individual fibers. Periodic burst discharges separated by silent periods were present at steady-state temperatures of 20-35 degrees C.

Animals↗
PubMed1975

[Double pain].

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Animals↗