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R Sumino

Publications and source records attributed to R Sumino.

At least 37 records · Page 2Linked to original sources
PubMed1990

Input-output relationships in the jaw and orofacial motor zones of the cat cerebral cortex.

Input-output relationships of the jaw and orofacial motor zones in the cerebral cortex of lightly anesthetized cats were studied. These relationships were examined by studying the motor effects produced by intracortical microstimulation (ICMS) and recording from single neuron. Jaw and orofacial motor effects were evoked by ICMS of the anterior part of the coronal and lateral sigmoid gyri (C-S motor zone) and the lateral wall of the presylvian sulcus (P motor zone). ICMS of the P motor zone produced more complex movements than that of the C-S motor zone. Repetitive stimulation of the P motor zone also evoked rhythmic jaw movements. Almost all cortical cells located in the C-S motor zone responded to tactile stimulation of cutaneous skin of the orofacial regions or the tooth, whereas those of the P motor zone received no cutaneous input from the orofacial regions. Cytoarchitectonically, the C-S motor zone was restricted to areas 3a, 6a beta and occasionally to area 4 gamma, whereas the P motor zone was represented to area 6a beta. Therefore, it is concluded that the C-S motor zone might be involved in sensorimotor integration of the jaw and orofacial motor functions, whereas the P motor zone might function only as a command area for jaw and orofacial movements.

Animals↗
PubMed1990

Distribution and response properties of cat SI neurons responsive to changes in tooth temperature.

1. The activity of 214 tooth pulp-driven neurons (TPNs) in the primary somatosensory cortex (SI) activated by electrical stimulation of the canine tooth pulp was studied in anesthetized cats. These neurons were tested for their responses to thermal stimulation of the tooth pulp. 2. One hundred fifty-five TPNs were not responsive to changes in tooth temperature (thermally insensitive, TINS-TPNs) and 59 TPNs were responsive (thermally sensitive, TS-TPNs: 38 TS-TPNs were heat sensitive and 21 were cold sensitive). TS-TPNs were also tested for responsiveness to mechanical and thermal stimulation of the skin, mucosa, or periodontal membrane. Each TS-TPN was classified on the basis of cutaneous, mucosal, or periodontal mechanical receptive-field properties as either low-threshold mechanoreceptive (LTM: 57%), wide dynamic range (WDR: 25%), nociceptive specific (NS: 10%) or pulp specific (PS: 8%). 3. TS-TPNs were distributed in an upper bank of the orbital sulcus of SI. The majority were located in laminae III (32%) and IV (60%) of area 3b. 4. Heat-sensitive LTM, WDR, PS TS-TPNs, and cold-sensitive LTM TS-TPNs were characterized by a rapid rise in firing rate during thermal stimulation of the tooth pulp. In contrast, heat-sensitive NS and cold-sensitive NS and PS TS-TPNs responded with a slow rise in firing frequency during thermal stimuli delivered to the tooth pulp. 5. A linear regression analysis was applied to the stimulus-response functions of neuronal discharges of TS-TPNs. Fifty-six percent of heat-sensitive LTM, WDR, and cold-sensitive LTM TS-TPNs showed statistically significant relation (P less than 0.5) between peak firing frequency and stimulus temperature and increasing firing frequency after increases in stimulus temperature, whereas heat-sensitive and cold-sensitive NS and PS TS-TPNs did not show a clear increase in firing frequency during the thermal stimulus. 6. These findings suggest that heat-sensitive LTM and WDR TS-TPNs and cold-sensitive LTM TS-TPNs that showed high regression coefficients in stimulus-response function may be involved in encoding the intensity of noxious thermal stimulation of the tooth pulp.

Animals↗
PubMed1989

Effects of intrastriatal injections of selective dopamine D-1 and D-2 agonists and antagonists on jaw movements of rats.

The effects of bilateral intrastriatal injections of the selective D-1 and D-2 antagonists, SCH23390 and sulpiride on apomorphine-induced jaw movements were studied in ketamine-anaesthetized rats after C1 spinal transection. A photo-transducer attached to the lower mandible automatically detected jaw movements. Apomorphine (0.2, 0.5 and 1.0 mg/kg i.v.) dose dependently increased jaw movements, an effect prevented by prior administration into the ventral striatum of either SCH23390 (0.1, 0.5 and 1 microgram) or sulpiride (125 ng). To be effective, SCH23390 had to be given less than 30 min before apomorphine whereas sulpiride had to be given earlier. Sulpiride injected into the dorsal striatum potentiated the effects of apomorphine, an action prevented by administering the sulpiride with SCH23390. Local application of the selective D-1 and D-2 agonists, SKF38393 (5 micrograms) and quinpirole (10 micrograms) into sites within the ventral striatum from which repeated jaw movements could be obtained by electrical stimulation, also evoked jaw movements; the effects of combining the two drugs were much greater than the effects of either drug alone.

Animals↗
PubMed1989

Distribution of movement-related cortical potential upon jaw-biting in humans.

We examined the cerebral location of the readiness potential (hereinafter referred to as "RP") upon activation of the masseter muscle by voluntary and unilateral jaw-biting movement. Four normal adults served as subjects. Five scalp electrodes were placed according to the international 10-20 method at CZ, C3, C4, T3 and T4. In addition, in one of the subjects, RPs were recorded by 12 scalp electrodes in order to study changes occurring in the distribution of RPs with time. The maximum amplitude of the RP was located at T4 in the temporal area, which was involved in the biting movement as a negative slow potential occurring 1.4-0.8 s before the beginning of the discharge to the masseter muscle. The maximum amplitude of the RP on the contralateral side was located at T3. This meant that the amplitude of the RP tended to be higher on the same side as the biting movement than on the contralateral side in all subjects. From scalp topography, the maximum amplitude of the RP was shown to be confined to T4, and was especially marked immediately before the beginning of discharge to the masseter muscle. From these results it is thought that in the case of voluntary biting movement, the RP reflects activities of the pyramidal cells in the masticatory area of the cortex, and that strong descending impulses from both sides then reach the masseter muscles.

Action Potentials↗
PubMed1987

Responses of bradykinin sensitive tooth-pulp driven neurons in cat cerebral cortex.

The properties of single cortical neurons responding to electrical stimulation of the tooth-pulp and to intrapulpal application of bradykinin were studied in the cat. The activities of tooth-pulp driven neurons (TPNs) were recorded from the middle and anterior parts of the coronal gyrus of the cerebral cortex. Bradykinin-sensitive tooth-pulp driven neurons (BK-TPNs) were located in layer IV of area 3b of the anterior part of the coronal gyrus. These neurons had a large cutaneous oro-facial receptive field and received a nociceptive input from the facial skin as well as from the tooth-pulp. The BK-TPNs had a higher threshold and longer latency to electrical stimulation than TPNs insensitive to bradykinin (non BK-TPNs). These findings suggest that BK-TPNs in this cortical area may be involved in sensory processing of noxious information from trigeminal regions.

Action Potentials↗
PubMed1986

Cortical cells driven by the low-threshold tooth pulpal afferent in cats.

The input pattern and spatial distribution of tooth pulp-driven neurons (TPNs) in the cat cortex were studied by recording the unitary activities of these neurons. Stimulation was applied to the upper and lower canine and molar tooth pulps. It was possible to record activities of TPNs in the deep layers of the areas 3a and 3b of the coronal gyrus of cerebral cortex. TPNs driven by the ipsilateral tooth pulp stimulation were distributed more anteroventrally than those driven by contralateral stimulation. Cells driven by bilateral pulp stimulation were situated between these two neurons. The threshold intensity for TPNs in the area 3a was lower than that for neurons in 3b. The majority of TPNs in the area 3a of the anterior part of the coronal gyrus received inputs from low-threshold masseteric muscular afferents as well as from tooth pulp afferents. The findings suggest that TPNs in the area 3a may have a relation to orofacial motor functions.

Animals↗
PubMed1985

Movements of the jaw and orofacial regions evoked by stimulation of two different cortical areas in cats.

Functional properties of the jaw and orofacial motor areas in the cerebral cortex of the lightly anesthetized cat were studied on the basis of the motor effects produced by intracortical microstimulation (ICMS). Jaw and orofacial motor effects were evoked by ICMS (less than 30 microA) delivered to the anterior parts of the coronal and lateral sigmoid gyri (C, coronal area), and the anterior part of the orbital gyrus (O, orbital area). Different patterns of movements in the jaw and orofacial regions were evoked from these two areas. In C one or, at most, two types of simple movement were produced by ICMS to one location, while in O more coordinated movements than those in C were produced. Cytoarchitectonically the jaw and orofacial motor areas were restricted to areas 3a, 4 gamma, and 6a beta in C, and to area 43 in O.

Animals↗
PubMed1985

Distribution and response characteristics of masseteric nerve-driven neurons in two separate cortical projection areas of cats.

Cortical projection areas and distribution and response characteristics of masseteric nerve-driven neurons (MDN) were studied by recording surface-evoked potentials and single neuronal activities elicited by stimulation of the contralateral masseteric nerve in cats. Neuronal activities of MDNs could be recorded in two separate cortical areas. One was located in laminae II-III of area 3b of the posterior part of the coronal gyrus (P), and the other in laminae IV-V of areas 3a and 6a beta of the anterior parts of the coronal and lateral sigmoid gyri (A). The majority of MDNs were driven by low-threshold muscle afferents (Group I and II). Peak latencies of MDNs in P were shorter than those in A. Intracortical microstimulation (less than 30 microA) in A produced oro-facial movements while stimulation in P did not produce any motor effects.

Animals↗
PubMed1984

Functional organization of trigeminal subnucleus interpolaris: nociceptive and innocuous afferent inputs, projections to thalamus, cerebellum, and spinal cord, and descending modulation from periaqueductal gray.

In view of continuing uncertainties concerning the organization, afferent inputs, and projection sites of neurons in the subnucleus interpolaris of the trigeminal (V) spinal tract nucleus, the characteristics of 222 single neurons in and adjacent to the subnucleus were examined electrophysiologically in adult cats anesthetized with chloralose. Neurons were tested for orthodromic responsiveness to a variety of stimuli that included nonnoxious tactile stimuli, noxious mechanical and radiant-heat stimuli, and graded electrical stimulation of the skin, mucosa, tooth pulp, and masseter nerve. Antidromic activation techniques were also used to determine if the functionally identified neurons projected directly to the contralateral posterior thalamus, ipsilateral cerebellum, or cervical spinal cord. In addition, the periaqueductal gray matter (PAG) was stimulated to test for conditioning influences from the PAG on orthodromic responses to noxious and nonnoxious oral-facial stimuli. Interpolaris neurons were somatotopically arranged in subnucleus interpolaris in a pattern conforming in general to the medially facing, inverted-head representation characteristic of other parts of the V brain stem sensory nuclear complex. On the basis of their responsiveness to cutaneous stimuli, the neurons could be functionally classified as either cutaneous nociceptive or low-threshold mechanoreceptive (LTM) neurons. The LTM neurons constituted the major neuron type, accounting for over 75% of our neuron sample. Most of them had a localized mechanoreceptive field of less than 100 mm2 in area that was restricted to one V division, and they had skin-evoked response latencies indicative of afferent input predominantly from A-beta cutaneous afferents. A population of nociceptive neurons was also encountered in the lateral, marginal region of interpolaris and at its medial or ventral border with the reticular formation. These neurons were of two types: nociceptive-specific (NS) neurons, which did not respond to nonnoxious stimuli but which required noxious stimuli for their activation; and wide dynamic range ( WDR ) neurons, which responded to both noxious and nonnoxious stimuli applied to the facial skin. Most had an ipsilateral receptive field that was greater than 100 mm2 in area and that often involved two or three V divisions. Their properties generally conformed to those previously described for nociceptive neurons in the medullary dorsal horn (V subnucleus caudalis) and spinal cord dorsal horn. Interpolaris neurons of all classes (LTM, WDR , and NS) were found to have direct axonal projections to the thalamus, cerebellum, and spinal cord.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1982

Stimulation sites in periaqueductal gray, nucleus raphe magnus and adjacent regions effective in suppressing oral-facial reflexes.

Electrode penetrations were made in the mesencephalon and caudal brainstem at the levels of the periaqueductal gray matter (PAG) and nucleus raphe magnus (NRM) in chloralose-anaesthetized or decerebrate cats. In a systematic fashion, mesencephalic and brainstem loci at every 1 mm of vertical depth were electrically stimulated in a series of mediolateral or anteroposterior electrode penetrations to determine the lowest stimulation threshold at each locus for suppressing the digastric jaw-opening reflex evoked by tooth pulp or infraorbital nerve stimulation; at some loci, the threshold current required for suppressing infraorbital nerve-evoked neck reflexes was also determined. Stimulation at sites within large regions of the mesencephalon and caudal brainstem was effective in suppressing these reflexes at less than 4 X the lowest threshold for reflex suppression in each animal. However, in these regions the areas of lowest threshold in the mesencephalon generally corresponded to the ventrolateral PAG and adjacent nucleus cuneiformis and part of the lateral reticular formation (LRF) and in the caudal brainstem they corresponded to NRM and the adjacent nuclei reticularis magnocellularis (RMC) and gigantocellularis (RGC). These findings suggest that there may be mesencephalic and caudal brainstem areas in addition to PAG and NRM that are equally effective in modulating reflex activity.

Animals↗
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↗