Constructing an adult orofacial premotor atlas in Allen mouse CCF.

Premotor circuits in the brainstem project to pools of orofacial motoneurons to execute essential motor action such as licking, chewing, breathing, and in rodent, whisking. Previous transsynaptic tracing studies only mapped orofacial premotor circuits in neonatal mice, but the adult circuits remain unknown as a consequence of technical difficulties. Here, we developed a three-step monosynaptic transsynaptic tracing strategy to identify premotor neurons controlling vibrissa, tongue protrusion, and jaw-closing muscles in the adult mouse. We registered these different groups of premotor neurons onto the Allen mouse brain common coordinate framework (CCF) and consequently generated a combined 3D orofacial premotor atlas, revealing unique spatial organizations of distinct premotor circuits. We further uncovered premotor neurons that simultaneously innervate multiple motor nuclei and, consequently, are likely to coordinate different muscles involved in the same orofacial motor actions. Our method for tracing adult premotor circuits and registering to Allen CCF is generally applicable and should facilitate the investigations of motor controls of diverse behaviors.

Effect of the parasympathetic vasodilation on temperature regulation via trigeminal afferents in the orofacial area.

The skin temperature (Tm) of the orofacial area influences orofacial functions and is related to the blood flow (BF). Marked increases in BF mediated by parasympathetic vasodilation may be important for orofacial Tm regulation. Therefore, we examined the relationship between parasympathetic reflex vasodilation and orofacial Tm in anesthetized rats. Electrical stimulation of the central cut end of the lingual nerve (LN) elicited significant increases in BF and Tm in the lower lip. These increases were significantly reduced by hexamethonium, but not atropine. VIP agonist increased both BF and Tm in the lower lip. The activation of the superior cervical sympathetic trunk (CST) decreased BF and Tm in the lower lip; however, these decreases were significantly inhibited by LN stimulation. Our results suggest that parasympathetic vasodilation plays an important role in the maintaining the hemodynamics and Tm in the orofacial area, and that VIP may be involved in this response.

Anatomical study of gasless transoral thyroidectomy and clinical application.

BACKGROUND: Transoral thyroidectomy is becoming a preferred technique because it has the advantage of not leaving a scar after surgery. However, it is not yet standard because of the anatomic nerve complexity of this oral cavity and difficulty of approach. The aim of this study was to determine the safety zone of a gasless transoral thyroidectomy approach using an anatomical study and to evaluate the efficacy of this approach on clinical application. METHODS: Phase 1, twenty unilateral specimens from fresh cadavers underwent staining by the modified Sihler's method to identify nerves around the oral vestibules. Then, the safety zone of the transoral thyroidectomy approach was proposed. Phase 2, a comparative analysis of the clinical outcomes of gasless transoral thyroidectomy through the safety zone versus transcutaneous thyroidectomy approach. RESULTS: In phase 1, numerous inferior labial branches diverged from the mental nerve and were distributed across the lower lip. In most cases, the most lateral branch reached almost to the corner of the mouth, whereas a nerve-free area was present at the medial region of the lower lip. The suggested safety zone was presented as a trapezoid shape. In phase 2, there were no significant differences in age, mass size, or complications between the two groups. However, the operation time in the transoral thyroidectomy group was longer than in the transcutaneous group (p = 0.001). CONCLUSIONS: Based on the anatomical study, we suggested a safety zone for the gasless transoral thyroidectomy. On application of this safety zone, gasless transoral thyroidectomy is a safe and feasible procedure.

Active expiratory oscillator regulates nasofacial and oral motor activities in rats.

NEW FINDINGS: What is the central question of this study? Does the parafacial respiratory group (pFRG), which mediates active expiration, recruit nasofacial and oral motoneurons to coordinate motor activities that engage muscles controlling airways in rats during active expiration. What is the main finding and its importance? Hypercapnia/acidosis or pFRG activation evoked active expiration and stimulated the motoneurons and nerves responsible for the control of nasofacial and oral airways patency simultaneously. Bilateral pFRG inhibition abolished active expiration and the simultaneous nasofacial and oral motor activities induced by hypercapnia/acidosis. The pFRG is more than a rhythmic oscillator for expiratory pump muscles: it also coordinates nasofacial and oral motor commands that engage muscles controlling airways. ABSTRACT: Active expiration is mediated by an expiratory oscillator located in the parafacial respiratory group (pFRG). Active expiration requires more than contracting expiratory muscles as multiple cranial nerves are recruited to stabilize the naso- and oropharyngeal airways. We tested the hypothesis that activation of the pFRG recruits facial and trigeminal motoneurons to coordinate nasofacial and oral motor activities that engage muscles controlling airways in rats during active expiration. Using a combination of electrophysiological and pharmacological approaches, we identified brainstem circuits that phase-lock active expiration, nasofacial and oral motor outputs in an in situ preparation of rat. We found that either high chemical drive (hypercapnia/acidosis) or unilateral excitation (glutamate microinjection) of the pFRG evoked active expiration and stimulated motoneurons (facial and trigeminal) and motor nerves responsible for the control of nasofacial (buccal and zygomatic branches of the facial nerve) and oral (mylohyoid nerve) motor outputs simultaneously. Bilateral pharmacological inhibition (GABAergic and glycinergic receptor activation) of the pFRG abolished active expiration and the simultaneous nasofacial and oral motor activities induced by hypercapnia/acidosis. We conclude that the pFRG provides the excitatory drive to phase-lock rhythmic nasofacial and oral motor circuits during active expiration in rats. Therefore, the pFRG is more than a rhythmic oscillator for expiratory pump muscles: it also coordinates nasofacial and oral motor commands that engage muscles controlling airways in rats during active expiration.

Taste bud formation depends on taste nerves.

It has been known for more than a century that, in adult vertebrates, the maintenance of taste buds depends on their afferent nerves. However, the initial formation of taste buds is proposed to be nerve-independent in amphibians, and evidence to the contrary in mammals has been endlessly debated, mostly due to indirect and incomplete means to impede innervation during the protracted perinatal period of taste bud differentiation. Here, by genetically ablating, in mice, all somatic (i.e. touch) or visceral (i.e. taste) neurons for the oral cavity, we show that the latter but not the former are absolutely required for the proper formation of their target organs, the taste buds.

Functional specialization of macaque premotor F5 subfields with respect to hand and mouth movements: A comparison of task and resting-state fMRI.

Based on architectonic, tract-tracing or functional criteria, the rostral portion of ventral premotor cortex in the macaque monkey, also termed area F5, has been divided into several subfields. Cytoarchitectonical investigations suggest the existence of three subfields, F5c (convexity), F5p (posterior) and F5a (anterior). Electrophysiological investigations have suggested a gradual dorso-ventral transition from hand- to mouth-dominated motor fields, with F5p and ventral F5c strictly related to hand movements and mouth movements, respectively. The involvement of F5a in this respect, however, has received much less attention. Recently, data-driven resting-state fMRI approaches have also been used to examine the presence of distinct functional fields in macaque ventral premotor cortex. Although these studies have suggested several functional clusters in/near macaque F5, so far the parcellation schemes derived from these clustering methods do not completely retrieve the same level of F5 specialization as suggested by aforementioned invasive techniques. Here, using seed-based resting-state fMRI analyses, we examined the functional connectivity of different F5 seeds with key regions of the hand and face/mouth parieto-frontal-insular motor networks. In addition, we trained monkeys to perform either hand grasping or ingestive mouth movements in the scanner in order to compare resting-state with task-derived functional hand and mouth motor networks. In line with previous single-cell investigations, task-fMRI suggests involvement of F5p, dorsal F5c and F5a in the execution of hand grasping movements, while non-communicative mouth movements yielded particularly pronounced responses in ventral F5c. Corroborating with anatomical tracing data of macaque F5 subfields, seed-based resting-state fMRI suggests a transition from predominant functional correlations with the hand-motor network in F5p to mostly mouth-motor network functional correlations in ventral F5c. Dorsal F5c yielded robust functional correlations with both hand- and mouth-motor networks. In addition, the deepest part of the fundus of the inferior arcuate, corresponding to area 44, displayed a strikingly different functional connectivity profile compared to neighboring F5a, suggesting a different functional specialization for these two neighboring regions.

Cortical and Subcortical Projections from Granular Insular Cortex Receiving Orofacial Proprioception.

We have recently revealed that the proprioceptive signal from jaw-closing muscle spindles (JCMSs) is conveyed to the dorsal part of granular insular cortex rostroventrally adjacent to the rostralmost part of secondary somatosensory cortex (dGIrvs2) via the caudo-ventromedial edge (VPMcvm) of ventral posteromedial thalamic nucleus (VPM) in rats. However, it remains unclear to which cortical or subcortical structures the JCMS proprioceptive information is subsequently conveyed from the dGIrvs2. To test this issue, we injected an anterograde tracer, biotinylated dextranamine, into the electophysiologically identified dGIrvs2, and analyzed the resultant distribution profiles of labeled axon terminals in rats. Labeled terminals were distributed with an ipsilateral predominance. In the cerebral cortex, they were seen in the primary and secondary somatosensory cortices, lateral and medial agranular cortices and dorsolateral orbital cortex. In the basal ganglia, they were found in the caudate putamen, core part of accumbens nucleus, lateral globus pallidus, subthalamic nucleus, and substantia nigra pars compacta and pars reticulata. They were also observed in the central amygdaloid nucleus and extended amygdala (the interstitial nucleus of posterior limb of anterior commissure and the juxtacapsular part of lateral division of bed nucleus of stria terminalis). In the thalamus, they were seen in the reticular nucleus, ventromedial nucleus, core VPM, parvicellular part of ventral posterior nucleus, oval paracentral nucleus, medial and triangular parts of posterior nucleus, and zona incerta as well as the VPMcvm. These data suggest that the JCMS proprioceptive information through the dGIrvs2 is transmitted to the emotional 'limbic' regions as well as sensorimotor regions.

Functional considerations in oral cavity reconstruction.

PURPOSE OF REVIEW: The treatment of oral cavity cancer may impair speech and swallowing function. Optimizing posttreatment function may lead to significant improvement of quality of life. RECENT FINDINGS: Although oncologic control remains the main goal of treatment for oral cavity cancer, posttreatment function for surviving patients has over the last decades been recognized as an important secondary outcome. Reconstruction of oral cavity defects range from primary closure to advanced microvascular reconstruction, including multiple tissue types. Free flap reconstruction has greatly enhanced the ability to tailor transferred tissue to specific defects. In this review, we describe recent findings in reconstruction of tongue defects, including data from perforator flaps. We also summarize recent evidence regarding reinnervated flaps. SUMMARY: When vascularized tissue is needed, it remains unclear how the reconstructive choice impacts postoperative outcome, although in many situations it appears to be dominated by the donor site morbidity rather than the reconstructive technique. Despite numerous case series, the functional impact of motor and sensory reinnervation in vascularized tissue remains unknown. Although perforator flaps have emerged as a promising flap option, with favorable donor site morbidity, their ultimate impact on functional outcomes remains unclear, whereas the success rate appears to be lower than traditional flaps.

Somatotopic Mapping of the Developing Sensorimotor Cortex in the Preterm Human Brain.

In the mature mammalian brain, the primary somatosensory and motor cortices are known to be spatially organized such that neural activity relating to specific body parts can be somatopically mapped onto an anatomical "homunculus". This organization creates an internal body representation which is fundamental for precise motor control, spatial awareness and social interaction. Although it is unknown when this organization develops in humans, animal studies suggest that it may emerge even before the time of normal birth. We therefore characterized the somatotopic organization of the primary sensorimotor cortices using functional MRI and a set of custom-made robotic tools in 35 healthy preterm infants aged from 31 + 6 to 36 + 3 weeks postmenstrual age. Functional responses induced by somatosensory stimulation of the wrists, ankles, and mouth had a distinct spatial organization as seen in the characteristic mature homunculus map. In comparison to the ankle, activation related to wrist stimulation was significantly larger and more commonly involved additional areas including the supplementary motor area and ipsilateral sensorimotor cortex. These results are in keeping with early intrinsic determination of a somatotopic map within the primary sensorimotor cortices. This may explain why acquired brain injury in this region during the preterm period cannot be compensated for by cortical reorganization and therefore can lead to long-lasting motor and sensory impairment.

Innervation of the Human Incisive Papilla: Comparison with Other Oral Regions.

Immunohistochemistry for several neurochemical substances was performed on the human incisive papilla and other oral structures. Sodium channel alpha subunit 7 (SCN7A) protein-immunoreactive (IR) Schwann cells and protein gene product 9.5 (PGP 9.5)-IR nerve fibers made nerve plexuses beneath the epithelium of the palate, including the incisive papilla, tongue, and lip. SCN7A immunoreactivity could also be detected in lamellated and nonlamellated capsules of corpuscle endings. Lamellated SCN7A-IR corpuscle endings were mostly restricted to the mucous and cutaneous lips. These endings had thick and spiral-shaped PGP 9.5-IR axons without ramification. Nonlamellated SCN7A-IR corpuscle endings were most numerous in the incisive papilla among the oral regions. On the basis of axonal morphology, the nonlamellated endings were divided into simple and complex types. PGP 9.5-IR terminal axons in the simple type ran straight or meandered with slight ramification, whereas those in the complex type were densely entangled with abundant ramification. Substance P (SP)-, calcitonin gene-related peptide (CGRP)-, and transient receptor potential cation channel subfamily V member 2 (TRPV2)-IR varicose fibers were rarely seen beneath the epithelium of oral structures. The present study indicates that the human incisive papilla has many low-threshold mechanoreceptors with nonlamellated capsules. SP-, CGRP-, and TRPV2-containing nociceptors may be infrequent in the incisive papilla and other oral regions.

Short-Term Interferential Transabdominal Electrical Stimulation Did Not Change Oral-Rectal Transit Time in Piglets.

BACKGROUND: Transcutaneous electrical stimulation (TES) using interferential current (IFC) is a new therapeutic treatment for constipation. Clinical studies show that TES-IFC for 3-6 months improves colonic transit, but it is not clear if short-term stimulation affects transit or the effect requires longer to develop. The aim of this study was to determine if TES-IFC for only four days affects oral-rectal transit time in healthy pigs. METHODS: Twenty-two 4-5-week old large white female piglets had transit studies during week 4 and week 5 by placing a capsule containing 18 radiopaque plastic markers in the esophagus under anesthetic followed by x-rays at 6, 30, 54, and 78 hours. Animals were randomly assigned to active or control groups. The active group received TES for 30 min daily for four days. Interferential current was applied through four electrodes (4 × 4 cm), with two para-spinal just below the last rib and two on the belly at the same level. Stimulation was at 4000 Hz and 4080-4160 Hz with currents crossing through the abdominal cavity. RESULTS: Whole bowel transit times ranged from 7.7 to 72.2 hours, stomach transit from <1 to 63 hours, and bowel with rectum transit time from 5 to 53 hours. Transit times were the same for the control (median 28.4 hours) and TES-IFC (23.0 hours) groups in the prestimulation and stimulation weeks (control 23.0, TES-IFC 19.8 hours) with no change within or between groups. CONCLUSION: Four days of half-hour TES-IFC daily in healthy 5-week-old piglets did not change oral-rectal transit time.

Circuits in the rodent brainstem that control whisking in concert with other orofacial motor actions.

The world view of rodents is largely determined by sensation on two length scales. One is within the animal's peri-personal space; sensorimotor control on this scale involves active movements of the nose, tongue, head, and vibrissa, along with sniffing to determine olfactory clues. The second scale involves the detection of more distant space through vision and audition; these detection processes also impact repositioning of the head, eyes, and ears. Here we focus on orofacial motor actions, primarily vibrissa-based touch but including nose twitching, head bobbing, and licking, that control sensation at short, peri-personal distances. The orofacial nuclei for control of the motor plants, as well as primary and secondary sensory nuclei associated with these motor actions, lie within the hindbrain. The current data support three themes: First, the position of the sensors is determined by the summation of two drive signals, i.e., a fast rhythmic component and an evolving orienting component. Second, the rhythmic component is coordinated across all orofacial motor actions and is phase-locked to sniffing as the animal explores. Reverse engineering reveals that the preBötzinger inspiratory complex provides the reset to the relevant premotor oscillators. Third, direct feedback from somatosensory trigeminal nuclei can rapidly alter motion of the sensors. This feedback is disynaptic and can be tuned by high-level inputs. A holistic model for the coordination of orofacial motor actions into behaviors will encompass feedback pathways through the midbrain and forebrain, as well as hindbrain areas.

Exploring mouthfeel in model wines: Sensory-to-instrumental approaches.

Wine creates a group of oral-tactile stimulations not related to taste or aroma, such as astringency or fullness; better known as mouthfeel. During wine consumption, mouthfeel is affected by ethanol content, phenolic compounds and their interactions with the oral components. Mouthfeel arises through changes in the salivary film when wine is consumed. In order to understand the role of each wine component, eight different model wines with/without ethanol (8%), glycerol (10g/L) and commercial tannins (1g/L) were described using a trained panel. Descriptive analysis techniques were used to train the panel and measure the intensity of the mouthfeel attributes. Alongside, the suitability of different instrumental techniques (rheology, particle size, tribology and microstructure, using Transmission Electron Microscopy (TEM)) to measure wine mouthfeel sensation was investigated. Panelists discriminated samples based on their tactile-related components (ethanol, glycerol and tannins) at the levels found naturally in wine. Higher scores were found for all sensory attributes in the samples containing ethanol. Sensory astringency was associated mainly with the addition of tannins to the wine model and glycerol did not seem to play a discriminating role at the levels found in red wines. Visual viscosity was correlated with instrumental viscosity (R=0.815, p=0.014). Hydrodynamic diameter of saliva showed an increase in presence of tannins (almost 2.5-3-folds). However, presence of ethanol or glycerol decreased hydrodynamic diameter. These results were related with the sensory astringency and earthiness as well as with the formation of nano-complexes as observed by TEM. Rheologically, the most viscous samples were those containing glycerol or tannins. Tribology results showed that at a boundary lubrication regime, differences in traction coefficient lubrication were due by the presence of glycerol. However, no differences in traction coefficients were observed in presence/absence of tannins. It is therefore necessary to use an integrative approach that combines complementary instrumental techniques for mouthfeel perception characterization.

The Functional Anatomy of Nerves Innervating the Ventral Grooved Blubber of Fin Whales (Balaenoptera Physalus).

Nerves that supply the floor of the oral cavity in rorqual whales are extensible to accommodate the dramatic changes in tissue dimensions that occur during "lunge feeding" in this group. We report here that the large nerves innervating the muscle component of the ventral grooved blubber (VGB) in fin whales are branches of cranial nerve VII (facial nerve). Therefore, the muscles of the VGB are homologous to second branchial arch derived muscles, which in humans include the muscles of "facial expression." We speculate, based on the presence of numerous foramina on the dorsolateral surface of the mandibular bones, that general sensation from the VGB likely is carried by branches of the mandibular division (V3) of cranial nerve V (trigeminal nerve), and that these small branches travel in the lipid-rich layer directly underlying the skin. We show that intercostal and phrenic nerves, which are not extensible, have a different wall and nerve core morphology than the large VGB nerves that are branches of VII. Although these VGB nerves are known to have two levels of waviness, the intercostal and phrenic nerves have only one in which the nerve fascicles in the nerve core are moderately wavy. In addition, the VGB nerves have inner and outer parts to their walls with numerous large elastin fibers in the outer part, whereas intercostal and phrenic nerves have single walls formed predominantly of collagen. Our results illustrate that overall nerve morphology depends greatly on location and the forces to which the structures are exposed. Anat Rec, 300:1963-1972, 2017. © 2017 Wiley Periodicals, Inc.

Concerted Interneuron Activity in the Cerebellar Molecular Layer During Rhythmic Oromotor Behaviors.

Molecular layer interneurons (MLIs, stellate and basket cells) of the cerebellar cortex are linked together by chemical and electrical synapses and exert a potent feedforward inhibition on Purkinje cells. The functional role of MLIs during specific motor tasks is uncertain. Here, we used two-photon imaging to study the patterns of activity of neighboring individual MLIs in the Crus II region of awake female mice during two types of oromotor activity, licking and bruxing, using specific expression of the genetically encoded calcium indicator protein GCaMP6s. We found that both stellate and basket cells engaged in synchronized waves of calcium activity during licking and bruxing, with high degrees of correlation among the signals collected in individual MLIs. In contrast, no calcium activity was observed during whisking. MLI activity tended to lag behind the onset of sustained licking episodes, indicating a regulatory action of MLIs during licking. Furthermore, during licking, stellate cell activity was anisotropic: the coordination was constant along the direction of parallel fibers (PFs), but fell off with distance along the orthogonal direction. These results suggest a PF drive for Ca2+ signals during licking. In contrast, during bruxing, MLI activity was neither clearly organized spatially nor temporally correlated with oromotor activity. In conclusion, MLI activity exhibits a high degree of correlation both in licking and in bruxing, but spatiotemporal patterns of activity display significant differences for the two types of behavior.SIGNIFICANCE STATEMENT It is known that, during movement, the activity of molecular layer interneurons (MLIs) of the cerebellar cortex is enhanced. However, MLI-MLI interactions are complex because they depend both from excitatory electrical synapses and from potentially inhibitory chemical synapses. Accordingly, the pattern of MLI activity during movement has been unclear. Here, during two oromotor tasks, licking and bruxism, individual neighboring MLIs displayed highly coordinated activity, showing that the positive influences binding MLIs together are predominant. We further find that spatiotemporal patterns differ between licking and bruxing, suggesting that the precise pattern of MLI activity depends on the nature of the motor task.

Two-point discrimination values vary depending on test site, sex and test modality in the orofacial region: a preliminary study.

OBJECTIVE: The aims of the present study were to determine the normal values of TPD in the six trigeminal sites (the forehead, cheek, mentum, upper lip, lower lip, and the tongue tip) and to investigate the effect of the site, sex, and test modality on the TPD perception. MATERIAL AND METHODS: Forty healthy volunteers consisting of age-matched men (20) and women (20) with a mean age of 27.1 years were recruited. One examiner performed the TPD test using a simple hand-operated device, i.e., by drawing compass with a blunt or sharp-pointed tip. The static TPD with a blunt-pointed tip (STPDB), moving TPD with a blunt-pointed tip (MTPDB), and static TPD with a sharp-pointed tip (STPDS) were measured. The predictors were the site, sex, and test modality, and the outcome variable was the TPD value. Three-way ANOVA was used for statistics. RESULTS: The analysis showed a significant effect of the site, sex and test modality on the TPD values. Significant differences between the test sites were observed with the descending order from the forehead and cheek>mentum>upper lip and lower lip>tongue tip and index finger. Women showed lower TPD values than those of men. The STPDS measurements were consistently lower than those of the STPDB and MTPDB. CONCLUSIONS: The normal values of TPD in this study suggest that the cheek and forehead were less sensitive than other regions evaluated and women were more sensitive than men. The STPDS was the most sensitive test modality.

The transcription factor Phox2b distinguishes between oral and non-oral sensory neurons in the geniculate ganglion.

Many basic characteristics of gustatory neurons remain unknown, partly due to the absence of specific markers. Some neurons in the geniculate ganglion project to taste regions in the oral cavity, whereas others innervate the outer ear. We hypothesized that the transcription factor Phox2b would identify oral cavity-projecting neurons in the geniculate ganglion. To test this possibility, we characterized mice in which Phox2b-Cre mediated gene recombination labeled neurons with tdTomato. Nerve labeling revealed that all taste neurons projecting through the chorda tympani (27%) and greater superficial petrosal nerves (15%) expressed Phox2b during development, whereas non-oral somatosensory neurons (58%) in the geniculate ganglion did not. We found tdTomato-positive innervation within all taste buds. Most (57%) of the fungiform papillae had labeled innervation only in taste buds, whereas 43% of the fungiform papillae also had additional labeled innervation to the papilla epithelium. Chorda tympani nerve transection eliminated all labeled innervation to taste buds, but most of the additional innervation in the fungiform papillae remained. Some of these additional fibers also expressed tyrosine hydroxylase, suggesting a sympathetic origin. Consistent with this, both sympathetic and parasympathetic fibers innervating blood vessels and salivary glands contained tdTomato labeling. Phox2b-tdTomato labels nerve fascicles in the tongue of the developing embryo and demonstrates a similar stereotyped branching pattern DiI-labeling.

Two-point discrimination values vary depending on test site, sex and test modality in the orofacial region: a preliminary study

Abstract The two-point discrimination (TPD) test is one of the most commonly used neurosensory tests to assess mechanoperception in the clinical settings. While there have been numerous studies of functional sensibility of the hand using TPD test, there have been relatively not enough reports on TPD in the orofacial region. Objective The aims of the present study were to determine the normal values of TPD in the six trigeminal sites (the forehead, cheek, mentum, upper lip, lower lip, and the tongue tip) and to investigate the effect of the site, sex, and test modality on the TPD perception. Material and Methods Forty healthy volunteers consisting of age-matched men (20) and women (20) with a mean age of 27.1 years were recruited. One examiner performed the TPD test using a simple hand-operated device, i.e., by drawing compass with a blunt or sharp-pointed tip. The static TPD with a blunt-pointed tip (STPDB), moving TPD with a blunt-pointed tip (MTPDB), and static TPD with a sharp-pointed tip (STPDS) were measured. The predictors were the site, sex, and test modality, and the outcome variable was the TPD value. Three-way ANOVA was used for statistics. Results The analysis showed a significant effect of the site, sex and test modality on the TPD values. Significant differences between the test sites were observed with the descending order from the forehead and cheek>mentum>upper lip and lower lip>tongue tip and index finger. Women showed lower TPD values than those of men. The STPDS measurements were consistently lower than those of the STPDB and MTPDB. Conclusions The normal values of TPD in this study suggest that the cheek and forehead were less sensitive than other regions evaluated and women were more sensitive than men. The STPDS was the most sensitive test modality.

Localization of orofacial representation in the corona radiata, internal capsule and cerebral peduncle in Macaca mulatta.

Subcortical white matter injury is often accompanied by orofacial motor dysfunction, but little is known about the structural substrates accounting for these common neurological deficits. We studied the trajectory of the corticobulbar projection from the orofacial region of the primary (M1), ventrolateral (LPMCv), supplementary (M2), rostral cingulate (M3) and caudal cingulate (M4) motor regions through the corona radiata (CR), internal capsule (IC) and crus cerebri of the cerebral peduncle (ccCP). In the CR each pathway was segregated. Medial motor area fibers (M2/M3/M4) arched over the caudate and lateral motor area fibers (M1/LPMCv) curved over the putamen. At superior IC levels, the pathways were widespread, involving the anterior limb, genu and posterior limb with the M3 projection located anteriorly, followed posteriorly by projections from M2, LPMCv, M4 and M1, respectively. Inferiorly, all pathways maintained this orientation but shifted posteriorly, with adjacent fiber bundles overlapping minimally. In the ccCP, M3 fibers were located medially and M1 fibers centromedially, with M2, LPMCv, and M4 pathways overlapping in between. Finally, at inferior ccCP levels, all pathways overlapped. Following CR and superior IC lesions, the dispersed pathway distribution may correlate with acute orofacial dysfunction with spared pathways contributing to orofacial motor recovery. In contrast, the gradually commixed nature of pathway representation inferiorly may enhance fiber vulnerability and correlate with severe, prolonged deficits following lower subcortical and midbrain injury. Additionally, in humans these findings may assist in interpreting orofacial movements evoked during deep brain stimulation, and neuroimaging tractography efforts to localize descending orofacial motor pathways.

Cheiro-oral syndrome.

We describe a 64-year-old man who presented to the emergency department with a two-day history of left perioral and hand numbness. Examination revealed impaired sensation of the left corner of the mouth and ipsilateral fingers. Neuroimaging showed an acute right thalamic lacunar infarct consistent with the diagnosis of cheiro-oral syndrome. In this report, we discuss the importance of recognising this syndrome and instituting appropriate management to prevent further cerebrovascular events.