Nerve electrical stimulation enhances osseointegration of implants in the beagle.

Dental implantation has been the primary method for the treatment of tooth loss, but longer than 3 months healing times are generally required. Because immediate load implants are suitable only for certain categories of implant patients, it has value to develop a novel method to facilitate the implant-bone osseointegration process. Cylindrical titanium implants were implanted in the tooth sockets of beagles, and microelectrode stimulation of the sympathetic nerves in the infraorbital nerve was performed after implantation for 1 week. The authors found that one-sided nerve stimulation was shown to evoke consistent electric potential changes in both sides of the infraorbital nerves. Moreover, after 4 weeks of implantation, more new bone was clearly observed around the implants in the beagles that received electrical stimulation treatment than was observed in the control animals. Furthermore, a higher mineralization density was measured in the new peri-implant bone tissues of the stimulated beagles when compared to controls. These results demonstrate that the simple and safe physical method of microelectrode stimulation to sympathetic nerves can promote the formation of new bone and the osseointegration of implants. This technique is worth promoting and has the potential to reduce the healing time of dental implantation in future clinical cases.

Comparative study of extracellular recording methods for analysis of afferent sensory information: Empirical modeling, data analysis and interpretation.

BACKGROUND: Physiological studies of sensorial systems often require the acquisition and processing of data extracted from their multiple components to evaluate how the neural information changes in relation to the environment changes. In this work, a comparative study about methodological aspects of two electrophysiological approaches is described. NEW METHOD: Extracellular recordings from deep vibrissal nerves were obtained by using a customized microelectrode Utah array during passive mechanical stimulation of rat´s whiskers. These recordings were compared with those obtained with bipolar electrodes. We also propose here a simplified empirical model of the electrophysiological activity obtained from a bundle of myelinated nerve fibers. RESULTS: The peripheral activity of the vibrissal system was characterized through the temporal and spectral features obtained with both recording methods. The empirical model not only allows the correlation between anatomical structures and functional features, but also allows to predict changes in the CAPs morphology when the arrangement and the geometry of the electrodes changes. COMPARISON WITH EXISTING METHOD(S): This study compares two extracellular recording methods based on analysis techniques, empirical modeling and data processing of vibrissal sensory information. CONCLUSIONS: This comparative study reveals a close relationship between the electrophysiological techniques and the processing methods necessary to extract sensory information. This relationship is the result of maximizing the extraction of information from recordings of sensory activity.

The Status of Affected Infraorbital Nerve and Inferior Alveolar Nerve in Patients With Jaw Fibrous Dysplasia: A Clinical and Radiographic Evaluation.

The affected infraorbital nerve (IFBN) and inferior alveolar nerve (IFAN) status in patients with jaw fibrous dysplasia has not been definitely depicted. In this study, the authors try to explore the status of affected IFBN and IFAN in patients with jaw fibrous dysplasia. Ten patients with jaw fibrous dysplasia were included in this study. The complaints of numbness in the IFBA and IFAN innervated area were asked and recorded, and careful clinical examination was performed to evaluate the touch sense, pain sense, pressure sense, and temperature sense in the IFBA and IFAN innervated areas. Computed tomography scans also were performed to evaluate the imaging characteristics of affected IFBA and IFAN. The results showed that 1 patient with maxillary lesion showed complaints of slight numbness, and clinical examination showed that the patient exhibited slight insensitive in pain sense. In addition, 1 patient with mandibular lesion showed relative obvious complaints of numbness, and clinical examination showed that the patient exhibited slight insensitive in pain sense and temperature sense, but not serious. All other patients exhibited no numbness in the IFBA and IFAN innervated area. Although the position and morphology changed in some patients, all neural canal of affected IFBA or IFAN existed and showed no invasion of lesion. Taking these findings together, it further confirmed that evaluation of the function of IFBAN and IFAN is necessary for patients with jaw fibrous dysplasia, and the affected IFBAN and IFAN may should be reserved in most patients with jaw fibrous dysplasia when resecting or recontouring the lesion.

Myelin Sheath Development in the Maxillary Nerve of the Newborn Pig.

Myelination, the ensheathing of neuronal axons by myelin, is important for the proper function of both central and peripheral nervous systems. Various studies have investigated the quantitative parameters of myelination in certain species. Pigs are among the species of which their use as laboratory animals in neuroscience research increased the past few decades. However, there is limited data regarding the myelination process in the pig. Moreover, the maxillary nerve is crucial for Pseudorabies Virus (PrV) neuropathogenesis. In this context, a quantitative analysis of various myelination parameters of the maxillary nerve was performed, during the first 5 weeks of porcine post-natal development, the time period, which exhibits the highest interest for PrV neuropathogenesis. The evaluation was conducted in four groups of uninfected pigs, at the time of birth (group 0w), at the age of 1 week (group 1w), 3 weeks (group 3w) and 5 weeks (group 5w), using toluidine blue staining, immunofluorescence and electron microscopy. Axon and fibre diameter, perimeter and surface, myelin sheath thickness and g-ratio were measured on histological sections transverse to the longitudinal axis of the maxillary nerve. The thickness of myelin sheath was 0.76 µm for group 0w, 0.94 µm for group 1w, 0.98 µm for group 3w and 1.03 µm for group 5w. The g-ratio was 0.529, 0.540, 0.542 and 0.531 for the respective animal groups. The results of this study contribute to the understanding of the myelination process in the pig will be used for the study of PrV effects on the myelination development of newborn piglets' maxillary nerve and may shed new light to their vulnerability to the virus.

Pain. Part 2a: Trigeminal Anatomy Related to Pain.

In order to understand the underlying principles of orofacial pain it is important to understand the corresponding anatomy and mechanisms. Paper 1 of this series explains the central nervous and peripheral nervous systems relating to pain. The trigeminal nerve is the 'great protector' of the most important region of our body. It is the largest sensory nerve of the body and over half of the sensory cortex is responsive to any stimulation within this system. This nerve is the main sensory system of the branchial arches and underpins the protection of the brain, sight, smell, airway, hearing and taste, underpinning our very existence. The brain reaction to pain within the trigeminal system has a significant and larger reaction to the threat of, and actual, pain compared with other sensory nerves. We are physiologically wired to run when threatened with pain in the trigeminal region and it is a 'miracle' that patients volunteer to sit in a dental chair and undergo dental treatment. Clinical Relevance: This paper aims to provide the dental and medical teams with a review of the trigeminal anatomy of pain and the principles of pain assessment.

Communications Between the Trigeminal Nerve and the Facial Nerve in the Face: A Systematic Review.

The aim of the article is to elucidate the communications between the trigeminal nerve and facial nerve in the face. In a PubMed search, 328 studies were found using the terms 'trigeminal nerve, facial nerve, and communication.' The abstracts were read and 39 full-text articles were reviewed. Among them, 11 articles were analyzed. In the studies using dissection, the maxillary branch (V2) had the highest frequency (95.0% ±â€Š8.0%) of communication with the facial nerve, followed by the mandibular branch (V3) (76.7% ±â€Š38.5%). The ophthalmic branch (V1) had the lowest frequency of communication (33.8% ±â€Š19.5%). In a Sihler stain, all of the maxillary branches and mandibular branches had communications with the facial nerve and 85.7% (12/14 hemifaces) of the ophthalmic branches had communications. The frequency of communications between the trigeminal nerve and facial nerve were significantly higher (P = 0.00, t-test) in the studies using a Sihler stain (94.7% ±â€Š1.1%) than the studies using dissection (76.9 ±â€Š35.8). The reason for the significantly higher frequency of trigeminal-facial communication in the studies using a Sihler stain is because of the limitation of the Sihler stain itself. This technique cannot differentiate the motor nerves from sensory nerves at the periphery, and a crossover can be misinterpreted as communication near to nerve terminal.

Trigeminofacial reflex: a means of detecting proximity to ophthalmic and maxillary divisions of the trigeminal nerve during surgery.

OBJECT: The aim in this paper was to localize and detect incipient damage to the ophthalmic and maxillary branches of the trigeminal nerve during tumor surgery. METHODS: This was an observational study of patients with skull base, retroorbital, or cavernous sinus tumors warranting dissection toward the cavernous sinus at a university hospital. Stimuli were applied as normal during approach to the cavernous sinus to localize cranial nerves (CNs) III, IV, and VI. Recordings were also obtained from the facial muscles to localize CN VII. The trigeminofacial reflex was sought simply by observing a longer time base routinely. RESULTS: Clear facial electromyography responses were reproduced when stimuli were applied to the region of V1, V2, and V3. Response latency was increased compared with direct CN VII stimuli seen in some cases. Responses gave early warning of approach to these sensory trigeminal branches. CONCLUSIONS: The authors submit this as a new technique, which may improve the chances of preserving trigeminal sensory branches during surgery in this region.

Optical survey of initial expression of synaptic function in the embryonic chick trigeminal sensory nucleus.

We examined the initial expression of synaptic function in the embryonic chick trigeminal nucleus using voltage-sensitive dye recording. Brainstem preparations with three trigeminal nerve afferents, the ophthalmic nerve (N.V1), maxillary nerve (N.V2) and mandibular nerve (N.V3), were dissected from 5.5- to 6.5-day-old chick embryos. In our previous study [Sato et al., 1999], we detected slow signals corresponding to glutamatergic excitatory postsynaptic potentials and identified the principal sensory nucleus of the trigeminal nerve (Pr5), spinal sensory nucleus of the trigeminal nerve (Sp5) and trigeminal motor nucleus. In this study, we examined the effects of removing Mg(2+) from the physiological solution, which enhanced N-methyl-d-aspartate receptor function in the sensory nuclei. In 6.5-day-old (St 29) embryos, the slow signal was observed in Pr5 and Sp5 only when N.V1 was stimulated, whereas it appeared in Mg(2+)-free solution with every nerve stimulation. In 6-day-old (St 28) embryos, the slow signal was observed in Sp5 with N.V1 stimulation, and the appearance of synaptic function in Mg(2+)-free solution varied, depending on the nerves and preparations used. In 5.5-day-old (St 27) embryos, synaptic function was not detected even when external Mg(2+) was removed. These results indicate that the initial expression of synaptic function in the trigeminal system occurs earlier than previously considered, and that the developmental organization of synaptic function differs among the three trigeminal nerves and between the two sensory nuclei.

Bilateral suprazygomatic maxillary nerve block for cleft palate repair in children: a prospective, randomized, double-blind study versus placebo.

BACKGROUND: The authors investigated the efficacy of bilateral suprazygomatic maxillary nerve block (SMB) for postoperative pain relief in infants undergoing cleft palate repair. METHODS: In this prospective, double-blind, single-site, randomized, and parallel-arm controlled trial, 60 children were assigned to undergo bilateral SMB with general anesthesia with either 0.15 ml/kg of 0.2% ropivacaine (Ropi group) or 0.15 ml/kg of isotonic saline (Saline group) on each side. The primary endpoint was total postoperative morphine consumption at 48 h. Pain scores and respiratory- and SMB-related complications were noted. RESULTS: The overall dose of intravenous morphine after 48 h (mean [95% CI]) was lower in the Ropi group compared with that in the Saline group (104.3 [68.9 to 139.6] vs. 205.2 [130.7 to 279.7] µg/kg; P = 0.033). Continuous morphine infusion was less frequent in the Ropi group compared with that in the Saline group (1 patient [3.6%] vs. 9 patients [31%]; P = 0.006). Three patients in the Saline group had an episode of oxygen desaturation requiring oxygen therapy. There were no technical failures or immediate complications of the SMB. Intraoperative hemodynamic parameters, doses of sufentanil, pain scores, and postoperative hydroxyzine requirements were not different between the two groups. CONCLUSION: Bilateral SMB is an easy regional anesthesia technique that reduces total morphine consumption at 48 h after cleft palate repair in children and the use of continuous infusion of morphine and may decrease postoperative respiratory complications.

On the maxillary nerve.

The trigeminal, the fifth cranial nerve of vertebrates, represents the rostralmost component of the nerves assigned to pharyngeal arches. It consists of the ophthalmic and maxillomandibular nerves, and in jawed vertebrates, the latter is further divided into two major branches dorsoventrally. Of these, the dorsal one is called the maxillary nerve because it predominantly innervates the upper jaw, as seen in the human anatomy. However, developmentally, the upper jaw is derived not only from the dorsal part of the mandibular arch, but also from the premandibular primordium: the medial nasal prominence rostral to the mandibular arch domain. The latter component forms the premaxillary region of the upper jaw in mammals. Thus, there is an apparent discrepancy between the morphological trigeminal innervation pattern and the developmental derivation of the gnathostome upper jaw. To reconcile this, we compared the embryonic developmental patterns of the trigeminal nerve in a variety of gnathostome species. With the exception of the diapsid species studied, we found that the maxillary nerve issues a branch (nasopalatine nerve in human) that innervates the medial nasal prominence derivatives. Because the trigeminal nerve in cyclostomes also possesses a similar branch, we conclude that the vertebrate maxillomandibular nerve primarily has had a premandibular branch as its dorsal element. The presence of this branch would thus represent the plesiomorphic condition for the gnathostomes, implying its secondary loss within some lineages. The branch for the maxillary process, more appropriately called the palatoquadrate component of the maxillary nerve (V(2)), represents the apomorphic gnathostome trait that has evolved in association with the acquisition of an upper jaw.

Sucking and swallowing rates after palatal anesthesia: an electromyographic study in infant pigs.

Infant mammalian feeding consists of rhythmic suck cycles and reflexive pharyngeal swallows. Although we know how oropharyngeal sensation influences the initiation and frequency of suck and swallow cycles, the role of palatal sensation is unknown. We implanted EMG electrodes into the mylohyoid muscle, a muscle active during suckling, and the thyrohyoid muscle, a muscle active during swallowing, in eight infant pigs. Pigs were then bottle-fed while lateral videofluoroscopy was simultaneously recorded from the electrodes. Two treatments were administered prior to feeding and compared with control feedings: 1) palatal anesthesia (0.5% bupivacaine hydrochloride), and 2) palatal saline. Using the timing of mylohyoid muscle and thyrohyoid muscle activity, we tested for differences between treatment and control feedings for swallowing frequency and suck cycle duration. Following palatal anesthesia, four pigs could not suck and exhibited excessive jaw movement. We categorized the four pigs that could suck after palatal anesthesia as group A, and those who could not as group B. Group A had no significant change in suck cycle duration and a higher swallowing frequency after palatal saline (P = 0.021). Group B had significantly longer suck cycles after palatal anesthesia (P < 0.001) and a slower swallowing frequency (P < 0.001). Swallowing frequency may be a way to predict group membership, since it was different in control feedings between groups (P < 0.001). The qualitative and bimodal group response to palatal anesthesia may reflect a developmental difference. This study demonstrates that palatal sensation is involved in the initiation and frequency of suck and swallow cycles in infant feeding.

Trigeminal nerve morphology in Alligator mississippiensis and its significance for crocodyliform facial sensation and evolution.

Modern crocodylians possess a derived sense of face touch, in which numerous trigeminal nerve-innervated dome pressure receptors speckle the face and mandible and sense mechanical stimuli. However, the morphological features of this system are not well known, and it remains unclear how the trigeminal system changes during ontogeny and how it scales with other cranial structures. Finally, when this system evolved within crocodyliforms remains a mystery. Thus, new morphological insights into the trigeminal system of extant crocodylians may offer new paleontological tools to investigate this evolutionary transformation. A cross-sectional study integrating histological, morphometric, and 3D imaging analyses was conducted to identify patterns in cranial nervous and bony structures of Alligator mississippiensis. Nine individuals from a broad size range were CT-scanned followed by histomorphometric sampling of mandibular and maxillary nerve divisions of the trigeminal nerve. Endocast volume, trigeminal fossa volume, and maxillomandibular foramen size were compared with axon counts from proximal and distal regions of the trigeminal nerves to identify scaling properties of the structures. The trigeminal fossa has a significant positive correlation with skull length and endocast volume. We also found that axon density is greater in smaller alligators and total axon count has a significant negative correlation with skull size. Six additional extant and fossil crocodyliforms were included in a supplementary scaling analysis, which found that size was not an accurate predictor of trigeminal anatomy. This suggests that phylogeny or somatosensory adaptations may be responsible for the variation in trigeminal ganglion and nerve size in crocodyliforms.

Morphological changes in the position of the mandibular foramen in dentate and edentate Brazilian subjects.

This study assessed the mandibular foramen (MF) position variability in dentate and edentate Brazilian mandibles. Eighty dentate and 79 edentate mandibles of unknown sex were measured bilaterally using a digital caliper (0.1-mm precision). Horizontal linear measurements (HM) were done from the MF to the anterior border of the mandibular ramus (MF-A) and from the MF to the posterior border of the mandibular ramus (MF-B). Vertical linear measurements (VM) were done from the MF to the most inferior point of the mandibular notch (MF-C) and from the MF to the inferior border of the mandibular ramus (MF-D). Data were analyzed by two-way ANOVA (alpha = 5%). The HM means and standard deviations (+/-SD) for MF-A were, edentate right (ER): 17.5 (+/-3.2) mm, edentate left (EL): 17.4 (+/-3.4) mm, dentate right (DR): 19.2 (+/-3.6) mm, and dentate left (DL): 18.8 (+/-3.8) mm. The means (+/-SD) for the MF-B measurements were, respectively, ER: 12.8 (+/-2.4) mm, EL: 12.9 (+/-2.3) mm, DR: 14.2 (+/-2.4) mm, and DL: 13.9 (+/-2.6) mm. The VM values for the MF-C measurements were, ER: 23.4 (+/-3.8) mm, EL: 22.9 (+/-3.7) mm, DR: 23.6 (+/-3.1) mm, and DL: 23.1 (+/-3) mm, and for the MF-D measurements, ER: 26.4 (+/-4.2) mm, EL: 26.4 (+/-4) mm, DR 28.3 (+/-3.9) mm, and DL 28 (+/-3.8) mm. Side had no influence (p>0.05) on any edentate or dentate mandible measurement. Dentate mandible measurements showed statistically significant differences compared to the edentate mandibles, except for MF-C. The mandibular foramen position changes with loss of teeth and this variability may be responsible for occasional failure of inferior alveolar nerve block.

Hypoglossal nucleus projections to the rat masseter muscle.

We investigated in the rat whether hypoglossal innervation extended to facial muscles other than the extrinsic musculature of the mystacial pad. Results showed that hypoglossal neurons also innervate the masseter muscle. Dil injected into the XII nucleus showed hypoglossal axons in the ipsilateral main trunk of the trigeminal nerve. After Gasser's ganglion crossing, the axons entered into the infraorbital division of the trigeminal nerve and targeted the extrinsic muscles of the mystacial pad. They also spread into the masseter branch of the trigeminal nerve to target the polar portions of the masseter muscle spindles. Retrograde double labelling, performed by injecting Dil into the pad and True Blue into the ipsilateral masseter muscle, showed labelled hypoglossal neurons in the medio-dorsal portion of the XII nucleus. The majority of these neurons were small (15-20 microm diameter), showed fluorescence for Dil and projected to the mystacial pad. Other medium-size neurons (25 microm diameter) were instead labelled with True Blue and projected to the masseter muscle. Finally, in the same area, other small hypoglossal neurons showed double labelling and projected to both structures. Functional hypotheses on the role of these hypoglossal projections have been discussed.

Sensory action potentials of the maxillary nerve: a methodologic study with clinical implications.

PURPOSE: Recently, recording of sensory nerve action potentials (SNAPs) of the inferior alveolar nerve (IAN) was described and is used as a diagnostic test of traumatic neuropathic trigeminal disorders. The technique is limited to IAN damage; therefore, we adapted the technique to the maxillary nerve, which is also frequently injured by either trauma or orthognathic surgery. PATIENTS AND METHODS: Fourteen healthy volunteers participated in this methodologic study in which the infraorbital nerve (ION) was stimulated with 2 needle electrodes. The SNAPs were recorded from the maxillary nerve with a unipolar needle electrode close to the foramen rotundum. RESULTS: The mean latency of the SNAPs was 0.73 ms (95% CI, 0.55 to 0.85 ms) with a 0.08+/-0.09 ms interside difference. The mean baseline to peak amplitude was 31.3+/-7.0 microV (95% CI, 24.2 to 38.3 microV) with a 6.5+/-32.4 microV interside difference. Repeated tests within a session test demonstrated no significant differences in the latency data (ANOVA: P= .225) or amplitude data (ANOVA: P= .44). Stimulus-response curves indicated that the SNAPs saturated at 5.1+/-4.4 mA stimulus intensity. In 1 subject, stimulation of the mental nerve elicited SNAPs (latency: 1.6 ms; amplitude 38 microV) in accordance with published values. A local anesthetic block of the ION was associated with a distinct decay of the SNAP in 1 subject. CONCLUSION: We suggest that SNAPs of the maxillary nerve can be a valuable technique for a comprehensive examination of the trigeminal system.

Vesicular glutamate transporters VGLUT1 and VGLUT2 in the developing mouse barrel cortex.

Three vesicular glutamate transporters have been identified in mammals. Two of them, VGLUT1 and VGLUT2, define the glutamatergic phenotype and their distribution in the brain is almost complementary. In the present study we examined the distribution and expression levels of these two VGLUTs during postnatal development of the mouse barrel cortex. We also investigated changes in the localization of VGLUT1 and VGLUT2 within particular compartments of the barrel field (barrels/septa) during its development. We found differences in the time course of developmental expression, with VGLUT1 peaking around P14, while VGLUT2 increased gradually until adulthood. Over the examined period (P3 - adult) both transporters had stronger expression in the barrel interiors, and in this compartment VGLUT2 dominated, whereas in the inter-barrel septa VGLUT1 dominated over VGLUT2. Furthermore, we found that some nerve terminals in the barrel cortex coexpressed both transporters until adulthood. Colocalization was observed within the barrels, but not within the septa.

Responses of the hypothalamic-pituitary-adrenal axis and pain threshold changes in the orofacial region upon cold pressor stimulation in normal volunteers.

AIM: This study focused on the relationship between the HPA axis function and the heat pain threshold in the orofacial region upon cold pressor (CP) stimulation. METHODS: Ten healthy male individuals participated in this study. CP stimulation was applied to each participant, and their peripheral blood was collected 5 min before, during and 5, 15, 30, 45, 60 min after receiving CP. In addition, 5 of those 10 participants were selected at random and they experienced a mock CP trial on different days. The heat pain thresholds on the facial skin about 10mm anterior to the right external auditory canal (trigeminal V2 region) in each subject were simultaneously recorded 5 min before and 5, 30, 60 min after CP stimulation. The blood pressure and heart rate were continuously monitored throughout the course of the CP and mock trials using an electric blood pressure meter. RESULTS: Significant increases in the plasma concentration of cortisol, beta-endorphin and ACTH were induced by CP stimulation, while no significant increases were observed under the mock trial conditions. The blood pressure and heart rate showed concomitant increases during CP stimulation. In addition, the heat pain threshold in the orofacial region significantly increased after receiving CP stimulation. These results suggest that CP stimulation activated the HPA axis thereby increasing the heat pain threshold in the orofacial region in healthy individuals. CONCLUSIONS: This observed pain threshold increase might be due to the activation of an endogenous opioid system, such as increase in the circulating beta-endorphin levels.

Functional role of lingual nerve in breastfeeding.

Functional role of lingual nerve in breastfeeding was investigated in rat pups during the suckling period. DiI, a postmortem neuronal tracer, was used to confirm the immature lingual nerve (LN) responsible for tongue sensation and resulted in successful fiber labeling anterogradely to the tongue, which showed different distribution patterns from fiber labeling derived from the hypoglossal nerve. Unilaterally LN-injured pups did not show suckling disturbance with absence of any shortening (P11 pups: 559+/-16s; 105% of the control value) in nipple attachment time and the survival rate remained high (P11: 100%). Bilaterally LN-injured pups showed suckling disturbance with marked shortening (P11 pups: 220+/-54 s; 42% of the control value) in nipple attachment time and a low survival rate (P1: 33%; P11: 41%). Bilaterally infraorbital nerve-injured or bilaterally bulbectomized pups did not show any nipple attachment at all and there were no survivors, confirming the crucial roles of upper lip sensation and olfaction in suckling. Based on these findings, we conclude that tongue sensation is very important, but not essential for suckling.

Transient diplopia following maxillary local anesthetic injection.

A 36-year-old female patient developed diplopia and an ipsilateral lateral rectus paresis following local anesthetic administration to remove a left maxillary second molar. Complete resolution occurred within 3 hours. The clinical examination and management plan are reviewed for this uncommon occurrence. The relevant anatomical pathways are discussed and illustrated with photographs.

Texture discrimination and multi-unit recording in the rat vibrissal nerve.

BACKGROUND: Rats distinguish objects differing in surface texture by actively moving their vibrissae. In this paper we characterized some aspects of texture sensing in anesthetized rats during active touch. We analyzed the multifiber discharge from a deep vibrissal nerve when the vibrissa sweeps materials (wood, metal, acrylic, sandpaper) having different textures. We polished these surfaces with sandpaper (P1000) to obtain close degrees of roughness and we induced vibrissal movement with two-branch facial nerve stimulation. We also consider the change in pressure against the vibrissa as a way to improve the tactile information acquisition. The signals were compared with a reference signal (control)--vibrissa sweeping the air--and were analyzed with the Root Mean Square (RMS) and the Power Spectrum Density (PSD). RESULTS: We extracted the information about texture discrimination hidden in the population activity of one vibrissa innervation, using the RMS values and the PSD. The pressure level 3 produced the best differentiation for RMS values and it could represent the "optimum" vibrissal pressure for texture discrimination. The frequency analysis (PSD) provided information only at low-pressure levels and showed that the differences are not related to the roughness of the materials but could be related to other texture parameters. CONCLUSION: Our results suggest that the physical properties of different materials could be transduced by the trigeminal sensory system of rats, as are shown by amplitude and frequency changes. Likewise, varying the pressure could represent a behavioral strategy that improves the information acquisition for texture discrimination.