Hemispheric Dominance for Stereognosis in a Patient With an Infarct of the Left Postcentral Sensory Hand Area.

The concept of left hemispheric dominance for praxis, speech, and language has been one of the pillars of neurology since the mid-19th century. In 1906, Hermann Oppenheim reported a patient with bilateral stereoagnosia (astereognosis) caused by a left parietal lobe tumor and proposed that the left hemisphere was also dominant for stereognosis. Surprisingly, few cases of bilateral stereoagnosia caused by a unilateral cerebral lesion have been documented in the literature since then. Here we report a 75-year-old right-handed man who developed bilateral stereoagnosia after suffering a small infarct in the crown of the left postcentral gyrus. He could not recognize objects with either hand, but retained the ability to localize stimuli applied to the palm of his left (ipsilesional) hand. He was severely disabled in ordinary activities requiring the use of his hands. The lesion corresponded to Brodmann area 1, where probabilistic anatomic, functional, and electrophysiologic studies have located one of the multiple somatosensory representations of the hand. The lesion was in a strategic position to interrupt both the processing of afferent tactile information issuing from the primary somatosensory cortex (areas 3a and 3b) and the forward higher-order processing in area 2, the secondary sensory cortex, and the contralateral area 1. The lesion also deprived the motor hand area of its afferent regulation from the sensory hand area (grasping), while leaving intact the visuomotor projections from the occipital cortex (reaching). Our patient supports Oppenheim's proposal that the left postcentral gyrus of some individuals is dominant for stereognosis.

Development of a new haptic perception instrument: a pilot study / Desenvolvimento de um novo instrumento de avaliação da percepção háptica: um estudo piloto

ABSTRACT Objective Hand sensory tests do not consider distinct physiological receptors, nor detect normal range variations concerning developmental or pathological changes. We developed an instrument with a set of tests with timing and scoring for assessing haptic perception, which is the interaction between sensory and motor systems, in surfaces exploration, by moving hands. Method Firstly, group meetings were set for test/manual conception and materials testing. The test/manual were submitted to 30 reviewers in 3 stages (10 reviewers on each stage). Results The Hand Haptic Perception Instrument (HHPI) evaluates hand sensorimotor performance on six domains: depression, elevation, texture, compressibility, weight (barognosis) and form perception. Each domain requires specific materials. Score ranges from 0 to 57, being 0 the worst rating. Conclusion This methodological process allowed the development of six domains and instructions to assess haptic perception. This version of HHPI is a pilot model. Further studies will determine reliability and normality ranges.

RESUMO Objetivo Testes de sensibilidade manual não consideram receptores fisiológicos distintos, tampouco variações do desenvolvimento normal ou patológico. Desenvolvemos um instrumento, com pontuação e tempo de desempenho, para avaliar percepção háptica, que é a interação sensório-motora na exploração de superfícies, pelo movimento das mãos. Método Reuniões de grupo foram estabelecidas para desenvolver os testes/ manual e testar materiais. O instrumento e seu manual foram submetidos a 30 revisores, em 3 estágios (com 10 revisores em cada estágio). Resultados O instrumento de avaliação da percepção háptica manual (IAPHM) avalia o desempenho sensório-motor da mão em seis domínios: depressão, elevação, textura, compressibilidade, peso (barognosia) e percepção de forma. Cada domínio requer materiais específicos. A pontuação vai de 0 a 57, sendo 0 a pior pontuação. Conclusão Esse método permitiu o desenvolvimento do instrumento para avaliar percepção háptica. Essa versão do IAPHM é um modelo piloto. Estudos futuros determinarão confiabilidade e variações de normalidade.

Development of a new haptic perception instrument: a pilot study.

OBJECTIVE: Hand sensory tests do not consider distinct physiological receptors, nor detect normal range variations concerning developmental or pathological changes. We developed an instrument with a set of tests with timing and scoring for assessing haptic perception, which is the interaction between sensory and motor systems, in surfaces exploration, by moving hands. METHOD: Firstly, group meetings were set for test/manual conception and materials testing. The test/manual were submitted to 30 reviewers in 3 stages (10 reviewers on each stage). RESULTS: The Hand Haptic Perception Instrument (HHPI) evaluates hand sensorimotor performance on six domains: depression, elevation, texture, compressibility, weight (barognosis) and form perception. Each domain requires specific materials. Score ranges from 0 to 57, being 0 the worst rating. CONCLUSION: This methodological process allowed the development of six domains and instructions to assess haptic perception. This version of HHPI is a pilot model. Further studies will determine reliability and normality ranges.

Relation between oral stereognosis and masticatory efficiency in complete denture wearers: an in vivo study

Aim: The purpose of the present study was to evaluate the possible association between the oral stereognostic ability and masticatory efficiency at the time of denture insertion and after 6 months in complete denture wearers. Methods: Sixty edentulous patients were selected. The study was conducted in two parts. First, on the day of denture fit-in oral stereognostic ability test was conducted,followed by masticatory efficiency was carried out. The patients were recalled for check up after 6months and the same test was performed again. Data were tabulated and analyzed statistically by paired t-test and Pearson’s correlation coefficient. Results: There was weak correlation between oral stereognosis and masticatory efficiency. Many opinions have been presented in the literature in the past regarding oral stereognosis. The issue whether oral stereognosis also helps inpatients’ adaptation towards complete denture prosthesis is still ambiguous. No consensus has been reached. This study is further an attempt to understand the basic physiology of oral stereognosis and whether there is any possible relation between oral stereognosis and masticatory efficiency.Conclusions: Within the limitation of this study, it can be concluded that oral stereognostic ability improves with time, which might be due to adaptation to the denture. As adaptation towardsdenture improves masticatory efficiency improves as well. This study showed that there might bea weak association between oral stereognosis and masticatory efficiency.

Vibrissal paralysis unveils a preference for textural rather than positional novelty in the one-trial object recognition task in rats.

In order to explore the role of active whisking in object novelty detection, the performance of rats having bilateral vibrissal paralysis was compared to that of non-lesioned animals in three modified versions of the one-trial object recognition task performed in the dark. Vibrissal paralysis was induced by crushing the buccal and mandibular branches of the facial nerve. Lesioned animals were not different from non-lesioned ones in terms of weight-gain, locomotive activity, motivation to explore, and ability to become habituated to a given environment. Only lesioned animals were unable to discriminate a change in object texture as novelty cue in the first task, designed to test textural novelty detection. In the second task, designed to test positional novelty detection, both lesioned and non-lesioned subjects were able to discriminate a change in object position as novelty cue. In the third task, designed to force the subjects to choose between two conflicting novelty cues (texture and position), non-lesioned subjects displayed a clear-cut preference for textural novelty while subjects having bilateral vibrissal paralysis preferred positional novelty. According to these results, active whisking is necessary for textural, but not for positional novelty detection. Moreover, these results indicate that textural novelty in non-lesioned animals seems to overcome positional novelty if these are in competition in an object recognition memory task.

The influence of gender and bruxism on human minimum interdental threshold ability

OBJECTIVE: To evaluate the influence of gender and bruxism on the ability to discriminate minimum interdental threshold. MATERIAL AND METHODS: One hundred and fifteen individuals, representing both genders, bruxers and non-bruxers, with a mean age of 23.64 years, were selected for this study. For group allocation, every individual was subjected to a specific physical examination to detect bruxism (performed by three different examiners). Evaluation of the ability to discriminate minimum interdental threshold was performed using industrialized 0.010 mm-, 0.024 mm-, 0.030 mm-, 0.050 mm-, 0.080 mm- and 0.094 mm-thick aluminum foils that were placed between upper and lower premolars. Data were analyzed statistically by multiple linear regression analysis at 5% significance level. RESULTS: Neither gender nor bruxism influenced the ability to discriminate minimum interdental threshold (p>0.05). CONCLUSIONS: Gender and the presence of bruxism do not play a role in the minimum interdental threshold.

The influence of gender and bruxism on human minimum interdental threshold ability.

OBJECTIVE: To evaluate the influence of gender and bruxism on the ability to discriminate minimum interdental threshold. MATERIAL AND METHODS: One hundred and fifteen individuals, representing both genders, bruxers and non-bruxers, with a mean age of 23.64 years, were selected for this study. For group allocation, every individual was subjected to a specific physical examination to detect bruxism (performed by three different examiners). Evaluation of the ability to discriminate minimum interdental threshold was performed using industrialized 0.010 mm-, 0.024 mm-, 0.030 mm-, 0.050 mm-, 0.080 mm- and 0.094 mm-thick aluminum foils that were placed between upper and lower premolars. Data were analyzed statistically by multiple linear regression analysis at 5% significance level. RESULTS: Neither gender nor bruxism influenced the ability to discriminate minimum interdental threshold (p>0.05). CONCLUSIONS: Gender and the presence of bruxism do not play a role in the minimum interdental threshold.

Progressive recovery of osseoperception as a function of the combination of implant-supported prostheses.

UNLABELLED: The extraction of teeth involves the elimination of extremely sensitive periodontal mechanoreceptors, which play an important role in oral sensory perception. OBJECTIVES: The aim of this study was to evaluate the recovery of interocclusal sensory perception for micro-thickness in individuals with different types of implant-supported prostheses. MATERIALS AND METHODS: Wearers of complete dentures (CDs) comprised the negative control group (group A, n=17). The experimental group consisted of wearers of prostheses supported by osseointegrated implants (Group B, n=29), which was subsequently divided into 4 subgroups: B(1) (n=5)--implant supported overdentures (ISO) occluding with CD; B(2) (n=6)--implant-supported fixed prostheses (ISFP) occluding with CD; B(3) (n=8)--wearers of maxillary and mandibular ISFP, and B(4) (n=10)--ISFP occluding with natural dentition (ND). Individuals with ND represented the positive control group (Group C, n=24). Aluminum foils measuring 10 microm, 24 microm, 30 microm, 50 microm, 80 microm, and 104 microm thickness were placed within the premolar area, adding up to 120 tests for each individual. RESULTS: The mean tactile thresholds of groups A, B1, B2, B3, B4, and C were 92 microm, 27 microm, 27 microm, 14 microm, 10 microm, and 10 microm, respectively. [Correction added after publication online 18 April 2008: in the preceding sentence 92 microm, 27 microm, 14 microm, 10 microm and 10 microm, was corrected to 92 microm, 27 microm, 27 microm, 14 microm, 10 microm and 10 microm]. The Kruskal-Wallis test revealed significant difference among groups (P<0.05). The Dunn test revealed that group A was statistically different from groups C, B(3), and B(4), and that B(1) and B(2) were statistically different from group C. CONCLUSION: Progressive recovery of osseoperception as a function of the combination of implant-supported prostheses could be observed. Moreover, ISO and/or ISFP combinations may similarly maximize the recovery of osseoperception.