RESUMEN
One of the most striking demonstrations of experience-dependent plasticity comes from studies of sensory-deprived individuals (e.g., blind or deaf), showing that brain regions deprived of their natural inputs change their sensory tuning to support the processing of inputs coming from the spared senses. These mechanisms of crossmodal plasticity have been traditionally conceptualized as having a double-edged sword effect on behavior. On one side, crossmodal plasticity is conceived as adaptive for the development of enhanced behavioral skills in the remaining senses of early-deaf or blind individuals. On the other side, crossmodal plasticity raises crucial challenges for sensory restoration and is typically conceived as maladaptive since its presence may prevent optimal recovery in sensory-re-afferented individuals. In the present review we stress that this dichotomic vision is oversimplified and we emphasize that the notions of the unavoidable adaptive/maladaptive effects of crossmodal reorganization for sensory compensation/restoration may actually be misleading. For this purpose we critically review the findings from the blind and deaf literatures, highlighting the complementary nature of these two fields of research. The integrated framework we propose here has the potential to impact on the way rehabilitation programs for sensory recovery are carried out, with the promising prospect of eventually improving their final outcomes.
Asunto(s)
Adaptación Fisiológica/fisiología , Modelos Neurológicos , Plasticidad Neuronal/fisiología , Trastornos de la Sensación/fisiopatología , Animales , Humanos , Estimulación Física , Privación SensorialRESUMEN
Although the topic of sensory integration has raised increasing interest, the differing behavioral outcome of combining unisensory versus multisensory inputs has surprisingly only been scarcely investigated. In the present experiment, observers were required to respond as fast as possible to (1) lateralized visual or tactile targets presented alone, (2) double stimulation within the same modality or (3) double stimulation across modalities. Each combination was either delivered within the same hemispace (spatially aligned) or in different hemispaces (spatially misaligned). Results show that the redundancy gains (RG) obtained from the cross-modal conditions were far greater than those obtained from combinations of two visual or two tactile targets. Consistently, we observed that the reaction time distributions of cross-modal targets, but not those of within-modal targets, surpass the predicted reaction time distribution based on the summed probability distributions of each constituent stimulus presented alone. Moreover, we found that the spatial alignment of the targets did not influence the RG obtained in cross-modal conditions, whereas within-modal stimuli produced a greater RG when the targets where delivered in separate hemispaces. These results suggest that within-modal and cross-modal integration are not only distinguishable by the amount of facilitation they produce, but also by the spatial configuration under which this facilitation occurs. Our study strongly supports the notion that estimates of the same event that are more independent produce enhanced integrative gains.
Asunto(s)
Percepción Espacial/fisiología , Tacto/fisiología , Percepción Visual/fisiología , Adulto , Femenino , Humanos , Masculino , Modelos Biológicos , Estimulación Luminosa , Estimulación Física , Desempeño Psicomotor/fisiología , Psicofísica , Tiempo de Reacción/fisiología , Adulto JovenRESUMEN
While the effects of early visual deprivation on auditory and tactile functions have been widely studied, little is known about olfactory function in early blind subjects. The present study investigated the potential effect of early blindness on the electrophysiological correlates of passive odour perception. Event-related potentials (ERPs) were recorded in eight early blind humans and eight sighted controls matched for age, sex and handedness during olfactory stimulation with 2-phenyl ethyl alcohol and trigeminal stimulation with CO2 Latencies, amplitudes and topographical distributions were analysed. As expected, the olfactory and trigeminal ERP components showed normal latencies, amplitudes and topography in both groups. Olfactory stimuli generated responses of smaller amplitude than those observed in response to trigeminal stimulation. In addition, ERP analyses did not reveal any major difference in electrocortical responses in occipital areas in early blind and sighted subjects. These results suggest that passive olfactory and trigeminal stimulation elicit the same electrophysiological responses in both groups, confirming that the neurophysiological correlates of the cross-modal compensatory mechanisms in early blind subjects do not appear during passive olfactory and trigeminal perception.
Asunto(s)
Ceguera/fisiopatología , Potenciales Evocados/fisiología , Nervio Olfatorio/fisiología , Olfato/fisiología , Nervio Trigémino/fisiología , Adulto , Edad de Inicio , Ceguera/epidemiología , Electroencefalografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Lóbulo Occipital/fisiopatología , Adulto JovenRESUMEN
BACKGROUND: Double-blind placebo-controlled food challenge (DBPCFC) is currently considered the gold standard for peanut allergy diagnosis. However, this procedure that requires the hospitalization of patients, mostly children, in specialized centers for oral exposure to allergens may cause severe reactions requiring emergency measures. Thus, a simpler and safer diagnosis procedure is needed. The aim of this study was to evaluate the diagnostic performance of a new set of in vitro blood tests for peanut allergy. METHODS: The levels of IgE directed towards peanut extract and recombinant peanut allergens Ara h 1, Ara h 2, Ara h 3, Ara h 6, Ara h 7, and Ara h 8 were measured in 3 groups of patients enrolled at 2 independent centers: patients with proven peanut allergy (n=166); pollen-sensitized subjects without peanut allergy (n=61), and control subjects without allergic disease (n=10). RESULTS: Seventy-nine percent of the pollen-sensitized patients showed IgE binding to peanut, despite their tolerance to peanut. In contrast, combining the results of specific IgE to peanut extract and to recombinant Ara h 2 and Ara h 6 yielded a peanut allergy diagnosis with a 98% sensitivity and an 85% specificity at a positivity threshold of 0.10 kU/l. Use of a threshold of 0.23 kU/l for recombinant Ara h 2 increased specificity (96%) at the cost of sensitivity (93%). CONCLUSION: A simple blood test can be used to diagnose peanut allergy with a high level of precision. However, DBPCFC will remain useful for the few cases where immunological and clinical observations yield conflicting results.
Asunto(s)
Albuminas 2S de Plantas/inmunología , Antígenos de Plantas/inmunología , Glicoproteínas/inmunología , Inmunoensayo/métodos , Hipersensibilidad al Cacahuete/diagnóstico , Albuminas 2S de Plantas/genética , Adolescente , Antígenos de Plantas/genética , Arachis/genética , Arachis/inmunología , Arachis/metabolismo , Niño , Preescolar , Método Doble Ciego , Femenino , Glicoproteínas/genética , Humanos , Inmunoglobulina E/sangre , Lactante , Masculino , Hipersensibilidad al Cacahuete/inmunología , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Sensibilidad y EspecificidadRESUMEN
Despite claims in the popular press, experiments investigating whether female are more efficient than male observers at processing expression of emotions produced inconsistent findings. In the present study, participants were asked to categorize fear and disgust expressions displayed auditorily, visually, or audio-visually. Results revealed an advantage of women in all the conditions of stimulus presentation. We also observed more nonlinear probabilistic summation in the bimodal conditions in female than male observers, indicating greater neural integration of different sensory-emotional informations. These findings indicate robust differences between genders in the multisensory perception of emotion expression.
Asunto(s)
Percepción Auditiva/fisiología , Emociones/fisiología , Expresión Facial , Reconocimiento Visual de Modelos/fisiología , Estimulación Acústica/métodos , Adolescente , Adulto , Análisis de Varianza , Sesgo , Femenino , Humanos , Masculino , Dinámicas no Lineales , Estimulación Luminosa/métodos , Probabilidad , Tiempo de Reacción/fisiología , Factores Sexuales , Adulto JovenRESUMEN
It is well known that, following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In particular, several studies have demonstrated an extensive activation of occipital brain areas, usually regarded as essentially "visual", when early blind subjects (EB) performed a task that requires spatial processing of sounds. However, little is known about the possible consequences of the activation of occipitals area on the function of the large cortical network known, in sighted subjects, to be involved in the processing of auditory spatial information. To address this issue, we used event-related transcranial magnetic stimulation (TMS) to induce virtual lesions of either the right intra-parietal sulcus (rIPS) or the right dorsal extrastriate occipital cortex (rOC) at different delays in EB subjects performing a sound lateralization task. Surprisingly, TMS applied over rIPS, a region critically involved in the spatial processing of sound in sighted subjects, had no influence on the task performance in EB. In contrast, TMS applied over rOC 50 ms after sound onset, disrupted the spatial processing of sounds originating from the contralateral hemifield. The present study shed new lights on the reorganisation of the cortical network dedicated to the spatial processing of sounds in EB by showing an early contribution of rOC and a lesser involvement of rIPS.
Asunto(s)
Vías Auditivas/fisiología , Percepción Auditiva/fisiología , Ceguera/fisiopatología , Plasticidad Neuronal/fisiología , Percepción Espacial/fisiología , Corteza Visual/fisiología , Estimulación Acústica , Adaptación Fisiológica/fisiología , Adulto , Vías Auditivas/anatomía & histología , Ceguera/psicología , Mapeo Encefálico , Potenciales Evocados , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Red Nerviosa/anatomía & histología , Red Nerviosa/fisiología , Pruebas Neuropsicológicas , Lóbulo Occipital/anatomía & histología , Lóbulo Occipital/fisiología , Lóbulo Parietal/anatomía & histología , Lóbulo Parietal/fisiología , Tiempo de Reacción/fisiología , Estimulación Magnética Transcraneal , Corteza Visual/anatomía & histología , Adulto JovenRESUMEN
We have previously shown that some visual motion areas can be specifically recruited by auditory motion processing in blindfolded sighted subjects [Poirier, C., Collignon, O., De Volder, A.G., Renier, L., Vanlierde, A., Tranduy, D., Scheiber, C., 2005. Specific activation of V5 brain area by auditory motion processing: an fMRI study. Brain Res. Cogn. Brain Res. 25, 650-658]. The present fMRI study investigated whether auditory motion processing may recruit the same brain areas in early blind subjects. The task consisted of simultaneously determining both the nature of a sound stimulus (pure tone or complex sound) and the presence or absence of its movement. When a movement was present, blind subjects had to identify its direction. Auditory motion processing, as compared to static sound processing, activated the brain network of auditory and visual motion processing classically observed in sighted subjects. Accordingly, brain areas previously considered as specific to visual motion processing could be specifically recruited in blind people by motion stimuli presented through the auditory modality. This indicates that the occipital cortex of blind people could be organized in a modular way, as in sighted people. The similarity of these results with those we previously observed in sighted subjects suggests that occipital recruitment in blind people could be mediated by the same anatomical connections as in sighted subjects.
Asunto(s)
Ceguera/fisiopatología , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional , Imagen por Resonancia Magnética , Percepción de Movimiento/fisiología , Lóbulo Occipital/fisiopatología , Reclutamiento Neurofisiológico/fisiología , Localización de Sonidos/fisiología , Percepción Visual/fisiología , Adolescente , Adulto , Anciano , Ceguera/congénito , Mapeo Encefálico , Corteza Cerebral/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Red Nerviosa/fisiopatología , Orientación/fisiología , Percepción de la Altura Tonal/fisiologíaRESUMEN
We tested the effects of using a prosthesis for substitution of vision with audition (PSVA) on sensitivity to the Ponzo illusion. The effects of visual experience on the susceptibility to this illusion were also assessed. In one experiment, both early-blind and blindfolded sighted volunteers used the PSVA to explore several variants of the Ponzo illusion as well as control stimuli. No effects of the illusion were observed. The results indicate that subjects focused their attention on the two central horizontal bars of the stimuli, without processing the contextual cues that convey perspective in the Ponzo figure. In a second experiment, we required subjects to use the PSVA to consider the two converging oblique lines of the stimuli before comparing the length of the two horizontal bars. Here we were able to observe susceptibility to the Ponzo illusion in the sighted group, but to a lesser extent than in a sighted non-PSVA control group. No clear effect of the ilusion was obtained in early-blind subjects. These results suggest that, at least in sighted subjects, perception obtained with the PSVA shares perceptual processes with vision. Visual experience appears mandatory for a Ponzo illusion to occur with the PSVA.
Asunto(s)
Percepción Auditiva/fisiología , Ceguera/psicología , Ilusiones , Adolescente , Adulto , Anciano , Análisis de Varianza , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Ilusiones Ópticas , Psicofísica , Umbral SensorialRESUMEN
The aim of this study was to evaluate the trends of indicators of cardiovascular risk (smoking, physical activity, cholesterol, triglycerides...) in adolescents between 14 and 18 years of age. The data was recensed at the Centre of Preventive Medicine of Vandoeuvre-lès-Nancy which was responsible for periodic Social Security health check-ups in 6,974 adolescents in 1980, 1984, 1988 and 1991. The analysis of the trends of the indicators of cardiovascular risk took into consideration the socio-economic changes of the population recruited during this period and the long-term analytical variations of biochemical parameters. Globally, between 1980 and 1991, there was a decrease in the percentage of smokers (21.8% to 13.5%) which was more marked in boys than in girls, an increase in physical activities (46.9% to 57.5%), a linear reduction in serum cholesterol (4.65 mmol/l to 4.33 mmol/l in boys, and 4.94 mmol/l to 4.72 mmol/l in girls), and no significant changes in serum triglycerides. These results confirm those reported by others and are encouraging for cardiovascular disease prevention and should be confirmed in adults groups.