Cortical Mechanisms of Multisensory Linear Self-motion Perception / 神经科学通报·英文版

Accurate self-motion perception, which is critical for organisms to survive, is a process involving multiple sensory cues. The two most powerful cues are visual (optic flow) and vestibular (inertial motion). Psychophysical studies have indicated that humans and nonhuman primates integrate the two cues to improve the estimation of self-motion direction, often in a statistically Bayesian-optimal way. In the last decade, single-unit recordings in awake, behaving animals have provided valuable neurophysiological data with a high spatial and temporal resolution, giving insight into possible neural mechanisms underlying multisensory self-motion perception. Here, we review these findings, along with new evidence from the most recent studies focusing on the temporal dynamics of signals in different modalities. We show that, in light of new data, conventional thoughts about the cortical mechanisms underlying visuo-vestibular integration for linear self-motion are challenged. We propose that different temporal component signals may mediate different functions, a possibility that requires future studies.

Anatomía, fisiología y rol clínico de la corteza vestibular / Anatomy, physiology and clinical role of the vestibular cortex

El sistema vestibular, mediante sus órganos periféricos, nos permite procesar correctamente los cambios de aceleración angular de la cabeza y lineal del cuerpo y así permitirnos una correcta orientación en el espacio. Esta información sensorial es dirigida hacia los núcleos vestibulares y desde aquí se comunica con los núcleos óculo-motores y estructuras del tálamo a través de tractos ascendentes del tronco encefálico. Posteriormente la información se dirige hacia centros subcorticales y corticales de naturaleza eminentemente multisensorial. La naturaleza y función de estas estructuras es controversial. En esta revisión se abordan los principales conceptos y descubrimientos a nivel de investigación básica y clínica del procesamiento cortical generado por estimulación de tipo vestibular.

The vestibular system, thanks to its peripheral organs, allows us to properly process the angular head movements and linear acceleration in order to give us a proper orientation in space. The information from these sensory inputs is routed to the vestibular nuclei and thence ascending tracts of the brainstem, which communicate with the oculomotor nuclei of the thalamus and structures. Then the information goes to subcortical and cortical centers, which are eminently multisensory nature. The nature and function of these structures are controversial. In this review the main concepts and discoveries at the level of basic and clinical research generated cortical processing of vestibular stimulation are addressed.

Ilusão da mão de borracha induzida por estímulos controlados por equipamento eletrônico / Rubber hand illusion induced by electronic equipment­controlled stimuli / Ilusión de la mano de goma inducida por estímulos controlados por los equipos electrónicos

A indução da ilusão da mão de borracha (IMB) é tipicamente realizada por pincéis de forma manual. Nesse sentido, elaboramos um equipamento eletrônico com intuito de aumentar a precisão dos estímulos táteis na IMB. Objetivo: verificar a eficácia de um equipamento eletrônico para indução da IMB. Método: participaram do estudo 51 participantes, com idades entre 11 e 59 anos divididos em quatro grupos. Para coleta de dados utilizamos próteses de mãos e o equipamento eletrônico desenvolvido. A intensidade da IMB foi avaliada por um questionário subjetivo contendo 13 perguntas classificadas entre concordância ou discordância sobre as sensações percebidas do paradigma. Resultados: encontramos efeitos significativos em todas as perguntas de incorporação da mão de borracha. Conclusão: o equipamento eletrônico mostrou‑se eficaz na velocidade, sincronia e precisão da movimentação dos pincéis, com indução robusta do paradigma da IMB. Sugere‑se a utilização desse equipamento em experimentação científica do paradigma da IMB.

The induction of rubber hand illusion (RHI) is typically manually performed by brushes. In this direction, we developed an electronic device in order to increase the accuracy of tactile stimuli in RHI. Objective: To determine the effectiveness of an electronic and programmable apparatus developed for induction of RHI. Method: The study included 51 participants, age (11 and 59 years) distributed in four groups. For data collection we used the prosthetic hands and the personaly developed electronic equipment. The intensity of RHI was assessed using a subjective questionnaire containing 13 questions ranked in agreement or disagreement on the sensations perceived paradigm. Results: We found significant effects on all questions about incorporation of the rubber hand. Conclusion: The electronic equipment was effective in speed, timing and accuracy of movement of brushes and displayed the robust induction of RHI. Hence, we propose the use of such eletronic equipment in the RHI paradigm in scientific studies.

La inducción de la ilusión de la mano de goma (IMG) se realiza normalmente manualmente mediante cepillos. De este modo, hemos elaborado un dispositivo electrónico con el fin de aumentar la precisión de los estímulos táctiles en IMG. Objetivo: determinar la eficacia de un aparato electrónico y programable desarrollado para la inducción de IMG. Método: el estudio incluyó a 51 participantes, entre 11 y 59 años, divididos en cuatro grupos. Para la obtención de datos se utilizaron prótesis de mano y equipos electrónicos desarrollados. Para evaluar la intensidad de la inducción la IMG, se utilizó un cuestionario subjetivo que contiene 13 preguntas sobre la sensación ilusoria de incorporación de la mano. Resultados: un efecto significativo de las preguntas sobre la sensación ilusoria de incorporación de la mano de goma fue observado. Conclusión: el equipo electrónico fue eficaz en la velocidad, el tiempo y la precisión de movimiento de los cepillos con la inducción robusta de la IMG. Sugerimos el uso de estos equipos en el paradigma de la IMG experimentación científica.

Reduced Gray Matter Volume of Auditory Cortical and Subcortical Areas in Congenitally Deaf Adolescents: A Voxel-Based Morphometric Study

PURPOSE: Several morphometric studies have been performed to investigate brain abnormalities in congenitally deaf people. But no report exists concerning structural brain abnormalities in congenitally deaf adolescents. We evaluated the regional volume changes in gray matter (GM) using voxel-based morphometry (VBM) in congenitally deaf adolescents. MATERIALS AND METHODS: A VBM8 methodology was applied to the T1-weighted magnetic resonance imaging (MRI) scans of eight congenitally deaf adolescents (mean age, 15.6 years) and nine adolescents with normal hearing. All MRI scans were normalized to a template and then segmented, modulated, and smoothed. Smoothed GM data were tested statistically using analysis of covariance (controlled for age, gender, and intracranial cavity volume). RESULTS: The mean values of age, gender, total volumes of GM, and total intracranial volume did not differ between the two groups. In the auditory centers, the left anterior Heschl's gyrus and both inferior colliculi showed decreased regional GM volume in the congenitally deaf adolescents. The GM volumes of the lingual gyri, nuclei accumbens, and left posterior thalamic reticular nucleus in the midbrain were also decreased. CONCLUSIONS: The results of the present study suggest that early deprivation of auditory stimulation in congenitally deaf adolescents might have caused significant underdevelopment of the auditory cortex (left Heschl's gyrus), subcortical auditory structures (inferior colliculi), auditory gain controllers (nucleus accumbens and thalamic reticular nucleus), and multisensory integration areas (inferior colliculi and lingual gyri). These defects might be related to the absence of general auditory perception, the auditory gating system of thalamocortical transmission, and failure in the maturation of the auditory-to-limbic connection and the auditorysomatosensory-visual interconnection.