Visual cells in the inferior colliculus of the cat.

Extracellular recordings from 91 cells of the pericentral nucleus (ICP) of the inferior colliculus of the cat revealed that 83 of them were responsive to auditory stimuli and the other 8 to visual stimuli. All visually driven cells were binocular and showed large receptive fields located in the contralateral hemifield. The best stimulus was either a spot or a bar moved in any direction across the receptive field. No directional selectivity was found. It is suggested that the visual input to the ICP participates in an integrated reflex-orienting behavior, in which the visual information is important for the localization of the sound source.

Análisis ultraestructural de las poblaciones celulares del trabéculo en la aniridia / Ultrastructural analysis of the celular population of the trabeculo in aniridia

El glaucoma que complica a la aniridia se debe generalmente a cambios post natales que se agregan a alteraciones determinadas congénitamente. Menos frecuente es el glaucoma congénito asociado a la aniridia. El principal cambio post natal es el cierre angular progresivo que finalmente termina adosando el muñón iridiano a la pared interna del trabéculo, alterando su función y determinando glaucoma. La patogenia que determina esta modificación morfológica y cierre angular es desconocida. El presente trabajo describe la proliferación de melanocitos en la superficie interna del trabéculo, espacios trabeculares, tejido yuxtacanalicular, pared externa del conducto de Schlemm y conductos colectores esclerales. Esta proliferación no ha sido descrita previamente en la aniridia y podría explicar las modificaciones angulares que llevan al glaucoma por cierre angular secundario en estos casos. Es probable que este mecanismo patogénico sea responsable de la refractariedad a los distintos tipos de tratamiento descritos en el glaucoma asociado a aniridia desde que el aspecto de las trabéculas, el conducto de Schiem y conductos colectores son aparentemente normales

The outflow pathway in congenital glaucoma.

We obtained specimens from the angle of the eye during a trabeculotomy-trabeculectomy operation of a 5-month-old boy with congenital glaucoma. Light and electron miscroscopy of the anterior chamber angle showed the presence of mesodermal tissue covering the entire trabecular area. The trabecular meshwork showed thickening of trabecular beams, and an increased amount of collagen fibrils in the trabecular matrix. Internal trabecular spaces contained red blood cells; outer trabecular spaces were not apparent. The juxtacanalicular trabecular meshwork was thicker than in normal cases, because of an increased amount of collagen fibrils. The endothelium of Schlemm's canal was underlined by a thick and constant layer of amorphous material. These observations suggested that the site of increased resistance to aqueous humor outflow in congenital glaucoma could be found in abnormalities of the trabecular meshwork and the internal wall of Schlemm's canal.

Macroelectrodic activity of the facial nucleus of the cat.

Bipolar stainless steel electrodes were implanted in the facial nucleus. Animals were stimulated with clicks, flashes and electric discharges applied over several points of the skin. The interaction among these modalities was presented before or after electrical stimulation of the cortex. All these stimuli produced evoked potentials in the facial nucleus. These were characterized by a biphasic potential of short latency (5 ms) and small amplitude (20-40 microvolts), followed by a negative monophasic deflection (latency of 35-40 ms and amplitude of 150-250 microvolts). This responses varied partially depending upon the modality of stimulation and the position of the facial nucleus electrode. Precollicular transection and ablation of the sigmoidean gyrus resulted in a marked reduction of the negative wave; while the initial deflection was not affected. It is concluded that the facial nucleus plays a role in the auditory localization and orienting reactions of the animal.