Etapa maculotópica: una propuesta sobre el inicio de la señalización visual según nuestra teoría sobre la visión / Maculotopic stage: one proposal on the start of the visual signpost according to our theory on the vision

Estamos considerando que a nivel de la mácula, región de la retina de máxima agudeza visual por su alta densidad de conos, debe conformarse una representación o mapa maculotópico de aquella imagen del mundo exterior donde fijamos nuestra atención. La estimulación fotónica reflectante del mundo exterior excitaría a los conos de la mácula, y la distribución topográfica de estos conos absorbentes de luz o excitados, coincidiría exactamente con la topografía de la imagen exterior excitante. Uno o más fotorreceptores excitados conformarían un componente de la imagen o de información visual. La sumatoria de estos componentes de información visual conformaría la imagen total

We are considering that the level of the macula, the retinal region of maximum visual acuity due to its high density of cones, must conform maculotopic representation or map of that image of the outside world where we focus our attention. Reflecting photonic stimulation from the outside world excite the cones in the macula, and the topographic distribution of these linght- absorbing cones or excited, coindice exictly with the topography of the exciting exterior image. One or more photorececeptors excited would form a component of the image or visual information. The sum of these componets of visual information would form the total picture

Cone photopigment variations in Cebus apella monkeys evidenced by electroretinogram measurements and genetic analysis.

We investigated the color vision pattern in Cebus apella monkeys by means of electroretinogram measurements (ERG) and genetic analysis. Based on ERG we could discriminate among three types of dichromatic males. Among females, this classification is more complex and requires additional genetic analysis. We found five among 10 possible different phenotypes, two trichromats and three dichromats. We also found that Cebus present a new allele with spectral peak near 552nm, with the amino acid combination SFT at positions 180, 277 and 285 of the opsin gene, in addition to the previously described SYT, AFT and AFA alleles.

Multiple photopigments from the Mexican blind cavefish, Astyanax fasciatus: a microspectrophotometric study.

The cave-dwelling (hypogean) form of the teleost Astyanax fasciatus is blind, having only subdermal eye rudiments, but nevertheless maintains intact opsin genes. Second generation offspring of a cross between these and the normally sighted surface (epigean) form inherit opsin genes from both ancestries. A study of the expressed hypogean opsins of the hybrids, in comparison to the epigean forms, was undertaken by microspectrophotometry. The hybrid population showed considerable variation in the visual pigments of double cones, with evidence for two groups of cells with lambda(max) intermediate to those of the epigean pigments. Possible explanations for these intermediate pigments are discussed, including the hypothesis that they may represent hybrid genes similar to the genes for anomalous cone pigments in humans. Evidence was also found for ultraviolet-sensitive single cones and for an additional MWS pigment.