Biology subjects

Barrionuevo, P. A.

Publications and source records attributed to Barrionuevo, P. A..

3 recordsLinked to original sources

bioRxiv2022

Temporal integration of rod signals in luminance and chromatic pathways

We assessed how rod excitation (R) affects luminance (L+M+S) and chromatic [L/(L+M)] reaction times (RTs). A four-primary display based on the overlapped images of two spectrally-modified monitors, which allowed specific or combined [L+M+S+R, L/(L+M) + R] photoreceptor stimulation, was used to present a C-target stimulus differing from the background only by the selected stimulation. For the luminance pathway, rod input increased RTs, suggesting a suppressive rod-cone interaction. The responses of the chromatic pathway were faster when rods were involved, suggesting a major role of rods in mesopic color perception.

physiology↗

bioRxiv2022

Comparing flickering and pulsed chromatic pupil light responses

Protocols for chromatic pupil light reflex (PLR) testing considered mostly pulsed stimulation (pPLR). A more sophisticated and promising technique is based on the PLR to flickering stimulation (fPLR). Our aim was to compare fPLR and pPLR parameters in order to validate fPLR paradigm. Two different experiments were carried out in young participants to compare parameters of chromatic pupillary measurements under flickering and pulsed conditions. We found that the fPLR amplitude parameter was significantly associated with pPLR transient constriction parameter. Also, for some conditions, typical pulse parameters can be identified directly in the fPLR recordings.

physiology↗

bioRxiv2022

Is Melanopsin Activation Affecting Large Field Color Matching Functions?

Color theory is based on the exclusive activation of cones. However, since the discovery of melanopsin expressing cells in the human retina, evidence of its intrusion in brightness and color vision is increasing. We aimed to assess if differences between peripheral or large field and foveal color matches can be accounted for melanopsin activation or rod intrusion. Photopic color matches by young observers showed that differences between extrafoveal and foveal results cannot be explained by rod intrusion. Furthermore, statistical analyses on existing color matching functions suggest a role of melanopsin activation, particularly, in Large Field S Fundamentals.

physiology↗