Conserved visual capacity of rats under red light

Abstract

Recent studies examine the behavioral capacities of rats and mice with and without visual input, and the neuronal mechanisms underlying such capacities. These animals are assumed to be functionally blind under red light, perhaps originating in the fact that they are dichromats who possess ultraviolet and green but not red cones. But the inability to see red as a color does not necessarily rule out form vision based on red light absorption through their rod-dominated retina. We measured Long-Evans rats' capacity for visual form discrimination under red light of various wavelength bands. Upon viewing a black and white grating, they had to distinguish between two categories of orientation, horizontal and vertical. Psychometric curves plotting judged orientation versus angle demonstrate the conserved visual capacity of rats under red light. Investigations aiming to explore rodent physiological and behavioral functions in the absence of visual input should not assume red-light blindness.

Cell-type-specific silence in thalamocortical circuits precedes hippocampal sharp-wave ripples

“…Second, the optogenetic silencing of thalamic axons (Figures 6, 7) was likely incomplete. To prevent the red laser light from triggering visual responses by reaching the back of the retina (Nikbakht and Diamond, 2021), we used a low power (2-4 mW/mm 2 ) and a small diameter light beam (400 µm). Although optical techniques have limitations in their ability to capture some features of neuronal activity, the cell type-, projection- and compartment-specific nature of viral-genetic tools, as well as the ability to image large neuronal populations, enabled us to capture previously unreported aspects of cortical circuit function during memory consolidation.…”

Cell-type-specific silence in thalamocortical circuits precedes hippocampal sharp-wave ripples

“…This precluded a definitive analysis of cell-type differences, which should be further investigated. Second, for optogenetic experiments, we used a low power (2-4 mW/mm 2 ) and small diameter (400 mm) beam to prevent the laser light from triggering responses at the back of the retina (Nikbakht and Diamond, 2021). Therefore, the optogenetic silencing of thalamic axons (Figures 6 and 7) was likely incomplete and may underestimate the thalamic contribution to RSC pre-SWR silence.…”

An Open Source Platform for Presenting Dynamic Visual Stimuli

“…First, the device is based on an 8 × 8 matrix of LEDs and not an LCD monitor. LCD monitors have been used in a number of classic ( Bussey et al, 1997 ) and more recent studies ( Zoccolan et al, 2009 ; Zoccolan, 2015 ; Broschard et al, 2019 ; Nikbakht and Diamond, 2021 ), and low-cost Arduino compatible LCD screen are available (e.g., http://www.dsdtech-global.com/ ) that could be used as an alternative to the LED matrices from Adafruit used in the present device. LCD monitors have an advantage for presenting highly detailed visual stimuli, beyond the 8 × 8 “pixels” available in the Adafruit LED matrices.…”