# Comprehensive quantification of cone dynamics

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2020 · $464,046

## Abstract

Project Summary
 Vision forms a prominent part of our daily lives, and this sensory process begins with the
capture of light by a particular class of photoreceptor called cones, a class well adapted to daylight
conditions, to high acuity vision, and to color perception. The basic response properties of cone
photoreceptors have been largely described in studies conducted in isolated cells or retinal tissue.
Surprisingly, many of these response properties, such as temporal dynamics and intensity
sensitivity range, remain controversial in the literature. Moreover, some of them conflict with
data acquired in vivo and with human visual performance when measured psychophysically. The
primary aims of this grant are to generate a more comprehensive characterization of cone
photoreceptors in cone-dominated animals, including primates. This will be achieved by conjoint
experiments conducted in intact retinal explants in parallel with in vivo recordings where it is
now possible to target single cones with adaptive optics microstimulation. Similar stimulation
paradigms will be employed in each experimental approach to the measure intensity response
functions, the rapidity of time-to-peak, the decay kinetics following saturating stimuli, and the
adaptation rate in response to changing background light levels. These data will be used to
develop a complete theoretical model of response properties based on cone phototransduction
which will be of great use to vision scientists and may delineate the limits and boundaries of in
vivo vs. in vitro experiments on the retina. An additional aim will be to detail how a novel form
of cone activation—via pulsed infrared 2-photon excitation—may be used for improved spatial
stimulation of cones. The 2-photon experiments are best done interleaved with traditional 1-
photon stimulation in order to examine how the 2-photon excitation mechanism differs from 1-
photon absorption, and also to determine how much endogenous fluorescence may be generated
by such stimuli. As 2-photon absorption may be used to measure the health of the cone visual
cycle, understanding the basic response properties of infrared stimulation will be foundational for
future studies of cone function and disease.

## Key facts

- **NIH application ID:** 9913552
- **Project number:** 5R01EY023603-06
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** Timothy W Kraft
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $464,046
- **Award type:** 5
- **Project period:** 2014-05-01 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9913552

## Citation

> US National Institutes of Health, RePORTER application 9913552, Comprehensive quantification of cone dynamics (5R01EY023603-06). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9913552. Licensed CC0.

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