A5038840061- Retinal Development and Disorders
- Photoreceptor and optogenetics research
- Neurobiology and Insect Physiology Research
- bioluminescence and chemiluminescence research
- Receptor Mechanisms and Signaling
- Neural dynamics and brain function
- Visual perception and processing mechanisms
- Circadian rhythm and melatonin
- Ocular and Laser Science Research
- Retinal Diseases and Treatments
- Neuroscience and Neuropharmacology Research
- Neuroscience and Neural Engineering
- Ichthyology and Marine Biology
- Physiological and biochemical adaptations
- Color Science and Applications
- Retinal Imaging and Analysis
- Electrochemical Analysis and Applications
- Photochromic and Fluorescence Chemistry
- Glaucoma and retinal disorders
- Advanced Fluorescence Microscopy Techniques
- Phosphodiesterase function and regulation
- Optical Imaging and Spectroscopy Techniques
- Fish Ecology and Management Studies
- Genetics, Bioinformatics, and Biomedical Research
- Single-cell and spatial transcriptomics
Australian National University
2013-2024
Curtin University
2006
Physiological Society
1981-2005
University of Cambridge
1993-2005
Harvard University
2002
University of Pennsylvania
1994-2002
Penn Presbyterian Medical Center
1994-1997
Bridge University
1981
1. A suction electrode was used to record the membrane current of single rod outer segments in pieces toad retina. During dim illumination showed pronounced fluctuations. 2. Amplitude histograms responses flashes fixed intensity exhibited two discrete peaks, one at 0 pA and near 1 pA, suggesting that response quantized. By setting a criterion amplitude level, flash could be classed as 'failures' (no response) or 'successes' (at least quantal event). 3. The variation fraction successes with...
1. We have undertaken a theoretical analysis of the steps contributing to phototransduction cascade in vertebrate photoreceptors. explicitly considered only activation steps, i.e. we not dealt with inactivation reactions. 2. From conclude that single photoisomerization leads phosphodiesterase (PDE) time course which approximates delayed ramp; delay is contributed by several short first‐order stages. 3. derive method for extracting PDE from measured electrical response, and apply this...
1. The linear response of turtle cones to weak flashes or steps light was usually well fitted by equations based on a chain six seven reactions with time constants varying over about 6‐fold range. 2. temperature coefficient ( Q 10 ) the reciprocal peak flash 1·8 (15‐25° C), corresponding an activation energy kcal/mole. 3. Electrical measurements one internal electrode and balancing circuit gave following results red‐sensitive high resistance: resistance across cell surface in dark 50–170 MΩ;...
1. The spread of activation and background desensitization in rods was studied by recording membrane current from single outer segments pieces isolated toad retina. 2. Flash sensitivity changed slightly along the segment, falling about 30% base to tip. 3. When only distal half an segment pipette, illumination unrecorded part elicited little or no photocurrent at recorded part, indicating that a photoisomerization does not cause entire segment. 4. With diffuse fully drawn into...
FIGURE 1. Anatomical features of the outer retina, retinal pigment epithelium, and photoreceptors.(A) Schematic mammalian rod photoreceptor, illustrating disposition in relation to (B).(B) Light micrograph parafoveal region rhesus monkey choroid, RPE, distal retina.(C) Cutaway schematic choriocapillaris, Bruch's membrane, epithelial cells
1. Theoretical equations which predict the electrical response of turtle cones to a wide range light stimuli are developed from experiments described in previous papers. 2. The central points theory that ( ) starts chain reactions leading production substance blocks ionic channels outer segment, b an equilibrium between blocking molecules and open is rapidly established, c removed or inactivated by reactions, first autocatalytic, d addition conductance decreases with there also increases...
1. Intracellular recordings from cones and rods in the retina of turtle, Pseudemys scripta elegans, revealed that darkness cell voltage fluctuated spontaneously about its mean level. The fluctuations were reduced during bright steady illmination often to a level close obtained with electrode outside where noise did not change significantly illumination. 2. magnitude intrinsic dark (voltage variance minus strong light) varied widely cell. In noisiest it was 0-4 mV2 while quiet as low 0-01...
1. In order to study the role of cytoplasmic calcium concentration (Ca2+i) in rod photoreceptor light adaptation, we have attempted prevent light‐induced changes Ca2+i by minimizing fluxes across outer segment plasma membrane. This was achieved exposing a low‐Ca2+, 0‐Na+ solution, which sodium replaced with either guanidinium or lithium and external (Ca2+o) reduced micromolar levels. 2. With 1‐3 microM‐Ca2+o, circulating current darkness maintained for period at least 15 s, consistent...
1. Intracellular recordings were made from horizontal cells in the retina of turtle Pseudemys scripta elegans. Spatial properties responses determined using brief flashes monochromatic light. 2. For a light stimulus form long narrow slit peak response decayed approximately exponentially with displacement centred position. 3. With variation area circular patch, increased graded manner but was not proportional to area. 4. The model electrical coupling cell layer proposed by Naka & Rushton...