Page 366 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Adaptation B. Differential threshold and luminance
0.8
10 6 0.7
Rod
adaptation
10 5 vision 0.6
Cone Day 0.5 Threshold
4
adaptation
10
Relative luminance 10 3 2 Retinal Dim-light vision Relative differential threshold ∆l/l 0.4 for day vision Smallest Adaptation to Light Intensity
0.3
10
10
(0.01)
0.1
1 adaptation 0.2 differential threshold
Absolute threshold
10 20 30 10 4 10 6 10 8 10 10
Adaptation time (min) Relative luminance
(After G. Schubert)
C. Mechanisms for adaptation Plate 12.22
Dim light Bright light Dim light Bright light
1 Pupil reflex 2 Sensory proteins

Wide pupil Narrow pupil Ample Sparse
Rhodopsin and transducin
3 Spatial Summation 4 Temporal Summation

Dim light Bright light
Potential

Time Time
Large retinal area Small retinal area
for each neuron for each neuron Longer stimulus Brief stimulus
required for AP sufficient for AP
D. Successive contrast (“local adaptation”) (see text)

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Despopoulos, Color Atlas of Physiology © 2003 Thieme
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