[CITATION][C] Suggested sequential mode of control of changes in cell behaviour in adult bone remodelling

R Hattner, BN Epker, HM Frost - Nature, 1965 - nature.com
R Hattner, BN Epker, HM Frost
Nature, 1965nature.com
No. 4993 May l, 1965 NATURE 489 the very paucity of opponent cells in the squirrel monkey
LGN makes it impossible, as yet, to give any quantitative analysis of them, although the
LGNs of some thirty squirrel monkeys have been investigated. The proportions of cells in the
various classes are indicated approximately by the numbers of cells given for each of the
class response curves in Fig. 2: there are more cells of the yellow-blue system than of the
red-green system. In the macaque monkey there are more red-green than yellow-blue cells• …
No. 4993 May l, 1965 NATURE 489 the very paucity of opponent cells in the squirrel monkey LGN makes it impossible, as yet, to give any quantitative analysis of them, although the LGNs of some thirty squirrel monkeys have been investigated. The proportions of cells in the various classes are indicated approximately by the numbers of cells given for each of the class response curves in Fig. 2: there are more cells of the yellow-blue system than of the red-green system. In the macaque monkey there are more red-green than yellow-blue cells•. With the few units at present available from the squirrel monkey it is possible that the observed preponderance of cells from the yellow-blue system does not indicate a real difference. In addition to the difference between the proportions of opponent cells in the squirrel monkey and the macaque, these visual systems differ in the nature of the opponent cells. The spectral response plots of the blue-yellow, the yellow-blue, and the green-red cells in the squirrel monkey appear not to differ from the corresponding cells in the macaque monkey. The evidence, however, tends to indicate that there are differences in the red component of the red-green cells in the squirrel monkey as compared with the macaque. The spectral peaks of the red excitatory phase of these cells in the squirrel monkey are displaced some 20-30 mf. l toward the shorter wave-lengths as compared with units of the same class from the macaque monkey, the macaque red cell peak occurring at about 655 mf. l whereas the squirrel monkey red cell peak is at about 630 mf. L. From about 600 mf. l to 440 mf. l, the curves from the two types of monkeys coincide exactly. An even clearer indication that there are some specific differences between the red components of the chromatic opponent cells of the squirrel and those of the macaque monkey comes from observations on the effects of intense chromatic adaptation on the opponent cell responses. It has been shown1 that chromatic adaptation of the appropriate wave-length can be used to eliminate either the excitatory or inhibitory phase of the opponent response pattern. Furthermore, in the macaque monkey, the spectral sensitivity of the component remaining after chromatic adaptation agrees well with estimates of the spectral sensitivities of retinal receptors obtained from other types of experiments•. It has so far been possible to get information about the effects of chromatic adaptation on only a few cells. The results tend to indicate that (a) the spectral sensitivity of the green component is very close to that of the green component from the macaque monkey, and (b) the spectral sensitivity of the red component has a peak sensitivity which is displaced toward the shorter wave-lengths as compared with that of the macaque red component.
It has sometimes been suggested that protanomaly can best be explained by assuming that the red mechanism in the protanomalous individual is less sensitive than that mechanism in the normal trichromat, and that the spectral location of the mechanism is shifted toward the shorter wave-lengths relative to the normal. The observations reported here indicate that the chromatic opponent cells of the protanomalous squirrel monkey constitute a far smaller proportion of the total number of cells in the LGN than they do in the normal trichromatic monkey, and that the red mechanism is displaced spectrally toward the shorter wave-lengths.
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