摘要:

Existing counts of the number of pyramidal tract fibers at the level of the inferior olivary nucleus on 21 different species of mammals are brought together and examined as a function of body weight. Orderly relationships are shown to exist, with improvement when the mammals are subdivided into two groups, the first being those with extensive corticospinal tracts and the second being those with short and diminutive corticospinal tracts. The number of pyramidal tract fibers varies as the 4/9power of body weight, the constant for the 1st group of mammals being 4 times that of the 2nd group. The number of pyramidal tract fibers per unit of brain weight also varies as the 4/9power of body weight, the two groups of mammals falling on nearly the same line. Man and 2 gibbons fall markedly below their line, having only about half the number of pyramidal tract fibers per unit of brain weight expected for mammals of their body size. Mean axon diameters correlate poorly with body size and with brain size, though primates tend to have the largest axons and rodents the smallest.The relationships shown, taken together with other measurements on mammalian brains, are used to derive a statement that the number of pyramidal tract neurons of any mammal is a constant fraction of the total number of neurons in its cerebral cortex, with man and the gibbons as exceptions. The latter have about twice as many cerebral neurons per pyramidal tract fiber as the other mammals. Some of the implications of these findings are discussed.

ISSN:0006-8977    

DOI:10.1159/000124395

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

The sexual behavior of 4 adult male pigtailmacaques was recorded during two tests with each of 2 estrogen-primed females. The behavior of the males was highly consistent across tests and females but, quantitatively, varied significantly from male to male. The pigtails were multiple mount ejaculators that achieved one to three ejaculations in 1 h. A median number of eight intromissive mounts, separated by intermount intervals of 1.6 min, preceded first ejaculations. Median ejaculatory latency was 18.5 min, while the postejaculatory interval was 33 min. Each male had a characteristic number of thrusts and rate of thrusting per mount. The group medians were 12 thrusts per mount and 2.3 thrusts per sec, respectively. The multiple mount pattern of the male pigtails resembles that of the rhesus and Japanese macaques but differs from the single mount pattern of the bonnet and stumptail macaques.

ISSN:0006-8977    

DOI:10.1159/000124396

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

The cellular structure of Clarke''s column is reviewed with respect to the organization of cell types and their afferent and efferent connections. What is known about the physiology of the spinocerebellar system in the cat is summarized with a critical review of current notions of its function. The paucity of comparative physiological work on the system is indicated.

ISSN:0006-8977    

DOI:10.1159/000124397

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

The cellular structure of Clarke''s column is reviewed with respect to the organization of cell types and their afferent and efferent connections. What is known about the physiology of the spinocerebellar system in the cat is summarized with a critical review of current notions of its function. The paucity of comparative physiological work on the system is indicated.

ISSN:0006-8977    

DOI:10.1159/000124398

出版商:S. Karger AG    

年代:1973

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000124404

出版商:S. Karger AG    

年代:1973

数据来源: Karger