摘要:

The anatomical differences in neocortex between man and the other primates are reviewed. It is found that man''s neocortex is roughly three times as great as would be expected for a primate of the same body size. In many respects, man''s neocortex does not differ from that of other primates and, where it does, the difference can be shown to be related to the differences in total size of neocortex. However, there is evidence for the anatomical specialization of the dominant hemisphere in man, suggesting that man''s brain is not simply a larger version of other primate brains.

ISSN:0006-8977    

DOI:10.1159/000124422

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

Trigeminal mechanoreceptive afferent fibers associated with either mystacial vibrissae or rhinarial receptive fields were isolated for single unit analysis by either microdissection of infraorbital nerve fibers or microelectrode recording from the trigeminal ganglion.Receptive fields of all but two of the 238 vibrissa units were confined to single vibrissae. 47% were rapidly adapting (RA), and 53% were slowly adapting (SA). 10% of the SA units displayed a resting discharge in the absence of mechanical stimulation. Different vibrissa units were found to respond to movements in from one to six primary directions (anterior, dorsal, posterior, or ventral deflection, pushing, pulling); the modal unit responded to deflection in two adjacent primary directions, plus pushing. No systematic relationships were found between directional sensitivities and either length of vibrissa or location of the vibrissa on the mystacial pad. However, SA units were somewhat more directionally sensitive, and were more likely to respond to pushing than were RA units. Each vibrissa is innervated by many units, differing in their response properties.The 25 rhinarial mechanoreceptors displayed unitary, punctiform receptive fields. Eight were RA; 17 were SA. No rhinarial unit of either type displayed a resting discharge. The relationship between velocity of skin indentation and unit discharge rate during indentation of rhinarial receptive fields was best described by a power function for both RA and SA units.

ISSN:0006-8977    

DOI:10.1159/000124423

出版商:S. Karger AG    

年代:1973

数据来源: Karger

摘要:

In addition to the retinofugal fibers from theganglion cells of the retina and the supraoptic commissural fibers (Gudden''s commissure), the optic tracts, chiasm, and nerves of the rhesus monkey contain centrifugal (retinopetal, optic efferent) fibers to the retina. The centrifugal fibers were identified in the optic nerves, chiasm, and tracts of bilaterally enucleated monkeys on the basis of the principle that, following enucleation, the retinofugal fibers within the optic nerves, chiasm, and tracts degenerate and fragment months before the centrifugal fibers to the retina.Normally stained axons are present in the optic tracts; chiasm, and nerves of adult rhesus monkeys 5 or more months following bilateral enucleation. Many of these fibers, revealed by the Romanes silver technique, are present in those regions which exhibit the intense glial reactions associated with the axonal degeneration of the retinofugal fibers.The axons located centrally in the optic nerves appear to be centrifugal fibers to the retina. The cells of origin of these fibers are probably in the superior collicular region, from which their axons course successively through the midbrain reticular formation, crus cerebri (and capsule of the lateral geniculate body), optic tract, chiasm and optic nerve before terminating in the retina. Some of these fibers decussate and some remain uncrossed in their passage through the optic chiasm.

ISSN:0006-8977    

DOI:10.1159/000124424

出版商:S. Karger AG    

年代:1973

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000124425

出版商:S. Karger AG    

年代:1973

数据来源: Karger