Аннотация
The cortical representations of the hand in area 3b in adult owl monkeys
were defined with use of microelectrode mapping techniques 2-8 months
after surgical amputation of digit 3, or of both digits 2 and 3.
Digital nerves were tied to prevent their regeneration within the
amputation stump. Successive maps were derived in several monkeys
to determine the nature of changes in map organization in the same
individuals over time. In all monkeys studied, the representations
of adjacent digits and palmar surfaces expanded topographically to
occupy most or all of the cortical territories formerly representing
the amputated digit(s). With the expansion of the representations
of these surrounding skin surfaces (1) there were severalfold increases
in their magnification and (2) roughly corresponding decreases in
receptive field areas. Thus, with increases in magnification, surrounding
skin surfaces were represented in correspondingly finer grain, implying
that the rule relating receptive field overlap to separation in distance
across the cortex (see Sur et al., '80) was dynamically maintained
as receptive fields progressively decreased in size. These studies
also revealed that: the discontinuities between the representations
of the digits underwent significant translocations (usually by hundreds
of microns) after amputation, and sharp new discontinuous boundaries
formed where usually separated, expanded digital representations
(e.g., of digits 1 and 4) approached each other in the reorganizing
map, implying that these map discontinuities are normally dynamically
maintained. Changes in receptive field sizes with expansion of representations
of surrounding skin surfaces into the deprived cortical zone had
a spatial distribution and time course similar to changes in sensory
acuity on the stumps of human amputees. This suggests that experience-dependent
map changes result in changes in sensory capabilities. The major
topographic changes were limited to a cortical zone 500-700 micron
on either side of the initial boundaries of the representation of
the amputated digits. More distant regions did not appear to reorganize
(i.e., were not occupied by inputs from surrounding skin surfaces)
even many months after amputation. The representations of some skin
surfaces moved in entirety to locations within the former territories
of representation of amputated digits in every monkey studied. In
man, no mislocation errors or perceptual distortions result from
stimulation of surfaces surrounding a digital amputation.(ABSTRACT
TRUNCATED AT 400 WORDS)
- afferent
- anatomy
- cortex,somatosensory
- cortex:
- histology
- histology,amputation,animals,aotus
- histology,median
- histology,nerve
- innervation,hand,hand:
- innervation,mechanoreceptors,mechanoreceptors:
- innervation,somatosensory
- mapping,fingers,fingers:
- nerve,median
- nerve:
- nn
- pathways,afferent
- pathways:
- plasticity,skin,skin:
- regeneration,neuronal
- trivirgatus,brain
- \&
Пользователи данного ресурса
Пожалуйста,
войдите в систему, чтобы принять участие в дискуссии (добавить собственные рецензию, или комментарий)