Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1106
    Keywords: Binocular interactions ; Proprioceptive inputs ; Visual inputs ; LGN X/Y ratio ; Monocular paralysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Prolonged periods of monocular paralysis alter the physiology of the dorsal lateral geniculate nucleus (LGN), shifting the X/Y cell ratio so that X cells are encountered less frequently than Y cells. The shift in the LGN X/Y cell ratio is observed in both the A-layers of both geniculates whether the innervating eye is paralyzed or mobile. This change in the LGN has been attributed to a mechanism that is sensitive to disruptions in binocular cues. The effects of monocular paralysis in the LGN were used to demonstrate that LGN cells possess a sensitivity to binocular cues of an extraretinal and retinal source. The removal of extraretinal signals, in the form of proprioceptive feedback from the extraocular muscles of the mobile eye, by section of the ophthalmic branch of the Vth cranial nerve, resulted in an immediate and long-lasting reversal in the effects of monocular paralysis. The LGN X/Y ratio was restored to a normal value in the layers innervated by the eye with intact proprioceptive inputs as well as in the layers innervated by the eye in which proprioceptive inputs were removed. In contrast to this, the removal of proprioceptive inputs from the paralyzed eye had no effect on the LGN X/Y ratio. The removal of visual inputs from the mobile eye by section of the optic nerve resulted in an immediate, but somewhat transient reversal in the effects of monocular paralysis. Within the first 25 h after optic nerve section, the LGN X/Y ratio was restored to a normal value in the layers innervated by the eye with intact visual inputs. A transient reversal was also observed when both visual and proprioceptive inputs from the mobile eye were removed. These results are consistent with the belief that the LGN is one site in the visual pathway where proprioceptive and visual signals from the two eyes converge.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1106
    Keywords: X/Y ratio ; Lateral geniculate ; Monocular paralysis ; Plasticity ; Barbiturate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Adult-onset stimulus modifications, such as monocular paralysis, alter the physiology of the lateral geniculate nucleus (LGN), reducing the encounter rate for X-latency cells in all of the principal layers of both LGNs whether the innervating eye is paralyzed or mobile. These reductions in encounter rate for X-latency cells are confined to those portions of the LGN representing central binocular visual space and are sensitive to the level of anesthesia in that, while these effects are evident in subjects sedated during recording, no such reductions are found when subjects are anesthetized with sodium pentobarbital during recording. Finally, conduction velocity and receptive field classification data from these experiments confirm, as the shifts in OX latency distributions would indicate, that chronic monocular paralysis does have a selective impact upon the recordability of LGN X-cells. These observations together with earlier ones involving monocular paralysis suggest that this adult-onset modification reduces the encounter rate for X-cells by disrupting a binocular mechanism which controls the relative excitability of X- and Y-cells which represent central visual space.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...