Optic tract lesions sparing pattern vision in cats

Galambos, Róbert; Norton, Thomas T.; Frommer, Gabriel P.

doi:10.1016/0014-4886(67)90084-2

Cited by 79 publications

(14 citation statements)

References 16 publications

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“…The observation that a small number of cells can mediate appropriate behavioral function is consistent with other studies (Galambos et al, 1967;Zigmond et al, 1984;Beattie et al, 1988;Ramirez and Sabel, 1990). Consistent with our earlier observations (Sautter and Sabel, 1993), in the present study we found relatively more RGCs with large cell diameter after mild optic nerve injury (with or without MK-801 treatment).…”

Section: Discussionsupporting

confidence: 87%

MK-801 Reduces Retinal Ganglion Cell Survival but Improves Visual Performance After Controlled Optic Nerve Crush

Schmitt¹,

Sabel²

1996

Journal of Neurotrauma

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Excitotoxicity is implicated in secondary cell death after ischemic or traumatic brain injury. We therefore evaluated the role of excitotoxicity mediated by the NMDA glutamate receptor subtype on retinal ganglion cell (RGC) survival and visual performance after optic nerve injury in adult rats. To monitor visual deficits after mild optic nerve crush, rats were trained in a two-choice pattern discrimination task. Immediately after the crush and on postoperative day 1, MK-801 (1 nmol), a noncompetitive open channel blocker of the NMDA-receptor, was injected intraocularly. Within the first few days after crush, all rats showed a loss of their discrimination ability that was followed by a significant recovery within a 3-week testing period. Although animals treated with MK-801 had a significantly smaller initial deficit compared with PBS-injected controls, anatomic investigations using retrograde HRP tracing revealed a significant retrograde loss of RGC in lesioned rats that was significantly exacerbated by MK-801. These results confirm our earlier studies suggesting that neuronal damage does not uniformly match behavioral defects in CNS injury paradigms and that near-normal visual performance occurs in rats with only about 10% of RGC being connected to their target. The observation that after traumatic injury MK-801 is neuroprotective functionally while being neurotoxic anatomically is a structural-functional paradox that needs to be explored further.

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Section: Discussionsupporting

confidence: 87%

MK-801 Reduces Retinal Ganglion Cell Survival but Improves Visual Performance After Controlled Optic Nerve Crush

Schmitt¹,

Sabel²

1996

Journal of Neurotrauma

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“…Nevertheless the cat was far from blind in this eye and showed good ability in discriminating fast motion (see below). It has previously been demonstrated by Galambos, Norton & Frommer (1967) that even a 98% loss of both optic tracts leaves cats with considerable ability in pattern discrimination performance, as well as in simpler tasks. Although there is undoubtedly much redundancy in the nervous system, we consider that most large lesions will result in a behavioural deficit which sometimes may be revealed only by the use of sophisticated tests.…”

Section: Acuitymentioning

confidence: 99%

Function of the Y optic nerve fibres in the cat: do they contribute to acuity and ability to discriminate fast motion?

Burke

Cottee

Hamilton

et al. 1987

The Journal of Physiology

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SUMMARY1. A controlled pressure block has been applied to the optic nerve of the cat, sufficient to bring about degeneration of the axons of the large (Y) nerve fibres caudal to the block site. This degeneration has been monitored by means of implanted electrodes in optic nerve and tract which have shown a loss of the short-latency (tl) response 4-6 days after the block, and also by histological examination of the optic nerve.2. Cats with one optic nerve blocked in this way have been used in behavioural experiments, one or other eye being covered during the tests. Tested via the blocked nerve, all cats with loss of only Y fibres could perform certain tests: the visual placing reaction, the blink reflex, the pupillary (light) reflex and simple manoeuvres such as walking a plank and jumping from table to floor.3. When acuity was tested by means of the Mitchell jumping apparatus, cats with loss of only Y fibres showed the same acuity using either eye. This was true also of one cat in which many X fibres had also degenerated, as evidenced by a 55 % loss of the medium-latency (t2) response, but in another cat with 90 % loss of the t2 response acuity was reduced to about half-normal.4. Ability to discriminate fast motion was tested by a modification of the Mitchell apparatus. All cats were able to discriminate the motion of an 11-5 deg spot up to a velocity of 6260 deg/s, whether using their normal eye or their affected eye. However, the loss of the Y fibres reduced the ability to discriminate fast motion, so that for any given level of contrast the velocity which could be discriminated was about twothirds of the velocity discriminated using the normal eye. The ability of the cat to discriminate fast motion seems to be similar to that of the human.5. These results suggest that there is no sharp restriction of function between the Y and X systems but instead considerable overlap. However, each system possesses specialized features giving it superiority in certain conditions.

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“…An estimate of the limits on the extent to which disruption can take place without undue influence on the state comes from experiments involving brain tissue removals. Some 85 (or in some experiments even more) of a neural system can be made ineffective without seriously impairing the performances dependent on that system [18][19][20]. What sort of state is it that can function effectively when only 10 or 15 percent of it remains and all of what remains need not be concentrated in one location?…”

Section: Brain Function In Awarenessmentioning

confidence: 99%

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Pribram

2006

J Biomed Discov Collaboration

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Optic tract lesions sparing pattern vision in cats

Cited by 79 publications

References 16 publications

MK-801 Reduces Retinal Ganglion Cell Survival but Improves Visual Performance After Controlled Optic Nerve Crush

MK-801 Reduces Retinal Ganglion Cell Survival but Improves Visual Performance After Controlled Optic Nerve Crush

Function of the Y optic nerve fibres in the cat: do they contribute to acuity and ability to discriminate fast motion?

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