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Recovery of the nasal field loss in esotropic cats after section of the optic chiasm
No full textIt is assumed that in esotropic cats the behavioural suppression of the nasal field reflects inhibition of the input conveyed through the temporal retinal afferents of the strabismic eye. We hypothesized that inhibition underlying the field defect might be actively operated by interocular competitive mechanisms. If so, effectiveness of the strabismic eye input might be restored and loss of the corresponding visual field might be recovered by interrupting the direct interactions between the eyes with the section of the optic chiasm. Results obtained in eight esotropic split-chiasm cats confirm the hypothesis and suggest that suppressive mechanisms of binocular rivarly are involved in the behavioral loss of the esotropic nasal field
The physiology of urinary continence: modification on 200 incontinent women examined by urodynamic testing.
No full text"Urogynaecological International Journal
Interocular interactions in esotropia
No full textIn cats the unilateral convergent strabismus surgically induced in the early postnatal life causes monocular spatial vision deficits and loss of binocular activation of the primary visual cortex. It is assumed that the asynchrony of inputs from the two eyes, by disrupting binocular convergence, leads to unbalanced binocular interactions that favour the non-deviated eye. The competitive advantage of this eye reduces both the excitatory drive to the cortex and the behavioural visual capabilities of the strabismic eye that exhibits the loss of the nasal portion of the visual field. Our experimental evidence indicate that the esotropic input, released by interocular influences by the chiasm section, recovers at least as much effectiveness to achieve orienting reactions in the previously neglected nasal field. In addition we found that the excitatory drive of the ipsilateral strabismic input, which is the one mostly impaired in esotropic animals, is fully preserved when the interocular interactions are impeded at birth and it is greatly improved in the esotropic cats with section of the optic chiasm performed in adulthood. All together these results suggest that functional impairment of the esotropic input prior of chiasmotomy does not reflect developmental changes of the visual afferents yet the active inhibition exerted by interocular mechanisms
Cortical binoculartity in convergent strabismus after section of the optic chiasm
Full text linkIn convergent strabismus (esotropia) the spatial asynchrony of the two eye inputs unbalances the interocular interactions, leading to the functional advantage of the nondeviated eye and the inhibition of the esotropic eye. It may be argued that the strabismic suppression, if it is the effect of inhibitory interactions between the eyes, could be removed by interrupting the interocular pathways at the optic chiasm. After chiasmatic section, each eye is connected only to the ipsilateral cortex through the uncrossed retinal projections and so the functionality of each eye's input is no longer interfered with by interocular mechanisms. In strabismic cats submitted, as adults, to section of the optic chiasm, we performed electrophysiological recordings from the striate cortex. Results show that in these animals: (1) the cortical responsiveness to the strabismic eye is strikingly higher than in esotropes with an intact optic chiasm; (2) the effectiveness of stimulation of the deviated eye is not different from that of the nondeviated eye in driving neurons of corresponding cortex; (3) surprisingly, a high degree of binocular activation is present in the cortex ipsilateral to the deviated eye, while in the cortex connected to the nondeviated eye the greatest majority of neurons are monocularly driven. Cortical binocularity depends on the corpus callosum, which conveys the input from the nondeviated eye to the opposite cortex (which receives the direct strabismic input), but not vice versa. The asymmetry of callosal transmission parallels the morphological asymmetry of callosal connections that occur in convergent strabismus. All together the findings indicate that the impaired effectiveness of esotropic input does not result from developmental deficit of the strabismic afferents but, rather, from inhibitory influences that are actively exerted through the interocular pathways. Strabismic suppression may be accomplished by the same interocular mechanisms underlying binocular rivalry
Il contributo di Roberto Di Stefano alla storiografia dell'architettura e dell'urbanistica: temi principali ed esperienze comuni
No full textIl saggio ripercorre le fasi principali dell'esperienza di Di Stefano nel campo della storia dell'architettura e dell'urbanistica, ponendo l'accento sul contributo dello studioso alla storia del Mezzogiorno e l'utilità del suo impegno didattico, cui l'autore ha potuto attingere in più occasioni nel corso della propria formazione critica, anche in occasione di comuni esperienze di ricerca
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