Possible functions of the interhemispheric connexions between visual cortical areas in the cat.

Blakemore, Colin; Diao, Yun‐Cheng; Pu, Mingliang; Wang, Y K; Xiao, Yue

doi:10.1113/jphysiol.1983.sp014627

Cited by 76 publications

(54 citation statements)

References 39 publications

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“…We have shown here a significant reduction in cortical activity after silencing of the contralateral side. This is consistent with previous studies in cats indicating that callosal projections provide a kind of general sustaining input to the contralateral hemisphere (Blakemore et al, 1983;Yinon et al, 1992). This activity deprivation might explain the impaired cortical development on the side contralateral to BoNT/E injection.…”

Section: Discussionsupporting

confidence: 93%

Transient Synaptic Silencing of Developing Striate Cortex Has Persistent Effects on Visual Function and Plasticity

Caleo¹,

Restani²,

Gianfranceschi³

et al. 2007

J. Neurosci.

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Neural circuits in the cerebral cortex are shaped by experience during "critical periods" early in life. For example, visual cortex is immature at the time of eye opening and gradually develops its functional properties during a sensitive period. Very few reports have addressed the role of intrinsic neural activity in cortical maturation. Here we have exploited the bacterial enzyme botulinum neurotoxin E (BoNT/E) to produce a unilateral, reversible blockade of neural activity in rat visual cortex during the sensitive period. BoNT/E is a highly selective protease that interferes with transmitter release via cleavage of the synaptic protein SNAP-25 (synaptosomal-associated protein of 25 kDa). Unilateral, intracortical injections of BoNT/E were made at the time of eye opening and resulted in the silencing of the treated, but not contralateral, hemisphere for a period of 2 weeks. We found that visual acuity was permanently reduced in the blocked hemisphere, and the critical period for ocular dominance plasticity persisted into adulthood. Unexpectedly, these effects extended equally to the contralateral, uninjected side, demonstrating a fundamental role for interhemispheric connections in cortical maturation.

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Section: Discussionsupporting

confidence: 93%

Transient Synaptic Silencing of Developing Striate Cortex Has Persistent Effects on Visual Function and Plasticity

Caleo¹,

Restani²,

Gianfranceschi³

et al. 2007

J. Neurosci.

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“…IPSI, Ipsilateral eye; CONTRA, contralateral eye. ularity in both cats (Payne et al, 1980;Blakemore et al, 1983;Diao et al, 1983;Yinon et al, 1992) and rats Restani et al, 2009), mostly in layers 2/3 and 5 (Payne et al, 1984). In line with this view, 5NPs, which project to contralateral V1 (Hallman et al, 1988;Kasper et al, 1994), were almost solely driven by the contralateral eye.…”

Section: Discussionsupporting

confidence: 68%

Layer- and Cell-Type-Specific Subthreshold and Suprathreshold Effects of Long-Term Monocular Deprivation in Rat Visual Cortex

Medini¹

2011

J. Neurosci.

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Connectivity and dendritic properties are determinants of plasticity that are layer and cell-type specific in the neocortex. However, the impact of experience-dependent plasticity at the level of synaptic inputs and spike outputs remains unclear along vertical cortical microcircuits. Here I compared subthreshold and suprathreshold sensitivity to prolonged monocular deprivation (MD) in rat binocular visual cortex in layer 4 and layer 2/3 pyramids (4Ps and 2/3Ps) and in thick-tufted and nontufted layer 5 pyramids (5TPs and 5NPs), which innervate different extracortical targets. In normal rats, 5TPs and 2/3Ps are the most binocular in terms of synaptic inputs, and 5NPs are the least. Spike responses of all 5TPs were highly binocular, whereas those of 2/3Ps were dominated by either the contralateral or ipsilateral eye. MD dramatically shifted the ocular preference of 2/3Ps and 4Ps, mostly by depressing deprived-eye inputs. Plasticity was profoundly different in layer 5. The subthreshold ocular preference shift was sevenfold smaller in 5TPs because of smaller depression of deprived inputs combined with a generalized loss of responsiveness, and was undetectable in 5NPs. Despite their modest ocular dominance change, spike responses of 5TPs consistently lost their typically high binocularity during MD. The comparison of MD effects on 2/3Ps and 5TPs, the main affected output cells of vertical microcircuits, indicated that subthreshold plasticity is not uniquely determined by the initial degree of input binocularity. The data raise the question of whether 5TPs are driven solely by 2/3Ps during MD. The different suprathreshold plasticity of the two cell populations could underlie distinct functional deficits in amblyopia.

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“…For most cortical areas they are restricted to the projection of the vertical meridian. The receptive field of callosal recipient neurones is made of two areas juxtaposed at the vertical meridian, one provided by the direct LGN input and the other by the callosal input (Berlucchi & Rizzolatti, 1968;Blakemore, Diao, Pu, Wang & Xiao, 1983;Antonini, Berlucchi & Lepore, 1983;Antonini, Di Stefano, Minciacchi & Tassinari, 1985). In addition non-linear interactions between the direct and the callosal input have been described in single cortical neurones of split-chiasm cats (Berardi, Bisti & Maffei, 1984).…”

Section: Discussionmentioning

confidence: 99%

Electrophysiological evidence for interhemispheric transmission of visual information in man.

Berardi

Bódis-Wollner

Fiorentini

et al. 1989

The Journal of Physiology

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SUMMARY1. Electrophysiological evidence is presented of interactions between two stimuli (sinusoidal gratings of equal spatial frequency but different contrast, phase-reversed sinusoidally at different temporal frequencies) located on opposite sides of, and within a few degrees from, the vertical meridian.2. These interactions are revealed by a depression of the cortical visual evoked potential (VEP) evoked by the grating of lower contrast in the presence of the grating of higher contrast. They are similar to, albeit weaker than, those obtained with superimposed asynchronously modulated gratings.3. The VEP reduction occurs also if the stimuli are presented dichoptically. 4. It does not occur if the gratings are located one above the other either on the same or on opposite sides of the vertical meridian.5. The strength of the VEP reduction depends on the relative contrast of the two gratings and vanishes for spatial frequencies beyond 4 cycles/deg and temporal frequencies of the high-contrast grating beyond 10 Hz.6. The results are in agreement with data on visual callosal connections in animals and confirm previous psychophysical findings (Berardi & Fiorentini, 1987) indicating the particular properties of the interhemispheric cross-talk between symmetric regions of the visual field astride the vertical meridian in man.

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Possible functions of the interhemispheric connexions between visual cortical areas in the cat.

Cited by 76 publications

References 39 publications

Transient Synaptic Silencing of Developing Striate Cortex Has Persistent Effects on Visual Function and Plasticity

Transient Synaptic Silencing of Developing Striate Cortex Has Persistent Effects on Visual Function and Plasticity

Layer- and Cell-Type-Specific Subthreshold and Suprathreshold Effects of Long-Term Monocular Deprivation in Rat Visual Cortex

Electrophysiological evidence for interhemispheric transmission of visual information in man.

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