Picrotoxin action on the receptive fields of the cat sensorimotor cortex neurons

Батуев, А. С.; Alexandrov, A. A.; Scheynikov, N. A.

doi:10.1002/jnr.490070106

Cited by 41 publications

(10 citation statements)

References 9 publications

(7 reference statements)

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“…Similar to the mechanism revealed in the present study, inhibitory masking of sensory afferent signals has been described throughout the CNS (Metzler & Marks, ; Batuev et al . ; Merzenich et al . ; Turnbull & Rasmusson, ; Garraghty et al .…”

Section: Discussionmentioning

confidence: 99%

Inhibitory masking controls the threshold sensitivity of retinal ganglion cells

Pan

Toychiev

Zhang

et al. 2016

The Journal of Physiology

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The responses of rod photoreceptors, which subserve dim light vision, are carried through the retina by three independent pathways. These pathways carry signals with largely different sensitivities. Retinal ganglion cells (RGCs), the output neurons of the retina, show a wide range of sensitivities in the same dark-adapted conditions, suggesting a divergence of the rod pathways. However, this organization is not supported by the known synaptic morphology of the retina. Here, we tested an alternative idea that the rod pathways converge onto single RGCs, but inhibitory circuits selectively mask signals so that one pathway predominates. Indeed, we found that application of GABA receptor blockers increased the sensitivity of most RGCs by unmasking rod signals, which were suppressed. Our results indicate that inhibition controls the threshold responses of RGCs under dim ambient light. This mechanism can ensure that appropriate signals cross the bottleneck of the optic nerve in changing stimulus conditions.

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Section: Discussionmentioning

confidence: 99%

Inhibitory masking controls the threshold sensitivity of retinal ganglion cells

Pan

Toychiev

Zhang

et al. 2016

The Journal of Physiology

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“…The rapid timeframe, within minutes, in which the receptive field changes occur virtually eliminates axonal sprouting and creation of new synapses as potential underlying mechanisms. Instead, it is believed that the receptive field changes reflect a release from tonic inhibition that unmasks previously latent synaptic inputs (Batuev et al 1982; Garraghty et al 1991; Jacobs & Donoghue, 1991; Wellman et al 2002; Foeller & Feldman, 2004). Masking can therefore be considered a component of the normal dynamics of the plastic brain in which neuronal responses are modified under changing stimulus conditions.…”

Section: Discussionmentioning

confidence: 99%

Masked excitatory crosstalk between the ON and OFF visual pathways in the mammalian retina

Farajian¹,

Pan

Akopian³

et al. 2011

The Journal of Physiology

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Non-technical summary An organizing principle of the visual system is the segregation of ON and OFF responses into parallel streams to signal light increment and decrement. This segregation begins in the retina where the output ganglion cells can be divided into ON and OFF subtypes based on their responses to light. Here we show that blockade of GABAergic inhibition reveals opposite polarity responses in ganglion cells whereby OFF cells display ON responses and ON cells display OFF responses. This crossover excitation was found in both the rabbit and mouse, indicating that it is a common synaptic mechanism in the mammalian retina. Overall, these results challenge the idea that light increment and decrement is signalled by different visual pathways. Moreover, our findings suggest that release of inhibition under certain light conditions can enable single ganglion cells to carry both ON and OFF signals, thereby allowing additional information to be propagated across the limited bandwidth of the optic nerve.Abstract A fundamental organizing feature of the visual system is the segregation of ON and OFF responses into parallel streams to signal light increment and decrement. However, we found that blockade of GABAergic inhibition unmasks robust ON responses in OFF α-ganglion cells (α-GCs). These ON responses had the same centre-mediated structure as the classic OFF responses of OFF α-GCs, but were abolished following disruption of the ON pathway with L-AP4. Experiments showed that both GABA A and GABA C receptors are involved in the masking inhibition of this ON response, located at presynaptic inhibitory synapses on bipolar cell axon terminals and possibly amacrine cell dendrites. Since the dendrites of OFF α-GCs are not positioned to receive excitatory inputs from ON bipolar cell axon terminals in sublamina-b of the inner plexiform layer (IPL), we investigated the possibility that gap junction-mediated electrical synapses made with neighbouring amacrine cells form the avenue for reception of ON signals. We found that the application of gap junction blockers eliminated the unmasked ON responses in OFF α-GCs, while the classic OFF responses remained. Furthermore, we found that amacrine cells coupled to OFF α-GCs display processes in both sublaminae of the IPL, thus forming a plausible substrate for the reception and delivery of ON signals to OFF α-GCs. Finally, using a multielectrode array, we found that masked ON and OFF signals are displayed by over one-third of ganglion cells in the rabbit and mouse retinas, suggesting that masked crossover excitation is a widespread phenomenon in the inner mammalian retina.

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“…Iontophoretic administration of γ-aminobutyric acid (GABA) blockers to neurons in somatosensory cortex showed that only a small proportion of the available excitatory input is normally expressed at any given time (Batuev et al 1982;Dykes et al 1984;Hicks and Dykes 1983). During the administration of bicuculline, a blocker of GABA receptors, the size of the receptive field of low-threshold mechanosensory neurons in cat primary somatosensory cortex increased by up to 11 times (Fig.…”

Section: Control Of Receptive Field Characteristics By Intracortical mentioning

confidence: 96%

Mechanisms controlling neuronal plasticity in somatosensory cortex

Dykes¹

1997

Can. J. Physiol. Pharmacol.

119

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gamma-Aminobutyric acid containing neurons in the somatosensory cortex are the major controlling element determining receptive field size and location. This control of the excitability of cortical neurons can be modulated by activity arising in the basal forebrain. A hypothesis is developed stating that both cholinergic and gamma-aminobutyric acid containing projections from the basal forebrain play important roles in the production of a state in cortex permitting neuronal plasticity to occur. This proposed mechanism involving a simultaneous reduction of inhibition and increased release of acetylcholine allows sensory signals to induce long-term changes in the location and responsiveness of cutaneous receptive fields, thereby changing the somatotopic organization of primary somatosensory cortex.

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Picrotoxin action on the receptive fields of the cat sensorimotor cortex neurons

Cited by 41 publications

References 9 publications

Inhibitory masking controls the threshold sensitivity of retinal ganglion cells

Inhibitory masking controls the threshold sensitivity of retinal ganglion cells

Masked excitatory crosstalk between the ON and OFF visual pathways in the mammalian retina

Mechanisms controlling neuronal plasticity in somatosensory cortex

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