Spatiotemporal Conversion of Auditory Information for Cochleotopic Mapping

Hoshino, Osamu

doi:10.1162/neco.2007.19.2.351

Cited by 8 publications

(3 citation statements)

References 24 publications

(42 reference statements)

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“…r G AB A ext (n; t) is the fraction of extrasynaptic GABAa receptors in the open state provoked by ambient GABA in column n. δ P , δ F and δ L denote the amounts of extrasynaptic GABAa receptors on P, F and L cells, respectively. For model parameters and their values, see Table 1 and our previous studies (Hoshino 2007a(Hoshino , b, 2008b(Hoshino , 2011aTotoki et al 2010;Miyamoto et al 2012). The receptor dynamics is defined in Appendix 2.…”

Section: Appendix 1: Description Of Network Modelmentioning

confidence: 99%

GABA diffusion across neuronal columns for efficient sensory tuning

2015

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Synaptic (phasic) lateral inhibition between neuronal columns mediated by GABAergic interneurons is, in general, essential for primary sensory cortices to respond selectively to elemental features. We propose here a neural network model with a nonsynaptic (tonic) lateral inhibitory mechanism. While firing, intrasynaptic GABA molecules spill over into extracellular space and accumulate in neuronal columns. Through accumulation in and diffusion across these columns, a level of ambient (extracellular) GABA changes in a neuronal activity-dependent manner. Ambient GABA molecules act on extrasynaptic receptors and provide neurons with tonic inhibitory currents. We examined whether and how the diffusion of GABA molecules across neuronal columns affects tuning performance of the network to a feature stimulus: selective responsiveness. The GABA diffusion led to reducing ambient GABA in the stimulus-relevant column while augmenting ambient GABA in stimulus-irrelevant columns, thereby improving the tuning performance. The GABA diffusion was effective especially when provided with a broader sensory input. Interestingly, this diffusion-based, nonsynaptic (tonic) lateral inhibitory scheme worked well together with the conventional, synaptic (phasic) lateral inhibitory scheme, enhancing the sensory tuning. We suggest that the nonsynaptic lateral inhibition, mediated through GABA diffusion across neuronal columns, may be beneficial for the cortex to tune to sensory features.

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Section: Appendix 1: Description Of Network Modelmentioning

confidence: 99%

GABA diffusion across neuronal columns for efficient sensory tuning

2015

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“…For the details of model parameters and their values, see Table 1 and our previous studies (Hoshino, 2007a(Hoshino, , 2007b(Hoshino, , 2008(Hoshino, , 2011a.…”

Section: Appendix C: Action Potential Generationmentioning

confidence: 99%

Regulation of Local Ambient GABA Levels via Transporter-Mediated GABA Import and Export for Subliminal Learning

Hoshino

2015

Neural Computation

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Perception of supraliminal stimuli might in general be reflected in bursts of action potentials (spikes), and their memory traces could be formed through spike-timing-dependent plasticity (STDP). Memory traces for subliminal stimuli might be formed in a different manner, because subliminal stimulation evokes a fraction (but not a burst) of spikes. Simulations of a cortical neural network model showed that a subliminal stimulus that was too brief (10 msec) to perceive transiently (more than about 500 msec) depolarized stimulus-relevant principal cells and hyperpolarized stimulus-irrelevant principal cells in a subthreshold manner. This led to a small increase or decrease in ongoing-spontaneous spiking activity frequency (less than 1 Hz). Synaptic modification based on STDP during this period effectively enhanced relevant synaptic weights, by which subliminal learning was improved. GABA transporters on GABAergic interneurons modulated local levels of ambient GABA. Ambient GABA molecules acted on extrasynaptic receptors, provided principal cells with tonic inhibitory currents, and contributed to achieving the subthreshold neuronal state. We suggest that ongoing-spontaneous synaptic alteration through STDP following subliminal stimulation may be a possible neuronal mechanism for leaving its memory trace in cortical circuitry. Regulation of local ambient GABA levels by transporter-mediated GABA import and export may be crucial for subliminal learning.

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“…The broadness of sensory input is determined by τ P (see equation A.5 in appendix A). A conductance-based, integrateand-fire neuron model (Hoshino, 2007a(Hoshino, , 2007b(Hoshino, , 2008 is employed. Figure 1B shows a gliotransmission-mediated ambient GABA regulatory system (Hoshino, 2012).…”

Section: Neural Network Modelmentioning

confidence: 99%

Facilitation of Neuronal Responses by Intrinsic Default Mode Network Activity

2014

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Default mode network (DMN) shows intrinsic, high-level activity at rest. We tested a hypothesis proposed for its role in sensory information processing: Intrinsic DMN activity facilitates neural responses to sensory input. A neural network model, consisting of a sensory network (Nsen) and a DMN, was simulated. The Nsen contained cell assemblies. Each cell assembly comprised principal cells, GABAergic interneurons (Ia, Ib), and glial cells. We let the Nsen carry out a perceptual task: detection of sensory stimuli. During DMN activation, glial cells were hyperpolarized by Ia-to-glia circuitry, by which glial membrane transporters imported GABA molecules from the extracellular space and decreased ambient GABA concentration. Acting on extrasynaptic GABA receptors, the decrease in ambient GABA concentration reduced inhibitory current in a tonic manner. This depolarized principal cells below their firing threshold during the ongoing spontaneous time period and accelerated their reaction speed to a sensory stimulus. During the stimulus presentation period, the Nsen inhibited the DMN and caused DMN deactivation. The DMN deactivation made Nsen Ia cells cease firing, thereby stopping the glial membrane hyperpolarization, quitting the GABA import, returning to the basal ambient GABA level, and thus enhancing global inhibition. Notably, the stimulus-relevant P cell firing could be maintained when GABAergic gliotransmission via Ia-glia signaling worked, decreasing ambient GABA concentration around the stimulus-relevant P cells. This enabled the Nsen to reliably detect the stimulus. We suggest that intrinsic default model network activity may accelerate the reaction speed of the sensory network by modulating its ongoing-spontaneous activity in a subthreshold manner. Ambient GABA contributes to achieve an optimal ongoing spontaneous subthreshold neuronal state, in which GABAergic gliotransmission triggered by the intrinsic default model network activity may play an important role.

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Spatiotemporal Conversion of Auditory Information for Cochleotopic Mapping

Cited by 8 publications

References 24 publications

GABA diffusion across neuronal columns for efficient sensory tuning

GABA diffusion across neuronal columns for efficient sensory tuning

Regulation of Local Ambient GABA Levels via Transporter-Mediated GABA Import and Export for Subliminal Learning

Facilitation of Neuronal Responses by Intrinsic Default Mode Network Activity

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