MULTIPLE-MODES OF ACTIVITY IN A MODEL NEURON SUGGEST A NOVEL MECHANISM FOR THE EFFECTS OF NEUROMODULATORS
MULTIPLE-MODES OF ACTIVITY IN A MODEL NEURON SUGGEST A NOVEL MECHANISM FOR THE EFFECTS OF NEUROMODULATORS
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DOI：
10.1152/jn.1994.72.2.872
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发表时间：
1994-08-01
影响因子：
2.5
通讯作者：
BYRNE, JH
中科院分区：
文献类型：
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作者：
CANAVIER, CC;BAXTER, DA;BYRNE, JH
1. 先前对软体动物神经元破裂数学模型相空间的研究已经证明存在多个稳定的振荡模式。本研究考察了多元稳定性在多大程度上可以被已知的调节剂调节，这种调节对神经元对突触输入的反应的后果，噪声的影响，以及多元稳定性丰富神经调节作用的潜力。当以模拟神经调节剂应用的方式改变电压依赖性电导时，可能会出现共存的稳定吸引子。一个小的瞬态扰动可以使模型神经元在稳定模式之间移动，极大地放大了原始扰动。因此，该模型对传统的突触输入变得更加敏感。在低振幅突触噪声存在的情况下，这些模式移位具有鲁棒性。在响应随机的高振幅突触噪声时，通过模拟神经调节剂的应用使模型神经元呈现多稳态，产生明显的随机活动，而在响应相同的突触噪声时，单稳态模型神经元产生几乎不受干扰的规则活动。因此，吸引子数量的增加提高了对传统突触输入和噪声的敏感性。相反，降低与敏感性降低有关。神经元对随后的瞬时神经调节剂水平扰动的反应取决于神经调节剂的稳态水平。例如，如果稳态水平与多稳定神经元相关联，则在电导逐渐恢复到原始值后，由神经调节剂水平的这种短暂变化（在我们的模型中表现为电导变化）产生的模式转换可以持续存在。因此，当神经调节剂不再存在时，多重稳定的动态活动允许神经调节剂的作用持续存在。在共存的稳定振荡模式之间的模式转换机制引入了许多新的可能性，对单个神经元的信息处理和存储具有潜在的深远影响。
1. Previous examination of the phase space of a mathematical model of a bursting molluscan neuron has demonstrated the existence of multiple stable oscillatory modes. The present study examined the extent to which multistability could be regulated by known modulatory agents, the consequences of that regulation on the response of the neuron to synaptic inputs, the effects of noise, and the potential of multistability to enrich the repertoire of neuromodulatory effects.2. Coexisting stable attractors may appear when a change is made in a voltage-dependent conductance in a manner that simulates the application of a neuromodulator. A small transient perturbation can shift the model neuron between stable modes, greatly amplifying the original perturbation. Thus the model becomes more sensitive to conventional synaptic inputs. These mode shifts are robust in the presence of low-amplitude synaptic noise.3. In response to random high-amplitude synaptic noise, a model neuron rendered multistable by a simulated application of a neuromodulator produces apparently random activity, whereas in response to the same synaptic noise, a monostable model neuron produces barely perturbed regular activity. Thus an increase in the number of attractors enhances sensitivity to both conventional synaptic inputs and noise. Conversely, a decrease is associated with a reduction in sensitivity.4. The response of a neuron to a subsequent transient perturbation in the level of neuromodulator depends on the steady-state level of the neuromodulator. For example, if the steady-state level is associated with a multistable neuron, a mode shift produced by such a transient change in the level of neuromodulator (manifested in our model as a conductance change) can persist after the conductance is returned gradually to its original value. Thus multistable dynamic activity permits the effects of a neuromodulator to persist when the neuromodulator is no longer present.5. The mechanism of mode shifting between coexisting stable oscillatory modes introduces a number of novel possibilities with potentially profound implications for information processing and storage in a single neuron.