Vadakkan Kunjumon I
Rev Neurosci. 2016 Feb;27(2):159-84. doi: 10.1515/revneuro-2015-0036.
When assigning a central role to the neuronal firing, a large number of incoming postsynaptic potentials not utilized during both supra- and subthreshold neuronal activations are not given any functional significance. Local synaptic potentials at the apical dendrites get attenuated as they arrive at the soma to nearly a twentieth of what a synapse proximal to the soma produces. Conservation of these functions necessitates searching for their functional roles. Potentials induced at the postsynapses of neurons of all the neuronal orders activated by sensory inputs carry small bits of sensory information. The activation of these postsynapses by any means other than the activation from their corresponding presynaptic terminals, that also contribute to oscillating potentials, induce the semblance of the arrival of activity from their presynaptic terminals. This is a candidate mechanism for inducing the first-person internal sensory elements of various higher brain functions as a systems property. They also contribute to the firing of subthreshold-activated neurons, including motor neurons. Operational mechanism of inter-postsynaptic functional LINKs can provide necessary structural requirements for these functions. The functional independence of the distal dendritic compartment and recent evidence for in vivo dendritic spikes indicate their independent role in the formation of internal sensory elements. In these contexts, a neuronal soma is flanked by a large number of quasi-functional internal sensory processing units operated using very little energy, even when a neuron is not firing. A large number of possible combinations of internal sensory units explains the corresponding number of specific memory retrievals by the system in response to various cue stimuli.
当赋予神经元放电核心作用时,在阈上和阈下神经元激活过程中未被利用的大量传入突触后电位未被赋予任何功能意义。顶树突上的局部突触电位在到达胞体时会衰减,衰减后的电位强度几乎只有胞体附近突触产生电位的二十分之一。要保留这些功能,就必须探寻它们的功能作用。由感觉输入激活的所有神经元层级的神经元突触后产生的电位携带少量感觉信息。通过除来自其相应突触前终末激活之外的任何方式激活这些突触后,也会导致振荡电位,从而诱发来自其突触前终末的活动到来的假象。这是一种作为系统属性诱导各种高级脑功能的第一人称内部感觉要素的候选机制。它们还会促进阈下激活神经元的放电,包括运动神经元。突触后功能连接的运作机制可为这些功能提供必要的结构要求。远端树突区室的功能独立性以及最近关于体内树突棘的证据表明它们在内部感觉要素形成中具有独立作用。在这些情况下,即使神经元不放电,神经元胞体两侧也有大量使用极少能量运作的准功能性内部感觉处理单元。大量内部感觉单元的可能组合解释了系统响应各种线索刺激进行相应数量特定记忆检索的现象。