Department of Cell Biology and Imaging, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland.
Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland.
Front Neural Circuits. 2018 May 2;12:32. doi: 10.3389/fncir.2018.00032. eCollection 2018.
In both vertebrate and invertebrate brains, neurons, glial cells and synapses are plastic, which means that the physiology and structure of these components are modified in response to internal and external stimuli during development and in mature brains. The term plasticity has been introduced in the last century to describe experience-dependent changes in synapse strength and number. These changes result from local functional and morphological synapse modifications; however, these modifications also occur more commonly in pre- and postsynaptic neurons. As a result, neuron morphology and neuronal networks are constantly modified during the life of animals and humans in response to different stimuli. Nevertheless, it has been discovered in flies and mammals that the number of synapses and size and shape of neurons also oscillate during the day. In most cases, these rhythms are circadian since they are generated by endogenous circadian clocks; however, some rhythmic changes in neuron morphology and synapse number and structure are controlled directly by environmental cues or by both external cues and circadian clocks. When the circadian clock is involved in generating cyclic changes in the nervous system, this type of plasticity is called circadian plasticity. It seems to be important in processing sensory information, in learning and in memory. Disruption of the clock may affect major brain functions.
在脊椎动物和无脊椎动物的大脑中，神经元、神经胶质细胞和突触都是可塑的，这意味着在发育过程中和成熟的大脑中，这些成分的生理学和结构会对外界和内部刺激做出调整。可塑性这个术语是在上个世纪引入的，用于描述突触强度和数量的经验依赖性变化。这些变化源自局部功能和形态突触的修改；然而，这些修改也更常见于突触前和突触后神经元中。因此，在动物和人类的一生中，神经元形态和神经网络会根据不同的刺激不断做出调整。然而，在果蝇和哺乳动物中已经发现，突触数量以及神经元的大小和形状也会在白天发生波动。在大多数情况下，这些节律是昼夜节律的，因为它们是由内源性生物钟产生的；然而，神经元形态和突触数量和结构的一些有节奏的变化是直接由环境线索或外部线索和生物钟共同控制的。当生物钟参与到神经系统的周期性变化中时，这种类型的可塑性被称为昼夜节律可塑性。它似乎在处理感官信息、学习和记忆方面很重要。生物钟的破坏可能会影响大脑的主要功能。
