For expressing the condolences on the passing away of Dr. Hsiang-Tung Chang, one of the distinguished members of the Chinese Academia of Sciences, the pioneer studies on cortical dendritic potentials that Dr. Chang carried out in the 1950s and the prosperous progresses since then, especially, concerning the modifications of synaptic plasticity by the dendritic back-propagating action potentials were briefly reviewed.
Action Potentials ; Dendrites ; physiology ; Humans ; Neuronal Plasticity

For decades, memory research has centered on the role of neurons, which do not function in isolation. However, astrocytes play important roles in regulating neuronal recruitment and function at the local and network levels, forming the basis for information processing as well as memory formation and storage. In this review, we discuss the role of astrocytes in memory functions and their cellular underpinnings at multiple time points. We summarize important breakthroughs and controversies in the field as well as potential avenues to further illuminate the role of astrocytes in memory processes.
Astrocytes ; Neuronal Plasticity/physiology* ; Memory/physiology* ; Neurons/physiology* ; Cognition/physiology*

Neural network plasticity is fundamental for learning and memory. Its abnormal change underlies some neural diseases. Measurement of the plasticity of cortex can help understand the mechanism of plasticity, and provide a quantitative way to observe the neural process of natural aging and neurodegenerative diseases, which may lead to a new approach for evaluation of anti-aging drugs and new medical treatments for neurodegenerative diseases. In this study, a systematic method was established based on whisker pairing (WP) experiment to measure the network plasticity in the barrel cortex in rat. WP experiment is a classical experiment to study the effect of innocuous bias of the flow of sensory activity from the whiskers for certain periods in awake and behaving rats on the receptive field organization in S1 barrel cortex neurons. In the experiment, one pair of adjacent whiskers D2 and D3 remained intact while others were being trimmed throughout a certain period. After that, receptive fields of single cells in the contralateral barrel were analyzed by post-stimulus time histogram after certain days of WP and compared with the controls. In the control group, response magnitudes to surrounding whiskers D1 and D3 deflection were not significantly different. However, after WP, a bias occurred in response to paired surrounding whisker D3 relative to the opposite trimmed surrounding whisker D1. In this study, by comparing the bias degree in rats in different groups after WP, a quantitative method was established to compare cortical plasticity. Example of corical plasticity comparison between adolescent and mature rats was employed in this paper to illustrate our method. The key techniques of this method such as the identification of D2 barrels, supragranular (L2-3) and barrel layer (L4) in real-time were described in details. The feasibility of this approach was further verified by compendious report of results and our previous study regarding cortical plasticity comparison between adolescent and mature rats.
Animals ; Neuronal Plasticity ; Rats ; Somatosensory Cortex ; physiology ; Vibrissae

Synaptic plasticity of barrel cortex is one of the most widely studied topics in neuroscience in recent years. The primary somatosensory cortex of the rodent has a good topology character,which provides an ideal experimental model for plasticity study. This system displays very strong experience-dependent plasticity both during development and in adulthood. The changes of sensory cortex's neural circuit can induce experience-dependent plasticity. In the synaptic level,thalamocortical synapse is considered to be the main location of plasticity. In the circuit level,both synapses from layer 4 to layer 2/3 and those within layer 2/3 are also the necessary parts of achieving synaptic plasticity in primary somatosensory cortex. The GABAergic inhibitory circuit may be involved in this plasticity of S1, but the exact mechanism remains unknown.
Animals ; Neural Pathways ; physiology ; Neuronal Plasticity ; Somatosensory Cortex ; physiology ; Synapses ; physiology ; Thalamus ; physiology ; Vibrissae ; physiology

The back-propagating action potential (bpAP) is crucial for neuronal signal integration and synaptic plasticity in dendritic trees. Its properties (velocity and amplitude) can be affected by dendritic morphology. Due to limited spatial resolution, it has been difficult to explore the specific propagation process of bpAPs along dendrites and examine the influence of dendritic morphology, such as the dendrite diameter and branching pattern, using patch-clamp recording. By taking advantage of Optopatch, an all-optical electrophysiological method, we made detailed recordings of the real-time propagation of bpAPs in dendritic trees. We found that the velocity of bpAPs was not uniform in a single dendrite, and the bpAP velocity differed among distinct dendrites of the same neuron. The velocity of a bpAP was positively correlated with the diameter of the dendrite on which it propagated. In addition, when bpAPs passed through a dendritic branch point, their velocity decreased significantly. Similar to velocity, the amplitude of bpAPs was also positively correlated with dendritic diameter, and the attenuation patterns of bpAPs differed among different dendrites. Simulation results from neuron models with different dendritic morphology corresponded well with the experimental results. These findings indicate that the dendritic diameter and branching pattern significantly influence the properties of bpAPs. The diversity among the bpAPs recorded in different neurons was mainly due to differences in dendritic morphology. These results may inspire the construction of neuronal models to predict the propagation of bpAPs in dendrites with enormous variation in morphology, to further illuminate the role of bpAPs in neuronal communication.
Action Potentials/physiology* ; Dendrites/physiology* ; Neurons/physiology* ; Neuronal Plasticity ; Pyramidal Cells/physiology*

Long-term synaptic plasticity is considered as a key part of the neural mechanism of learning and memory. The production of learned vocalization of male zebra finches is closely related to high vocal center (HVC)-robust nucleus of the arcopallium (RA) pathway. However, the long-term plasticity of HVC-RA synapses is unclear. This study investigated the long-term plasticity of HVC-RA synapses in adult male zebra finches through in vivo field potential recording. The results showed that physiologic stimulation, i.e., δ rhythmic stimulation and low frequency stimulation could not effectively induce long-term synaptic plasticity. The former leaded to no change of the amplitudes of evoked population spikes, and the latter induced short-term depression (STD) of the amplitudes of the second evoked population spikes caused by paired pulses. But high frequency stimulation induced long-term depression (LTD) of the amplitudes of evoked population spikes to show out long-term synaptic plasticity. These results suggest that LTD represents the long-term plasticity of HVC-RA synapses in adult male zebra finches, which may be a key part of the neural mechanism of vocal learning and memory and can explain the plasticity of adult song to some degree.
Animals ; Evoked Potentials, Auditory ; Finches ; physiology ; High Vocal Center ; physiology ; Learning ; Male ; Neuronal Plasticity ; Synapses ; physiology

Neuritin is a new member of the neurotrophic factor family, whose gene is named cpg15 (candidate plasticity-related gene 15) and can be activated by neural activity or neurotrophins (NTs). Experiments show that neuritin is able to promote the growth and branching of neurites, and plays an important role in neuronal plasticity and neuronal regeneration. Recent studies have proved that neuritin is not only involved in the regulation of various physiological functions in the nervous system, but also related in angiogenesis and tumorigenesis. Here we review the mechanisms involved in cpg15 expression and regulation, biological effects of neuritin, and how neuritin plays its biological activities. The hot issues and difficulties in the study of neuritin are also discussed.
GPI-Linked Proteins ; physiology ; Humans ; Neurites ; physiology ; Neuronal Plasticity ; Neuropeptides ; physiology

This review focuses on our effort in addressing the development and lesion-induced plasticity of the gravity sensing system. After severance of sensory input from one inner ear, there is a bilateral imbalance in response dynamics and spatial coding behavior between neuronal subpopulations on the two sides. These data provide the basis for deranged spatial coding and motor deficits accompanying unilateral labyrinthectomy. Recent studies have also confirmed that both glutamate receptors and neurotrophin receptors within the bilateral vestibular nuclei are implicated in the plasticity during vestibular compensation and development. Changes in plasticity not only provide insight into the formation of a spatial map and recovery of vestibular function but also on the design of drugs for therapeutic strategies applicable to infants or vestibular disorders such as vertigo and dizziness.
Animals ; Humans ; Neuronal Plasticity ; Neurons ; physiology ; Otolithic Membrane ; innervation ; physiology ; Vestibule, Labyrinth ; innervation ; physiology

The cAMP-responsive element binding protein (CREB)-regulated transcription coactivator, CRTC (also known as transducer of regulated CREB, TORC), is identified as a potent modulator of cAMP response element (CRE)-driven gene transcription. The CRTC family consists of three members (CRTC1-3), among which the CRTC1 shows the highest expression in the brain. Several studies have demonstrated that the CRTC1 plays critical roles in neuronal dendritic growth, long-term synaptic plasticity, memory consolidation and reconsolidation etc., whereas dysfunction of CRTC1 is mainly involved in neurodegenerative disorders. In light of these findings, we aim to review recent research reports that indicate the CRTC1 dysfunction and its underlying mechanisms in the neurodegenerative disorders.
Brain ; physiology ; Dendrites ; physiology ; Humans ; Neurodegenerative Diseases ; physiopathology ; Neuronal Plasticity ; Transcription Factors ; physiology

Crossmodal information processing in sensory cortices has been reported in sparsely distributed neurons under normal conditions and can undergo experience- or activity-induced plasticity. Given the potential role in brain function as indicated by previous reports, crossmodal connectivity in the sensory cortex needs to be further explored. Using perforated whole-cell recording in anesthetized adult rats, we found that almost all neurons recorded in the primary somatosensory, auditory, and visual cortices exhibited significant membrane-potential responses to crossmodal stimulation, as recorded when brain activity states were pharmacologically down-regulated in light anesthesia. These crossmodal cortical responses were excitatory and subthreshold, and further seemed to be relayed primarily by the sensory thalamus, but not the sensory cortex, of the stimulated modality. Our experiments indicate a sensory cortical presence of widespread excitatory crossmodal inputs, which might play roles in brain functions involving crossmodal information processing or plasticity.
Animals ; Auditory Cortex/physiology* ; Neuronal Plasticity/physiology* ; Neurons ; Rats ; Thalamus ; Visual Cortex/physiology*