Previously believed to solely play a supportive role in the central nervous system, astrocytes are now considered active players in normal brain function. Evidence in recent decades extends their contributions beyond the classically held brain glue role; it's now known that astrocytes act as a unique excitable component with functions extending into local network modulation, synaptic plasticity, and memory formation, and postinjury repair. In this review article, we highlight our growing understanding of astrocyte function and physiology, the increasing role of gliotransmitters in neuron-glia communication, and the role of astrocytes in modulating synaptic plasticity and cognitive function. Owing to the duality of both beneficial and deleterious roles attributed to astrocytes, we also discuss the implications of this new knowledge as it applies to neurological disorders including Alzheimer disease, epilepsy, and schizophrenia.
Adhesives* ; Alzheimer Disease ; Astrocytes* ; Brain ; Central Nervous System ; Cognition ; Epilepsy ; Memory ; Nervous System Diseases* ; Neuronal Plasticity* ; Physiology ; Schizophrenia

BACKGROUND: Anesthesia induces the spectral changes in EEG. Attempts to relate these spectral changes to adequacy of anesthesia have been hindered due to the complex waveforms of EEG. The objective of this investigation is to monitor the awareness of patients during cesarean section by means of EEG spectral analysis. METHODS: 20 patients for cesarean section aged from 24 to 39 and ASA class I or II, were maintained with O2(50%)-N2O(50%)-enflurane(0.8%). And they were administered with midazolam(0.07 mg/kg) in group I(n=6), fentanyl(1 microgram/kg) in group II(n=7), and fentanyl(2 microgram/kg) in group III(n=7) after birth. The density of each spectral band in EEG (delta 1-3.25 Hz, theta 3.5-7.75 Hz, alpha 8-12.15 Hz and beta 13-31.75Hz) was analyzed to derive total density, delta ratio and median power frequency. RESULTS: The spectral data demonstrated that the alpha rhythm was dominant in pre-induction period and beta rhythm was abundant both in the immediate post-induction period and after birth for all three groups. Delta ratio and median power frequency decreased after injection of midazolam and fentanyl in all three groups. None of patients could recall the memory about experience during cesarean section. CONCLUSIONS: These findings indicate that EEG spectral analysis is potentially useful to determine the changes of cerebroelectrical activity but difficult to monitor the awareness of patients during cesarean section.
Alpha Rhythm ; Anesthesia ; Anesthetics ; Anesthetics, Intravenous* ; Beta Rhythm ; Cesarean Section* ; Electroencephalography* ; Enflurane ; Female ; Fentanyl ; Humans ; Isoflurane ; Memory ; Midazolam ; Parturition ; Pregnancy

Central Nervous System ; physiopathology ; Facial Nerve Injuries ; physiopathology ; Humans ; Neuronal Plasticity ; Synapses ; physiology

As a rhythmic neural activity, neural oscillation exists all over the nervous system, in structures as diverse as the cerebral cortex, hippocampus, subcortical nuclei and sense organs. This review firstly presents some evidence that synchronous neural oscillations in theta and gamma bands reveal much about the origin and nature of cognitive processes such as learning and memory. And then it introduces the novel analyzing algorithms of neural oscillations, which is a directionality index of neural information flow (NIF) as a measure of synaptic plasticity. An example of application used such an analyzing algorithms of neural oscillations has been provided.
Animals ; Biological Clocks ; Brain ; physiology ; Cognition ; physiology ; Humans ; Learning ; physiology ; Memory ; physiology ; Nervous System Physiological Phenomena ; physiology ; Neural Pathways ; physiology ; Neuronal Plasticity ; physiology ; Synapses ; physiology ; Theta Rhythm ; physiology

OBJECTIVE: To determine the effect of cold air therapy on relieving spasticity, the optimal intramuscular temperature, and the duration of spasticity relief. METHOD: Twenty-three 4 months old Korean white rabbits weighing 2 to 3 kg were used. After posterior laminectomy at thoracolumbar junction, the spinal cord was completely transected. After spasticity occurred, cold air was applied to the triceps surae muscles for 30 minutes at three different intramuscular temperatures (32.5, 30, and 25degrees C). Spasticity was measured pre-treatment, immediately following treatment, after 30 minutes, and after 60 minutes. Clinical parameters (muscle tone, deep tendon reflex, ankle clonus, and Babinski's sign) and electrophysiologic parameters (F/M ratio and H/M ratio) were measured. RESULT: Muscle tone and Babinski's sign significantly decreased immediately following treatment in the 32.5degrees C group, immediately following treatment and after 30 minutes in the 30degrees C and 25degrees C group. Deep tendon reflex and ankle clonus significantly decreased immediately following treatment in the 32.5degrees C group, immdiately following treatment, after 30 minutes in the 30degrees C group, immediately following treatment, after 30 minutes and after 60 minutes in the 25degrees C group. The F/M ratio and H/M ratio were not significantly affected in the 32.5degrees C group but decrease immediately following treatment in the 30degrees C and 25degrees C groups. Compound motor unit action potentials were not evoked in 6 out of 16 cases (37.5%) in the 25degrees C group, resulting in blockage of conduction. CONCLUSION: To relieve spasticity with cold air therapy, the intramuscular temperature should be maintained at 30degrees C. The duration of spasticity relief lasted from 30 minutes to one hour after cold air therapy.
Action Potentials ; Ankle ; Humans ; Infant ; Laminectomy ; Muscle Spasticity* ; Muscles ; Rabbits ; Reflex, Babinski ; Reflex, Stretch ; Spinal Cord ; Spinal Cord Injuries

Perineuronal nets (PNNs) are reticular structures resulting from the aggregation of extracellular matrix (ECM) molecules around the cell body and proximal neurite of specific population of neurons in the central nervous system (CNS). Since the first description of PNNs by Camillo Golgi in 1883, the molecular composition, developmental formation and potential functions of these specialized extracellular matrix structures have only been intensively studied over the last few decades. The main components of PNNs are hyaluronan (HA), chondroitin sulfate proteoglycans (CSPGs) of the lectican family, link proteins and tenascin-R. PNNs appear late in neural development, inversely correlating with the level of neural plasticity. PNNs have long been hypothesized to play a role in stabilizing the extracellular milieu, which secures the characteristic features of enveloped neurons and protects them from the influence of malicious agents. Aberrant PNN signaling can lead to CNS dysfunctions like epilepsy, stroke and Alzheimer's disease. On the other hand, PNNs create a barrier which constrains the neural plasticity and counteracts the regeneration after nerve injury. Digestion of PNNs with chondroitinase ABC accelerates functional recovery from the spinal cord injury and restores activity-dependent mechanisms for modifying neuronal connections in the adult animals, indicating that PNN is an important regulator of neural plasticity. Here, we review recent progress in the studies on the formation of PNNs during early development and the identification of CSPG receptor - an essential molecular component of PNN signaling, along with a discussion on their unique regulatory roles in neural plasticity.
Animals ; Central Nervous System ; physiology ; physiopathology ; Chondroitin Sulfate Proteoglycans ; Extracellular Matrix ; physiology ; Humans ; Neuronal Plasticity ; Neurons ; Receptors, Cell Surface ; physiology

P21-activated kinases (PAK) participate in a variety of important cellular activities, such as cytoskeleton remodeling, cell migration, cell cycle regulation, and apoptosis or survival. PAK also has an important impact on brain development, neuronal differentiation, and regulation of synaptic plasticity in the nervous system. PAK abnormalities result in diseases including cancer, Parkinson's disease (PD), Alzheimer's disease (AD) and neural retardation. Therefore, it is of vital physiological significance to investigate the neuronal function of PAK. In this paper we review the advancement of research on the neuronal biological function and the underlying mechanisms of PAK.
Alzheimer Disease ; physiopathology ; Apoptosis ; Cell Cycle ; Cell Movement ; Cytoskeleton ; physiology ; Humans ; Nervous System ; enzymology ; Neuronal Plasticity ; Neurons ; physiology ; Parkinson Disease ; physiopathology ; p21-Activated Kinases ; physiology

We investigated blood pressure (BP) reactivity of obstructive sleep apnea (OSA) during rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. The influences on BP reactivity of degree of arousal, the lowest O2 saturation (SaO2), and respiratory disturbance (RD) duration were compared. Ten normotensive or borderline hypertensive patients with OSA were studied with one-night polysomnography including non-invasive beat-to-beat BP monitoring (Finapres(R)). We compared baseline BP, pre-apneic BP, and post-apneic BP during both REM and NREM sleep. Also, relationships between delta BP (post-apneic BP minus pre-apneic BP) and degree of arousal, the lowest SaO2, and RD duration were examined. During both REM and NREM sleep, pre-apneic BP was elevated compared with baseline BP. Post-apneic BP elevation was noted compared with pre-apneic BP. The degree of arousal was more significantly correlated with delta BP than the lowest SaO2. RD duration was hardly correlated with delta BP. Pre-apneic BP elevation seems to result from cumulation of sympathetic activation and sympathetic nervous system resetting. The correlation between delta BP and degree of arousal suggests that sympathetic activation causing post-apneic BP elevation may result mainly from an arousal response regardless of hypoxia.
Adult ; Aged ; Anoxia/physiopathology ; Arousal/*physiology ; Blood Pressure/*physiology ; Human ; Male ; Middle Age ; Oxygen/blood ; Sleep Apnea, Obstructive/diagnosis/*physiopathology ; Sleep, REM/*physiology ; Sympathetic Nervous System/physiology

All of neural stem cell within the central nervous system and derived from transplantation or embryonic stem cell have the ability of differentiating into various kinds of neural cells. Regeneration of neural cells plays a critical role on function recovery damaged central nervous system (CNS). Advances in repairing of injury in central nervous system with neural stem cell and embryonic stem cell in recent years are reviewed in this article.
Adult Stem Cells ; cytology ; Animals ; Central Nervous System Diseases ; physiopathology ; surgery ; Embryonic Stem Cells ; cytology ; Humans ; Nerve Regeneration ; physiology ; Neuronal Plasticity ; Neurons ; cytology ; Stem Cell Transplantation

Hippocampal neuronal network oscillation is closely related to the memory, anxiety and behavioral inhibition of mammalian. The cognitive decline and behavioral disinhibition in the patients with Alzheimer's disease (AD) may be relevant to amyloid β protein (Aβ)-induced impairment in hippocampal neuronal cooperative activity. However, it is not well known whether intrahippocampal injection of Aβ could induce behavioral disinhibition and neuronal network disorder, as well as cognition decline in animals. In the present study, we observed the effects of intracerebral injection of Aβ(1-42) on the spatial memory and behavioral inhibition of rats by using Morris water maze and elevated plus-maze tests. Further, we analyzed hippocampal theta rhythm by recording hippocampal local field potential. The results showed that: (1) bilateral hippocampal injection of Aβ(1-42) reduced the anxious behavior of rats, with a significant behavioral disinhibition in the elevated plus-maze test, representing as an increase in the mean entering times and mean residence time in the open arm; (2) Aβ(1-42) injection resulted in a significant impairment of spatial memory in rats, with significantly increased mean escape latencies in hidden platform test; (3) Aβ(1-42) disrupted the induction of theta rhythm induced by tail pinch, with a significant reduction in the peak power, not the peak power frequency of the theta rhythm. These experimental results indicate that intrahippocampal injection of Aβ(1-42) can induce behavioral disinhibition and theta rhythm suppression, as well as spatial memory impairment in rats, which suggests that the cognition deficits and behavior impairments in AD are probably associated with the Aβ-induced disruption of hippocampal theta rhythm and consequent down-regulation of synaptic plasticity.
Amyloid beta-Peptides ; adverse effects ; Animals ; Down-Regulation ; Hippocampus ; physiopathology ; Maze Learning ; Neuronal Plasticity ; Peptide Fragments ; adverse effects ; Rats ; Spatial Memory ; Theta Rhythm