Effects of electroacupuncture on cardiac function and local field potential of sensory and motor cortices in mice with stress cardiomyopathy / 中国针灸

OBJECTIVE@#To observe the effects of electroacupuncture (EA) on cardiac function and local field potential (LFP) in sensory and motor cortices in mice with stress cardiomyopathy (SC), and to explore the possible mechanism of EA in improving SC.@*METHODS@#Twenty-seven female C57BL/6 mice were randomized into a blank group, a model group and an EA group, 9 mice in each group. In the model group and the EA group, SC model was established by continuous intraperitoneal injection of isoproterenol (ISO) for 14 days. At the same time of modeling, EA was applied at "Neiguan" (PC 6) and "Shenmen" (HT 7) in the EA group, with disperse-dense wave, in frequency of 2 Hz/15 Hz, 15 min each time, once a day for 14 days. After intervention, the total movement distance, the number of crossing grid and the number of crossing central grid of open field test within 5 minutes were observed; the left ventricular function indexes (left ventricular diameter of end-diastole [LVIDd], left ventricular diameter of end-systole [LVIDs], left ventricular volume of end-diastole [LVEDV], left ventricular volume of end-systole [LVESV], ejection fraction [EF] and fraction shortening [FS]) were detected by echocardiography; the changes in ST-segment amplitude and PR interval of electrocardiogram were observed; the morphology of myocardial tissue was observed by HE staining; the serum levels of cortisol (CORT), cardiac troponin T (cTnT) and brain natriuretic peptide (BNP) were detected by ELISA; the changes of LFP in sensory and motor cortices were recorded by Plexon multi-channel acquisition system.@*RESULTS@#Compared with the blank group, in the model group, the total movement distance, the number of crossing grid and the number of crossing central grid of open field test were decreased (P<0.05); LVIDd, LVIDs, LVEDV and LVESV were increased (P<0.05), EF and FS were decreased (P<0.05); ST-segment amplitude was increased (P<0.05) and PR interval was prolonged (P<0.05); irregular myocardial fiber arrangement, interstitial edema and inflammatory cell infiltration were observed; the serum levels of CORT, cTnT and BNP were increased (P<0.05); in the sensory cortex, the ratios of delta, theta, alpha and beta frequency bands were increased (P<0.05), the maximum energy spectrum of theta and beta frequency bands was increased (P<0.05), the power spectral density (PSD) of delta, theta, alpha, beta and gamma frequency bands was increased (P<0.05); in the motor cortex, the ratios of delta, theta, alpha and beta frequency bands were increased (P<0.05), the maximum energy spectrum as well as PSD of delta, theta, alpha, beta and gamma frequency bands were increased (P<0.05). Compared with model group, in the EA group, the total movement distance, the number of crossing grid and the number of crossing central grid of open field test were increased (P<0.05); LVIDd, LVIDs, LVEDV and LVESV were decreased (P<0.05), EF and FS were increased (P<0.05); ST-segment amplitude was decreased (P<0.05), and the PR interval was shortened (P<0.05); myocardial fiber injury and inflammatory cell infiltration were reduced; the serum levels of CORT, cTnT and BNP were decreased (P<0.05); in the sensory cortex, the ratios of theta, alpha and beta frequency bands were decreased (P<0.05), the ratio of gamma frequency band was increased (P<0.05), the maximum energy spectrum of theta frequency band as well as the PSD of theta, alpha, beta and gamma frequency bands were decreased (P<0.05); in the motor cortex, the ratios of theta, alpha and beta frequency bands were decreased (P<0.05) and the ratio of gamma frequency band was increased (P<0.05), the maximum energy spectrum of delta frequency band was increased (P<0.05), the maximum energy spectrum of theta frequency band as well as the PSD of theta and gamma frequency bands were decreased (P<0.05).@*CONCLUSION@#EA can improve cardiac function in mice with stress cardiomyopathy, and its mechanism may be related to the regulation of local field potentials in sensory and motor cortices.

Effects of 50 Hz electromagnetic field on rat working memory and investigation of neural mechanisms / 生物医学工程学杂志

With the widespread use of electrical equipment, cognitive functions such as working memory (WM) could be severely affected when people are exposed to 50 Hz electromagnetic fields (EMF) for long term. However, the effects of EMF exposure on WM and its neural mechanism remain unclear. In the present paper, 15 rats were randomly assigned to three groups, and exposed to an EMF environment at 50 Hz and 2 mT for a different duration: 0 days (control group), 24 days (experimental group I), and 48 days (experimental group II). Then, their WM function was assessed by the T-maze task. Besides, their local field potential (LFP) in the media prefrontal cortex (mPFC) was recorded by the in vivo multichannel electrophysiological recording system to study the power spectral density (PSD) of θ and γ oscillations and the phase-amplitude coupling (PAC) intensity of θ-γ oscillations during the T-maze task. The results showed that the PSD of θ and γ oscillations decreased in experimental groups I and II, and the PAC intensity between θ and high-frequency γ (hγ) decreased significantly compared to the control group. The number of days needed to meet the task criterion was more in experimental groups I and II than that of control group. The results indicate that long-term exposure to EMF could impair WM function. The possible reason may be the impaired communication between different rhythmic oscillations caused by a decrease in θ-hγ PAC intensity. This paper demonstrates the negative effects of EMF on WM and reveals the potential neural mechanisms from the changes of PAC intensity, which provides important support for further investigation of the biological effects of EMF and its mechanisms.

High frequency repeated transcranial magnetic stimulation improves learning and memory of global cerebral ischemia rats and its mechanism / 中华神经科杂志

Objective To study the effect of high frequency repeated transcranial magnetic stimulation (rTMS) on learning and memory in rats with global cerebral ischemia and to investigate its mechanism.Methods Thirty-five male Sprague-Dawley rats (8-10 weeks old) were randomly divided into sham operation group (n=8),model group (n=9),sham-rTMS (s-rTMS) group (n=9) and rTMS group (n=9).The global cerebral ischemia model was established by modified four-vessel occlusion method.The rTMS group received 10 Hz rTMS stimulation for two weeks,whereas the s-rTMS group received sham stimulation.Morris water maze test was used to detect the spatial learning ability,multi-channel recording technique was used to detect the local field potentials in the hippocampus CA1 region of theta and gamma oscillation,and immunohistochemical staining and Western blotting were used to detect the expression of protein kinase A (PKA) and phosphorylated cyclic adenosine monophosphate response element binding protein (p-CREB) of hippocampus.Results The average escape latency in the model group was longer than that in the sham operation group ((35.16±0.80) s vs (16.57±0.74) s,k=3.723,P=0.013),the spanning platform times and the original platform quadrant swimming time in the model group were shorter than that in the sham operation group (1.14±0.42 vs 4.46±0.23,k=3.185,P=0.042;(14.46±0.73) s vs (29.31±0.42) s,k=3.027,P=0.047).Compared with the sham operation group,the mean power spectral density of theta and gamma reduced ((-68.48±2.61) Hz vs (-59.38±2.25) Hz,k=2.958,P=0.048;(-82.23±4.60) Hz vs (-70.50±4.25) Hz,k=3.729,P=0.021),and the expression of PKA and p-CREB protein decreased in the model group (7 184.26±975.12 vs 25 137.35±1 010.62,k=3.588,P=0.027;1 803.73±336.18 vs 20 175.25±727.23,k=2.912,P=0.049).The average escape latency in the rTMS group was shorter than that in the model group ((24.69± 1.01) s vs (35.16±0.80) s,k=4.082,P=0.034),and the spanning platform times and the original platform quadrant swimming time in the rTMS group was longer than that in the model group (2.42±0.31 vs 1.14±0.42,k=3.296,P=0.039;(23.07±0.67) s vs (14.46±0.73) s,k=4.323,P=0.012).Compared with the rTMS group,the power spectral density of theta and gamma reduced ((-63.81±3.12) Hz vs (-68.48±2.61) Hz,k=3.582,P=0.015;(-75.80±4.58) Hz vs (-82.23±4.60) Hz,k=4.051,P=0.026),and the expression of PKA and p-CREB protein decreased in the model group (13 065.32±1 045.18 vs 7 184.26±975.12,k=3.923,P=0.031;11 032.83±562.86 vs 18 03.73±336.18,k=3.178,P=0.038).Conclusion High frequency rTMS could improve learning and memory of global cerebral ischemia rats,the mechanism of which might be that rTMS enhance the hippocampal theta and gamma oscillations and increase the expression of PKA and p-CREB protein in the hippocampus,thus increasing the hippocampus synaptic plasticity.

Altered Local Field Potential Relationship Between the Parafascicular Thalamic Nucleus and Dorsal Striatum in Hemiparkinsonian Rats / 神经科学通报·英文版

The thalamostriatal pathway is implicated in Parkinson's disease (PD); however, PD-related changes in the relationship between oscillatory activity in the centromedian-parafascicular complex (CM/Pf, or the Pf in rodents) and the dorsal striatum (DS) remain unclear. Therefore, we simultaneously recorded local field potentials (LFPs) in both the Pf and DS of hemiparkinsonian and control rats during epochs of rest or treadmill walking. The dopamine-lesioned rats showed increased LFP power in the beta band (12 Hz-35 Hz) in the Pf and DS during both epochs, but decreased LFP power in the delta (0.5 Hz-3 Hz) band in the Pf during rest epochs and in the DS during both epochs, compared to control rats. In addition, exaggerated low gamma (35 Hz-70 Hz) oscillations after dopamine loss were restricted to the Pf regardless of the behavioral state. Furthermore, enhanced synchronization of LFP oscillations was found between the Pf and DS after the dopamine lesion. Significant increases occurred in the mean coherence in both theta (3 Hz-7 Hz) and beta bands, and a significant increase was also noted in the phase coherence in the beta band between the Pf and DS during rest epochs. During the treadmill walking epochs, significant increases were found in both the alpha (7 Hz-12 Hz) and beta bands for two coherence measures. Collectively, dramatic changes in the relative LFP power and coherence in the thalamostriatal pathway may underlie the dysfunction of the basal ganglia-thalamocortical network circuits in PD, contributing to some of the motor and non-motor symptoms of the disease.

Effect of hypothalamic nerve growth factor precursor on field potential of paraventrucular nucleus during rat cardiopulmonary bypass / 临床麻醉学杂志

Objective To evaluate the effect of cardiopulmonary bypass (CPB) on the expression of hypothalamic nerve growth factor precursor (proNGF) and the influence of hypothalamic proNGF on the sympathetic output of paraventrucular nucleus. Methods Forty-two male SD rats, aged 3-4 months, weighing 350-500 g, were divided into control group, CPB group and ischemia reperfusion (IR) group. At the end of CPB for 110 min, hypothalamus and dorsal root ganglion (DRG) were taken to measure the levels of proNGF mRNA and hypothalamic proNGF protein. Mini pipe was put into bilateral paraventrucular nucleus (PVN) and human recombination proNGF protein was injected into PVN for 7 d before the local field potentials (LFP) of RVLM was recoreded. Human recombination proNGF protein was administrated into lateral ventricle, the prior-administration-LFP of PVN and post-administration-LFP were recorded and compared. At the end of the experiment, hypothalamus was taken to measure the levels of glutamate and gammer amino butyric acid (GABA). Results Hypothalamic proNGF protein in CPB group and IR group was higher than that in the control group (P ＜ 0.05); NGF mRNA of hypothalamus and DRG in CPB and IR group were higher than those of control group (P ＜ 0.05). In PVN and RVLM, after the administration of proNGF protein, the power of delta band significantly decreased and other bands increased (P ＜ 0.05). The hypothalamic GABA level decreased (P ＜ 0.05) with no change of hypothalamic glutamate after proNGF was injected into lateral ventricle. Conclusion CPB increases the expression of proNGF in the hypothalamus contributing to the changes of hypothalamic sympathetic output.

Comparison of decoding performance between spike and local field potential signals during goal-directed decision-making task of pigeons / 生物医学工程学杂志

Both spike and local field potential (LFP) signals are two of the most important candidate signals for neural decoding. At present there are numerous studies on their decoding performance in mammals, but the decoding performance in birds is still not clear. We analyzed the decoding performance of both signals recorded from nidopallium caudolaterale area in six pigeons during the goal-directed decision-making task using the decoding algorithm combining leave-one-out and -nearest neighbor (LOO- NN). And the influence of the parameters, include the number of channels, the position and size of decoding window, and the nearest neighbor value, on the decoding performance was also studied. The results in this study have shown that the two signals can effectively decode the movement intention of pigeons during the this task, but in contrast, the decoding performance of LFP signal is higher than that of spike signal and it is less affected by the number of channels. The best decoding window is in the second half of the goal-directed decision-making process, and the optimal decoding window size of LFP signal (0.3 s) is shorter than that of spike signal (1 s). For the LOO- NN algorithm, the accuracy is inversely proportional to the value. The smaller the value is, the larger the accuracy of decoding is. The results in this study will help to parse the neural information processing mechanism of brain and also have reference value for brain-computer interface.

Prepulse Inhibition of Auditory Cortical Responses in the Caudolateral Superior Temporal Gyrus in Macaca mulatta / 神经科学通报·英文版

Prepulse inhibition (PPI) refers to a decreased response to a startling stimulus when another weaker stimulus precedes it. Most PPI studies have focused on the physiological startle reflex and fewer have reported the PPI of cortical responses. We recorded local field potentials (LFPs) in four monkeys and investigated whether the PPI of auditory cortical responses (alpha, beta, and gamma oscillations and evoked potentials) can be demonstrated in the caudolateral belt of the superior temporal gyrus (STGcb). We also investigated whether the presence of a conspecific, which draws attention away from the auditory stimuli, affects the PPI of auditory cortical responses. The PPI paradigm consisted of Pulse-only and Prepulse + Pulse trials that were presented randomly while the monkey was alone (ALONE) and while another monkey was present in the same room (ACCOMP). The LFPs to the Pulse were significantly suppressed by the Prepulse thus, demonstrating PPI of cortical responses in the STGcb. The PPI-related inhibition of the N1 amplitude of the evoked responses and cortical oscillations to the Pulse were not affected by the presence of a conspecific. In contrast, gamma oscillations and the amplitude of the N1 response to Pulse-only were suppressed in the ACCOMP condition compared to the ALONE condition. These findings demonstrate PPI in the monkey STGcb and suggest that the PPI of auditory cortical responses in the monkey STGcb is a pre-attentive inhibitory process that is independent of attentional modulation.

Adaptive common average reference for in vivo multichannel local field potentials

For in vivo neural recording, local field potential (LFP) is often corrupted by spatially correlated artifacts, especially in awake/behaving subjects. A method named adaptive common average reference (ACAR) based on the concept of adaptive noise canceling (ANC) that utilizes the correlative features of common noise sources and implements with common average referencing (CAR), was proposed for removing the spatially correlated artifacts. Moreover, a correlation analysis was devised to automatically select appropriate channels before generating the CAR reference. The performance was evaluated in both synthesized data and real data from the hippocampus of pigeons, and the results were compared with the standard CAR and several previously proposed artifacts removal methods. Comparative testing results suggest that the ACAR performs better than the available algorithms, especially in a low SNR. In addition, feasibility of this method was provided theoretically. The proposed method would be an important pre-processing step for in vivo LFP processing.

Study of Microelectrode Array Probe for Simultaneous Detection of Glutamate and Local Field Potential during Brain Death / 分析化学

High extracellular potassium can induce spreading depression-like depolarizations, elevations of extracellular glutamate and even neuronal death in normal brain. To investigate the contribution of high potassium in vivo, a microelectrode arrays ( MEAs ) probe integrated with recording sites for glutamate concentration (50í150 μm) and local field potential ( LFP) ( diameter=15 μm) was fabricated by Micro-electro-mechanical-systems ( MEMS) technologies. We implanted the MEA probe acutely in the rat brain and exposed the brain to a high potassium solution. During these multi-modal recordings, it was observed that high potassium elevated extracellular glutamate while suppressing the LFP irreversibly. This is one of the first studies in which a dual mode MEA probes is applied in vivo for neuronal death, and it is concluded that our MEA probes are capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.

Binocular integration of binocular neurons in striate cortex of Kitten / 中华实验眼科杂志

Background The integration of segregated pathways from the two eyes first appears in V1 neurons,where it not only plays a critical role in the generation of a three-dimensional visual representation.Abnormal visual experiences in critical period usually lead to amblyopia and binocular integration defects.Objective Present study was to investigate how neurons of kitten coordinate their activity patterns in response to synchronous dichoptic stimulus inputs in striate cortex.Methods Spike rate and local field potential(LFP) gamma band(20-90Hz) power of three kitten(1-1.2Kg,8-10 weeks old) to monocular and synchronous dichoptic presented gratings were assessed for 28 binocular neurons in V1 of kitten by in vivo extracellular record method under anaesthesia and paralysis.Ocular dominance index(ODI) and binocular integration index(BII) were assessed and the correlation between these two indexes were analyzed.Results In 28 cells with binocular characteristic,the absolute value of spike-ODI was significant larger than that of LFP-ODI(t=2.606,P=0.021).A positive linear correlation between the ocular preferences of spike and LFP was found(R2=0.513,F=27.423,P=0.003).In dichotic trails,binocular facilitation with BII for spike was 2.348±0.996,showing a significant reduce in comparison with BII for LFP(3.678±1.974)(t=2.671,P=0.019).Binocular integration index for two signals were greater when monocular responses of both eyes were similar(P=0.035 and P=0.124,respectively).Conclusion Both spike rate and gamma band power of LFP exhibited binocular facilitation to synchronous presented dichotic stimuli with significant facilitation induced by balanced monocular responses.Spiking activity and LFP reflect neural activities of different spatial scales and source components.

Spontaneous Oscillatory Rhythm in Retinal Activities of Two Retinal Degeneration (rd1 and rd10) Mice

Previously, we reported that besides retinal ganglion cell (RGC) spike, there is ~ 10 Hz oscillatory rhythmic activity in local field potential (LFP) in retinal degeneration model, rd1 mice. The more recently identified rd10 mice have a later onset and slower rate of photoreceptor degeneration than the rd1 mice, providing more therapeutic potential. In this study, before adapting rd10 mice as a new animal model for our electrical stimulation study, we investigated electrical characteristics of rd10 mice. From the raw waveform of recording using 8x8 microelectrode array (MEA) from in vitro-whole mount retina, RGC spikes and LFP were isolated by using different filter setting. Fourier transform was performed for detection of frequency of bursting RGC spikes and oscillatory field potential (OFP). In rd1 mice, ~10 Hz rhythmic burst of spontaneous RGC spikes is always phase-locked with the OFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, there is a strong phase-locking tendency between the spectral peak of bursting RGC spikes (~5 Hz) and the first peak of OFP (~5 Hz) across different age groups. But this phase-locking property is not robust as in rd1 retina, but maintains for a few seconds. Since rd1 and rd10 retina show phase-locking property at different frequency (~10 Hz vs. ~5 Hz), we expect different response patterns to electrical stimulus between rd1 and rd10 retina. Therefore, to extract optimal stimulation parameters in rd10 retina, first we might define selection criteria for responding rd10 ganglion cells to electrical stimulus.