Less efficacy of valproic acid monotherapy may be caused by neural excitatory rebound in seizures

Valproic acid (VPA) represents one of the most efficient antiepileptic drugs (AEDs) with either general or focal seizures, but a certain percentage of patients are not recovered or even worse, the mechanism under this phenomenon remains unclear. Here, we retrospectively reviewed 16 patients who received awake craniotomy surgery. Intro-operative high density electrocorticogram (ECoG) was used to record the local field potential (LFP) response to VPA treatment. We found the less efficacy of VPA monotherapy was associated with ECoG spectrum power shift from higher to lower frequency after VPA injection, together with increased synchronization of the LFP. Furthermore, we established the computational model to testify the hypothesis that the ineffectivity of VPA may be caused by excitatory dynamic rebound during the inhibitory power increasing. In addition to test the hypothesis, we employed the mice with Kanic Acid (KA)-induced epileptic model to confirm that it would be inhibited by VPA on behavior and neural activity. Also, the neural activity shows significant rebound on spike firing. Then we discovered that the LFP would increase the power spectral density in multiple wave bands after the VPA delivers. These findings suggest that less efficacy of valproic acid monotherapy in focal seizures may be caused by neural excitatory rebound which mediated by elevated inhibitory power.

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Ultrasonic thalamic stimulation modulates neural activity of thalamus and motor cortex in the mouse

Journal of Neural Engineering ◽

10.1088/1741-2552/ac409f ◽

2021 ◽

Author(s):

Xingran Wang ◽

Jiaqing Yan ◽

Huiran Zhang ◽

Yi Yuan

Keyword(s):

Motor Cortex ◽

Power Spectrum ◽

Neural Activity ◽

Field Potential ◽

Strong Connection ◽

Coupling Relationship ◽

Thalamic Stimulation ◽

Neural Activities ◽

Relationship Of ◽

Local Field Potential Lfp

Abstract Objective. Previous studies have demonstrated that ultrasound thalamic stimulation (UTS) can treat disorders of consciousness. However, it is still unclear how UTS modulates neural activity in the thalamus and cortex. Approach. In this study, we performed UTS in mice and recorded the neural activities including spike and local field potential (LFP) of the thalamus and motor cortex. We analyzed the firing rate of spikes and the power spectrum of LFPs and evaluated the coupling relationship between LFPs from the thalamus and motor cortex with Granger causality. Main results. Our results clearly indicate that UTS can directly induce neural activity in the thalamus and indirectly induce neural activity in the motor cortex. We also found that there is a strong connection relationship of neural activity between thalamus and motor cortex under UTS. Significance. These results demonstrate that UTS can modulate the neural activity of the thalamus and motor cortex in mice. It has the potential to provide guidance for the ultrasound treatment of thalamus-related diseases.

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Enhanced hippocampal theta rhythmicity and emergence of eta oscillation in virtual reality

10.1101/2020.06.29.178186 ◽

2020 ◽

Author(s):

Karen Safaryan ◽

Mayank R. Mehta

Keyword(s):

Virtual Reality ◽

Neural Activity ◽

Pyramidal Neurons ◽

Cell Layer ◽

Field Potential ◽

Theta Oscillations ◽

Spatial Coding ◽

Slow Oscillations ◽

Hippocampal Theta ◽

Local Field Potential Lfp

AbstractHippocampal theta oscillations in rodents profoundly impact neural activity, spatial coding, and synaptic plasticity and learning. What are the sensory mechanisms governing slow oscillations? We hypothesized that the nature of multisensory inputs is a crucial factor in hippocampal rhythmogenesis. We compared the rat hippocampal slow oscillations in the multisensory-rich real world (RW) and in a body-fixed, visual virtual reality (VR). The amplitude and rhythmicity of the hippocampal ~8 Hz theta were enhanced in VR compared to RW. This was accompanied by the emergence of a ~4 Hz oscillation, termed the eta rhythm, evident in the local field potential (LFP) in VR, but not in RW. Similar to theta, eta band amplitude increased with running speed in VR, but not in RW. However, contrary to theta, eta amplitude was highest in the CA1 cell layer, implicating intra-CA1 mechanisms. Consistently, putative CA1 interneurons, but not pyramidal neurons, showed substantially more eta modulation in VR than in RW. These results elucidate the multisensory mechanisms of hippocampal rhythms and the surprising effects of VR on enhancing these rhythms, which has not been achieved pharmacologically and has significant broader implications for VR use in humans.One Sentence SummaryNavigation in virtual reality greatly enhances hippocampal 8Hz theta rhythmicity, and generates a novel, ~4Hz eta rhythm that is localized in the CA1 cell layer and influences interneurons more than pyramidal neurons.

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nNOS-expressing interneurons control basal and behaviorally evoked arterial dilation in somatosensory cortex of mice

eLife ◽

10.7554/elife.60533 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Christina T Echagarruga ◽

Kyle W Gheres ◽

Jordan N Norwood ◽

Patrick J Drew

Keyword(s):

Neural Activity ◽

Cerebral Arteries ◽

Field Potential ◽

Neuron Activity ◽

Arterial Diameter ◽

Cellular Mechanisms ◽

Basal Diameter ◽

Arterial Dilation ◽

Oxide Synthase ◽

Local Field Potential Lfp

Cortical neural activity is coupled to local arterial diameter and blood flow. However, which neurons control the dynamics of cerebral arteries is not well understood. We dissected the cellular mechanisms controlling the basal diameter and evoked dilation in cortical arteries in awake, head-fixed mice. Locomotion drove robust arterial dilation, increases in gamma band power in the local field potential (LFP), and increases calcium signals in pyramidal and neuronal nitric oxide synthase (nNOS)-expressing neurons. Chemogenetic or pharmocological modulation of overall neural activity up or down caused corresponding increases or decreases in basal arterial diameter. Modulation of pyramidal neuron activity alone had little effect on basal or evoked arterial dilation, despite pronounced changes in the LFP. Modulation of the activity of nNOS-expressing neurons drove changes in the basal and evoked arterial diameter without corresponding changes in population neural activity.

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Coherent network oscillations by olfactory interneurons: modulation by endogenous amines

Journal of Neurophysiology ◽

10.1152/jn.1993.69.6.1930 ◽

1993 ◽

Vol 69 (6) ◽

pp. 1930-1939 ◽

Cited By ~ 36

Author(s):

A. Gelperin ◽

L. D. Rhines ◽

J. Flores ◽

D. W. Tank

Keyword(s):

Second Messengers ◽

Field Potential ◽

Learning Ability ◽

Odor Recognition ◽

Axonal Projections ◽

Odor Learning ◽

Olfactory Systems ◽

Olfactory Interneurons ◽

Limax Maximus ◽

Local Field Potential Lfp

1. The procerebral (PC) lobe of the terrestrial mollusk Limax maximus contains a highly interconnected network of local olfactory interneurons that receives direct axonal projections from the two pairs of noses. This olfactory processing network generates a 0.7-Hz oscillation in its local field potential (LFP) that is coherent throughout the network. The oscillating LFP is modulated by natural odorants applied to the neuroepithelium of the superior nose. 2. Two amines known to be present in the PC lobe, dopamine and serotonin, increase the frequency of the PC lobe oscillation and alter its waveform. 3. Glutamate, another putative neurotransmitter known to be present in the lobe, suppresses the PC lobe oscillation by a quisqualate-type receptor and appears to be used by one of the two classes of neurons in the PC lobe to generate the basic LFP oscillation. 4. The known activation of second messengers in Limax PC lobe by dopamine and serotonin together with their effects on the oscillatory rhythm suggest the hypothesis that these amines augment mechanisms mediating synaptic plasticity in the olfactory network, similar to hypothesized effects of amines in vertebrate olfactory systems. 5. The use of a distributed network of interneurons showing coherent oscillations may relate to the highly developed odor recognition and odor learning ability of Limax.

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Triggering Slow Waves During NREM Sleep in the Rat by Intracortical Electrical Stimulation: Effects of Sleep/Wake History and Background Activity

Journal of Neurophysiology ◽

10.1152/jn.91157.2008 ◽

2009 ◽

Vol 101 (4) ◽

pp. 1921-1931 ◽

Cited By ~ 69

Author(s):

Vladyslav V. Vyazovskiy ◽

Ugo Faraguna ◽

Chiara Cirelli ◽

Giulio Tononi

Keyword(s):

Electrical Stimulation ◽

Field Potential ◽

Nrem Sleep ◽

Neuronal Population ◽

Slow Waves ◽

Light Onset ◽

Naturally Occurring ◽

Profound Influence ◽

Electrical Pulses ◽

Local Field Potential Lfp

In humans, non-rapid eye movement (NREM) sleep slow waves occur not only spontaneously but can also be induced by transcranial magnetic stimulation. Here we investigated whether slow waves can also be induced by intracortical electrical stimulation during sleep in rats. Intracortical local field potential (LFP) recordings were obtained from several cortical locations while the frontal or the parietal area was stimulated intracortically with brief (0.1 ms) electrical pulses. Recordings were performed in early sleep (1st 2–3 h after light onset) and late sleep (6–8 h after light onset). The stimuli reliably triggered LFP potentials that were visually indistinguishable from naturally occurring slow waves. The induced slow waves shared the following features with spontaneous slow waves: they were followed by spindling activity in the same frequency range (∼15 Hz) as spontaneously occurring sleep spindles; they propagated through the neocortex from the area of the stimulation; and compared with late sleep, waves triggered during early sleep were larger, had steeper slopes and fewer multipeaks. Peristimulus background spontaneous activity had a profound influence on the amplitude of the induced slow waves: they were virtually absent if the stimulus was delivered immediately after the spontaneous slow wave. These results show that in the rat a volley of electrical activity that is sufficiently strong to excite and recruit a large cortical neuronal population is capable of inducing slow waves during natural sleep.

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Oscillatory integration windows in neurons

10.1101/081471 ◽

2016 ◽

Author(s):

Nitin Gupta ◽

Swikriti Saran Singh ◽

Mark Stopfer

Keyword(s):

Neural Circuits ◽

Neural Circuit ◽

Field Potential ◽

Coincidence Detection ◽

Uniform Structure ◽

Detection Mechanism ◽

Oscillation Frequencies ◽

Local Field Potential Lfp ◽

Oscillatory Cycle

AbstractOscillatory synchrony among neurons occurs in many species and brain areas, and has been proposed to help neural circuits process information. One hypothesis states that oscillatory input creates cyclic integration windows: specific times in each oscillatory cycle when postsynaptic neurons become especially responsive to inputs. With paired local field potential (LFP) and intracellular recordings and controlled stimulus manipulations we directly tested this idea in the locust olfactory system. We found that inputs arriving in Kenyon cells (KCs) sum most effectively in a preferred window of the oscillation cycle. With a computational model, we found that the non-uniform structure of noise in the membrane potential helps mediate this process. Further experiments performed in vivo demonstrated that integration windows can form in the absence of inhibition and at a broad range of oscillation frequencies. Our results reveal how a fundamental coincidence-detection mechanism in a neural circuit functions to decode temporally organized spiking.

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Differential Recordings of Local Field Potential:A Genuine Tool to Quantify Functional Connectivity

10.1101/270439 ◽

2018 ◽

Author(s):

Meyer Gabriel ◽

Caponcy Julien ◽

Paul A. Salin ◽

Comte Jean-Christophe

Keyword(s):

Functional Connectivity ◽

Local Field ◽

Signal To Noise Ratio ◽

Field Potential ◽

Low Frequency ◽

Large Area ◽

Signal To Noise ◽

Cortical Areas ◽

Electrophysiological Method ◽

Local Field Potential Lfp

AbstractLocal field potential (LFP) recording is a very useful electrophysiological method to study brain processes. However, this method is criticized for recording low frequency activity in a large area of extracellular space potentially contaminated by distal activity. Here, we theoretically and experimentally compare ground-referenced (RR) with differential recordings (DR). We analyze electrical activity in the rat cortex with these two methods. Compared with RR, DR reveals the importance of local phasic oscillatory activities and their coherence between cortical areas. Finally, we show that DR provides a more faithful assessment of functional connectivity caused by an increase in the signal to noise ratio, and of the delay in the propagation of information between two cortical structures.

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Intracortical neural activity distal to seizure-onset-areas predicts human focal seizures

PLoS ONE ◽

10.1371/journal.pone.0211847 ◽

2019 ◽

Vol 14 (7) ◽

pp. e0211847 ◽

Cited By ~ 1

Author(s):

Timothée Proix ◽

Mehdi Aghagolzadeh ◽

Joseph R. Madsen ◽

Rees Cosgrove ◽

Emad Eskandar ◽

...

Keyword(s):

Neural Activity ◽

Seizure Onset ◽

Focal Seizures

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Coherent Electrical Activity Between Vibrissa Sensory Areas of Cerebellum and Neocortex Is Enhanced During Free Whisking

Journal of Neurophysiology ◽

10.1152/jn.00229.2001 ◽

2002 ◽

Vol 87 (4) ◽

pp. 2137-2148 ◽

Cited By ~ 70

Author(s):

Sean M. O'Connor ◽

Rune W. Berg ◽

David Kleinfeld

Keyword(s):

Electrical Activity ◽

Sensory Input ◽

Field Potential ◽

Sensory Cortex ◽

Brain Areas ◽

Low Coherence ◽

Primary Sensory Cortex ◽

High Level ◽

The Brain ◽

Local Field Potential Lfp

We tested if coherent signaling between the sensory vibrissa areas of cerebellum and neocortex in rats was enhanced as they whisked in air. Whisking was accompanied by 5- to 15-Hz oscillations in the mystatial electromyogram, a measure of vibrissa position, and by 5- to 20-Hz oscillations in the differentially recorded local field potential (∇LFP) within the vibrissa area of cerebellum and within the ∇LFP of primary sensory cortex. We observed that only 10% of the activity in either cerebellum or sensory neocortex was significantly phase-locked to rhythmic motion of the vibrissae; the extent of this modulation is in agreement with the results from previous single-unit measurements in sensory neocortex. In addition, we found that 40% of the activity in the vibrissa areas of cerebellum and neocortex was significantly coherent during periods of whisking. The relatively high level of coherence between these two brain areas, in comparison with their relatively low coherence with whisking per se, implies that the vibrissa areas of cerebellum and neocortex communicate in a manner that is incommensurate with whisking. To the extent that the vibrissa areas of cerebellum and neocortex communicate over the same frequency band as that used by whisking, these areas must multiplex electrical activity that is internal to the brain with activity that is that phase-locked to vibrissa sensory input.

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Individual and synergistic effects of sniffing frequency and flow rate on olfactory bulb activity

Journal of Neurophysiology ◽

10.1152/jn.00672.2011 ◽

2011 ◽

Vol 106 (6) ◽

pp. 2813-2824 ◽

Cited By ~ 22

Author(s):

Emmanuelle Courtiol ◽

Chloé Hegoburu ◽

Philippe Litaudon ◽

Samuel Garcia ◽

Nicolas Fourcaud-Trocmé ◽

...

Keyword(s):

Olfactory Bulb ◽

Flow Rate ◽

Animal Behavior ◽

Synergistic Effects ◽

Field Potential ◽

Sampling Frequency ◽

Experimental Approaches ◽

Sampling Flow Rate ◽

Additional Support ◽

Local Field Potential Lfp

Is faster or stronger sniffing important for the olfactory system? Odorant molecules are captured by sniffing. The features of sniffing constrain both the temporality and intensity of the input to the olfactory structures. In this context, it is clear that variations in both the sniff frequency and flow rate have a major impact on the activation of olfactory structures. However, the question of how frequency and flow rate individually or synergistically impact bulbar output has not been answered. We have addressed this question using multiple experimental approaches. In double-tracheotomized, anesthetized rats, we recorded both the bulbar local field potential (LFP) and mitral/tufted cells' activities when the sampling flow rate and frequency were controlled independently. We found that a tradeoff between the sampling frequency and the flow rate could maintain olfactory bulb sampling-related rhythmicity and that only an increase in flow rate could induce a faster, odor-evoked response. LFP and sniffing were recorded in awake rats. We found that sampling-related rhythmicity was maintained during high-frequency sniffing. Furthermore, we observed that the covariation between the frequency and flow rate, which was necessary for the tradeoff seen in the anesthetized preparations, also occurred in awake animals. Our study shows that the sampling frequency and flow rate can act either independently or synergistically on bulbar output to shape the neuronal message. The system likely takes advantage of this flexibility to adapt sniffing strategies to animal behavior. Our study provides additional support for the idea that sniffing and olfaction function in an integrated manner.

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