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

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.

scholarly journals Optogenetic activation of SST-positive interneurons restores hippocampal theta oscillation impairment induced by soluble amyloid beta oligomersin vivo

2018 ◽  
Author(s):  
Hyowon Chung ◽  
Kyerl Park ◽  
Hyun Jae Jang ◽  
Michael M Kohl ◽  
Jeehyun Kwag
Keyword(s):  
Learning And Memory ◽  
Peak Power ◽  
Pyramidal Neurons ◽  
Hippocampal Slices ◽  
Field Potential ◽  
Theta Oscillations ◽  
Ca1 Pyramidal Neurons ◽  
Theta Frequency ◽  
Hippocampal Theta

AbstractAbnormal accumulation of amyloid β oligomers (AβO) is a hallmark of Alzheimer’s disease (AD), which leads to learning and memory deficits. Hippocampal theta oscillations that are critical in spatial navigation, learning and memory are impaired in AD. Since GABAergic interneurons, such as somatostatin-positive (SST+) and parvalbumin-positive (PV+) interneurons, are believed to play key roles in the hippocampal oscillogenesis, we asked whether AβO selectively impairs these SST+ and PV+ interneurons. To selectively manipulate SST+ or PV+ interneuron activity in mice with AβO pathologyin vivo, we co-injected AβO and adeno-associated virus (AAV) for expressing floxed channelrhodopsin-2 (ChR2) into the hippocampus of SST-Cre or PV-Cre mice. Local field potential (LFP) recordingsin vivoin these AβO–injected mice showed a reduction in the peak power of theta oscillations and desynchronization of spikes from CA1 pyramidal neurons relative to theta oscillations compared to those in control mice. Optogenetic-activation of SST+ but not PV+ interneurons in AβO–injected mice fully restored the peak power of theta oscillations and resynchronized the theta spike phases to a level observed in control mice.In vitrowhole-cell voltage-clamp recordings in CA1 pyramidal neurons in hippocampal slices treated with AβO revealed that short-term plasticity of SST+ interneuron inhibitory inputs to CA1 pyramidal neurons at theta frequency were selectively disrupted while that of PV+ interneuron inputs were unaffected. Together, our results suggest that dysfunction in inputs from SST+ interneurons to CA1 pyramidal neurons may underlie the impairment of theta oscillations observed in AβO-injected micein vivo.Our findings identify SST+ interneurons as a target for restoring theta-frequency oscillations in early AD.

scholarly journals Hippocampal theta bursting and waveform shape reflect CA1 spiking patterns

2018 ◽  
Author(s):  
Scott Cole ◽  
Bradley Voytek
Keyword(s):  
Local Field ◽  
Pyramidal Neurons ◽  
Field Potential ◽  
Brain Regions ◽  
Neuronal Firing ◽  
Detectable Effect ◽  
Field Recordings ◽  
Cognitive States ◽  
Open Questions ◽  
Hippocampal Theta

AbstractBrain rhythms are nearly always analyzed in the spectral domain in terms of their power, phase, and frequency. While this conventional approach has uncovered spike-field coupling, as well as correlations to normal behaviors and pathological states, emerging work has highlighted the physiological and behavioral importance of multiple novel oscillation features. Oscillatory bursts, for example, uniquely index a variety of cognitive states, and the nonsinusoidal shape of oscillations relate to physiological changes, including Parkinson’s disease. Open questions remain regarding how bursts and nonsinusoidal features relate to circuit-level processes, and how they interrelate. By analyzing unit and local field recordings in the rodent hippocampus, we uncover a number of significant relationships between oscillatory bursts, nonsinusoidal waveforms, and local inhibitory and excitatory spiking patterns. Bursts of theta oscillations are surprisingly related to a decrease in pyramidal neuron synchrony, and have no detectable effect on firing sequences, despite significant increases in neuronal firing rates during periods of theta bursting. Theta burst duration is predicted by the asymmetries of its first cycle, and cycle asymmetries relate to firing rate, synchrony, and sequences of pyramidal neurons and interneurons. These results provide compelling physiological evidence that time-domain features, of both nonsinusoidal hippocampal theta waveform and the theta bursting state, reflects local circuit properties. These results point to the possibility of inferring circuit states from local field potential features in the hippocampus and perhaps other brain regions with other rhythms.

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

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.

scholarly journals High-order theta harmonics account for the detection of slow gamma

2018 ◽  
Author(s):  
Y. Zhou ◽  
A. Sheremet ◽  
Y. Qin ◽  
J.P. Kennedy ◽  
N.M. DiCola ◽  
...  
Keyword(s):  
Current Source ◽  
Field Potential ◽  
Low Frequency ◽  
High Order ◽  
Time Frequency ◽  
Source Density ◽  
Inhibitory Postsynaptic Potentials ◽  
Hippocampal Theta ◽  
Frequency Burst ◽  
Local Field Potential Lfp

ABSTRACTLocal field potential (LFP) oscillations are the superposition of excitatory/inhibitory postsynaptic potentials. In the hippocampus, the 20-55 Hz range (‘slow gamma’) is proposed to support cognition independent of other frequencies. However, this band overlaps with theta harmonics. We aimed to dissociate the generators of slow gamma versus theta harmonics with current source density and different LFP decompositions. Hippocampal theta harmonic and slow gamma generators were not dissociable. Moreover, comparison of wavelet, ensemble empirical-mode (EEMD), and Fourier decompositions produced distinct outcomes with wavelet and EEMD failing to resolve high-order theta harmonics well defined by Fourier analysis. The varying sizes of the time-frequency atoms used by wavelet distributed the higher-order harmonics over a broader range giving the impression of a low frequency burst (“slow gamma”). The absence of detectable slow gamma refutes a multiplexed model of cognition in favor of the energy cascade hypothesis in which dependency across oscillatory frequencies exists.

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

2021 ◽  
Author(s):  
Xiang Zou ◽  
Zilu Zhu ◽  
Yu Guo ◽  
Hongmiao Zhang ◽  
Yuchen Liu ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Neural Activity ◽  
Field Potential ◽  
Multiple Wave ◽  
Focal Seizures ◽  
Power Shift ◽  
Power Spectral ◽  
Inhibitory Power ◽  
Local Field Potential Lfp ◽  
Spike Firing

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.

scholarly journals Restoring memory by optogenetic synchronization of hippocampal oscillations in an Alzheimer’s disease mouse model

2018 ◽  
Author(s):  
Eleonora Ambrad Giovannetti ◽  
Stefanie Poll ◽  
Daniel Justus ◽  
Hiroshi Kaneko ◽  
Falko Fuhrmann ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Field Potential ◽  
Temporal Organization ◽  
Theta Oscillations ◽  
The Novel ◽  
Object Recognition Test ◽  
Reduced Frequency ◽  
Local Field Potential Lfp

Disrupted neural oscillations are a feature of Alzheimer’s disease (AD). We observed reduced frequency of theta oscillations in the hippocampal local field potential (LFP) in a mouse model of beta-amyloidosis. By restoring the temporal organization of theta oscillations using LFP-guided closed-loop optogenetic stimulation of parvalbumin-positive interneurons, we could rescue memory deficits of APP/PS1 mice in the novel object recognition test.

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

eLife ◽  
2020 ◽  
Vol 9 ◽  
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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