scholarly journals Network and synaptic mechanisms underlying high frequency oscillations in the rat and cat olfactory bulb under ketamine-xylazine anesthesia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Władysław Średniawa ◽  
Jacek Wróbel ◽  
Ewa Kublik ◽  
Daniel Krzysztof Wójcik ◽  
Miles Adrian Whittington ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
High Frequency ◽  
Piriform Cortex ◽  
Surgical Excision ◽  
Synaptic Activity ◽  
High Frequency Oscillations ◽  
Gamma Power ◽  
Subcortical Regions ◽  
Inhibitory Interactions ◽  
Synaptic Mechanisms

AbstractWake-related ketamine-dependent high frequency oscillations (HFO) can be recorded in local field potentials (LFP) from cortical and subcortical regions in rodents. The mechanisms underlying their generation and occurrence in higher mammals are unclear. Unfortunately, anesthetic doses of pure ketamine attenuate HFO, which has precluded their investigation under anesthesia. Here, we show ketamine-xylazine (KX) anesthesia is associated with a prominent 80–130 Hz rhythm in the olfactory bulb (OB) of rats, whereas 30–65 Hz gamma power is diminished. Simultaneous LFP and thermocouple recordings revealed the 80–130 Hz rhythm was dependent on nasal respiration. This rhythm persisted despite surgical excision of the piriform cortex. Silicon probes spanning the dorsoventral aspect of the OB revealed this rhythm was strongest in ventral areas and associated with microcurrent sources about the mitral layer. Pharmacological microinfusion studies revealed dependency on excitatory-inhibitory synaptic activity, but not gap junctions. Finally, a similar rhythm occurred in the OB of KX-anesthetized cats, which shared key features with our rodent studies. We conclude that the activity we report here is driven by nasal airflow, local excitatory-inhibitory interactions, and conserved in higher mammals. Additionally, KX anesthesia is a convenient model to investigate further the mechanisms underlying wake-related ketamine-dependent HFO.

scholarly journals Network and synaptic mechanisms underlying high frequency oscillations in the rat and cat olfactory bulb under ketamine-xylazine anesthesia

2020 ◽  
Author(s):  
Władysław Średniawa ◽  
Jacek Wróbel ◽  
Ewa Kublik ◽  
Daniel Krzysztof Wójcik ◽  
Miles Adrian Whittington ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
High Frequency ◽  
Piriform Cortex ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Synaptic Activity ◽  
Surgical Removal ◽  
Nasal Airflow ◽  
High Frequency Oscillations ◽  
Subcortical Regions

AbstractHigh frequency oscillations (HFO) are receiving increased attention for their role in health and disease. Ketamine-dependent HFO have been identified in cortical and subcortical regions in rodents, however, the mechanisms underlying their generation and whether they occur in higher mammals is unclear. Here, we show under ketamine-xylazine anesthesia, classical gamma oscillations diminish and a prominent > 80 Hz oscillation emerges in the olfactory bulb of rats and cats. In cats negligible HFO was observed in the thamalus and visual cortex indicating the OB was a suitable site for further investigation. Simultaneous local field potential and thermocouple recordings demonstrated HFO was dependent on nasal airflow. Silicon probe mapping studies spanning almost the entire dorsal ventral aspect of the OB revealed this rhythm was strongest in ventral areas of the bulb and associated with microcurrent sources about the mitral layer. Pharmacological microinfusion studies revealed HFO was dependent on excitatory-inhibitory synaptic activity, but not gap junctions. Finally, we showed HFO was preserved despite surgical removal of the piriform cortex. We conclude that ketamine-dependent HFO in the OB are driven by nasal airflow and local dendrodendritic interactions. The relevance of our findings to ketamine’s model of psychosis in awake state are also discussed.

scholarly journals Pathological high frequency oscillations associate with increased GABA synaptic activity in pediatric epilepsy surgery patients

2020 ◽  
Vol 134 ◽  
pp. 104618 ◽  
Author(s):  
Carlos Cepeda ◽  
Simon Levinson ◽  
Hiroki Nariai ◽  
Vannah-Wila Yazon ◽  
Conny Tran ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
High Frequency ◽  
Synaptic Activity ◽  
Pediatric Epilepsy ◽  
High Frequency Oscillations ◽  
Pediatric Epilepsy Surgery

scholarly journals The olfactory bulb is a source of high-frequency oscillations (130–180 Hz) associated with a subanesthetic dose of ketamine in rodents

2018 ◽  
Vol 44 (2) ◽  
pp. 435-442 ◽  
Author(s):  
Mark Jeremy Hunt ◽  
Natalie E Adams ◽  
Władysław Średniawa ◽  
Daniel K Wójcik ◽  
Anna Simon ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
High Frequency ◽  
High Frequency Oscillations

scholarly journals Nasal respiration is necessary for the emergence of ketamine-induced high frequency network oscillations and behavioral hyperactivity in freely moving rats

2020 ◽  
Author(s):  
Jacek Wróbel ◽  
Władysław Średniawa ◽  
Gabriela Bernatowicz ◽  
Jaroslaw Zygierewicz ◽  
Daniel K Wójcik ◽  
...  
Keyword(s):  
High Frequency ◽  
Behavioral Activation ◽  
Brain Regions ◽  
Basal Respiration ◽  
Oscillatory Activity ◽  
High Frequency Oscillations ◽  
Freely Moving Rats ◽  
Theta Frequency ◽  
Freely Moving ◽  
Subcortical Regions

AbstractChanges in oscillatory activity are widely reported after subanesthetic ketamine, however their mechanisms of generation are unclear. Here, we tested the hypothesis that nasal respiration underlies the emergence of high-frequency oscillations (130-180 Hz, HFO) and behavioral activation after ketamine in freely moving rats. We found ketamine 20 mg/kg provoked “fast” theta sniffing in rodents which correlated with increased locomotor activity and HFO power in the OB. Bursts of ketamine-dependent HFO were coupled to “fast” theta frequency sniffing. Theta coupling of HFO bursts were also found in the prefrontal cortex and ventral striatum which, although of smaller amplitude, were in phase with OB activity. Haloperidol 1 mg/kg pretreatment prevented ketamine-dependent increases in fast sniffing and instead HFO coupling to slower basal respiration. Consistent with ketamine-dependent HFO being driven by nasal respiration, unilateral naris blockade led to an ipsilateral reduction in ketamine-dependent HFO power compared to the control side. Bilateral nares blockade reduced ketamine-induced hyperactivity and HFO power and frequency. In conclusion, nasal entrainment of ketamine-dependent HFO across cortical and subcortical regions at theta frequencies represents a mechanism of orchestrated neural activity across distinct brain regions. The dense divergent connectivity of the olfactory system serves to broadcast this HFO to limbic areas.

scholarly journals Synaptic Noise and Physiological Coupling Generate High-Frequency Oscillations in a Hippocampal Computational Model

2009 ◽  
Vol 102 (4) ◽  
pp. 2342-2357 ◽  
Author(s):  
William C. Stacey ◽  
Maciej T. Lazarewicz ◽  
Brian Litt
Keyword(s):  
High Frequency ◽  
Gamma Oscillations ◽  
Low Noise ◽  
Synaptic Activity ◽  
Signal Frequency ◽  
Model Parameters ◽  
Periodic Signal ◽  
Normal Brain ◽  
High Frequency Oscillations ◽  
Synaptic Noise

There is great interest in the role of coherent oscillations in the brain. In some cases, high-frequency oscillations (HFOs) are integral to normal brain function, whereas at other times they are implicated as markers of epileptic tissue. Mechanisms underlying HFO generation, especially in abnormal tissue, are not well understood. Using a physiological computer model of hippocampus, we investigate random synaptic activity (noise) as a potential initiator of HFOs. We explore parameters necessary to produce these oscillations and quantify the response using the tools of stochastic resonance (SR) and coherence resonance (CR). As predicted by SR, when noise was added to the network the model was able to detect a subthreshold periodic signal. Addition of basket cell interneurons produced two novel SR effects: 1) improved signal detection at low noise levels and 2) formation of coherent oscillations at high noise that were entrained to harmonics of the signal frequency. The periodic signal was then removed to study oscillations generated only by noise. The combined effects of network coupling and synaptic noise produced coherent, periodic oscillations within the network, an example of CR. Our results show that, under normal coupling conditions, synaptic noise was able to produce gamma (30–100 Hz) frequency oscillations. Synaptic noise generated HFOs in the ripple range (100–200 Hz) when the network had parameters similar to pathological findings in epilepsy: increased gap junctions or recurrent synaptic connections, loss of inhibitory interneurons such as basket cells, and increased synaptic noise. The model parameters that generated these effects are comparable with published experimental data. We propose that increased synaptic noise and physiological coupling mechanisms are sufficient to generate gamma oscillations and that pathologic changes in noise and coupling similar to those in epilepsy can produce abnormal ripples.

scholarly journals Subcortical Hyperexcitability in Migraineurs: A High-Frequency Oscillation Study

2011 ◽  
Vol 38 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Kuan-Lin Lai ◽  
Kwong-Kum Liao ◽  
Jong-Ling Fuh ◽  
Shuu-Jiun Wang
Keyword(s):  
High Frequency ◽  
Area Under Curve ◽  
Late Phase ◽  
Intracortical Inhibition ◽  
High Frequency Oscillation ◽  
Frequency Filter ◽  
Frequency Oscillation ◽  
High Frequency Oscillations ◽  
Subcortical Regions ◽  
And Control

Objective:An abnormal central nervous system excitability level was found in patients with migraine. Whether it is hyper- or hypo-excitable is still debated. This study aimed to compare the somatosensory high-frequency oscillations (HFOs), which reflected subcortical excitability (early phase) and intracortical inhibition (late phase), between patients with migraine and control subjects.Methods:HFOs were recorded from C3'-Fz, using a 500-1000 Hz frequency filter after stimulation at right median nerves at the wrists, and divided into early and late phases based on the N20 peak. Fifty-nine untreated patients (n=24 during ictal period; n=35, interictal) and 22 controls finished the study.Results:In early HFOs, patients both during ictal and interictal periods had higher maximal amplitudes (p =0.039) and area-under-curve (p =0.029) than those of the controls. Regarding the late HFOs, there were no significant differences among these groups.Conclusion:Our study suggests a hyper-excitable state in the subcortical regions in patients with migraine both during interictal and ictal periods.

scholarly journals Smell-induced gamma oscillations in human olfactory cortex are required for accurate perception of odor identity

PLoS Biology ◽  
2022 ◽  
Vol 20 (1) ◽  
pp. e3001509
Author(s):  
Qiaohan Yang ◽  
Guangyu Zhou ◽  
Torben Noto ◽  
Jessica W. Templer ◽  
Stephan U. Schuele ◽  
...  
Keyword(s):  
High Frequency ◽  
Olfactory System ◽  
Piriform Cortex ◽  
Low Frequency ◽  
Gamma Oscillations ◽  
Odor Identification ◽  
Identification Accuracy ◽  
Electrophysiological Response ◽  
Electrophysiological Properties ◽  
High Frequency Oscillations

Studies of neuronal oscillations have contributed substantial insight into the mechanisms of visual, auditory, and somatosensory perception. However, progress in such research in the human olfactory system has lagged behind. As a result, the electrophysiological properties of the human olfactory system are poorly understood, and, in particular, whether stimulus-driven high-frequency oscillations play a role in odor processing is unknown. Here, we used direct intracranial recordings from human piriform cortex during an odor identification task to show that 3 key oscillatory rhythms are an integral part of the human olfactory cortical response to smell: Odor induces theta, beta, and gamma rhythms in human piriform cortex. We further show that these rhythms have distinct relationships with perceptual behavior. Odor-elicited gamma oscillations occur only during trials in which the odor is accurately perceived, and features of gamma oscillations predict odor identification accuracy, suggesting that they are critical for odor identity perception in humans. We also found that the amplitude of high-frequency oscillations is organized by the phase of low-frequency signals shortly following sniff onset, only when odor is present. Our findings reinforce previous work on theta oscillations, suggest that gamma oscillations in human piriform cortex are important for perception of odor identity, and constitute a robust identification of the characteristic electrophysiological response to smell in the human brain. Future work will determine whether the distinct oscillations we identified reflect distinct perceptual features of odor stimuli.

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