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

2011 ◽  
Vol 106 (6) ◽  
pp. 2813-2824 ◽  
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.

scholarly journals The Olfactory Bulb Facilitates Use of Category Bounds for Classification of Odorants in Different Intensity Groups

2020 ◽  
Vol 14 ◽  
Author(s):  
Justin Losacco ◽  
Nicholas M. George ◽  
Naoki Hiratani ◽  
Diego Restrepo
Keyword(s):  
Decision Making ◽  
Olfactory Bulb ◽  
Field Potential ◽  
Odor Concentration ◽  
Linear Discriminant ◽  
Percent Correct ◽  
Theta Phase ◽  
Decoding Accuracy ◽  
Local Field Potential Lfp

Signal processing of odor inputs to the olfactory bulb (OB) changes through top-down modulation whose shaping of neural rhythms in response to changes in stimulus intensity is not understood. Here we asked whether the representation of a high vs. low intensity odorant in the OB by oscillatory neural activity changed as the animal learned to discriminate odorant concentration ranges in a go-no go task. We trained mice to discriminate between high vs. low concentration odorants by learning to lick to the rewarded group (low or high). We recorded the local field potential (LFP) in the OB of these mice and calculated the theta-referenced beta or gamma oscillation power (theta phase-referenced power, or tPRP). We found that as the mouse learned to differentiate odorant concentrations, tPRP diverged between trials for the rewarded vs. the unrewarded concentration range. For the proficient animal, linear discriminant analysis was able to predict the rewarded odorant group and the performance of this classifier correlated with the percent correct behavior in the odor concentration discrimination task. Interestingly, the behavioral response and decoding accuracy were asymmetric as a function of concentration when the rewarded stimulus was shifted between the high and low odorant concentration ranges. A model for decision making motivated by the statistics of OB activity that uses a single threshold in a logarithmic concentration scale displays this asymmetry. Taken together with previous studies on the intensity criteria for decisions on odorant concentrations, our finding suggests that OB oscillatory events facilitate decision making to classify concentrations using a single intensity criterion.

scholarly journals Effect of Xylazine–Tiletamine–Zolazepam on the Local Field Potential of the Rat Olfactory Bulb

2020 ◽  
Vol 70 (6) ◽  
pp. 492-498
Author(s):  
Peter Olegovich Kosenko ◽  
Aleksey Borisovich Smolikov ◽  
Viktor Borisovich Voynov ◽  
Pavel Dmitrievich Shaposhnikov ◽  
Anton Igorevich Saevskiy ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Local Field ◽  
Local Field Potential ◽  
Chloral Hydrate ◽  
Field Potential ◽  
Extended Period ◽  
Information Analysis ◽  
Dynamic Changes ◽  
Local Field Potential Lfp ◽  
Oscillatory Processes

Neural oscillations of the mammalian olfactory system have been studied for decades. This research suggests they are linked to various processes involved in odor information analysis, depending on the vigilance state and presentation of stimuli. In addition, the effects of various anesthetics, including commonly used ones like chloral hydrate, pentobarbital, ketamine, and urethane, on the local field potential (LFP) in the olfactory bulb (OB) have been studied. In particular, the combination of xylazine and tiletamine–zolazepam has been shown to produce steady anesthesia for an extended period and relatively few adverse effects; however, their effects on the LFP in the OB remain unknown. To study those effects, we recorded the LFP in the OB of rats under xylazine–tiletamine–zolazepam anesthesia. During the period of anesthesia, the spectral powers of the 1–4, 9–16, 31–64, 65–90 frequency bands increased significantly, and that of 91–170 Hz frequency band decreased significantly, whereas no significant changes were observed in the 5–8 and 17–30 Hz ranges. These results reveal dynamic changes in the time and frequency characteristics of the LFP in the OB of rats under xylazine–tiletamine– zolazepam anesthesia and suggest that this combination of anesthetics could be used for studying oscillatory processes in the OB of rats.

Coherent network oscillations by olfactory interneurons: modulation by endogenous amines

1993 ◽  
Vol 69 (6) ◽  
pp. 1930-1939 ◽  
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.

Dopamine D2 Receptor–Mediated Presynaptic Inhibition of Olfactory Nerve Terminals

2001 ◽  
Vol 86 (6) ◽  
pp. 2986-2997 ◽  
Author(s):  
Matthew Ennis ◽  
Fu-Ming Zhou ◽  
Kelly J. Ciombor ◽  
Vassiliki Aroniadou-Anderjaska ◽  
Abdallah Hayar ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Dopamine D2 Receptor ◽  
Signal Transmission ◽  
D2 Receptor ◽  
Field Potential ◽  
Olfactory Nerve ◽  
D2 Receptors ◽  
Receptor Subtype ◽  
Juxtaglomerular Cells ◽  
Synaptic Responses

Olfactory receptor neurons of the nasal epithelium project via the olfactory nerve (ON) to the glomeruli of the main olfactory bulb, where they form glutamatergic synapses with the apical dendrites of mitral and tufted cells, the output cells of the olfactory bulb, and with juxtaglomerular interneurons. The glomerular layer contains one of the largest population of dopamine (DA) neurons in the brain, and DA in the olfactory bulb is found exclusively in juxtaglomerular neurons. D2 receptors, the predominant DA receptor subtype in the olfactory bulb, are found in the ON and glomerular layers, and are present on ON terminals. In the present study, field potential and single-unit recordings, as well as whole cell patch-clamp techniques, were used to investigate the role of DA and D2 receptors in glomerular synaptic processing in rat and mouse olfactory bulb slices. DA and D2 receptor agonists reduced ON-evoked synaptic responses in mitral/tufted and juxtaglomerular cells. Spontaneous and ON-evoked spiking of mitral cells was also reduced by DA and D2 agonists, and enhanced by D2 antagonists. DA did not produce measurable postsynaptic changes in juxtaglomerular cells, nor did it alter their responses to mitral/tufted cell inputs. DA also reduced 1) paired-pulse depression of ON-evoked synaptic responses in mitral/tufted and juxtaglomerular cells and 2) the amplitude and frequency of spontaneous, but not miniature, excitatory postsynaptic currents in juxtaglomerular cells. Taken together, these findings are consistent with the hypothesis that activation of D2 receptors presynaptically inhibits ON terminals. DA and D2 agonists had no effect in D2 receptor knockout mice, suggesting that D2 receptors are the only type of DA receptors that affect signal transmission from the ON to the rodent olfactory bulb.

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

2009 ◽  
Vol 101 (4) ◽  
pp. 1921-1931 ◽  
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.

scholarly journals Oscillatory integration windows in neurons

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.

scholarly journals Ozone removal efficiency of the KI-denuder in the carbonyl sampling

2019 ◽  
Vol 2 (5) ◽  
pp. 153-160
Author(s):  
Huy Huu Duong ◽  
Vui Thi Kim Tran ◽  
Chuong Thanh Nguyen ◽  
Hien Thi To
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Carbonyl Compounds ◽  
Climatic Conditions ◽  
Ho Chi Minh City ◽  
High Humidity ◽  
Optimum Parameters ◽  
Sampling Flow Rate ◽  
High Humidity Condition ◽  
Sampling Flow

In the carbonyl sampling of 2, 4- dinitrophenylhydrazine (DNPH) impregnated cartridge, the ozone removal was necessary because ozone reacted with the DNPH derivatives. A commercial ozone scrubber was usually used to remove O3. However, high humidity leaded to carbonyl compounds being trapped on the ozone scrubber before passing through the DNPH cartridge. The purpose of this study was to assess the ozone removal by KI-denuder under the climatic conditions of Ho Chi Minh City. Several parameters including air sampling flow rate and denuder length were optimized to achieve the highest removal efficiency. The optimum parameters of the KI denuder were the sampling flow rate of less than 1 L/min, and the denuder length of 20 cm. The effect of the initial O3 concentration on the removal efficiency was also investigated. Finally, the ozone removal efficiency of KI-denuder was compared to that of ozone scrubber when two devices were applied for the carbonyl sampling during field measurement. The results show that KI-denuder could be used to replace the ozone scrubber with high removal efficiency, particularly in high humidity condition. In conclusion, KI-denuder was effective, simple, easy to use and cheap. Therefore, it was encouraged to use in carbonyl sampling.

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

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.

Respiratory Gas Analysers

2011 ◽  
Author(s):  
Patrick Magee ◽  
Mark Tooley
Keyword(s):  
Flow Rate ◽  
Delay Time ◽  
Physical Principle ◽  
Breathing System ◽  
Sampling Tube ◽  
Gas Concentration ◽  
Square Wave ◽  
Gas Sampling ◽  
Sampling Flow Rate ◽  
Sampling Flow

The purpose of respiratory gas analysis during anaesthesia is to identify and measure the concentrations, on a breath by breath basis, of the individual gases and vapours in use. It may also be useful as a guide to cardiac function or to identify trace contaminant gases. Different techniques use different physicochemical properties of the gas or vapour. An understanding of the physical principle underlying each method is necessary in order to recognise the value and limitations of each. In terms of the device’s ability to respond on a breath by breath basis, there are two important components: the time taken for the gas to be sampled from the anaesthetic machine or breathing system, the delay time; then there is the time taken for the device to measure the gas concentration, the response time. This is depicted in Figure 16.1. Most of the delay occurs in the delay time or transit time and can be reduced either by analysing the gas sample close to the airway, or by using as short and thin a sampling tube and as high a sampling flow rate to the analyser as possible [Chan et al. 2003]; the sampling flow rate is usually of the order of 100 to 200 ml min−1. If minimal fresh gas flow rates are being used in a circle anaesthetic breathing system and the sampled gas is not returned to the breathing system, then a high gas sampling rate could represent a significant gas leak. Figure 16.1 shows a sigmoid curve of recorded gas concentration change in response to a square wave input change. The response of a gas analyser is often expressed as the time taken to produce a 90–95% response to a step or square wave input change. A square wave change in gas concentration can be produced by moving a gas sampling tube rapidly into and out of a gas stream, by bursting a small balloon within a sampling volume containing a gas sample, or by switching a shutter to a gas sample volume using a solenoid valve. An important part of the use of gas analysers is zeroing and calibration since they are all prone to drift in both zero and gain.

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