Navegando por Autor "Draguhn, Andreas"
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Artigo Global slowing of network oscillations in mouse neocortex by diazepam(2013) Scheffzük, Claudia; Kukushka, Valeriy I.; Vyssotski, Alexei L.; Draguhn, Andreas; Tort, Adriano Bretanha Lopes; Branka, JurijArtigo Hippocampal Respiration-Driven Rhythm Distinct from Theta Oscillations in Awake Mice(2016) Chi, Vivan Nguyen; Muller, Carola; Wolfenstetter, Thérèse; Yanovsky, Yevgenij; Draguhn, Andreas; Tort, Adriano Bretanha Lopes; Brankack, JurijWe have recently described a slow oscillation in the hippocampus of urethane-anesthetized mice, which couples to nasal respiration and is clearly distinct from co-occurring theta oscillations. Here we set out to investigate whether such type of patterned network activity, which we named “hippocampal respiration rhythm” (HRR), also occurs in awake mice. In freely moving mice, instantaneous respiration rate is extremely variable, and respiration is superimposed by bouts of sniffing. To reduce this variability, we clamped the behavior of the animal to either awake immobility or treadmill running by using a head-fixed setup while simultaneously recording respiration and field potentials from the olfactory bulb (OB) and hippocampus. Head-fixed animals often exhibited long periods of steady respiration rate during either immobility or running, which allowed for spectral and coherence analyses with a sufficient frequency resolution to sort apart respiration and theta activities. We could thus demonstrate the existence of HRR in awake animals, namely, a respiration-entrained slow rhythm with highest amplitude at the dentate gyrus. HRR was most prominent during immobility and running with respiration rates slower than theta oscillations. Nevertheless, HRR could also be faster than theta. Discharges of juxtacellularly recorded cells in CA1 and dentate gyrus were modulated by HRR and theta oscillations. Granger directionality analysis revealed that HRR is caused by the OB and that theta oscillations in OB are caused by the hippocampus. Our results suggest that respiration-coupled oscillations aid the exchange of information between olfactory and memory networks.Artigo Impaired theta-gamma coupling in APP-defcient mice(2016-02-24) Zhang, Xiaomin; Zhong, Wewei; Brankačk, Jurij; Weyer, Sascha W.; Müller, Ulrike C.; Tort, Adriano Bretanha Lopes; Draguhn, AndreasAmyloid precursor protein (APP) is critically involved in the pathophysiology of Alzheimer's disease, but its physiological functions remain elusive. Importantly, APP knockout (APP-KO) mice exhibit cognitive deficits, suggesting that APP plays a role at the neuronal network level. To investigate this possibility, we recorded local field potentials (LFPs) from the posterior parietal cortex, dorsal hippocampus and lateral prefrontal cortex of freely moving APP-KO mice. Spectral analyses showed that network oscillations within the theta- and gamma-frequency bands were not different between APP-KO and wild-type mice. Surprisingly, however, while gamma amplitude coupled to theta phase in all recorded regions of wild-type animals, in APP-KO mice theta-gamma coupling was strongly diminished in recordings from the parietal cortex and hippocampus, but not in LFPs recorded from the prefrontal cortex. Thus, lack of APP reduces oscillatory coupling in LFP recordings from specific brain regions, despite not affecting the amplitude of the oscillations. Together, our findings reveal reduced cross-frequency coupling as a functional marker of APP deficiency at the network level.Artigo Parallel detection of theta and respiration-coupled oscillations throughout the mouse brain(2018-04-24) Tort, Adriano Bretanha Lopes; Ponsel, Simon; Jessberger, Jakob; Yanovsky, Yevgenij; Brankačk, Jurij; Draguhn, AndreasSlow brain oscillations are usually coherent over long distances and thought to link distributed cell assemblies. In mice, theta (5–10 Hz) stands as one of the most studied slow rhythms. However, mice often breathe at theta frequency, and we recently reported that nasal respiration leads to local field potential (LFP) oscillations that are independent of theta. Namely, we showed respiration-coupled oscillations in the hippocampus, prelimbic cortex, and parietal cortex, suggesting that respiration could impose a global brain rhythm. Here we extend these findings by analyzing LFPs from 15 brain regions recorded simultaneously with respiration during exploration and REM sleep. We find that respiration-coupled oscillations can be detected in parallel with theta in several neocortical regions, from prefrontal to visual areas, and also in subcortical structures such as the thalamus, amygdala and ventral hippocampus. They might have escaped attention in previous studies due to the absence of respiration monitoring, the similarity with theta oscillations, and the highly variable peak frequency. We hypothesize that respiration-coupled oscillations constitute a global brain rhythm suited to entrain distributed networks into a common regime. However, whether their widespread presence reflects local network activity or is due to volume conduction remains to be determined.Artigo Respiration and rapid eye movement (REM) sleep substructure: short versus long episodes(Wiley, 2022-11) Hammer, Maximilian; Jung, Felix; Brankačk, Jurij; Yanovsky, Yevgenij; Tort, Adriano Bretanha Lopes; Draguhn, AndreasRapid eye movement (REM) sleep in rodents is defined by the presence of theta rhythm in the absence of movement. The amplitude and frequency of theta oscillations have been used to distinguish between tonic and phasic REM sleep. However, tonic REM sleep has not been further subdivided, although characteristics of network oscillations such as cross-frequency coupling between theta and gamma vary within this sub-state. Recently, it has been shown that theta-gamma coupling depends on an optimal breathing rate of ~5 Hz. The frequency of breathing varies strongly throughout REM sleep, and the duration of single REM sleep episodes ranges from several seconds to minutes, whereby short episodes predominate. Here we studied the relation between breathing frequency, accelerometer activity, and the length of REM sleep periods. We found that small movements detected with three-dimensional accelerometry positively correlate with breathing rate. Interestingly, breathing is slow in short REM sleep episodes, while faster respiration regimes exclusively occur after a certain delay in longer REM sleep episodes. Thus, merging REM sleep episodes of different lengths will result in a predominance of slow respiration due to the higher occurrence of short REM sleep periods. Moreover, our results reveal that not only do phasic REM sleep epochs predominantly occur during long REM sleep episodes, but that the long episodes also have faster theta and higher gamma activity. These observations suggest that REM sleep can be further divided from a physiological point of view depending on its duration. Higher levels of arousal during REM sleep, indicated by higher breathing rates, can only be captured in long REM sleepArtigo Respiration-entrained brain rhythms are global but often overlooked(2018-04) Tort, Adriano Bretanha Lopes; Brankack, Jurij; Draguhn, AndreasWe revisit recent evidence showing that nasal respiration entrains oscillations at the same frequency as breathing in several regions of the rodent brain. Moreover, respiration modulates the amplitude of a specific gamma sub-band (70-120Hz), most prominently in frontal regions. Since rodents often breathe at delta and theta frequencies, we caution that previous studies on delta and theta power and their cross-regional synchrony, as well as on delta-gamma and theta-gamma coupling, may have detected the respiration-entrained rhythm and respiration-gamma coupling. We argue that the simultaneous tracking of respiration along with electrophysiological recordings is necessary to properly identify brain oscillations. We hypothesize that respiration-entrained oscillations aid long-range communication in the brain.Artigo Selective Coupling between Theta Phase and Neocortical Fast Gamma Oscillations during REM-Sleep in Mice(2011) Scheffzu¨ k, Claudia; Kukushka, Valeriy I.; Vyssotski, Alexei L.; Draguhn, Andreas; Tort, Adriano Bretanha Lopes; Brankacˇk, JurijArtigo Selective entrainment of gamma subbands by different slow network oscillations(2017-03-16) Zhong, Weiwei; Ciatipis, Mareva; Wolfenstetter, Thérèse; Jessberger, Jakob; Müller, Carola; Ponsel, Simon; Yanovsky, Yevgenij; Brankack, Jurij; Tort, Adriano Bretanha Lopes; Draguhn, AndreasTheta oscillations (4–12 Hz) are thought to provide a common temporal reference for the exchange of information among distant brain networks. On the other hand, faster gamma-frequency oscillations (30–160 Hz) nested within theta cycles are believed to underlie local information processing. Whether oscillatory coupling between global and local oscillations, as showcased by theta-gamma coupling, is a general coding mechanism remains unknown. Here, we investigated two different patterns of oscillatory network activity, theta and respiration-induced network rhythms, in four brain regions of freely moving mice: olfactory bulb (OB), prelimbic cortex (PLC), parietal cortex (PAC), and dorsal hippocampus [cornu ammonis 1 (CA1)]. We report differential state- and region-specific coupling between the slow large-scale rhythms and superimposed fast oscillations. During awake immobility, all four regions displayed a respiration-entrained rhythm (RR) with decreasing power from OB to CA1, which coupled exclusively to the 80- to 120-Hz gamma subband (γ2). During exploration, when theta activity was prevailing, OB and PLC still showed exclusive coupling of RR with γ2 and no thetagamma coupling, whereas PAC and CA1 switched to selective coupling of theta with 40- to 80-Hz (γ1) and 120- to 160-Hz (γ3) gamma subbands. Our data illustrate a strong, specific interaction between neuronal activity patterns and respiration. Moreover, our results suggest that the coupling between slow and fast oscillations is a general brain mechanism not limited to the theta rhythm.Artigo Slow Oscillations in the Mouse Hippocampus Entrained by Nasal Respiration(2014-04-23) Yanovsky, Yevgenij; Ciatipis, Mareva; Draguhn, Andreas; Tort, Adriano Bretanha Lopes; Brankacˇk, JurijArtigo Theta-associated high-frequency oscillations (110–160 Hz) in the hippocampus and neocortex(2013) Tort, Adriano Bretanha Lopes; Scheffer-Teixeira, Robson; Souza, Bryan C.; Draguhn, Andreas; Brankacˇk, JurijArtigo Theta-gamma coupling during REM sleep depends on breathing rate(Oxford University Press, 2021-07-23) Hammer, Maximilian; Schwale, Chrysovalandis; Brankačk, Jurij; Draguhn, Andreas; Tort, Adriano Bretanha LopesTemporal coupling between theta and gamma oscillations is a hallmark activity pattern of several cortical networks and becomes especially prominent during REM sleep. In a parallel approach, nasal breathing has been recently shown to generate phase-entrained network oscillations which also modulate gamma. Both slow rhythms (theta and respiration-entrained oscillations) have been suggested to aid large-scale integration but they differ in frequency, display low coherence, and modulate different gamma sub-bands. Respiration and theta are therefore believed to be largely independent. In the present work, however, we report an unexpected but robust relation between theta-gamma coupling and respiration in mice. Interestingly, this relation takes place not through the phase of individual respiration cycles, but through respiration rate: the strength of theta-gamma coupling exhibits an inverted V-shaped dependence on breathing rate, leading to maximal coupling at breathing frequencies of 4-6 Hz. Noteworthy, when subdividing sleep epochs into phasic and tonic REM patterns, we find that breathing differentially relates to theta-gamma coupling in each state, providing new evidence for their physiological distinctiveness. Altogether, our results reveal that breathing correlates with brain activity not only through phase-entrainment but also through rate-dependent relations with theta-gamma coupling. Thus, the link between respiration and other patterns of cortical network activity is more complex than previously assumed