The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
J Konopacki - One of the best experts on this subject based on the ideXlab platform.
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effects of locus coeruleus activation and inactivation on hippocampal formation Theta Rhythm in anesthetized rats
Brain Research Bulletin, 2020Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously obtained data suggests that noradrenaline (NE) released from the efferent locus coeruleus (LC) endings in hippocampal formation (HPC) may serve as an important modulating signal involved in the pharmacological mechanisms responsible for the production of type 2 Theta Rhythm in rats. Hence, two distinct hypotheses were tested in the present study: 1/ if the decrease in HPC level of NE is correlated with the desynchronization of HPC field potential, then the inhibition of LC would be expected to abolish HPC type 2 Theta Rhythm; 2/ if the increase in HPC NE level is correlated with synchronization of HPC field potential, then the stimulation of LC would be expected to produce type 2 Theta. The experiments were performed using an experimental model of HPC type 2 Theta Rhythm recorded in urethanized rats. It was demonstrated that electrical stimulation of LC produced type 2 Theta Rhythm whereas procaine injection into LC, in contrast, reversibly abolished type 2 Theta. The possible relation of type 2 Theta Rhythm with some disturbances of Alzheimer disease are addressed.
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gabaergic mediation of hippocampal Theta Rhythm induced by stimulation of the vagal nerve
Brain Research Bulletin, 2019Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:The key question to be answered in the present study was whether the medial septal GABAergic receptors are engaged in the pharmacological profile of the hippocampal formation (HPC) Theta Rhythm induced by vagal nerve stimulation (VNS). It was demonstrated that the medial septal microinfusion of GABAA and GABAB agonists (muscimol and baclofen) resulted in a progressive reduction of the power of VNS-induced Theta. The medial septal microinfusion of GABAA and GABAB antagonists (bicuculline and 2-OH saclofen) resulted in the generation of VNS-induced Theta with increased power. The effect of the combined medial septal microinfusion of GABAA agonist and antagonist and GABAB agonist and antagonist on VNS-induced Theta Rhythm was also evaluated: in the presence of GABAA,B antagonists the effect of agonists predominated. In separate experiments, GABAA and GABAB antagonists were administrated in anesthetized rats pretreated with i.v. administration of atropine sulfate. Atropine was found to abolish spontaneous Theta and VNS-induced Theta examined in the presence of bicuculline or 2-OH saclofen. The present data provide evidence that the medial septal GABAA and GABAB receptors are involved in the central mechanisms responsible for modulation of VNS-induced HPC Theta oscillations. Furthermore, the results of the present study also demonstrate that, in fact, both GABAergic and cholinergic involvement is necessary for the appearance of VNS-induced Theta.
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medial septal cholinergic mediation of hippocampal Theta Rhythm induced by vagal nerve stimulation
PLOS ONE, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:BACKGROUND Electrical vagal nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. This technique also remains under investigation as a specific treatment of patients with Alzheimer's disease. Recently we discovered that VNS induced hippocampal formation (HPC) type II Theta Rhythm, which is involved in memory consolidation. In the present study, we have extended our previous observation and addressed the neuronal substrate and pharmacological profile of HPC type II Theta Rhythm induced by VNS in anesthetized rats. METHODS Male Wistar rats were implanted with a VNS cuff electrode around the left vagus nerve, a tungsten microelectrode for recording the HPC field activity, and a medial septal (MS) cannula for the injection of a local anesthetic, procaine, and muscarinic agents. A direct, brief effect of VNS on the HPC field potential was evaluated before and after medial-septal drug injection. RESULTS Medial septal injection of local anesthetic, procaine, reversibly abolished VNS-induced HPC Theta Rhythm. With the use of cholinergic muscarinic agonist and antagonists, we demonstrated that medial septal M1 receptors are involved in the mediation of the VNS effect on HPC Theta field potential. CONCLUSION The MS cholinergic M1 receptor mechanism integrates not only central inputs from the brainstem synchronizing pathway, which underlies the production of HPC type II Theta Rhythm, but also the input from the vagal afferents in the brain stem.
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some technical issues of vagal nerve stimulation an approach using a hippocampal formation Theta Rhythm
Brain Research Bulletin, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously, we have demonstrated that hippocampal (HPC) Theta Rhythm can be produced, depending on current intensity, directly during vagal nerve stimulation (VNS) or with a time delay following stimulation. This suggests that Theta EEG pattern can also be used as a bio-indicator of the efficiency of VNS. In the present study, we focused on three specific, technical issues related to the stimulation procedure of the vagal nerve: i/does the type of the electrode used for VNS and the technique of its implantation affect the parameters of the HPC Theta Rhythm? ii/does the type of electrode used determine the current intensity threshold of VNS-induced HPC Theta? iii/is the repeatability of the VNS effect determined by the type of electrode used? We demonstrated that a platinum-iridium cuff electrode offers some important advantages over a tungsten electrode. Firstly, despite some possible mechanical and compression nerve damage related to permanent contact with the vagal nerve, it offers a lower current intensity threshold for inducing Theta oscillations. Secondly, and most importantly, the cuff electrode offers repeatability of the VNS effect on the HPC Theta Rhythm. However, one disadvantage of using this type of an electrode is that the permanent pressure on the vagal nerve by the cuff itself may decrease the amplitude of the investigated field potential.
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development of Theta Rhythm in hippocampal formation slices perfused with 5 ht1a antagonist s way 100135
Brain Research, 2015Co-Authors: P Kazmierska, J KonopackiAbstract:Numerous studies have revealed that median raphe nuclei stimulation induces desynchronization of hippocampal field activity in vivo. Some findings provide evidence for tonic regulation of the Theta oscillation of the septo-hippocampal system via the serotonergic system. To date the involvement of serotonergic transmission in Theta Rhythm generation in hippocampal slices has never been investigated. Thus the aim of the present study was to test whether HPC in vitro preparation is capable of producing Theta in the presence of compounds modulating the activity of 5-HT1A receptors. To achieve this a series of experiments designed to determine the effect of different concentrations of the 5-HT1A receptor antagonist (S)WAY 100135 on HPC field activity was carried out. The dominant field potential pattern recorded within HPC slices was epileptiform activity, with a maximum frequency ranging from 0.19 ± 0.06 Hz to 0.69 ± 0.10 Hz. In addition, after the bath application of (S)WAY 100135 in concentrations 3 and 10 µM Rhythmic epochs in the Theta frequency range were also noted. The highest probability of Theta Rhythm production was observed after the bath perfusion with a solution of (S) WAY 100135 at a concentration of 10 μM. These Theta Rhythm epochs were characterized by a higher-than-average amplitude compared to carbachol-induced Theta epochs and shorter time duration, with no apparent differences in the average frequency and duration of intervals between Theta epochs. These results obtained herein of in vitro studies provide direct evidence for the involvement of serotonergic receptors in the depression of oscillatory activity in the HPC Theta band.
R Bocian - One of the best experts on this subject based on the ideXlab platform.
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effects of locus coeruleus activation and inactivation on hippocampal formation Theta Rhythm in anesthetized rats
Brain Research Bulletin, 2020Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously obtained data suggests that noradrenaline (NE) released from the efferent locus coeruleus (LC) endings in hippocampal formation (HPC) may serve as an important modulating signal involved in the pharmacological mechanisms responsible for the production of type 2 Theta Rhythm in rats. Hence, two distinct hypotheses were tested in the present study: 1/ if the decrease in HPC level of NE is correlated with the desynchronization of HPC field potential, then the inhibition of LC would be expected to abolish HPC type 2 Theta Rhythm; 2/ if the increase in HPC NE level is correlated with synchronization of HPC field potential, then the stimulation of LC would be expected to produce type 2 Theta. The experiments were performed using an experimental model of HPC type 2 Theta Rhythm recorded in urethanized rats. It was demonstrated that electrical stimulation of LC produced type 2 Theta Rhythm whereas procaine injection into LC, in contrast, reversibly abolished type 2 Theta. The possible relation of type 2 Theta Rhythm with some disturbances of Alzheimer disease are addressed.
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gabaergic mediation of hippocampal Theta Rhythm induced by stimulation of the vagal nerve
Brain Research Bulletin, 2019Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:The key question to be answered in the present study was whether the medial septal GABAergic receptors are engaged in the pharmacological profile of the hippocampal formation (HPC) Theta Rhythm induced by vagal nerve stimulation (VNS). It was demonstrated that the medial septal microinfusion of GABAA and GABAB agonists (muscimol and baclofen) resulted in a progressive reduction of the power of VNS-induced Theta. The medial septal microinfusion of GABAA and GABAB antagonists (bicuculline and 2-OH saclofen) resulted in the generation of VNS-induced Theta with increased power. The effect of the combined medial septal microinfusion of GABAA agonist and antagonist and GABAB agonist and antagonist on VNS-induced Theta Rhythm was also evaluated: in the presence of GABAA,B antagonists the effect of agonists predominated. In separate experiments, GABAA and GABAB antagonists were administrated in anesthetized rats pretreated with i.v. administration of atropine sulfate. Atropine was found to abolish spontaneous Theta and VNS-induced Theta examined in the presence of bicuculline or 2-OH saclofen. The present data provide evidence that the medial septal GABAA and GABAB receptors are involved in the central mechanisms responsible for modulation of VNS-induced HPC Theta oscillations. Furthermore, the results of the present study also demonstrate that, in fact, both GABAergic and cholinergic involvement is necessary for the appearance of VNS-induced Theta.
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medial septal cholinergic mediation of hippocampal Theta Rhythm induced by vagal nerve stimulation
PLOS ONE, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:BACKGROUND Electrical vagal nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. This technique also remains under investigation as a specific treatment of patients with Alzheimer's disease. Recently we discovered that VNS induced hippocampal formation (HPC) type II Theta Rhythm, which is involved in memory consolidation. In the present study, we have extended our previous observation and addressed the neuronal substrate and pharmacological profile of HPC type II Theta Rhythm induced by VNS in anesthetized rats. METHODS Male Wistar rats were implanted with a VNS cuff electrode around the left vagus nerve, a tungsten microelectrode for recording the HPC field activity, and a medial septal (MS) cannula for the injection of a local anesthetic, procaine, and muscarinic agents. A direct, brief effect of VNS on the HPC field potential was evaluated before and after medial-septal drug injection. RESULTS Medial septal injection of local anesthetic, procaine, reversibly abolished VNS-induced HPC Theta Rhythm. With the use of cholinergic muscarinic agonist and antagonists, we demonstrated that medial septal M1 receptors are involved in the mediation of the VNS effect on HPC Theta field potential. CONCLUSION The MS cholinergic M1 receptor mechanism integrates not only central inputs from the brainstem synchronizing pathway, which underlies the production of HPC type II Theta Rhythm, but also the input from the vagal afferents in the brain stem.
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some technical issues of vagal nerve stimulation an approach using a hippocampal formation Theta Rhythm
Brain Research Bulletin, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously, we have demonstrated that hippocampal (HPC) Theta Rhythm can be produced, depending on current intensity, directly during vagal nerve stimulation (VNS) or with a time delay following stimulation. This suggests that Theta EEG pattern can also be used as a bio-indicator of the efficiency of VNS. In the present study, we focused on three specific, technical issues related to the stimulation procedure of the vagal nerve: i/does the type of the electrode used for VNS and the technique of its implantation affect the parameters of the HPC Theta Rhythm? ii/does the type of electrode used determine the current intensity threshold of VNS-induced HPC Theta? iii/is the repeatability of the VNS effect determined by the type of electrode used? We demonstrated that a platinum-iridium cuff electrode offers some important advantages over a tungsten electrode. Firstly, despite some possible mechanical and compression nerve damage related to permanent contact with the vagal nerve, it offers a lower current intensity threshold for inducing Theta oscillations. Secondly, and most importantly, the cuff electrode offers repeatability of the VNS effect on the HPC Theta Rhythm. However, one disadvantage of using this type of an electrode is that the permanent pressure on the vagal nerve by the cuff itself may decrease the amplitude of the investigated field potential.
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vagus nerve stimulation produces a hippocampal formation Theta Rhythm in anesthetized rats
Brain Research, 2017Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, Jan KonopackiAbstract:Vagus nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. In the present study, the effect of different stimulation protocols of VNS on the hippocampal formation (HPC) type II Theta field potentials were evaluated in anesthetized rats. The following Theta parameters were analysed: power, frequency and duration of Theta epochs. We documented for the first time the presence of HPC type II Theta in response to the application of VNS. A VNS-induced Theta Rhythm appeared in different experimental protocols and, depending on the current intensity, could occur directly during VNS (brief effect) or after vagal stimulation (delayed effect), using lower intensity stimuli.
Adam Broncel - One of the best experts on this subject based on the ideXlab platform.
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effects of locus coeruleus activation and inactivation on hippocampal formation Theta Rhythm in anesthetized rats
Brain Research Bulletin, 2020Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously obtained data suggests that noradrenaline (NE) released from the efferent locus coeruleus (LC) endings in hippocampal formation (HPC) may serve as an important modulating signal involved in the pharmacological mechanisms responsible for the production of type 2 Theta Rhythm in rats. Hence, two distinct hypotheses were tested in the present study: 1/ if the decrease in HPC level of NE is correlated with the desynchronization of HPC field potential, then the inhibition of LC would be expected to abolish HPC type 2 Theta Rhythm; 2/ if the increase in HPC NE level is correlated with synchronization of HPC field potential, then the stimulation of LC would be expected to produce type 2 Theta. The experiments were performed using an experimental model of HPC type 2 Theta Rhythm recorded in urethanized rats. It was demonstrated that electrical stimulation of LC produced type 2 Theta Rhythm whereas procaine injection into LC, in contrast, reversibly abolished type 2 Theta. The possible relation of type 2 Theta Rhythm with some disturbances of Alzheimer disease are addressed.
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Hippocampal Theta Rhythm induced by vagal nerve stimulation: The effect of modulation of electrical coupling
Brain Research Bulletin, 2019Co-Authors: Adam Broncel, Renata Bocian, Paulina Kłos-wojtczak, Jan KonopackiAbstract:Abstract Previously we have demonstrated that vagal nerve stimulation (VNS) is capable of inducing hippocampal formation (HPC) Theta Rhythm ( Broncel et al., 2017 ). The neuronal substrate underlying this novel phenomenon is poorly known, though the cholinergic and GABAergic profile of VNS-induced Theta Rhythm in anesthetized rats has just recently been addressed ( Broncel et al., 2018a , 2019 ). In this study we extended our earlier observation concerning the pharmacological profile of VNS-induced Theta oscillations. Specifically, the purpose of the present study was to test the hypothesis that VNS-induced hippocampal Theta Rhythm could be modulated by local HPC gap junctions (GJs) transmission. Two GJs agents were used: carbenoxolone, nonspecific GJs blocker and trimethylamine, a nonspecific opener of GJs. Two basic parameters of Theta Rhythm were evaluated: frequency and power. It was demonstrated that carbenoxolone inhibits VNS-induced Theta while trimethylamine facilities it. These observations indicate that HPC electrical coupling mediates the Theta Rhythm induced by vagal nerve stimulation.
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gabaergic mediation of hippocampal Theta Rhythm induced by stimulation of the vagal nerve
Brain Research Bulletin, 2019Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:The key question to be answered in the present study was whether the medial septal GABAergic receptors are engaged in the pharmacological profile of the hippocampal formation (HPC) Theta Rhythm induced by vagal nerve stimulation (VNS). It was demonstrated that the medial septal microinfusion of GABAA and GABAB agonists (muscimol and baclofen) resulted in a progressive reduction of the power of VNS-induced Theta. The medial septal microinfusion of GABAA and GABAB antagonists (bicuculline and 2-OH saclofen) resulted in the generation of VNS-induced Theta with increased power. The effect of the combined medial septal microinfusion of GABAA agonist and antagonist and GABAB agonist and antagonist on VNS-induced Theta Rhythm was also evaluated: in the presence of GABAA,B antagonists the effect of agonists predominated. In separate experiments, GABAA and GABAB antagonists were administrated in anesthetized rats pretreated with i.v. administration of atropine sulfate. Atropine was found to abolish spontaneous Theta and VNS-induced Theta examined in the presence of bicuculline or 2-OH saclofen. The present data provide evidence that the medial septal GABAA and GABAB receptors are involved in the central mechanisms responsible for modulation of VNS-induced HPC Theta oscillations. Furthermore, the results of the present study also demonstrate that, in fact, both GABAergic and cholinergic involvement is necessary for the appearance of VNS-induced Theta.
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medial septal cholinergic mediation of hippocampal Theta Rhythm induced by vagal nerve stimulation
PLOS ONE, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:BACKGROUND Electrical vagal nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. This technique also remains under investigation as a specific treatment of patients with Alzheimer's disease. Recently we discovered that VNS induced hippocampal formation (HPC) type II Theta Rhythm, which is involved in memory consolidation. In the present study, we have extended our previous observation and addressed the neuronal substrate and pharmacological profile of HPC type II Theta Rhythm induced by VNS in anesthetized rats. METHODS Male Wistar rats were implanted with a VNS cuff electrode around the left vagus nerve, a tungsten microelectrode for recording the HPC field activity, and a medial septal (MS) cannula for the injection of a local anesthetic, procaine, and muscarinic agents. A direct, brief effect of VNS on the HPC field potential was evaluated before and after medial-septal drug injection. RESULTS Medial septal injection of local anesthetic, procaine, reversibly abolished VNS-induced HPC Theta Rhythm. With the use of cholinergic muscarinic agonist and antagonists, we demonstrated that medial septal M1 receptors are involved in the mediation of the VNS effect on HPC Theta field potential. CONCLUSION The MS cholinergic M1 receptor mechanism integrates not only central inputs from the brainstem synchronizing pathway, which underlies the production of HPC type II Theta Rhythm, but also the input from the vagal afferents in the brain stem.
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some technical issues of vagal nerve stimulation an approach using a hippocampal formation Theta Rhythm
Brain Research Bulletin, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously, we have demonstrated that hippocampal (HPC) Theta Rhythm can be produced, depending on current intensity, directly during vagal nerve stimulation (VNS) or with a time delay following stimulation. This suggests that Theta EEG pattern can also be used as a bio-indicator of the efficiency of VNS. In the present study, we focused on three specific, technical issues related to the stimulation procedure of the vagal nerve: i/does the type of the electrode used for VNS and the technique of its implantation affect the parameters of the HPC Theta Rhythm? ii/does the type of electrode used determine the current intensity threshold of VNS-induced HPC Theta? iii/is the repeatability of the VNS effect determined by the type of electrode used? We demonstrated that a platinum-iridium cuff electrode offers some important advantages over a tungsten electrode. Firstly, despite some possible mechanical and compression nerve damage related to permanent contact with the vagal nerve, it offers a lower current intensity threshold for inducing Theta oscillations. Secondly, and most importantly, the cuff electrode offers repeatability of the VNS effect on the HPC Theta Rhythm. However, one disadvantage of using this type of an electrode is that the permanent pressure on the vagal nerve by the cuff itself may decrease the amplitude of the investigated field potential.
E Jurkowlaniec - One of the best experts on this subject based on the ideXlab platform.
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dopaminergic transmission in the midbrain ventral tegmental area in the induction of hippocampal Theta Rhythm
Brain Research, 2013Co-Authors: Jolanta Orzelgryglewska, Magda Kuśmierczak, Pawel Matulewicz, E JurkowlaniecAbstract:Hippocampal Rhythmic slow activity (RSA, Theta) is regulated by many brainstem structures, including the midbrain ventral tegmental area (VTA). This work aimed at assessing the role of the dopaminergic (DA) transmission of the VTA in this regulation. Male Wistar rats (n=35) in urethane anaesthesia received an intra-VTA microinjection of either flupenthixol (FLU; doses of 5.0, 2.5, 1.25 and 0.625 μg) or amphetamine (AMPH; 2.5 and 5.0 μg) following control solvent microinjection. Peak power (Pmax) and corresponding peak frequency (Fmax) for delta and Theta bands were extracted from EEG recording. Flupenthixol at a dose of 1.25 μg evoked long-lasting Theta, continuing for 32.0 min on average, with a mean latency of 7.1 min. Other doses of FLU caused an increase of Pmax Theta and reduction of Pmax delta without generating visually recognizable, regular Theta Rhythm. 5 μg of AMPH evoked Theta continuing for 24.4 min on average, with a mean latency of 9.7 min. The lower dose was much less effective, with its outcome resembling the one after the less active FLU doses. During pharmacologically induced Theta Rhythm, both after FLU and AMPH, brief episodes of asynchronous activity appeared periodically, and they were more frequent and longer in AMPH groups. AMPH may act locally on multiple sites, inhibiting DA cells in somatodendritic region but also increasing dopamine release in target structures, and this, depending on AMPH dose, can lead to induction of Theta Rhythm. Locally administered DA antagonist on the other hand, when used at a proper dose, can produce Theta most likely by the mechanism of inhibiting autoreceptors.
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hippocampal Theta Rhythm after serotonergic activation of the pedunculopontine tegmental nucleus in anesthetized rats
Brain Research Bulletin, 2010Co-Authors: Pawel Matulewicz, Jolanta Orzelgryglewska, W Trojniar, Mark J Hunt, E JurkowlaniecAbstract:The pedunculopontine tegmental nucleus (PPN), as a part of reticular formation activating system, is thought to be involved in the sleep/wake cycle regulation, and plays an important role in the generation and regulation of hippocampal Rhythmical slow activity. The activity of PPN can be modulated by serotonergic system, mainly through multiple projections from raphe nuclei, which can influence PPN neurons through different classes of 5-HT receptors. In the present study, the effect of intra-PPN injection of two serotonin agonists: 8-OH-DPAT and 5-CT, on hippocampal formation EEG activity was examined in urethane-anesthetized rats. The study found that the microinjections induced prolonged spontaneous Theta Rhythm in both hippocampi with a short latency. The results obtained suggest that local inhibition of presumably cholinergic neurons in the PPN acts as a trigger for hippocampal Theta activity.
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microinjection of procaine and electrolytic lesion in the ventral tegmental area suppresses hippocampal Theta Rhythm in urethane anesthetized rats
Brain Research Bulletin, 2006Co-Authors: Jolanta Orzelgryglewska, E Jurkowlaniec, W TrojniarAbstract:The midbrain ventral tegmental area (VTA), a key structure of the mesocorticolimbic system is anatomically connected with the hippocampal formation. In addition mesocortical dopamine was found to influence hippocampus-related memory and hippocampal synaptic plasticity, both being linked to the Theta Rhythm. Therefore, the aim of the present study was to evaluate the possible role of the VTA in the regulation of the hippocampal Theta activity. The study was performed on urethane-anesthetized male Wistar rats in which Theta Rhythm was evoked by tail pinch. It was found that unilateral, temporal inactivation of the VTA by means of direct procaine injection resulted in bilateral suppression of the hippocampal Theta which manifested as a loss of synchronization of hippocampal EEG and respective reduction of the power and also the frequency of the 3-6 Hz Theta band. Depression of the power of the 3-6 Hz component of the EEG signal was also seen in spontaneous hippocampal EEG after procaine. The permanent destruction of the VTA by means of unilateral electrocoagulation evoked a long-lasting, mainly ipsilateral depression of the power of the Theta with some influence on its frequency. Simultaneously, there was a substantial increase of the power in higher frequency bands indicating decrease of a synchrony of the hippocampal EEG activity. On the basis of these results indicating impairment of synchronization of the hippocampal activity the VTA may be considered as another part of the brainstem Theta synchroning system.
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microinjection of procaine into the pedunculopontine tegmental nucleus suppresses hippocampal Theta Rhythm in urethane anesthetized rats
Brain Research Bulletin, 2002Co-Authors: A Nowacka, E Jurkowlaniec, W TrojniarAbstract:It was found that the cholinergic component of the pedunculopontine tegmental nucleus (PPN) is involved in the generation of Theta Rhythm in the hippocampus. However, it is still not known how important PPN is in the brainstem Theta-generating system, where the nucleus reticularis pontis oralis is regarded as a primary generator. In the present experiment, performed on urethane-anesthetized rats, we studied the effect on the tail pinch-elicited hippocampal Theta of unilateral inactivation of PPN by means of direct procaine microinjection. Procaine induced ipsilateral suppression of Theta Rhythm, manifested as desynchronization of hippocampal EEG, a shift of the fast Fourier transformation (FFT) power peak toward lower frequencies, and a reduction of FFT peak magnitude at Theta band. Hippocampal field activity returned to normal (both its FFT peak frequency and magnitude) within 30 min after the injection. The results obtained indicate that PPN is critical for hippocampal Theta generation but it may not be involved in encoding Theta frequency.
P Kloswojtczak - One of the best experts on this subject based on the ideXlab platform.
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effects of locus coeruleus activation and inactivation on hippocampal formation Theta Rhythm in anesthetized rats
Brain Research Bulletin, 2020Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously obtained data suggests that noradrenaline (NE) released from the efferent locus coeruleus (LC) endings in hippocampal formation (HPC) may serve as an important modulating signal involved in the pharmacological mechanisms responsible for the production of type 2 Theta Rhythm in rats. Hence, two distinct hypotheses were tested in the present study: 1/ if the decrease in HPC level of NE is correlated with the desynchronization of HPC field potential, then the inhibition of LC would be expected to abolish HPC type 2 Theta Rhythm; 2/ if the increase in HPC NE level is correlated with synchronization of HPC field potential, then the stimulation of LC would be expected to produce type 2 Theta. The experiments were performed using an experimental model of HPC type 2 Theta Rhythm recorded in urethanized rats. It was demonstrated that electrical stimulation of LC produced type 2 Theta Rhythm whereas procaine injection into LC, in contrast, reversibly abolished type 2 Theta. The possible relation of type 2 Theta Rhythm with some disturbances of Alzheimer disease are addressed.
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gabaergic mediation of hippocampal Theta Rhythm induced by stimulation of the vagal nerve
Brain Research Bulletin, 2019Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:The key question to be answered in the present study was whether the medial septal GABAergic receptors are engaged in the pharmacological profile of the hippocampal formation (HPC) Theta Rhythm induced by vagal nerve stimulation (VNS). It was demonstrated that the medial septal microinfusion of GABAA and GABAB agonists (muscimol and baclofen) resulted in a progressive reduction of the power of VNS-induced Theta. The medial septal microinfusion of GABAA and GABAB antagonists (bicuculline and 2-OH saclofen) resulted in the generation of VNS-induced Theta with increased power. The effect of the combined medial septal microinfusion of GABAA agonist and antagonist and GABAB agonist and antagonist on VNS-induced Theta Rhythm was also evaluated: in the presence of GABAA,B antagonists the effect of agonists predominated. In separate experiments, GABAA and GABAB antagonists were administrated in anesthetized rats pretreated with i.v. administration of atropine sulfate. Atropine was found to abolish spontaneous Theta and VNS-induced Theta examined in the presence of bicuculline or 2-OH saclofen. The present data provide evidence that the medial septal GABAA and GABAB receptors are involved in the central mechanisms responsible for modulation of VNS-induced HPC Theta oscillations. Furthermore, the results of the present study also demonstrate that, in fact, both GABAergic and cholinergic involvement is necessary for the appearance of VNS-induced Theta.
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medial septal cholinergic mediation of hippocampal Theta Rhythm induced by vagal nerve stimulation
PLOS ONE, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:BACKGROUND Electrical vagal nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. This technique also remains under investigation as a specific treatment of patients with Alzheimer's disease. Recently we discovered that VNS induced hippocampal formation (HPC) type II Theta Rhythm, which is involved in memory consolidation. In the present study, we have extended our previous observation and addressed the neuronal substrate and pharmacological profile of HPC type II Theta Rhythm induced by VNS in anesthetized rats. METHODS Male Wistar rats were implanted with a VNS cuff electrode around the left vagus nerve, a tungsten microelectrode for recording the HPC field activity, and a medial septal (MS) cannula for the injection of a local anesthetic, procaine, and muscarinic agents. A direct, brief effect of VNS on the HPC field potential was evaluated before and after medial-septal drug injection. RESULTS Medial septal injection of local anesthetic, procaine, reversibly abolished VNS-induced HPC Theta Rhythm. With the use of cholinergic muscarinic agonist and antagonists, we demonstrated that medial septal M1 receptors are involved in the mediation of the VNS effect on HPC Theta field potential. CONCLUSION The MS cholinergic M1 receptor mechanism integrates not only central inputs from the brainstem synchronizing pathway, which underlies the production of HPC type II Theta Rhythm, but also the input from the vagal afferents in the brain stem.
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some technical issues of vagal nerve stimulation an approach using a hippocampal formation Theta Rhythm
Brain Research Bulletin, 2018Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, J KonopackiAbstract:Abstract Previously, we have demonstrated that hippocampal (HPC) Theta Rhythm can be produced, depending on current intensity, directly during vagal nerve stimulation (VNS) or with a time delay following stimulation. This suggests that Theta EEG pattern can also be used as a bio-indicator of the efficiency of VNS. In the present study, we focused on three specific, technical issues related to the stimulation procedure of the vagal nerve: i/does the type of the electrode used for VNS and the technique of its implantation affect the parameters of the HPC Theta Rhythm? ii/does the type of electrode used determine the current intensity threshold of VNS-induced HPC Theta? iii/is the repeatability of the VNS effect determined by the type of electrode used? We demonstrated that a platinum-iridium cuff electrode offers some important advantages over a tungsten electrode. Firstly, despite some possible mechanical and compression nerve damage related to permanent contact with the vagal nerve, it offers a lower current intensity threshold for inducing Theta oscillations. Secondly, and most importantly, the cuff electrode offers repeatability of the VNS effect on the HPC Theta Rhythm. However, one disadvantage of using this type of an electrode is that the permanent pressure on the vagal nerve by the cuff itself may decrease the amplitude of the investigated field potential.
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vagus nerve stimulation produces a hippocampal formation Theta Rhythm in anesthetized rats
Brain Research, 2017Co-Authors: Adam Broncel, R Bocian, P Kloswojtczak, Jan KonopackiAbstract:Vagus nerve stimulation (VNS) has been used for years to treat patients with drug-resistant epilepsy. In the present study, the effect of different stimulation protocols of VNS on the hippocampal formation (HPC) type II Theta field potentials were evaluated in anesthetized rats. The following Theta parameters were analysed: power, frequency and duration of Theta epochs. We documented for the first time the presence of HPC type II Theta in response to the application of VNS. A VNS-induced Theta Rhythm appeared in different experimental protocols and, depending on the current intensity, could occur directly during VNS (brief effect) or after vagal stimulation (delayed effect), using lower intensity stimuli.
