Crossmodal stimulation influences communication in visual-somatosensory cortical networks of the Brown Norway rat

2012 ◽  
Vol 25 (0) ◽  
pp. 92
Author(s):  
Kay Sieben ◽  
Ileana Hanganu-Opatz
Keyword(s):  
Barrel Cortex ◽  
Visual Stimulation ◽  
Multisensory Processing ◽  
Oscillatory Activity ◽  
Brown Norway ◽  
Norway Rat ◽  
Baseline Activity ◽  
Sensory Cortices ◽  
Oscillatory Coupling

Processing of most action goals and complete perception of the environment, like spatial localization of events, require integration of information from different sensory systems. The classical idea of a hierarchical sensory organization is challenged by recent evidence from both human and primate work showing that multisensory processing is already taking place in primary sensory cortices. However, the mechanisms underlying this multisensory processing and the role of primary sensory cortices in crossmodal communication and oscillatory coupling remain largely unknown. Congruent and incongruent uni- and bimodal visual (light spot) and tactile (whisker deflection) stimulation was performed simultaneously with extracellular multielectrode recordings in the primary visual (V1) and somatosensory (S1, barrel field) neocortices of adolescent Brown Norway rats in vivo. Tactile stimulation led after 10–30 ms to a phase-locked, large amplitude response in the contralateral S1 that is accompanied by prominent, layer-specific sinks and sources. Additionally, non-phase-locked oscillations were induced in different frequency ranges. Visual stimulation alone did not change the amplitude of oscillations compared to baseline activity in the contralateral S1, but reset the phase of ongoing oscillatory activity. Because of the visual impact in the S1, bimodal congruent stimulation led to an increase of the evoked response and changed the timing of amplitude enhancement of oscillations. These data indicate that networks in the barrel cortex are modulated by crossmodal visual input.

Auditory modulation of oscillatory activity in extra-striate visual cortex and its contribution to audio–visual multisensory integration: A human intracranial EEG study

2012 ◽  
Vol 25 (0) ◽  
pp. 198
Author(s):  
Manuel R. Mercier ◽  
John J. Foxe ◽  
Ian C. Fiebelkorn ◽  
John S. Butler ◽  
Theodore H. Schwartz ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Multisensory Integration ◽  
Multisensory Processing ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Additive Model ◽  
Oscillatory Activity ◽  
Time Frequency ◽  
Electrical Brain Activity ◽  
Sensory Cortices

Investigations have traditionally focused on activity in the sensory cortices as a function of their respective sensory inputs. However, converging evidence from multisensory research has shown that neural activity in a given sensory region can be modulated by stimulation of other so-called ancillary sensory systems. Both electrophysiology and functional imaging support the occurrence of multisensory processing in human sensory cortex based on the latency of multisensory effects and their precise anatomical localization. Still, due to inherent methodological limitations, direct evidence of the precise mechanisms by which multisensory integration occurs within human sensory cortices is lacking. Using intracranial recordings in epileptic patients () undergoing presurgical evaluation, we investigated the neurophysiological basis of multisensory integration in visual cortex. Subdural electrical brain activity was recorded while patients performed a simple detection task of randomly ordered Auditory alone (A), Visual alone (V) and Audio–Visual stimuli (AV). We then performed time-frequency analysis: first we investigated each condition separately to evaluate responses compared to baseline, then we indexed multisensory integration using both the maximum criterion model (AV vs. V) and the additive model (AV vs. A+V). Our results show that auditory input significantly modulates neuronal activity in visual cortex by resetting the phase of ongoing oscillatory activity. This in turn leads to multisensory integration when auditory and visual stimuli are simultaneously presented.

Inflammatory and cardiac response to end-stage pneumonic plague

2015 ◽  
Author(s):  
◽  
Eric Allan Coate
Keyword(s):  
Host Response ◽  
Etiologic Agent ◽  
Cardiac Response ◽  
Brown Norway ◽  
Critical Threshold ◽  
Post Exposure Prophylaxis ◽  
Pneumonic Plague ◽  
Norway Rat ◽  
End Stage

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Yersinia pestis is the etiologic agent of pneumonic plague, a devastating disease in humans characterized by acute bronchopneumonia that is frequently accompanied by bacteremia and sepsis. In 2001, the Amerithrax attacks occurred resulting in an increased awareness for better understanding of threat agents which can be weaponized and the need for therapeutic development. Within, we report on studies on the role of Y. pestis virulence factors on the host response as well on evaluation of therapeutics. As such, we refined a Brown Norway rat animal model with the goal of studying the pathophysiological and therapeutic response to pneumonic plague. We defined the natural history of pneumonic plague in this model. Interestingly, development of cardiac arrhythmias during the end-stage of the infection was discovered. In addition, the host response to the virulence factor YopJ was characterized in an in vivo pneumonic plague infection. Although bacteremia was present in WT and yopJ-infected animals during late stage disease, there was a delay in sepsis in the absence of YopJ. Electrophysiology of the cardiac system was analyzed to elucidate the cause of the arrhythmia development as a disease progression. Findings included elevation of the STE interval in the heart indicating potential disruption of electrical ion channels. Significant differences in the STE were found between WT and mutant yopJ-infected animals. Overall, the discovery of the STE interval could potentially be a finding used for prognostic development for biomarker. Lastly, doxycycline and meropenem were evaluated as a therapeutic for post-exposure prophylaxis (PEP). We report within this dissertation critical threshold PEP treatment windows for both antibiotics.

Allergen-induced airway hyperresponsiveness in Brown-Norway rat: role of parasympathetic mechanisms

1993 ◽  
Vol 75 (1) ◽  
pp. 279-284 ◽  
Author(s):  
W. Elwood ◽  
T. Sakamoto ◽  
P. J. Barnes ◽  
K. F. Chung
Keyword(s):  
Airway Hyperresponsiveness ◽  
Allergen Challenge ◽  
Electrical Field Stimulation ◽  
Airway Responsiveness ◽  
Brown Norway ◽  
Field Stimulation ◽  
Electrical Field ◽  
Norway Rat

Enhanced parasympathetic mechanisms may contribute to airway hyperresponsiveness. The present study examined whether the in vivo increase in airway responsiveness seen 18–24 h after either a single or chronic aerosolized allergen challenge protocol in actively sensitized Brown-Norway rats was due to altered parasympathetic mechanisms. The roles of central and reflex vagal mechanisms were studied by performing bilateral cervical vagotomy before measurement of airway responsiveness. Bilateral vagotomy failed to reduce the increase in airway responsiveness after either a single or chronic allergen challenge. The roles of increased neural release of acetylcholine (ACh) and increased end organ responsiveness were studied in vitro. The isometric responses of tracheal and bronchial strips to both electrical field stimulation and exogenously applied ACh from rats exposed both to single and chronic allergen challenges were compared with those from saline-exposed rats. The responses to electrical field stimulation and to exogenous ACh were not significantly enhanced 18–24 h after either protocol. We conclude that the airway hyperresponsiveness observed in this allergic rat model is not mediated through an enhancement of parasympathetic mechanisms.

scholarly journals Multichannel brain recordings in behaving Drosophila reveal oscillatory activity and local coherence in response to sensory stimulation and circuit activation

2013 ◽  
Vol 110 (7) ◽  
pp. 1703-1721 ◽  
Author(s):  
Angelique C. Paulk ◽  
Yanqiong Zhou ◽  
Peter Stratton ◽  
Li Liu ◽  
Bruno van Swinderen
Keyword(s):  
Visual Stimulation ◽  
Sensory Modality ◽  
Field Potential ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Insect Brain ◽  
Sensory Stimuli ◽  
Multichannel Recording ◽  
Frequency Bands

Neural networks in vertebrates exhibit endogenous oscillations that have been associated with functions ranging from sensory processing to locomotion. It remains unclear whether oscillations may play a similar role in the insect brain. We describe a novel “whole brain” readout for Drosophila melanogaster using a simple multichannel recording preparation to study electrical activity across the brain of flies exposed to different sensory stimuli. We recorded local field potential (LFP) activity from >2,000 registered recording sites across the fly brain in >200 wild-type and transgenic animals to uncover specific LFP frequency bands that correlate with: 1) brain region; 2) sensory modality (olfactory, visual, or mechanosensory); and 3) activity in specific neural circuits. We found endogenous and stimulus-specific oscillations throughout the fly brain. Central (higher-order) brain regions exhibited sensory modality-specific increases in power within narrow frequency bands. Conversely, in sensory brain regions such as the optic or antennal lobes, LFP coherence, rather than power, best defined sensory responses across modalities. By transiently activating specific circuits via expression of TrpA1, we found that several circuits in the fly brain modulate LFP power and coherence across brain regions and frequency domains. However, activation of a neuromodulatory octopaminergic circuit specifically increased neuronal coherence in the optic lobes during visual stimulation while decreasing coherence in central brain regions. Our multichannel recording and brain registration approach provides an effective way to track activity simultaneously across the fly brain in vivo, allowing investigation of functional roles for oscillations in processing sensory stimuli and modulating behavior.

scholarly journals Integration of Evoked Responses in Supragranular Cortex Studied With Optical Recordings In Vivo

2006 ◽  
Vol 96 (1) ◽  
pp. 336-351 ◽  
Author(s):  
Eugene F. Civillico ◽  
Diego Contreras
Keyword(s):  
High Speed ◽  
Barrel Cortex ◽  
Somatosensory System ◽  
Electrical Stimulus ◽  
Evoked Responses ◽  
Response Summation ◽  
Sensory Cortices ◽  
Functional Representations ◽  
Whisker Stimulation

Complex representations in sensory cortices rely on the integration of inputs that overlap temporally and spatially, particularly in supragranular layers, yet the spatiotemporal dynamics of this synaptic integration are largely unknown. The rodent somatosensory system offers an excellent opportunity to study these dynamics because of the overlapping functional representations of single-whisker inputs. We recorded responses in mouse primary somatosensory (barrel) cortex to single and paired whisker deflections using high-speed voltage-sensitive dye imaging. Responses to paired deflections at intervals of 0 and 10 ms summed sublinearly, producing a single transient smaller in amplitude than the sum of the component responses. At longer intervals of 50 and 100 ms, the response to the second deflection was reduced in amplitude and limited spatially relative to control. Between 100 and 200 ms, the response to the second deflection recovered and often showed areas of facilitation. With increasing interstimulus interval from 50 to 200 ms, recovery of the second response occurred from the second stimulated whisker’s barrel column outward. In contrast to results with paired-whisker stimulation, when a whisker deflection was preceded by a weak electrical stimulus applied to the neighboring cortex, the summation of evoked responses was predominantly linear at all intervals tested. Thus under our conditions, the linearity of response summation in cortex was not predicted by the amplitudes of the component responses on a column-by-column basis, but rather by the timing and nature of the inputs.

scholarly journals Activity in the Barrel Cortex During Active Behavior and Sleep

2010 ◽  
Vol 103 (4) ◽  
pp. 2074-2084 ◽  
Author(s):  
Sujith Vijayan ◽  
Greg J. Hale ◽  
Christopher I. Moore ◽  
Emery N. Brown ◽  
Matthew Wilson
Keyword(s):  
Barrel Cortex ◽  
Slow Wave Sleep ◽  
Neural Firing ◽  
Related Activity ◽  
Firing Rates ◽  
Coding Schemes ◽  
Baseline Activity ◽  
Sensory Cue ◽  
The Individual

The rate at which neurons fire has wide-reaching implications for the coding schemes used by neural systems. Despite the extensive use of the barrel cortex as a model system, relatively few studies have examined the rate of sensory activity in single neurons in freely moving animals. We examined the activity of barrel cortex neurons in behaving animals during sensory cue interaction, during non–stimulus-related activity, during various states of sleep, and during the administration of isoflurane. The activity of regular-spiking units (RSUs: predominantly excitatory neurons) and fast spiking units (FSUs: a subtype of inhibitory interneurons) was examined separately. We characterized activity by calculating neural firing rates, because several reports have emphasized the low firing rates in this system, reporting that both baseline activity and stimulus evoked activity is <1 Hz. We report that, during sensory cue interaction or non–stimulus-related activity, the majority of RSUs in rat barrel cortex fired at rates significantly >1 Hz, with 27.4% showing rates above 10 Hz during cue interaction. Even during slow wave sleep, which had the lowest mean and median firing rates of any nonanesthetized state observed, 80.0% of RSUs fired above 1 Hz. During all of the nonanesthetized states observed 100% of the FSUs fired well above 1 Hz. When rats were administered isoflurane and at a depth of anesthesia used in standard in vivo electrophysiological preparations, all of the RSUs fired below 1 Hz. We also found that >80% of RSUs either upmodulated or downmodulated their firing during cue interaction. These data suggest that low firing rates do not typify the output of the barrel cortex during awake activity and during sleep and indicate that sensory coding at both the individual and population levels may be nonsparse.

scholarly journals Drug Ligand-Induced Activation of Translocator Protein (TSPO) Stimulates Steroid Production by Aged Brown Norway Rat Leydig Cells

Endocrinology ◽  
2013 ◽  
Vol 154 (6) ◽  
pp. 2156-2165 ◽  
Author(s):  
J.-Y. Chung ◽  
H. Chen ◽  
A. Midzak ◽  
A. L. Burnett ◽  
V. Papadopoulos ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Translocator Protein ◽  
Brown Norway ◽  
Aged Rats ◽  
Steroid Production ◽  
Norway Rat ◽  
Rate Determining Step ◽  
In Vitro Effects

Abstract Translocator protein (TSPO; 18 kDA) is a high-affinity cholesterol-binding protein that is integrally involved in cholesterol transfer from intracellular stores into mitochondria, the rate-determining step in steroid formation. Previous studies have shown that TSPO drug ligands are able to activate steroid production by MA-10 mouse Leydig tumor cells and by mitochondria isolated from steroidogenic cells. We hypothesized herein that the direct, pharmacological activation of TSPO might induce aged Leydig cells, which are characterized by reduced T production, to produce significantly higher levels of T both in vitro and in vivo. To test this, we first examined the in vitro effects of the TSPO selective and structurally distinct drug ligands N,N-dihexyl-2-(4-fluorophenyl)indole-3-acetamide (FGIN-1-27) and benzodiazepine 4′-chlorodiazepam (Ro5-4864) on steroidogenesis by Leydig cells isolated from aged (21-24 months old) and young adult (3-6 months old) Brown Norway rats. The ligands stimulated Leydig cell T production significantly, and equivalently, in cells of both ages, an effect that was significantly inhibited by the specific TSPO inhibitor 5-androsten-3,17,19-triol (19-Atriol). Additionally, we examined the in vivo effects of administering FGIN-1-27 to young and aged rats. In both cases, serum T levels increased significantly, consistent with the in vitro results. Indeed, serum T levels in aged rats administered FGIN-1-27 were equivalent to T levels in the serum of control young rats. Taken together, these results indicate that although there are reduced amounts of TSPO in aged Leydig cells, its direct activation is able to increase T production. We suggest that this approach might serve as a therapeutic means to increase steroid levels in vivo in cases of primary hypogonadism.

Ozone-induced airway hyperresponsiveness: role of superoxide anions, NEP, and BK receptors

1995 ◽  
Vol 78 (3) ◽  
pp. 1015-1022 ◽  
Author(s):  
H. Tsukagoshi ◽  
E. B. Haddad ◽  
J. Sun ◽  
P. J. Barnes ◽  
K. F. Chung
Keyword(s):  
Airway Hyperresponsiveness ◽  
Lavage Fluid ◽  
Airway Responsiveness ◽  
Ozone Exposure ◽  
Brown Norway ◽  
Superoxide Anions ◽  
Norway Rat

We investigated the role of reactive oxygen species in ozone-induced airway hyperresponsiveness (AHR) in Brown Norway rats. Airway responsiveness to inhaled acetylcholine (ACh) and bradykinin (BK) and inflammatory cell recruitment in bronchoalveolar lavage fluid (BALF) were measured in vivo. Neutral endopeptidase (NEP) activity assay and measurement of BK-receptor binding sites in Brown Norway rat lungs were carried out in vitro. Apocynin (5 mg/kg), an inhibitor of superoxide anion-generating NADPH oxidase, was administered perorally 30 min before a 3- or 6-h exposure to 3 ppm of ozone, and the animals were studied 18–24 h postexposure. Ozone induced increases in airway responsiveness to ACh and BK and in neutrophil counts in BALF. Apocynin inhibited the increase in airway responsiveness to BK but not to ACh without affecting the neutrophil counts in BALF. The antioxidants allopurinol and deferoxamine prevented ozone-induced AHR to both ACh and BK but did not reduce neutrophil counts. To further examine the mechanisms of ozone-induced AHR to BK, we measured NEP activity and the density of BK receptors in vitro after ozone exposure. Ozone exposure had no significant effect either on NEP activity or on the affinity and the number of BK receptors in lungs from rats treated with or without apocynin. We conclude that superoxide anions released from inflammatory cells in the airway may be involved in ozone-induced AHR. Inactivation of NEP or upregulation of BK receptors do not appear to be involved, but the possibility of localized changes cannot be excluded.

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