scholarly journals Bimodal modulation of background activity in an identified descending interneuron

2019 ◽  
Vol 122 (6) ◽  
pp. 2316-2330
Author(s):  
Gaëtan Lepreux ◽  
Stephan Shuichi Haupt ◽  
Volker Dürr
Keyword(s):  
Spontaneous Activity ◽  
Background Activity ◽  
Neuronal Response ◽  
Stick Insect ◽  
Activity Levels ◽  
Movement Velocity ◽  
Substrate Vibration ◽  
Bilateral Effects ◽  
Functional Relevance ◽  
Antennal Movement

In the absence of any obvious input, sensory neurons and interneurons can display resting or spontaneous activity. This is often regarded as noise and removed through trial averaging, although it may reflect history-dependent modulation of tuning or fidelity and, thus, be of functional relevance to downstream interneurons. We investigated the history dependence of spontaneous activity in a pair of identified, bimodal descending interneurons of the stick insect, called contralateral ON-type velocity-sensitive interneurons (cONv). The bilateral pair of cONv conveys antennal mechanosensory information to the thoracic ganglia, where it arborizes in regions containing locomotor networks. Each cONv encodes the movement velocity of the contralateral antenna, but also substrate vibration as induced by discrete tapping events. Moreover, cONv display highly fluctuating spontaneous activity that can reach rates similar to those during antennal movement at moderate velocities. Hence, cONv offer a unique opportunity to study history-dependent effects on spontaneous activity and, thus, encoding fidelity in two modalities. In this work, we studied unimodal and cross-modal effects as well as unilateral and bilateral effects, using bilateral recordings of both cONv neurons, while moving one antenna and/or delivering taps to induce substrate vibration. Tapping could reduce spontaneous activity of both neurons, whereas antennal movement reduced spontaneous activity of the contralateral cONv neuron only. Combination of both modalities showed a cooperative effect for some parameter constellations, suggesting bimodal enhancement. Since both stimulus modalities could cause a reduction of spontaneous activity at stimulus intensities occurring during natural locomotion, we conclude that this should enhance neuronal response fidelity during locomotion. NEW & NOTEWORTHY The spontaneous activity in a pair of identified, descending insect interneurons is reduced depending on stimulus history. At rest, spontaneous activity levels are correlated in both interneurons, indicating a common drive from background activity. Whereas taps on the substrate affect both interneurons, antennal movement affects the contralateral interneuron only. Cross-modal interaction occurs, too. Since spontaneous activity is reduced at stimulus intensities encountered during natural locomotion, the mechanism could enhance neuronal response fidelity during locomotion.

scholarly journals Tagging motor memories with transcranial direct current stimulation allows later artificially-controlled retrieval

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Daichi Nozaki ◽  
Atsushi Yokoi ◽  
Takahiro Kimura ◽  
Masaya Hirashima ◽  
Jean-Jacques Orban de Xivry
Keyword(s):  
Direct Current ◽  
Sensorimotor Cortex ◽  
Transcranial Direct Current Stimulation ◽  
Background Activity ◽  
Training Session ◽  
Motor Memory ◽  
Activity Levels ◽  
Direct Current Stimulation ◽  
Cathodal Tdcs ◽  
Human Motor

We demonstrate that human motor memories can be artificially tagged and later retrieved by noninvasive transcranial direct current stimulation (tDCS). Participants learned to adapt reaching movements to two conflicting dynamical environments that were each associated with a different tDCS polarity (anodal or cathodal tDCS) on the sensorimotor cortex. That is, we sought to determine whether divergent background activity levels within the sensorimotor cortex (anodal: higher activity; cathodal: lower activity) give rise to distinct motor memories. After a training session, application of each tDCS polarity automatically resulted in the retrieval of the motor memory corresponding to that polarity. These results reveal that artificial modulation of neural activity in the sensorimotor cortex through tDCS can act as a context for the formation and recollection of motor memories.

Quantitative characterization and spinal pathway mediating inhibition of spinal nociceptive transmission from the lateral reticular nucleus in the rat

1988 ◽  
Vol 59 (1) ◽  
pp. 226-247 ◽  
Author(s):  
A. J. Janss ◽  
G. F. Gebhart
Keyword(s):  
Electrical Stimulation ◽  
Spontaneous Activity ◽  
Pulse Duration ◽  
Neuronal Response ◽  
Response Threshold ◽  
Reticular Nucleus ◽  
Lateral Reticular Nucleus ◽  
Descending Inhibition ◽  
Nociceptive Transmission ◽  
Spinal Pathway

1. The modulation of spinal nociceptive transmission from the lateral reticular nucleus (LRN) was characterized for 47 spinal dorsal horn neurons in pentobarbital-anesthetized, paralyzed rats. All 47 units studied had receptive fields confined to the glabrous skin of the plantar surface of the ipsilateral hind foot and responded to mechanical stimulation as well as noxious heating (50 degrees C). Rostral projections contained in the ventrolateral quadrant of the cervical spinal cord were demonstrated for 15 of the 47 units by antidromic invasion. Glutamate- and stimulation-produced descending inhibition, the spinal pathway, and tonic descending inhibition from the LRN were systematically examined. 2. Inhibition of unit responses to heating of the skin by electrical stimulation in the LRN varied with the intensity, pulse duration (100 or 400 microseconds), and frequency (25–100 Hz) of stimulation. Greater inhibition was produced at lower intensities of stimulation with the 400-microseconds pulse duration and a frequency of 100 Hz. The effects of stimulation on spontaneous activity and responses to heat were compared in 16 experiments; inhibition of spontaneous activity was intensity dependent and did not differ significantly in magnitude from stimulation-produced inhibition of responses to heating of the skin. 3. Tracking experiments established that stimulation in the ipsilateral and contralateral ventrolateral medulla reliably attenuated unit responses to noxious heating of the skin and that stimulation in the LRN produced maximal inhibition at a low intensity of stimulation. Descending inhibition was quantitatively characterized from sites within (n = 32) and outside (n = 30) the LRN. Both the extrapolated mean stimulation threshold for inhibition and mean intensity inhibiting unit responses to heat to 50% of control were significantly lower for sites in the LRN. 4. The responses of seven spinal units to graded noxious heating of the skin were studied; all exhibited linear monotonic stimulus-response functions (SRFs) throughout the temperature range examined (42–50 degrees C). Electrical stimulation in the LRN significantly decreased the slope (42 +/- 4% of control) of the SRFs and increased the neuronal response threshold (2.0 +/- 0.7 degrees C). 5. S-glutamate (50 nmol, 0.5 microliter) was microinjected into stimulation sites within (n = 15) and distant from (n = 6) the LRN. Glutamate produced a transient (less than 7 min) but significant attenuation of neuronal responses to heat to 35 +/- 6% of control only when microinjected into the LRN.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Whisker row deprivation affects the flow of sensory information through rat barrel cortex

2017 ◽  
Vol 117 (1) ◽  
pp. 4-17 ◽  
Author(s):  
Vincent Jacob ◽  
Akinori Mitani ◽  
Taro Toyoizumi ◽  
Kevin Fox
Keyword(s):  
Spontaneous Activity ◽  
Information Content ◽  
Barrel Cortex ◽  
Cortical Plasticity ◽  
Neuronal Response ◽  
Sensory Deprivation ◽  
Sensory Information ◽  
Short Latency ◽  
Characteristic Analysis

Whisker trimming causes substantial reorganization of neuronal response properties in barrel cortex. However, little is known about experience-dependent rerouting of sensory processing following sensory deprivation. To address this, we performed in vivo intracellular recordings from layers 2/3 (L2/3), layer 4 (L4), layer 5 regular-spiking (L5RS), and L5 intrinsically bursting (L5IB) neurons and measured their multiwhisker receptive field at the level of spiking activity, membrane potential, and synaptic conductance before and after sensory deprivation. We used Chernoff information to quantify the “sensory information” contained in the firing patterns of cells in response to spared and deprived whisker stimulation. In the control condition, information for flanking-row and same-row whiskers decreased in the order L4, L2/3, L5IB, L5RS. However, after whisker-row deprivation, spared flanking-row whisker information was reordered to L4, L5RS, L5IB, L2/3. Sensory information from the trimmed whiskers was reduced and delayed in L2/3 and L5IB neurons, whereas sensory information from spared whiskers was increased and advanced in L4 and L5RS neurons. Sensory information from spared whiskers was increased in L5IB neurons without a latency change. L5RS cells exhibited the largest changes in sensory information content through an atypical plasticity combining a significant decrease in spontaneous activity and an increase in a short-latency excitatory conductance. NEW & NOTEWORTHY Sensory cortical plasticity is usually quantified by changes in evoked firing rate. In this study we quantified plasticity by changes in sensory detection performance using Chernoff information and receiver operating characteristic analysis. We found that whisker deprivation causes a change in information flow within the cortical layers and that layer 5 regular-spiking cells, despite showing only a small potentiation of short-latency input, show the greatest increase in information content for the spared input partly by decreasing their spontaneous activity.

Input of hair field afferents to a descending interneuron

2021 ◽  
Author(s):  
Bianca Jaske ◽  
Gaetan Lepreux ◽  
Volker Dürr
Keyword(s):  
Joint Angle ◽  
Stick Insect ◽  
Passive Movement ◽  
Activity Level ◽  
Reach To Grasp ◽  
Movement Velocity ◽  
Before And After ◽  
Steady State Activity ◽  
Transfer Of Information ◽  
Antennal Contact

In insects the tactile sense is important for near-range orientation and is involved in various behaviors. Nocturnal insects such as the stick insect Carausius morosus continuously explore their surroundings by actively moving their antennae when walking. Upon antennal contact with objects, stick insects show a targeted front-leg movement. As this reaction occurs within 40 ms, descending transfer of information from the brain to the thorax needs to be fast. So far, a number of descending interneurons have been described that may be involved in this reach-to-grasp behavior. One of these is the contralateral ON-type velocity-sensitive neuron (cONv). cONv was found to encode antennal joint-angle velocity during passive movement. Here, we characterize the transient response properties of cONv, including its dependence on joint angle range and direction. Since antennal hair field afferent terminals were shown to arborize close to cONv dendrites, we test whether antennal hair fields contribute to the joint-angle velocity encoding of cONv. To do so, we conducted bilateral extracellular recordings of both cONv interneurons per animal before and after hair field ablations. Our results show that cONv responses are highly transient, with velocity-dependent differences in delay and response magnitude. As yet, the steady state activity level was maintained until the stop of antennal movement, irrespective of movement velocity. Hair field ablation caused a moderate but significant reduction of movement-induced cONv firing rate by up to 40 %. We conclude that antennal proprioceptive hair fields contribute to the velocity-tuning of cONv, though further antennal mechanoreceptors must be involved, too.

Effects of Halothane and Sevoflurane on Inhibitory Neurotransmission to Medullary Expiratory Neurons in a Decerebrate Dog Model

2002 ◽  
Vol 96 (4) ◽  
pp. 955-962 ◽  
Author(s):  
Astrid G. Stucke ◽  
Eckehard A. E. Stuth ◽  
Viseslav Tonkovic-Capin ◽  
Mislav Tonkovic-Capin ◽  
Francis A. Hopp ◽  
...  
Keyword(s):  
Spontaneous Activity ◽  
Gabaa Receptor ◽  
Neuronal Activity ◽  
Neuronal Response ◽  
Inhibitory Input ◽  
Gamma Aminobutyric Acid ◽  
Receptor Function ◽  
Presynaptic Site ◽  
Gabaa Receptor Antagonist ◽  
Expiratory Neurons

Background In canine expiratory bulbospinal neurons, 1 minimum alveolar concentration (MAC) halothane and sevoflurane reduced the glutamatergic excitatory drive at a presynaptic site and enhanced the overall gamma-aminobutyric acid (GABA)-mediated inhibitory input. The authors investigated if this inhibitory enhancement was mainly caused by postsynaptic effects. Methods Two separate anesthetic studies were performed in two sets of decerebrate, vagotomized, paralyzed, and mechanically ventilated dogs during hypercapnic hyperoxia. The effect of 1 MAC halothane or sevoflurane on extracellularly recorded neuronal activity was measured during localized picoejection of the GABAA receptor agonist muscimol and the GABAA receptor antagonist bicuculline. Complete blockade of GABAA-mediated inhibition with bicuculline was used to assess the prevailing overall inhibitory input to the neuron. The neuronal response to muscimol was used to estimate the anesthetic effect on postsynaptic GABAA receptor function. Results Halothane at 1 MAC depressed the spontaneous activity of 12 expiratory neurons 22.2 +/- 14.8% (mean +/- SD) and overall glutamatergic excitation 14.5 +/- 17.9%. Overall GABA-mediated inhibition was enhanced 14.1 +/- 17.9% and postsynaptic GABAA receptor function 74.2 +/- 69.2%. Sevoflurane at 1 MAC depressed the spontaneous activity of 23 neurons 20.6 +/- 19.3% and overall excitation 10.6 +/- 21.7%. Overall inhibition was enhanced 15.4 +/- 34.0% and postsynaptic GABAA receptor function 65.0 +/- 70.9%. The effects of halothane and sevoflurane were not statistically different. Conclusion Halothane and sevoflurane at 1 MAC produced a small increase in overall inhibition of expiratory premotor neuronal activity. The increase in inhibition results from a marked enhancement of postsynaptic GABAA receptor function that is partially offset by a reduction in presynaptic inhibitory input by the anesthetics.

Neuron-Specific Response Characteristics Predict the Magnitude of Multisensory Integration

2003 ◽  
Vol 90 (6) ◽  
pp. 4022-4026 ◽  
Author(s):  
Thomas J. Perrault ◽  
J. William Vaughan ◽  
Barry E. Stein ◽  
Mark T. Wallace
Keyword(s):  
Spontaneous Activity ◽  
Multisensory Integration ◽  
Neuronal Response ◽  
Full Range ◽  
Specific Response ◽  
Multisensory Interaction ◽  
Response Characteristics ◽  
Response Profile ◽  
Sensory Responses ◽  
Stimulus Effectiveness

Multisensory neurons in the superior colliculus (SC) typically respond to combinations of stimuli from multiple modalities with enhancements and/or depressions in their activity. Although such changes in response have been shown to follow a predictive set of integrative principles, these principles fail to completely account for the full range of interactions seen throughout the SC population. In an effort to better define this variability, we sought to determine if there were additional features of the neuronal response profile that were predictive of the magnitude of the multisensory interaction. To do this, we recorded from 109 visual-auditory SC neurons while systematically manipulating stimulus intensity. Along with the previously described roles of space, time, and stimulus effectiveness, two features of a neuron's response profile were found to offer predictive value as to the magnitude of the multisensory interaction: spontaneous activity and the level of sensory responsiveness. Multisensory neurons with little or no spontaneous activity and weak sensory responses had the capacity to exhibit large response enhancements. Conversely, neurons with modest spontaneous activity and robust sensory responses exhibited relatively small response enhancements. Together, these results provide a better view into multisensory integration, and suggest substantial heterogeneity in the integrative characteristics of the multisensory SC population.

scholarly journals Barriers and Facilitators for Physical Activity in Already Active Pregnant and Postpartum Women? Findings from a Qualitative Study to Inform the Design of an Intervention for Active Women.

2020 ◽  
Author(s):  
Murali Krishnan Perumbakkam Subramanian ◽  
Peter Van der Graaf ◽  
Rosemary Dawson ◽  
Louise Hayes ◽  
Louisa J Ells ◽  
...  
Keyword(s):  
Physical Activity ◽  
Thematic Analysis ◽  
Physical Activity Intervention ◽  
Background Activity ◽  
Barriers And Facilitators ◽  
Postpartum Women ◽  
Activity Levels ◽  
Limited Information ◽  
Pregnancy And Postpartum ◽  
Physical Activity Levels

Abstract Background – Activity levels decline substantially in both inactive and active women during pregnancy and postpartum. There is limited information on the barriers and facilitators for physical activity participation in active women during this period. The primary aim of this study is to identify the barriers and facilitators for physical activity in already active women during pregnancy and postpartum. We also explore their views on, and requirements for, the development of an intervention to support the maintenance of or increase in physical activity. Methods - Five focus groups, with a total of 19 participants, were conducted. Transcripts were analysed using a thematic analysis approach. Results – Out of the 19 participants, four were postpartum, and 15 were pregnant. Analysing the focus group transcripts, 22 codes were generated and grouped into eight themes: 1-cognizant of physical activity’s benefits, 2-sources of advice, 3-reasons to be active during pregnancy, 4-reasons for reducing physical activity levels during pregnancy, 5-barriers to physical activity during and after pregnancy, 6-facilitators of physical activity during and after pregnancy, 7-ideal physical activity intervention, and 8-evaluation support. Conclusions – Among already active pregnant and postpartum women, factors such as pregnancy-related body changes, childcare and lack of targeted activities deter participation in physical activity. A new programme with social and group elements, including both familiar and new activities, and providing ‘satisfaction and fun’ should be developed to help increase or maintain their activity levels.

scholarly journals Long-term, layer-specific reverberant activity in the mouse somatosensory cortex following sensory stimulation

2016 ◽  
Author(s):  
Elena Phoka ◽  
Aleksandra Berditchevskaia ◽  
Mauricio Barahona ◽  
Simon R Schultz
Keyword(s):  
Spontaneous Activity ◽  
Somatosensory Cortex ◽  
Receptive Fields ◽  
Sensory Stimulation ◽  
Memory Storage ◽  
Firing Patterns ◽  
Neural Ensemble ◽  
Functional Relevance ◽  
Stimulus Offset

Neocortical circuits exhibit spontaneous neuronal activity whose functional relevance remains enigmatic. Several proposed functions assume that sensory experience can influence subsequent spontaneous activity. However, long-term alterations in spontaneous firing rates following sensory stimulation have not been reported until now. Here we show that multi-whisker, spatiotemporally rich stimulation of mouse vibrissae induces a laminar-specific, long-term increase of spontaneous activity in the somatosensory cortex. Such stimulation additionally produces stereotypical neural ensemble firing patterns from simultaneously recorded single neurons, which are maintained during spontaneous activity following stimulus offset. The increased neural activity and concomitant ensemble firing patterns are sustained for at least 25 minutes after stimulation, and specific to layers IV and Vb. In contrast, the same stimulation protocol applied to a single whisker fails to elicit this effect. Since layer Vb has the largest receptive fields and, together with layer IV, receives direct thalamic and lateral drive, the increase in firing activity could be the result of mechanisms involving the integration of spatiotemporal patterns across multiple whiskers. Our results provide direct evidence of modification of spontaneous cortical activity by sensory stimulation and could offer insight into the role of spatiotemporal integration in memory storage mechanisms for complex stimuli.

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