Neural Gating Research Articles

Conditioned fear selectively increases the perception and neural processing of respiratory stimuli relative to somatosensory stimuli

Interoception is crucial to the experience of bodily complaints in chronic conditions. Fear can distort the perception of sensations like breathlessness and pain, yet few studies investigated the effects of conditioned fear on both self-report and neural processing of these sensations. In the current study, we conditioned fear of neutral female faces in healthy adults, pairing certain faces (CS+) with an aversive scream. In Experiment 1, we delivered paired inspiratory occlusions during the viewing of the faces. We collected self-reported intensity and unpleasantness of occlusions, and measured N1 and P2 amplitudes of the respiratory-related evoked potential (RREP) in the electroencephalogram, as well as neural gating (the ratio of N1 response to the second over the first occlusion, S2/S1). Skin conductance and self-reported fear increased in response to CS+ faces, and perception of occlusions increased during fear conditioning (FC) relative to baseline, with higher unpleasantness and RREP amplitudes during CS+ relative to CS- trials. We found no effects on neural gating. In Experiment 2, we used the same FC protocol, and delivered paired electrocutaneous pulses during the viewing of the faces. We measured intensity/unpleasantness, fear, N1/P2 amplitudes of the somatosensory evoked potential (SEP), and neural gating. While skin conductance and fear increased, no perceptual effects were found. Unexpectedly, SEP amplitudes decreased and neural gating increased during FC, likely due to habituation. The current results indicate that FC increases the perception and neural processing of respiratory stimuli specifically, consistent with previous literature on respiratory psychophysiology and fearful states.

Study protocol: Cerebral characterization of sensory gating in disconnected dreaming states during propofol anesthesia using fMRI.

Disconnected consciousness describes a state in which subjective experience (i.e., consciousness) becomes isolated from the external world. It appears frequently during sleep or sedation, when subjective experiences remain vivid but are unaffected by external stimuli. Traditional methods of differentiating connected and disconnected consciousness, such as relying on behavioral responsiveness or on post-anesthesia reports, have demonstrated limited accuracy: unresponsiveness has been shown to not necessarily equate to unconsciousness and amnesic effects of anesthesia and sleep can impair explicit recollection of events occurred during sleep/sedation. Due to these methodological challenges, our understanding of the neural mechanisms underlying sensory disconnection remains limited. To overcome these methodological challenges, we employ a distinctive strategy by combining a serial awakening paradigm with auditory stimulation during mild propofol sedation. While under sedation, participants are systematically exposed to auditory stimuli and questioned about their subjective experience (to assess consciousness) and their awareness of the sounds (to evaluate connectedness/disconnectedness from the environment). The data collected through interviews are used to categorize participants into connected and disconnected consciousness states. This method circumvents the requirement for responsiveness in assessing consciousness and mitigates amnesic effects of anesthesia as participants are questioned while still under sedation. Functional MRI data are concurrently collected to investigate cerebral activity patterns during connected and disconnected states, to elucidate sensory disconnection neural gating mechanisms. We examine whether this gating mechanism resides at the thalamic level or results from disruptions in information propagation to higher cortices. Furthermore, we explore the potential role of slow-wave activity (SWA) in inducing disconnected consciousness by quantifying high-frequency BOLD oscillations, a known correlate of slow-wave activity. This study represents a notable advancement in the investigation of sensory disconnection. The serial awakening paradigm effectively mitigates amnesic effects by collecting reports immediately after regaining responsiveness, while still under sedation. Ultimately, this research holds the potential to understand how sensory gating is achieved at the neural level. These biomarkers might be relevant for the development of sensitive anesthesia monitoring to avoid intraoperative connected consciousness and for the assessment of patients suffering from pathologically reduced consciousness. European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), identifier 2020-003524-17.

Neural oscillations underlying the neural gating of respiratory sensations in generalized anxiety disorder

Individuals with generalized anxiety disorder (GAD) have been shown to have altered neural gating of respiratory sensations (NGRS) using respiratory-related evoked potentials (RREP); however, corresponding neural oscillatory activities remain unexplored. The present study aimed to investigate altered NGRS in individuals with GAD using both time and time-frequency analysis. Nineteen individuals with GAD and 28 healthy controls were recruited. Paired inspiratory occlusions were delivered to elicit cortical neural activations measured from electroencephalography. The GAD group showed smaller N1 amplitudes to the first stimulus (S1), lower evoked gamma and larger evoked beta oscillations compared to controls. Both groups showed larger N1, P3, beta power and theta power in response to S1 compared to S2, suggesting a neural gating phenomenon. These findings suggest that N1, gamma and beta frequency oscillations may be indicators for altered respiratory sensation in GAD populations and that the N1, P3, beta and theta oscillations can reflect the neural gating of respiratory sensations.

Age-related changes in the neural gating of respiratory sensations in humans.

Neural gating of respiratory sensations (NGRS) characterises the brain's ability to filter out repetitive respiratory sensory stimuli. This mechanism plays a crucial role in the neural processing of respiratory stimuli. However, whether ageing affects NGRS in healthy adults is still unclear. Therefore, we aimed to measure the effect of age on NGRS as well as the corresponding S1 and S2 components of the respiratory-related evoked potentials (RREPs). Three age groups of healthy adults participated in this study: a young group (YG; age 20-39 years), a middle-aged group (MG; age 40-59 years) and an old group (OG; age ≥60 years). NGRS was measured by the RREPs in the electroencephalogram in response to short-paired respiratory occlusion stimuli (S1 and S2). The S2/S1 ratio of the RREP N1 amplitude (the negative deflection of the RREP at ∼85-135 ms) was used to characterise NGRS. The results showed a significantly smaller N1 S2/S1 ratio in the YG than in the MG (p=0.01) and OG (p=0.03). Further analysis showed that the S1 N1 amplitude was larger for the YG compared with the MG (p=0.03) and OG (p=0.007). Moreover, age was significantly correlated with the N1 S2/S1 ratio (r=0.43), with higher age relating to higher N1 S2/S1 ratios. The greater N1 S2/S1 ratios observed in older adults suggest that ageing has a negative impact on the NGRS. This might contribute to increased experiences of respiratory sensations such as dyspnoea in ageing adults.

Neural oscillatory markers of respiratory sensory gating in human cortices

BackgroundHuman respiratory sensory gating is a neural process associated with inhibiting the cortical processing of repetitive respiratory mechanical stimuli. While this gating is typically examined in the time domain, the neural oscillatory dynamics, which could offer supplementary insights into respiratory sensory gating, remain unknown. The purpose of the present study was to investigate central neural gating of respiratory sensation using both time- and frequency-domain analyses. MethodsA total of 37 healthy adults participated in this study. Two transient inspiratory occlusions were presented within one inspiration, while responses in the electroencephalogram (EEG) were recorded. N1 amplitudes and oscillatory activities to the first stimulus (S1) and the second stimulus (S2) were measured. The perceived level of breathlessness and level of unpleasantness elicited by the occlusions were measured after the experiment. ResultsAs expected, the N1 peak amplitude to the S1 was significantly larger than to the S2. The averaged respiratory sensory gating S2/S1 ratio for the N1 peak amplitude was 0.71. For both the evoked- and induced-oscillations, time-frequency analysis showed higher theta activations in response to S1 relative to S2. A positive correlation was observed between the perceived unpleasantness and induced theta power. ConclusionsOur results suggest that theta oscillations, evoked as well as induced, reflect the “gating” of respiratory sensation. Theta oscillation, particularly theta-induced power, may be indicative of the emotional processing of respiratory mechanosensation. The findings of this study serve as a foundation for future investigations into the underlying mechanisms of respiratory sensory gating, particularly in patient populations.

Repeated exposure to aversive sensations differentially affects neural gating and bodily perception

Habituation to bodily sensations is highly relevant for the experience of chronic bodily symptoms, but the neural mechanisms behind diminished habituation are currently unclear. One potentially relevant mechanism is neural gating (NG), reflected as the short-term suppression of cortical responses to redundant stimuli. We investigated the effects of repeated exposure to aversive sensations on NG and subjective perception in 91 healthy adults, by measuring their NG of respiratory and electrocutaneous stimuli using electroencephalography during two sessions separated by one week, in addition to their self-report of intensity and unpleasantness of the sensations. To test for intra- and cross-modal effects, 1/2 participants returned three times in the intervening week to experience additional aversive respiratory stimulation, while the other 1/2 received aversive electrocutaneous stimulation. Participants reported lower unpleasantness of all sensations in the final session (intra- and cross-modal habituation). NG was improved for respiratory sensations only in the group receiving additional respiratory stimulation (intra-modal habituation). We found no relationships between NG and perceptual habituation, adding to the mixed results on the relevance of NG to perceptual changes in healthy adults. Future research with clinical populations and different methods is encouraged to further clarify the mechanisms behind neural gating and diminished symptom habituation.

Motor and visual influences on auditory neural processing during speaking and listening

During speaking or listening, endogenous motor or exogenous visual processes have been shown to fine-tune the auditory neural processing of incoming acoustic speech signal. To compare the impact of these cross-modal effects on auditory evoked responses, two sets of speech production and perception tasks were contrasted using EEG. In a first set, participants produced vowels in a self-paced manner while listening to their auditory feedback. Following the production task, they passively listened to the entire recorded speech sequence. In a second set, the procedure was identical except that participants also watched online their own articulatory movements. While both endogenous motor and exogenous visual processes fine-tuned auditory neural processing, these cross-modal effects were found to act differentially on the amplitude and latency of auditory evoked responses. A reduced amplitude was observed on auditory evoked responses during speaking compared to listening, irrespective of the auditory or audiovisual feedback. Adding orofacial visual movements to the acoustic speech signal also speeded up the latency of auditory evoked responses, irrespective of the perception or production task. Taken together, these results suggest distinct motor and visual influences on auditory neural processing, possibly through different neural gating and predictive mechanisms.

Neural substrates of respiratory sensory gating: A human fMRI study

The involvement of neural substrates in respiratory sensory gating remained unclear. This study aimed to investigate cortical and subcortical activations associated with respiratory sensory gating by using functional magnetic resonance imaging. First, we hypothesized that paired occlusions would induce neural activation in cortical and subcortical areas, including the thalamus and sensorimotor cortices. Secondly, we hypothesized that, in terms of parameter estimates in the general linear model, the activation effect size β ratios (βpaired/βsingle) would be less than 2 due to central neural gating mechanism. Forty-six healthy participants were included in the study. Our analyses showed that the βpaired/βsingle ratios for the supramarginal gyrus, basal ganglia, thalamus, and middle frontal gyrus were less than 2. In conclusion, our results demonstrated a non-linear relationship regarding brain neural activations in response to paired versus single occlusions, suggesting that respiratory sensory information is gated at the subcortical and cortical levels.

The effects of unpredictability and negative affect on perception and neural gating in different interoceptive modalities

Breathlessness and pain frequently co-occur in chronic conditions, and their unpredictability is often reported to amplify perception and negative affect (NA), however any common neural mechanisms remain largely unexplored. This study examined the effects of (unpredictable) bodily threat on perception and neural gating of respiratory and somatosensory stimuli. Healthy adults (N = 51) experienced brief paired inspiratory occlusions and electrocutaneous stimuli, with their neural activity monitored via electroencephalography. Neural gating was measured as a ratio of the N1 response to the second relative to the first stimulus in a pair. In 4/6 blocks, threatening stimulation, in form of additional loaded breaths or electrocutaneous pulses, was presented predictably or unpredictably. Participants reported: perceived intensity and unpleasantness of all stimuli, fear, trait NA and intolerance of uncertainty (IU). Threatening stimulation increased perception, fear, and N1 amplitudes, without affecting neural gating. There was no group effect of unpredictability, though interactions were found with NA and IU. Cross-modal correlations revealed significant baseline relationships in neural gating and perception, though not in their modulation by threat. The present findings demonstrate that respiratory and somatosensory modalities relate in baseline perception and neural gating, and exhibit similar modulation effects by unpleasant stimulation. Further research is encouraged to elucidate the underlying mechanisms of these relationships, and the potential interactions with stimulus unpredictability.

Early Schizophrenia and Bipolar Disorder Patients Display Reduced Neural Prepulse Inhibition.

Background: Altered sensorimotor gating has been demonstrated by Prepulse Inhibition (PPI) tests in patients with psychosis. Recent advances in signal processing methods allow assessment of neural PPI through electroencephalogram (EEG) recording during acoustic startle response measures (classic muscular PPI). Simultaneous measurements of muscular (eye-blink) and neural gating phenomena during PPI test may help to better understand sensorial processing dysfunctions in psychosis. In this study, we aimed to assess simultaneously muscular and neural PPI in early bipolar disorder and schizophrenia patients. Method: Participants were recruited from a population-based case-control study of first episode psychosis. PPI was measured using electromyography (EMG) and EEG in pulse alone and prepulse + pulse with intervals of 30, 60, and 120 ms in early bipolar disorder (n = 18) and schizophrenia (n = 11) patients. As control group, 15 socio-economically matched healthy subjects were recruited. All subjects were evaluated with Rating Scale, Hamilton Rating Scale for Depression, and Young Mania Rating Scale questionnaires at recruitment and just before PPI test. Wilcoxon ranked sum tests were used to compare PPI test results between groups. Results: In comparison to healthy participants, neural PPI was significantly reduced in PPI 30 and PPI60 among bipolar and schizophrenia patients, while muscular PPI was reduced in PPI60 and PPI120 intervals only among patients with schizophrenia. Conclusion: The combination of muscular and neural PPI evaluations suggested distinct impairment patterns among schizophrenia and bipolar disorder patients. Simultaneous recording may contribute with novel information in sensory gating investigations.

The impact of unpredictability of dyspnea offset on dyspnea perception, fear, and respiratory neural gating

Dyspnea is a debilitating and threatening symptom in various diseases. Affected patients often report the unpredictability of dyspnea episodes being particularly anxiety-provoking and amplifying the perception of dyspnea. Experimental studies testing dyspnea unpredictability together with related neural processes, physiological fear responses, and dyspnea-related personality traits are sparse. Therefore, we investigated the impact of unpredictability of dyspnea offset on dyspnea perception and fear ratings, respiratory neural gating and physiological fear indices, as well as the influence of interindividual differences in fear of suffocation (FoS). Forty healthy participants underwent a task manipulating the offset predictability of resistive load-induced dyspnea including one unloaded safety condition. Respiratory variables, self-reports of dyspnea intensity, dyspnea unpleasantness, and fear were recorded. Moreover, respiratory neural gating was measured in a paired inspiratory occlusion paradigm using electroencephalography, while electrodermal activity, startle eyeblink, and startle probe N100 were assessed as physiological fear indices. Participants reported higher dyspnea unpleasantness and fear when dyspnea offset was unpredictable compared to being predictable. Individuals with high levels of FoS showed the greatest increase in fear and overall higher levels of fear and physiological arousal across all conditions. Respiratory neural gating, startle eyeblink, and startle probe N100 showed general reductions during dyspnea conditions but no difference between unpredictable and predictable dyspnea conditions. Together, the current results suggest that the unpredictable offset of dyspnea amplifies dyspnea perception and fear, especially in individuals with high levels of FoS. These effects were unrelated to respiratory neural gating or physiological fear responses, requiring future studies on underlying mechanisms.

Enhanced mirroring upon mutual gaze: multimodal evidence from TMS-assessed corticospinal excitability and the EEG mu rhythm

Previous research has demonstrated that eye contact between actor and observer specifically enhances the ‘mirroring’ of others’ actions, as measured by transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs). However, it remains unknown whether other markers of mirror system activation, such as suppression of the EEG mu rhythm (8–13 Hz) over the sensorimotor strip, are also susceptible to perceived eye contact. Here, both TMS-induced MEPs and EEG mu suppression indices were assessed (in separate sessions) while 32 participants (mean age: 24y; 8m) observed a simple hand movement combined with direct or averted gaze from the actor. Both measures were significantly modulated by perceived eye gaze during action observation; showing an increase in MEP amplitude and an attenuation of the mu rhythm during direct vs. averted gaze. Importantly, while absolute MEP and mu suppression scores were not related, a significant association was identified between gaze-related changes in MEPs and mu suppression, indicating that both measures are similarly affected by the modulatory impact of gaze cues. Our results suggest that although the neural substrates underlying TMS-induced MEPs and the EEG mu rhythm may differ, both are sensitive to the social relevance of the observed actions, which might reflect a similar neural gating mechanism.

Cross-modal relationships of neural gating with the subjective perception of respiratory and somatosensory sensations.

Neural gating is a phenomenon whereby the response to a stimulus in the electroencephalogram (EEG) is attenuated when preceded by an identical stimulus. Attenuation of paired auditory clicks has repeatedly been shown to be affected in mental disorders, for example, schizophrenia. Neural gating has also been measured for respiratory and somatosensory sensations, however the attenuation of bodily relevant stimuli has not yet been systematically related to the subjective perception of bodily sensations. This research direction is potentially relevant to explaining disease trajectories in psychosomatic conditions characterized by chronic breathlessness and/or pain. In the present study, we recorded high-density EEG from 85 healthy young adults while they experienced brief paired respiratory occlusions and brief paired electrocutaneous stimulation of the wrist. The event-related potential N1 was measured centro-laterally in response to the second relative to the first stimulus to quantify neural gating in both sensory domains. Participants experienced resistive loaded breaths and electrocutaneous stimuli of various intensities, rated their perceived intensity and unpleasantness, and performed magnitude estimation. Relationships of respiratory and somatosensory neural gating to the subjective intensity and unpleasantness of sensations, as well as the ability to discriminate sensations of varying intensities, were investigated intra-modally and cross-modally. We report significant relationships of the somatosensory neural gating to perceived intensity and unpleasantness of respiratory and somatosensory sensations, with the stronger neural gating relating to a stronger subjective intensity and unpleasantness. We discuss these unexpected findings through the lens of individual differences and different theoretical accounts on the origins of cortical attenuation of repetitive stimuli.

Confidence drives a neural confirmation bias

A prominent source of polarised and entrenched beliefs is confirmation bias, where evidence against one’s position is selectively disregarded. This effect is most starkly evident when opposing parties are highly confident in their decisions. Here we combine human magnetoencephalography (MEG) with behavioural and neural modelling to identify alterations in post-decisional processing that contribute to the phenomenon of confirmation bias. We show that holding high confidence in a decision leads to a striking modulation of post-decision neural processing, such that integration of confirmatory evidence is amplified while disconfirmatory evidence processing is abolished. We conclude that confidence shapes a selective neural gating for choice-consistent information, reducing the likelihood of changes of mind on the basis of new information. A central role for confidence in shaping the fidelity of evidence accumulation indicates that metacognitive interventions may help ameliorate this pervasive cognitive bias.

A neural circuit model for a contextual association task inspired by recommender systems.

Behavioral data shows that humans and animals have the capacity to learn rules of associations applied to specific examples, and generalize these rules to a broad variety of contexts. This article focuses on neural circuit mechanisms to perform a context-dependent association task that requires linking sensory stimuli to behavioral responses and generalizing to multiple other symmetrical contexts. The model uses neural gating units that regulate the pattern of physiological connectivity within the circuit. These neural gating units can be used in a learning framework that performs low-rank matrix factorization analogous to recommender systems, allowing generalization with high accuracy to a wide range of additional symmetrical contexts. The neural gating units are trained with a biologically inspired framework involving traces of Hebbian modification that are updated based on the correct behavioral output of the network. This modeling demonstrates potential neural mechanisms for learning context-dependent association rules and for the change in selectivity of neurophysiological responses in the hippocampus. The proposed computational model is evaluated using simulations of the learning process and the application of the model to new stimuli. Further, human subject behavioral experiments were performed and the results validate the key observation of a low-rank synaptic matrix structure linking stimuli to responses.

S 2 ‐Net: Machine reading comprehension with SRU‐based self‐matching networks

Machine reading comprehension is the task of understanding a given context and finding the correct response in that context. A simple recurrent unit (SRU) is a model that solves the vanishing gradient problem in a recurrent neural network (RNN) using a neural gate, such as a gated recurrent unit (GRU) and long short-term memory (LSTM); moreover, it removes the previous hidden state from the input gate to improve the speed compared to GRU and LSTM. A self-matching network, used in R-Net, can have a similar effect to coreference resolution because the self-matching network can obtain context information of a similar meaning by calculating the attention weight for its own RNN sequence. In this paper, we construct a dataset for Korean machine reading comprehension and propose an S2-Net model that adds a self-matching layer to an encoder RNN using multilayer SRU. The experimental results show that the proposed S2-Net model has performance of single 68.82% EM and 81.25% F1, and ensemble 70.81% EM, 82.48% F1 in the Korean machine reading comprehension test dataset, and has single 71.30% EM and 80.37% F1 and ensemble 73.29% EM and 81.54% F1 performance in the SQuAD dev dataset.

A Method for Simultaneous Evaluation of Muscular and Neural Prepulse Inhibition.

Prepulse inhibition (PPI) test has been widely used to evaluate sensorimotor gating. In humans, deficits in this mechanism are measured through the orbicularis muscle response using electromyography (EMG). Although this mechanism can be modulated by several brain structures and is impaired in some pathologies as schizophrenia and bipolar disorder, neural PPI evaluation is rarely performed in humans. Since eye blinks are a consequence of PPI stimulation, they strongly contaminate the electroencephalogram (EEG) signal. This paper describes a method to reduce muscular artifacts and enable neural PPI assessment through EEG in parallel to muscular PPI evaluation using EMG. Both types of signal were simultaneously recorded in 22 healthy subjects. PPI was evaluated by the acoustical startle response with EMG and by the P2-N1 event-related potential (ERP) using EEG in Fz, Cz, and Pz electrodes. In order to remove EEG artifacts, Independent Component Analysis (ICA) was performed using two methods. Firstly, visual inspection discarded components containing artifact characteristics as ocular and tonic muscle artifacts. The second method used visual inspection as gold standard to validate parameters in an automated component selection using the SASICA algorithm. As an outcome, EEG artifacts were effectively removed and equivalent neural PPI evaluation performance was obtained using both methods, with subjects exhibiting consistent neural as well as muscular PPI. This novel method improves PPI test, enabling neural gating mechanisms assessment within the latency of 100–200 ms, which is not evaluated by other sensory gating tests as P50 and mismatch negativity.

Laboratory Medicine in Pain Management: Evolution to Guidelines - Defining a Standard of Care.

It was in 1965 that Drs. Ron Malzack and Patrick Wall published the “gate control theory” of pain in Science (1). This theory of chronic pain speculated that neural gates in the spinal cord could be made to open or close by signals …

A Cognitive Neural Architecture Able to Learn and Communicate through Natural Language.

Communicative interactions involve a kind of procedural knowledge that is used by the human brain for processing verbal and nonverbal inputs and for language production. Although considerable work has been done on modeling human language abilities, it has been difficult to bring them together to a comprehensive tabula rasa system compatible with current knowledge of how verbal information is processed in the brain. This work presents a cognitive system, entirely based on a large-scale neural architecture, which was developed to shed light on the procedural knowledge involved in language elaboration. The main component of this system is the central executive, which is a supervising system that coordinates the other components of the working memory. In our model, the central executive is a neural network that takes as input the neural activation states of the short-term memory and yields as output mental actions, which control the flow of information among the working memory components through neural gating mechanisms. The proposed system is capable of learning to communicate through natural language starting from tabula rasa, without any a priori knowledge of the structure of phrases, meaning of words, role of the different classes of words, only by interacting with a human through a text-based interface, using an open-ended incremental learning process. It is able to learn nouns, verbs, adjectives, pronouns and other word classes, and to use them in expressive language. The model was validated on a corpus of 1587 input sentences, based on literature on early language assessment, at the level of about 4-years old child, and produced 521 output sentences, expressing a broad range of language processing functionalities.

A Cognitive Neural Model of Executive Functions in Natural Language Processing

Abstract Although extensive research has been devoted to cognitive models of human language, the role of executive functions in language processing has little been explored. In this work we present a neural-network-based cognitive architecture which models the development of the procedural knowledge that underpin language processing. The large scale organization of the architecture is based on a multi-component working memory model, with a central executive that controls the flow of information among the slave systems through neural gating mechanisms. The system was validated, starting from a tabula rasa condition, on a on a corpus of five datasets, each devoted to a thematic group, based on literature on early language assessment, at the level of a preschool child. The results show that the system is capable of learning different word classes, and to use them in expressive language, through an open-ended incremental learning process, expressing a broad range of language processing functionalities.