Dynamics of the auditory continuity illusion

ABSTRACTIllusions give intriguing insights into perceptual and neural dynamics. In the auditory continuity illusion, two brief tones separated by a silent gap may be heard as one continuous tone if a noise burst with appropriate characteristics fills the gap. This illusion probes the conditions under which listeners link related sounds across time and maintain perceptual continuity in the face of sudden changes in sound mixtures. Conceptual explanations of this illusion have been proposed, but its neural basis is still being investigated. In this work we provide a dynamical systems framework, grounded in principles of neural dynamics, to explain the continuity illusion. We construct an idealized firing rate model of a neural population and analyze the conditions under which firing rate responses persist during the interruption between the two tones. First, we show that sustained inputs and hysteresis dynamics (a mismatch between tone levels needed to activate and inactivate the population) can produce continuous responses. Second, we show that transient inputs and bistable dynamics (coexistence of two stable firing rate levels) can also produce continuous responses. Finally, we combine these input types together to obtain neural dynamics consistent with two requirements for the continuity illusion as articulated in a well-known theory of auditory scene analysis: sustained responses occur if noise provides sufficient evidence that the tone continues and if there is no evidence of discontinuities between the tones and noise. By grounding these notions in a quantitative model that incorporates elements of neural circuits (recurrent excitation, and mutual inhibition, specifically), we identify plausible mechanisms for the continuity illusion. Our findings can help guide future studies of neural correlate of this illusion and inform development of more biophysically-based models of the auditory continuity illusion.

Download Full-text

Dynamics of the Auditory Continuity Illusion

Frontiers in Computational Neuroscience ◽

10.3389/fncom.2021.676637 ◽

2021 ◽

Vol 15 ◽

Author(s):

Qianyi Cao ◽

Noah Parks ◽

Joshua H. Goldwyn

Keyword(s):

Firing Rate ◽

Noise Burst ◽

Auditory Scene Analysis ◽

Quantitative Model ◽

Neural Dynamics ◽

Sufficient Evidence ◽

Neural Population ◽

Neural Basis ◽

Continuous Responses ◽

Conceptual Explanations

Illusions give intriguing insights into perceptual and neural dynamics. In the auditory continuity illusion, two brief tones separated by a silent gap may be heard as one continuous tone if a noise burst with appropriate characteristics fills the gap. This illusion probes the conditions under which listeners link related sounds across time and maintain perceptual continuity in the face of sudden changes in sound mixtures. Conceptual explanations of this illusion have been proposed, but its neural basis is still being investigated. In this work we provide a dynamical systems framework, grounded in principles of neural dynamics, to explain the continuity illusion. We construct an idealized firing rate model of a neural population and analyze the conditions under which firing rate responses persist during the interruption between the two tones. First, we show that sustained inputs and hysteresis dynamics (a mismatch between tone levels needed to activate and inactivate the population) can produce continuous responses. Second, we show that transient inputs and bistable dynamics (coexistence of two stable firing rate levels) can also produce continuous responses. Finally, we combine these input types together to obtain neural dynamics consistent with two requirements for the continuity illusion as articulated in a well-known theory of auditory scene analysis: responses persist through the noise-filled gap if noise provides sufficient evidence that the tone continues and if there is no evidence of discontinuities between the tones and noise. By grounding these notions in a quantitative model that incorporates elements of neural circuits (recurrent excitation, and mutual inhibition, specifically), we identify plausible mechanisms for the continuity illusion. Our findings can help guide future studies of neural correlates of this illusion and inform development of more biophysically-based models of the auditory continuity illusion.

Download Full-text

Neural Ensemble Coding during Working Memory Task in Rat Prefrontal Cortex

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.467-469.1291 ◽

2011 ◽

Vol 467-469 ◽

pp. 1291-1296

Author(s):

Wen Wen Bai ◽

Xin Tian

Keyword(s):

Working Memory ◽

Prefrontal Cortex ◽

Firing Rate ◽

Memory Task ◽

Neural Population ◽

Average Firing Rate ◽

Population Activity ◽

Ensemble Coding ◽

Neural Ensemble ◽

Ensemble Activity

Working memory is one of important cognitive functions and recent studies demonstrate that prefrontal cortex plays an important role in working memory. But the issue that how neural activity encodes during working memory task is still a question that lies at the heart of cognitive neuroscience. The aim of this study is to investigate neural ensemble coding mechanism via average firing rate during working memory task. Neural population activity was measured simultaneously from multiple electrodes placed in prefrontal cortex while rats were performing a working memory task in Y-maze. Then the original data was filtered by a high-pass filtering, spike detection and spike sorting, spatio-temporal trains of neural population were ultimately obtained. Then, the average firing rates were computed in a selected window (500ms) with a moving step (125ms). The results showed that the average firing rate were higher during workinig memory task, along with obvious ensemble activity. Conclusion: The results indicate that the working memory information is encoded with neural ensemble activity.

Download Full-text

Circuit Properties Generating Gamma Oscillations in a Network Model of the Olfactory Bulb

Journal of Neurophysiology ◽

10.1152/jn.01141.2005 ◽

2006 ◽

Vol 95 (4) ◽

pp. 2678-2691 ◽

Cited By ~ 71

Author(s):

Brice Bathellier ◽

Samuel Lagier ◽

Philippe Faure ◽

Pierre-Marie Lledo

Keyword(s):

Olfactory Bulb ◽

Firing Rate ◽

Lateral Inhibition ◽

Temporal Structure ◽

Gamma Oscillations ◽

Synaptic Organization ◽

Neural Basis ◽

Sensory Inputs ◽

Model Based

The study of the neural basis of olfaction is important both for understanding the sense of smell and for understanding the mechanisms of neural computation. In the olfactory bulb (OB), the spatial patterning of both sensory inputs and synaptic interactions is crucial for processing odor information, although this patterning alone is not sufficient. Recent studies have suggested that representations of odor may already be distributed and dynamic in the first olfactory relay. The growing evidence demonstrating a functional role for the temporal structure of bulbar neuronal activity supports this assumption. However, the detailed mechanisms underlying this temporal structure have never been thoroughly studied. Our study focused on gamma (40–100 Hz) network oscillations in the mammalian OB, which is a form of temporal patterning in bulbar activity elicited by olfactory stimuli. We used computational modeling combined with electrophysiological recordings to investigate the basic synaptic organization necessary and sufficient to generate sustained gamma rhythms. We found that features of gamma oscillations obtained in vitro were identical to those of a model based on lateral inhibition as the coupling modality (i.e., low irregular firing rate and high oscillation stability). In contrast, they differed substantially from those of a model based on lateral excitatory coupling (i.e., high regular firing rate and instable oscillations). Therefore we could precisely tune the oscillation frequency by changing the kinetics of inhibitory events supporting the lateral inhibition. Moreover, gradually decreasing GABAergic synaptic transmission decreased the degree of relay neuron synchronization in response to sensory inputs, both theoretically and experimentally. Thus we have shown that lateral inhibition provides a mechanism by which the dynamic processing of odor information might be finely tuned within the OB circuit.

Download Full-text

Role of the Primate Superior Colliculus in the Control of Head Movements

Journal of Neurophysiology ◽

10.1152/jn.00258.2007 ◽

2007 ◽

Vol 98 (4) ◽

pp. 2022-2037 ◽

Cited By ~ 45

Author(s):

Mark M. G. Walton ◽

Bernard Bechara ◽

Neeraj J. Gandhi

Keyword(s):

Superior Colliculus ◽

Firing Rate ◽

Head Movements ◽

Neural Basis ◽

Average Firing Rate ◽

Gaze Shifts ◽

Burst Neurons ◽

The Gaze ◽

Head Displacement ◽

Elevated Frequency

One important behavioral role for head movements is to assist in the redirection of gaze. However, primates also frequently make head movements that do not involve changes in the line of sight. Virtually nothing is known about the neural basis of these head-only movements. In the present study, single-unit extracellular activity was recorded from the superior colliculus while monkeys performed behavioral tasks that permit the temporal dissociation of gaze shifts and head movements. We sought to determine whether superior colliculus contains neurons that modulate their activity in association with head movements in the absence of gaze shifts and whether classic gaze-related burst neurons also discharge for head-only movements. For 26% of the neurons in our sample, significant changes in average firing rate could be attributed to head-only movements. Most of these increased their firing rate immediately prior to the onset of a head movement and continued to discharge at elevated frequency until the offset of the movement. Others discharged at a tonic rate when the head was stable and decreased their activity, or paused, during head movements. For many putative head cells, average firing rate was found to be predictive of head displacement. Some neurons exhibited significant changes in activity associated with gaze, eye-only, and head-only movements, although none of the gaze-related burst neurons significantly modulated its activity in association with head-only movements. These results suggest the possibility that the superior colliculus plays a role in the control of head movements independent of gaze shifts.

Download Full-text

Neural population dynamics underlying expected value computation

10.1101/2020.06.01.127738 ◽

2020 ◽

Author(s):

Hiroshi Yamada ◽

Yuri Imaizumi ◽

Masayuki Matsumoto

Keyword(s):

Ventral Striatum ◽

Temporal Dynamics ◽

Dorsal Striatum ◽

Expected Value ◽

Economic Behavior ◽

Neural Dynamics ◽

Neural Population ◽

Integrative Process ◽

Expected Values ◽

The Brain

AbstractComputation of expected values, i.e., probability times magnitude, seems to be a dynamic integrative process performed in the brain for efficient economic behavior. However, neural dynamics underlying this computation remain largely unknown. We examined (1) whether four core reward-related regions detect and integrate the probability and magnitude cued by numerical symbols and (2) whether these regions have distinct dynamics in the integrative process. Extractions of mechanistic structure of neural population signal demonstrated that expected-value signals simultaneously arose in central part of orbitofrontal cortex (cOFC, area 13m) and ventral striatum (VS). These expected-value signals were incredibly stable in contrast to weak and/or fluctuated signals in dorsal striatum and medial OFC. Notably, temporal dynamics of these stable expected-value signals were unambiguously distinct: sharp and gradual signal evolutions in cOFC and VS, respectively. These intimate dynamics suggest that cOFC and VS compute the expected-values with unique time constants, as distinct, partially overlapping processes.

Download Full-text

A signature of neural coding at human perceptual limits

10.1101/051714 ◽

2016 ◽

Author(s):

Paul M Bays

Keyword(s):

Neural Coding ◽

Empirical Relationship ◽

Human Perception ◽

Population Coding ◽

Neural Population ◽

Perceptual Awareness ◽

Neural Basis ◽

Visual Neurons ◽

Error Magnitude ◽

Subjective Confidence

AbstractSimple visual features, such as orientation, are thought to be represented in the spiking of visual neurons using population codes. I show that optimal decoding of such activity predicts characteristic deviations from the normal distribution of errors at low gains. Examining human perception of orientation stimuli, I show that these predicted deviations are present at near-threshold levels of contrast. The findings may provide a neural-level explanation for the appearance of a threshold in perceptual awareness, whereby stimuli are categorized as seen or unseen. As well as varying in error magnitude, perceptual judgments differ in certainty about what was observed. I demonstrate that variations in the total spiking activity of a neural population can account for the empirical relationship between subjective confidence and precision. These results establish population coding and decoding as the neural basis of perception and perceptual confidence.

Download Full-text

Neural basis for motor learning in the vestibuloocular reflex of primates. I. Changes in the responses of brain stem neurons

Journal of Neurophysiology ◽

10.1152/jn.1994.72.2.928 ◽

1994 ◽

Vol 72 (2) ◽

pp. 928-953 ◽

Cited By ~ 102

Author(s):

S. G. Lisberger ◽

T. A. Pavelko ◽

D. M. Broussard

Keyword(s):

Eye Movements ◽

Motor Learning ◽

Firing Rate ◽

Brain Stem ◽

Head Rotation ◽

Head Motion ◽

Vestibuloocular Reflex ◽

Neural Basis ◽

Ventral Paraflocculus ◽

The Brain

1. We recorded from neurons in the brain stem of monkeys before and after they had worn magnifying or miniaturizing spectacles to cause changes in the gain of the vestibuloocular reflex (VOR). The gain of the VOR was estimated as eye speed divided by head speed during passive horizontal head rotation in darkness. Electrical stimulation in the cerebellum was used to identify neurons that receive inhibition at monosynaptic latencies from the flocculus and ventral paraflocculus (flocculus target neurons or FTNs). Cells were studied during smooth pursuit eye movements with the head stationary, fixation of different positions, cancellation of the VOR, and the VOR evoked by rapid changes in head velocity. 2. FTNs were divided into two populations according to their responses during pursuit with the head stationary. The two groups showed increased firing during smooth eye motion toward the side of recording (Eye-ipsiversive or E-i) or away from the side of recording (Eye-contraversive or E-c). A higher percentage of FTNs showed increased firing rate for contraversive pursuit when the gain of the VOR was high (> or = 1.6) than when the gain of the VOR was low (< or = 0.4). 3. Changes in the gain of the VOR had a striking effect on the responses during the VOR for the FTNs that were E-c during pursuit with the head stationary. Firing rate increased during contraversive VOR eye movements when the gain of the VOR was high or normal and decreased during contraversive VOR eye movements when the gain of the VOR was low. Changes in the gain of the VOR caused smaller changes in the responses during the VOR of FTNs that were E-i during pursuit with the head stationary. We argue that motor learning in the VOR is the result of changes in the responses of individual FTNs. 4. The responses of E-i and E-c FTNS during cancellation of the VOR depended on the gain of the VOR. Responses tended to be in phase with contraversive head motion when the gain of the VOR was low and in phase with ipsiversive head motion when the gain of the VOR was high. Comparison of the effect of motor learning on the responses of FTNs during cancellation of the VOR with the results of similar experiments on horizontal-gaze velocity Purkinje cells in the flocculus and ventral paraflocculus suggests that the brain stem vestibular inputs to FTNs are one site of motor learning in the VOR.(ABSTRACT TRUNCATED AT 400 WORDS)

Download Full-text

Neural mechanisms of rhythmic masking release in monkey primary auditory cortex: implications for models of auditory scene analysis

Journal of Neurophysiology ◽

10.1152/jn.01010.2011 ◽

2012 ◽

Vol 107 (9) ◽

pp. 2366-2382 ◽

Cited By ~ 13

Author(s):

Yonatan I. Fishman ◽

Christophe Micheyl ◽

Mitchell Steinschneider

Keyword(s):

Auditory Cortex ◽

Perceptual Organization ◽

Primary Auditory Cortex ◽

Auditory Scene Analysis ◽

Neural Mechanisms ◽

Stream Segregation ◽

Scene Analysis ◽

Neural Basis ◽

Masking Release ◽

Auditory Scene

The ability to detect and track relevant acoustic signals embedded in a background of other sounds is crucial for hearing in complex acoustic environments. This ability is exemplified by a perceptual phenomenon known as “rhythmic masking release” (RMR). To demonstrate RMR, a sequence of tones forming a target rhythm is intermingled with physically identical “Distracter” sounds that perceptually mask the rhythm. The rhythm can be “released from masking” by adding “Flanker” tones in adjacent frequency channels that are synchronous with the Distracters. RMR represents a special case of auditory stream segregation, whereby the target rhythm is perceptually segregated from the background of Distracters when they are accompanied by the synchronous Flankers. The neural basis of RMR is unknown. Previous studies suggest the involvement of primary auditory cortex (A1) in the perceptual organization of sound patterns. Here, we recorded neural responses to RMR sequences in A1 of awake monkeys in order to identify neural correlates and potential mechanisms of RMR. We also tested whether two current models of stream segregation, when applied to these responses, could account for the perceptual organization of RMR sequences. Results suggest a key role for suppression of Distracter-evoked responses by the simultaneous Flankers in the perceptual restoration of the target rhythm in RMR. Furthermore, predictions of stream segregation models paralleled the psychoacoustics of RMR in humans. These findings reinforce the view that preattentive or “primitive” aspects of auditory scene analysis may be explained by relatively basic neural mechanisms at the cortical level.

Download Full-text

Delusional Infestation

Clinical Microbiology Reviews ◽

10.1128/cmr.00018-09 ◽

2009 ◽

Vol 22 (4) ◽

pp. 690-732 ◽

Cited By ~ 137

Author(s):

Roland W. Freudenmann ◽

Peter Lepping

Keyword(s):

Clinical Trials ◽

Clinical Pathways ◽

Specific Treatment ◽

Medical System ◽

Outpatient Clinics ◽

Sufficient Evidence ◽

Future Research ◽

Medical Evidence ◽

Neural Basis ◽

Morgellons Disease

SUMMARY This papers aims at familiarizing psychiatric and nonpsychiatric readers with delusional infestation (DI), also known as delusional parasitosis. It is characterized by the fixed belief of being infested with pathogens against all medical evidence. DI is no single disorder but can occur as a delusional disorder of the somatic type (primary DI) or secondary to numerous other conditions. A set of minimal diagnostic criteria and a classification are provided. Patients with DI pose a truly interdisciplinary problem to the medical system. They avoid psychiatrists and consult dermatologists, microbiologists, or general practitioners but often lose faith in professional medicine. Epidemiology and history suggest that the imaginary pathogens change constantly, while the delusional theme “infestation” is stable and ubiquitous. Patients with self-diagnosed “Morgellons disease” can be seen as a variation of this delusional theme. For clinicians, clinical pathways for efficient diagnostics and etiology-specific treatment are provided. Specialized outpatient clinics in dermatology with a liaison psychiatrist are theoretically best placed to provide care. The most intricate problem is to engage patients in psychiatric therapy. In primary DI, antipsychotics are the treatment of choice, according to limited but sufficient evidence. Pimozide is no longer the treatment of choice for reasons of drug safety. Future research should focus on pathophysiology and the neural basis of DI, as well as on conclusive clinical trials, which are widely lacking. Innovative approaches will be needed, since otherwise patients are unlikely to adhere to any study protocol.

Download Full-text