Cue weighting and vestibular mediation of temporal dynamics in sound localization via head rotation

2013 ◽  
Author(s):  
Ewan A. Macpherson
Keyword(s):  
Sound Localization ◽  
Temporal Dynamics ◽  
Head Rotation ◽  
Cue Weighting

scholarly journals Heart-brain interactions in the MR environment: characterization of the ballistocardiogram in EEG signals collected during simultaneous fMRI

2017 ◽  
Author(s):  
Marco Marino ◽  
Quanying Liu ◽  
Mariangela Del Castello ◽  
Cristiana Corsi ◽  
Nicole Wenderoth ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Cardiac Activity ◽  
Principal Component ◽  
Head Rotation ◽  
Temporal Variations ◽  
Single Subject ◽  
Cardiac Events ◽  
Large Variability ◽  
Eeg Recordings

AbstractThe ballistocardiographic (BCG) artifact is linked to cardiac activity and occurs in electroencephalographic (EEG) recordings acquired inside the magnetic resonance (MR) environment. Its variability in terms of amplitude, waveform shape and spatial distribution over subject’s scalp makes its attenuation a challenging task. In this study, we aimed to provide a detailed characterization of the BCG properties, including its temporal dependency on cardiac events and its spatio-temporal dynamics. To this end, we used high-density EEG data acquired during simultaneous functional MR imaging in six healthy volunteers. First, we investigated the relationship between cardiac activity and BCG occurrences in the EEG recordings. We observed large variability in the delay between ECG and subsequent BCG events (ECG-BCG delay) across subjects and non-negligible epoch-by-epoch variations at the single subject level. Also, we found positive correlations between heart rate variability and ECG-BCG delay. The inspection of spatial-temporal variations revealed a prominent non-stationarity of the BCG signal. We identified five main BCG waves, which were common across subjects. Principal component analysis revealed two spatially distinct patterns to explain most of the variance (85% in total). These components are possibly related to head rotation and pulse-driven scalp expansion, respectively. Our results may inspire the development of novel, more effective methods for the removal of the BCG, capable of isolating and attenuating artifact occurrences while preserving true neuronal activity.

scholarly journals Re-weighting of Sound Localization Cues by Audiovisual Training

2019 ◽  
Author(s):  
Daniel P. Kumpik ◽  
Connor Campbell ◽  
Jan W.H. Schnupp ◽  
Andrew J King
Keyword(s):  
Sound Localization ◽  
Visual Cues ◽  
Transfer Functions ◽  
Contextual Information ◽  
Auditory Localization ◽  
Spatial Cues ◽  
Auditory Cues ◽  
Cue Weighting ◽  
Auditory Spatial Cues ◽  
Interaural Level Differences

AbstractSound localization requires the integration in the brain of auditory spatial cues generated by interactions with the external ears, head and body. Perceptual learning studies have shown that the relative weighting of these cues can change in a context-dependent fashion if their relative reliability is altered. One factor that may influence this process is vision, which tends to dominate localization judgments when both modalities are present and induces a recalibration of auditory space if they become misaligned. It is not known, however, whether vision can alter the weighting of individual auditory localization cues. Using non-individualized head-related transfer functions, we measured changes in subjects’ sound localization biases and binaural localization cue weights after ~55 minutes of training on an audiovisual spatial oddball task. Four different configurations of spatial congruence between visual and auditory cues (interaural time differences (ITDs) and frequency-dependent interaural level differences (interaural level spectra, ILS) were used. When visual cues were spatially congruent with both auditory spatial cues, we observed an improvement in sound localization, as shown by a reduction in the variance of subjects’ localization biases, which was accompanied by an up-weighting of the more salient ILS cue. However, if the position of either one of the auditory cues was randomized during training, no overall improvement in sound localization occurred. Nevertheless, the spatial gain of whichever cue was matched with vision increased, with different effects observed on the gain for the randomized cue depending on whether ITDs or ILS were matched with vision. As a result, we observed a similar up-weighting in ILS when this cue alone was matched with vision, but no overall change in binaural cue weighting when ITDs corresponded to the visual cues and ILS were randomized. Consistently misaligning both cues with vision produced the ventriloquism aftereffect, i.e., a corresponding shift in auditory localization bias, without affecting the variability of the subjects’ sound localization judgments, and no overall change in binaural cue weighting. These data show that visual contextual information can invoke a reweighting of auditory localization cues, although concomitant improvements in sound localization are only likely to accompany training with fully congruent audiovisual information.

scholarly journals Active head rolls enhance sonar-based auditory localization performance

2021 ◽  
Vol 17 (5) ◽  
pp. e1008973
Author(s):  
Lakshitha P. Wijesinghe ◽  
Melville J. Wohlgemuth ◽  
Richard H. Y. So ◽  
Jochen Triesch ◽  
Cynthia F. Moss ◽  
...  
Keyword(s):  
Sound Localization ◽  
Head Rotation ◽  
Auditory Localization ◽  
Head Movements ◽  
Head Direction ◽  
Big Brown Bat ◽  
The World ◽  
Localization Performance ◽  
Head Roll ◽  
Time Required

Animals utilize a variety of active sensing mechanisms to perceive the world around them. Echolocating bats are an excellent model for the study of active auditory localization. The big brown bat (Eptesicus fuscus), for instance, employs active head roll movements during sonar prey tracking. The function of head rolls in sound source localization is not well understood. Here, we propose an echolocation model with multi-axis head rotation to investigate the effect of active head roll movements on sound localization performance. The model autonomously learns to align the bat’s head direction towards the target. We show that a model with active head roll movements better localizes targets than a model without head rolls. Furthermore, we demonstrate that active head rolls also reduce the time required for localization in elevation. Finally, our model offers key insights to sound localization cues used by echolocating bats employing active head movements during echolocation.

Spike Transmission Delay at the Calyx of Held In Vivo: Rate Dependence, Phenomenological Modeling, and Relevance for Sound Localization

2009 ◽  
Vol 102 (2) ◽  
pp. 1206-1217 ◽  
Author(s):  
Sandra Tolnai ◽  
Bernhard Englitz ◽  
Jonathan Scholbach ◽  
Jürgen Jost ◽  
Rudolf Rübsamen
Keyword(s):  
Action Potential ◽  
Sound Localization ◽  
Temporal Dynamics ◽  
Transmission Delay ◽  
Mongolian Gerbils ◽  
Calyx Of Held ◽  
Time Constants ◽  
Medial Nucleus ◽  
Central Synapses

Transmission at central synapses exhibits rapid changes in response amplitude under different patterns of stimulation. Whether the delay associated with the transmission of action potentials is similarly modifiable is important for temporally precise computations. We address this question at the calyx of Held of the medial nucleus of the trapezoid body (MNTB) in Mongolian gerbils in vivo using extracellular recordings. Here the pre- and postsynaptic activity can be observed simultaneously, allowing the definition of an action potential transmission delay (ATD) from the pre- to the postsynaptic side. We find the ATD to increase as a function of spike rate (10–40%). The temporal dynamics of the ATD increase exhibit an exponential shape with activity-dependent time constants (∼15–25 ms). Recovery dynamics of ATD were mono- (20–70 ms) or biexponential with fast (3–20 ms) and slow time constants (50–500 ms). Using a phenomenological model to capture ATD dynamics, we estimated ΔATD = 5–30 μs per transmitted action potential. Using vocalizations and cage noise stimuli, we confirm that substantial changes in ATD occur in natural situations. Because the ATD changes cover the behaviorally relevant range of interaural time differences in gerbils, these results could provide constraints for models of sound localization.

Effects of Monetary Incentives on Task Switching

2012 ◽  
Vol 59 (4) ◽  
pp. 216-226 ◽  
Author(s):  
Thomas Kleinsorge ◽  
Gerhard Rinkenauer
Keyword(s):  
Task Switching ◽  
Temporal Dynamics ◽  
Reward Processing ◽  
General Level ◽  
Monetary Incentives ◽  
Switch Costs ◽  
Expectancy Effect ◽  
Reward Expectancy ◽  
Trial Basis

In two experiments, effects of incentives on task switching were investigated. Incentives were provided as a monetary bonus. In both experiments, the availability of a bonus varied on a trial-to-trial basis. The main difference between the experiments relates to the association of incentives to individual tasks. In Experiment 1, the association of incentives to individual tasks was fixed. Under these conditions, the effect of incentives was largely due to reward expectancy. Switch costs were reduced to statistical insignificance. This was true even with the task that was not associated with a bonus. In Experiment 2, there was a variable association of incentives to individual tasks. Under these conditions, the reward expectancy effect was bound to conditions with a well-established bonus-task association. In conditions in which the bonus-task association was not established in advance, enhanced performance of the bonus task was accompanied by performance decrements with the task that was not associated with a bonus. Reward expectancy affected mainly the general level of performance. The outcome of this study may also inform recently suggested neurobiological accounts about the temporal dynamics of reward processing.

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