scholarly journals Cortical Temporal Integration Window for Binaural Cues accounts for Sluggish Auditory Spatial Perception

2021 ◽  
Author(s):  
Ravinderjit Singh ◽  
Hari Bharadwaj
Keyword(s):  
Auditory System ◽  
Frequency Modulation ◽  
Spatial Information ◽  
Spatial Perception ◽  
Temporal Integration ◽  
Temporal Coding ◽  
Binaural Cues ◽  
Acoustic Fluctuations ◽  
Identification Technique ◽  
Spatial Unmasking

The auditory system has exquisite temporal coding in the periphery which is transformed into a rate-based code in central auditory structures like auditory cortex. However, the cortex is still able to synchronize, albeit at lower modulation rates, to acoustic fluctuations. The perceptual significance of this cortical synchronization is unknown. We estimated physiological synchronization limits of cortex (in humans with electroencephalography) and brainstem neurons (in chinchillas) to dynamic binaural cues using a novel system-identification technique, along with parallel perceptual measurements. We find that cortex can synchronize to dynamic binaural cues up to approximately 10 Hz, which aligns well with our measured limits of perceiving dynamic spatial information and utilizing dynamic binaural cues for spatial unmasking, i.e. measures of binaural sluggishness. We also find the tracking limit for frequency modulation (FM) is similar to the limit for spatial tracking, demonstrating that this sluggish tracking is a more general perceptual limit that can be accounted for by cortical temporal integration limits.

Tactile Displays

1995 ◽  
Author(s):  
Kurt A. Kaczmarek ◽  
Paul Bach-Y-Rita
Keyword(s):  
Spatial Information ◽  
Temporal Integration ◽  
Temporal Coding ◽  
The Body ◽  
Tactile Display ◽  
Topological Transformation ◽  
Temperature Changes ◽  
Tactile Displays ◽  
Spatial Dimensions ◽  
To Receive

The average adult has approximately 2m2 of skin (Gibson, 1968), about 90% hairy, and remainder smooth or glabrous. Although the glabrous areas are more sensitive than the hairy, both types are highly innervated with sensory receptors and nerves (Sinclair, 1981). Tactile displays have utilized both glabrous and hairy skin, the type selected being relative to the sensory display needs of the various investigators. There are several advantages for selecting the skin as the sensory surface to receive information. (1) It is accessible, extensive in area, richly innervated, and capable of precise discrimination. Further, when the skin of the forehead or trunk is used, the tactile display system does not interfere materially with motor or other sensory functions. (2) The skin shows a number of functional similarities to the retina of the eye in its capacity to mediate information. Large parts of the body surface are relatively flat, and the receptor surfaces of the skin, like the retina, are capable of mediating displays in two spatial dimensions as well as having the potential for temporal integration (summation over time). Thus, there is generally no need for complex topological transformation or for temporal coding of pictorial information for direct presentation onto the accessible areas of the skin, although temporal display factors have been explored with the goal of transmitting spatial information across the skin more quickly than is possible with present systems (Kaczmarek et al., 1984; Bach-y-Rita and Hughes, 1985; Kaczmarek et al., 1985; Loomis and Lederman, 1986). Spatial patterns learned visually can be identified factually, and vice versa (Epstein et al., 1989; Hughes et al., 1990). (3) Certain types of sensory inhibition, including the Mach band phenomenon and other examples of lateral inhibition originally demonstrated for vision, are equally demonstrable in the skin (Bekesy, 1967). (4) Finally, there is evidence that the skin normally functions as an exteroceptor at least in a limited sense: Katz noted that to some extent both vibration and temperature changes can be felt at a distance (Krueger, 1970). For example, a blind person can “feel” the approach of a warm cylinder at three times the distance required by the sighted individual (Krueger, 1970).

scholarly journals Overview of Popular Techniques of Raman Spectroscopy and Their Potential in the Study of Plant Tissues

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1537
Author(s):  
Aneta Saletnik ◽  
Bogdan Saletnik ◽  
Czesław Puchalski
Keyword(s):  
Raman Spectroscopy ◽  
Cell Walls ◽  
Structural Changes ◽  
Spatial Information ◽  
Technological Development ◽  
Analytical Techniques ◽  
High Sensitivity ◽  
Plant Tissues ◽  
Wide Range ◽  
Identification Technique

Raman spectroscopy is one of the main analytical techniques used in optical metrology. It is a vibration, marker-free technique that provides insight into the structure and composition of tissues and cells at the molecular level. Raman spectroscopy is an outstanding material identification technique. It provides spatial information of vibrations from complex biological samples which renders it a very accurate tool for the analysis of highly complex plant tissues. Raman spectra can be used as a fingerprint tool for a very wide range of compounds. Raman spectroscopy enables all the polymers that build the cell walls of plants to be tracked simultaneously; it facilitates the analysis of both the molecular composition and the molecular structure of cell walls. Due to its high sensitivity to even minute structural changes, this method is used for comparative tests. The introduction of new and improved Raman techniques by scientists as well as the constant technological development of the apparatus has resulted in an increased importance of Raman spectroscopy in the discovery and defining of tissues and the processes taking place in them.

Human Stereopsis, Fusion, and Stereoscopic Virtual Environments

1995 ◽  
Author(s):  
Elizabeth Thorpe Davis ◽  
Larry F. Hodges
Keyword(s):  
Virtual Environments ◽  
Visual Cues ◽  
Spatial Information ◽  
Spatial Perception ◽  
Human Perception ◽  
Stereoscopic Vision ◽  
Human Vision ◽  
Spatial Factors ◽  
Stereoscopic Displays ◽  
And Performance

Two fundamental purposes of human spatial perception, in either a real or virtual 3D environment, are to determine where objects are located in the environment and to distinguish one object from another. Although various sensory inputs, such as haptic and auditory inputs, can provide this spatial information, vision usually provides the most accurate, salient, and useful information (Welch and Warren, 1986). Moreover, of the visual cues available to humans, stereopsis provides an enhanced perception of depth and of three-dimensionality for a visual scene (Yeh and Silverstein, 1992). (Stereopsis or stereoscopic vision results from the fusion of the two slightly different views of the external world that our laterally displaced eyes receive (Schor, 1987; Tyler, 1983).) In fact, users often prefer using 3D stereoscopic displays (Spain and Holzhausen, 1991) and find that such displays provide more fun and excitement than do simpler monoscopic displays (Wichanski, 1991). Thus, in creating 3D virtual environments or 3D simulated displays, much attention recently has been devoted to visual 3D stereoscopic displays. Yet, given the costs and technical requirements of such displays, we should consider several issues. First, we should consider in what conditions and situations these stereoscopic displays enhance perception and performance. Second, we should consider how binocular geometry and various spatial factors can affect human stereoscopic vision and, thus, constrain the design and use of stereoscopic displays. Finally, we should consider the modeling geometry of the software, the display geometry of the hardware, and some technological limitations that constrain the design and use of stereoscopic displays by humans. In the following section we consider when 3D stereoscopic displays are useful and why they are useful in some conditions but not others. In the section after that we review some basic concepts about human stereopsis and fusion that are of interest to those who design or use 3D stereoscopic displays. Also in that section we point out some spatial factors that limit stereopsis and fusion in human vision as well as some potential problems that should be considered in designing and using 3D stereoscopic displays. Following that we discuss some software and hardware issues, such as modelling geometry and display geometry as well as geometric distortions and other artifacts that can affect human perception.

Interdependence of Spatial and Temporal Coding in the Auditory Midbrain

2000 ◽  
Vol 83 (4) ◽  
pp. 2300-2314 ◽  
Author(s):  
U. Koch ◽  
B. Grothe
Keyword(s):  
Sound Localization ◽  
Feature Detection ◽  
Transfer Functions ◽  
Temporal Structure ◽  
Temporal Coding ◽  
Sound Recognition ◽  
Spatial Cues ◽  
Auditory Midbrain ◽  
Binaural Cues ◽  
Binaural Processing

To date, most physiological studies that investigated binaural auditory processing have addressed the topic rather exclusively in the context of sound localization. However, there is strong psychophysical evidence that binaural processing serves more than only sound localization. This raises the question of how binaural processing of spatial cues interacts with cues important for feature detection. The temporal structure of a sound is one such feature important for sound recognition. As a first approach, we investigated the influence of binaural cues on temporal processing in the mammalian auditory system. Here, we present evidence that binaural cues, namely interaural intensity differences (IIDs), have profound effects on filter properties for stimulus periodicity of auditory midbrain neurons in the echolocating big brown bat, Eptesicus fuscus. Our data indicate that these effects are partially due to changes in strength and timing of binaural inhibitory inputs. We measured filter characteristics for the periodicity (modulation frequency) of sinusoidally frequency modulated sounds (SFM) under different binaural conditions. As criteria, we used 50% filter cutoff frequencies of modulation transfer functions based on discharge rate as well as synchronicity of discharge to the sound envelope. The binaural conditions were contralateral stimulation only, equal stimulation at both ears (IID = 0 dB), and more intense at the ipsilateral ear (IID = −20, −30 dB). In 32% of neurons, the range of modulation frequencies the neurons responded to changed considerably comparing monaural and binaural (IID =0) stimulation. Moreover, in ∼50% of neurons the range of modulation frequencies was narrower when the ipsilateral ear was favored (IID = −20) compared with equal stimulation at both ears (IID = 0). In ∼10% of the neurons synchronization differed when comparing different binaural cues. Blockade of the GABAergic or glycinergic inputs to the cells recorded from revealed that inhibitory inputs were at least partially responsible for the observed changes in SFM filtering. In 25% of the neurons, drug application abolished those changes. Experiments using electronically introduced interaural time differences showed that the strength of ipsilaterally evoked inhibition increased with increasing modulation frequencies in one third of the cells tested. Thus glycinergic and GABAergic inhibition is at least one source responsible for the observed interdependence of temporal structure of a sound and spatial cues.

scholarly journals Temporal integration at consecutive processing stages in the auditory pathway of the grasshopper

2015 ◽  
Vol 113 (7) ◽  
pp. 2280-2288 ◽  
Author(s):  
Sarah Wirtssohn ◽  
Bernhard Ronacher
Keyword(s):  
Auditory System ◽  
Time Windows ◽  
Temporal Integration ◽  
Auditory Pathway ◽  
Network Activity ◽  
High Temporal Resolution ◽  
Energy Integration ◽  
Metathoracic Ganglion ◽  
Feed Forward Network ◽  
Receptor Neurons

Temporal integration in the auditory system of locusts was quantified by presenting single clicks and click pairs while performing intracellular recordings. Auditory neurons were studied at three processing stages, which form a feed-forward network in the metathoracic ganglion. Receptor neurons and most first-order interneurons (“local neurons”) encode the signal envelope, while second-order interneurons (“ascending neurons”) tend to extract more complex, behaviorally relevant sound features. In different neuron types of the auditory pathway we found three response types: no significant temporal integration (some ascending neurons), leaky energy integration (receptor neurons and some local neurons), and facilitatory processes (some local and ascending neurons). The receptor neurons integrated input over very short time windows (<2 ms). Temporal integration on longer time scales was found at subsequent processing stages, indicative of within-neuron computations and network activity. These different strategies, realized at separate processing stages and in parallel neuronal pathways within one processing stage, could enable the grasshopper's auditory system to evaluate longer time windows and thus to implement temporal filters, while at the same time maintaining a high temporal resolution.

Amplitude-Modulated Auditory Steady-State Responses in Younger and Older Listeners

2006 ◽  
Vol 17 (08) ◽  
pp. 582-597 ◽  
Author(s):  
E. D. Leigh-Paffenroth ◽  
Cynthia G. Fowler
Keyword(s):  
Steady State ◽  
Auditory System ◽  
Carrier Frequency ◽  
Recognition Performance ◽  
Phase Locking ◽  
Timing Analysis ◽  
Temporal Coding ◽  
Steady State Responses ◽  
Auditory Steady State Responses ◽  
State Responses

The primary purpose of this investigation was to determine whether temporal coding in the auditory system was the same for younger and older listeners. Temporal coding was assessed by amplitude-modulated auditory steady-state responses (AM ASSRs) as a physiologic measure of phase-locking capability. The secondary purpose of this study was to determine whether AM ASSRs were related to behavioral speech understanding ability. AM ASSRs showed that the ability of the auditory system to phase lock to a temporally altered signal is dependent on modulation rate, carrier frequency, and age of the listener. Specifically, the interaction of frequency and age showed that younger listeners had more phase locking than old listeners at 500 Hz. The number of phase-locked responses for the 500 Hz carrier frequency was significantly correlated to word-recognition performance. In conclusion, the effect of aging on temporal processing, as measured by phase locking with AM ASSRs, was found for low-frequency stimuli where phase locking in the auditory system should be optimal. The exploration, and use, of electrophysiologic responses to measure auditory timing analysis in humans has the potential to facilitate the understanding of speech perception difficulties in older listeners.

Auditory Psychomotor Coordination

1988 ◽  
Vol 32 (2) ◽  
pp. 81-85 ◽  
Author(s):  
David R. Perrott
Keyword(s):  
Visual Search ◽  
Reaction Time ◽  
Auditory System ◽  
Spatial Information ◽  
Visual Target ◽  
Lateral Position ◽  
Head Movements ◽  
Vertical Position ◽  
Lateral Field ◽  
Initial Line

A series of choice-reaction time experiments are described in which subjects were required to locate and identify the information contained on a small visual target. Across trials, the lateral position of the target was randomly varied across a 240° region (± 120° relative to the subject's initial line of gaze). The vertical position of the target was either fixed at 0° elevation or varied by ± 46°. Whether the target was in the forward or lateral field, a significant reduction in the visual search period was evident when an acoustic signal indicated the location of the visual target. Auditory spatial information was particularly effective in improving performance when the position of the target was varied in elevation or the target was located in the rear field. The current results support the notion that the auditory system can be used to direct eye-head movements toward a remote visual target.

scholarly journals Impaired Interval Timing and Spatial–Temporal Integration in Mice Deficient in CHL1, a Gene Associated with Schizophrenia

2013 ◽  
Vol 1 (1) ◽  
pp. 21-38 ◽  
Author(s):  
Mona Buhusi ◽  
Ioana Scripa ◽  
Christina L. Williams ◽  
Catalin V. Buhusi
Keyword(s):  
Spatial Information ◽  
Neurodevelopmental Disorder ◽  
Temporal Integration ◽  
Gene Mutations ◽  
Interval Timing ◽  
Reference Memory ◽  
Synaptic Function ◽  
Temporal Information ◽  
Adult Brain ◽  
Central Platform

Interval timing is crucial for decision-making and motor control and is impaired in many neuropsychiatric disorders, including schizophrenia — a neurodevelopmental disorder with a strong genetic component. Several gene mutations, polymorphisms or rare copy number variants have been associated with schizophrenia. L1 cell adhesion molecules (L1CAMs) are involved in neurodevelopmental processes, and in synaptic function and plasticity in the adult brain. Mice deficient in the Close Homolog to L1 (CHL1) adhesion molecule show alterations of hippocampal and thalamo-cortical neuroanatomy as well as deficits in sensorimotor gating and exploratory behavior. We analyzed interval timing and attentional control of temporal and spatial information in male CHL1 deficient (KO) mice and wild type (WT) controls. In a 20-s peak-interval timing procedure (standard and reversed), KO mice showed a maintained leftward shift of the response function relative to WT, indicative of a deficit in memory encoding/decoding. In trials with 2, 5, or 10-s gaps, KO mice shifted their peak times less than WT controls at longer gap durations, suggesting a decreased (attentional) effect of interruptions. In the spatial–temporal task, KO mice made more working and reference memory errors than controls, suggestive of impaired use of spatial and/or temporal information. When the duration spent on the central platform of the maze was manipulated, WT mice showed fewer spatial errors at the trained duration than at shorter or longer durations, indicative of discrimination based upon spatial–temporal integration. In contrast, performance was similar at all tested durations in KO mice, indicative of control by spatial cues, but not by temporal cues. These results suggest that CHL1 KO mice selectively attend to the more relevant cues of the task, and fail to integrate more complex spatial–temporal information, possibly as a result of reduced memory capacity related to hippocampal impairment, and altered temporal-integration mechanisms possibly due to thalamo-cortical anomalies.

Temporal Acuity in Listeners with Sensorineural Hearing Loss

1976 ◽  
Vol 19 (2) ◽  
pp. 357-370 ◽  
Author(s):  
Walt Jesteadt ◽  
Robert C. Bilger ◽  
David M. Green ◽  
James H. Patterson
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Auditory System ◽  
Temporal Integration ◽  
Sensorineural Hearing ◽  
Time Interval ◽  
Speech Discrimination ◽  
Temporal Acuity ◽  
Temporal Measures ◽  
Sensorineural Loss

Temporal acuity, the minimum time interval within which the auditory system can discriminate the order of auditory events, was measured for three listeners with normal hearing and for 10 listeners with sensorineural hearing loss. Eight of the 10 listeners with sensorineural loss showed better temporal acuity for conditions with greater loss. The remaining two listeners showed the opposite effect. The temporal acuity results are not well correlated with either speech discrimination scores or measures of recruitment. The temporal acuity results do appear to be correlated with results observed in studies of temporal integration or brief-tone audiometry. Listeners with sensorineural loss tend to have both poor temporal integration and good temporal acuity. This suggests that the two temporal measures may reflect a single time constant in the auditory system.

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