Home About us Contact
|
Home About us Contact | ||
|
|
||
Auditory Information (auditory + information)
Selected AbstractsTonotopic gradients of Eph family proteins in the chick nucleus laminaris during synaptogenesisDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2004Abigail L. Person Abstract Topographically precise projections are established early in neural development. One such topographically organized network is the auditory brainstem. In the chick, the auditory nerve transmits auditory information from the cochlea to nucleus magnocellularis (NM). NM in turn innervates nucleus laminaris (NL) bilaterally. These projections preserve the tonotopy established at the level of the cochlea. We have begun to examine the expression of Eph family proteins during the formation of these connections. Optical density measurements were used to describe gradients of Eph proteins along the tonotopic axis of NL in the neuropil, the somata, and the NM axons innervating NL at embryonic day 10, when synaptic connections from NM to NL are established. At E10,11, NL dorsal neuropil expresses EphA4 at a higher concentration in regions encoding high frequency sounds, decreasing in concentration monotonically toward the low frequency (caudolateral) end. In the somata, both EphA4 and ephrin-B2 are concentrated at the high frequency end of the nucleus. These tonotopic gradients disappear between E13 and E15, and expression of these molecules is completely downregulated by hatching. The E10,11 patterns run counter to an apparent gradient in dendrite density, as indicated by microtubule associated protein 2 (MAP2) immunolabeling. Finally, ephrin-B2 is also expressed in a gradient in tissue ventral to the NL neuropil. Our findings thus suggest a possible conserved mechanism for establishing topographic projections in diverse sensory systems. These results of this study provide a basis for the functional examination of the role of Eph proteins in the formation of tonotopic maps in the brainstem. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 28,39, 2004 [source] Patterns of calcium-binding proteins support parallel and hierarchical organization of human auditory areasEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2003Oriana Chiry Abstract The human primary auditory cortex (AI) is surrounded by several other auditory areas, which can be identified by cyto-, myelo- and chemoarchitectonic criteria. We report here on the pattern of calcium-binding protein immunoreactivity within these areas. The supratemporal regions of four normal human brains (eight hemispheres) were processed histologically, and serial sections were stained for parvalbumin, calretinin or calbindin. Each calcium-binding protein yielded a specific pattern of labelling, which differed between auditory areas. In AI, defined as area TC [see C. von Economo and L. Horn (1930) Z. Ges. Neurol. Psychiatr.,130, 678,757], parvalbumin labelling was dark in layer IV; several parvalbumin-positive multipolar neurons were distributed in layers III and IV. Calbindin yielded dark labelling in layers I,III and V; it revealed numerous multipolar and pyramidal neurons in layers II and III. Calretinin labelling was lighter than that of parvalbumin or calbindin in AI; calretinin-positive bipolar and bitufted neurons were present in supragranular layers. In non-primary auditory areas, the intensity of labelling tended to become progressively lighter while moving away from AI, with qualitative differences between the cytoarchitectonically defined areas. In analogy to non-human primates, our results suggest differences in intrinsic organization between auditory areas that are compatible with parallel and hierarchical processing of auditory information. [source] Topographical projection from the superior colliculus to the nucleus of the brachium of the inferior colliculus in the ferret: convergence of visual and auditory informationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2000Timothy P. Doubell Abstract The normal maturation of the auditory space map in the deeper layers of the ferret superior colliculus (SC) depends on signals provided by the superficial visual layers, but it is unknown where or how these signals influence the developing auditory responses. Here we report that tracer injections in the superficial layers label axons with en passant and terminal boutons, both in the deeper layers of the SC and in their primary source of auditory input, the nucleus of the brachium of the inferior colliculus (nBIC). Electron microscopy confirmed that biocytin-labelled SC axons form axodendritic synapses on nBIC neurons. Injections of biotinylated dextran amine in the nBIC resulted in anterograde labelling in the deeper layers of the SC, as well as retrogradely labelled superficial and deep SC neurons, whose distribution varied systematically with the rostrocaudal placement of the injection sites in the nBIC. Topographical order in the projection from the SC to the ipsilateral nBIC was confirmed using fluorescent microspheres. We demonstrated the existence of functional SC-nBIC connections by making whole-cell current-clamp recordings from young ferret slices. Both monosynaptic and polysynaptic EPSPs were generated by electrical stimulation of either the superficial or deep SC layers. In addition to unimodal auditory units, both visual and bimodal visual,auditory units were recorded in the nBIC in vivo and their incidence was higher in juvenile ferrets than in adults. The SC-nBIC circuit provides a potential means by which visual and other sensory or premotor signals may be delivered to the nBIC to calibrate the representation of auditory space. [source] Influence of vowel context on the audio-visual speech perception of voiced stop consonantsJAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2000Sumi Shigeno The work reported here investigated whether the extent of McGurk effect differs according to the vowel context, and differs when cross-modal vowels are matched or mismatched in Japanese. Two audio-visual experiments were conducted to examine the process of audio-visual phonetic-feature extraction and integration. The first experiment was designed to compare the extent of the McGurk effect in Japanese in three different vowel contexts. The results indicated that the effect was largest in the /i/ context, moderate in the /a/ context, and almost nonexistent in the /u/ context. This suggests that the occurrence of McGurk effect depends on the characteristics of vowels and the visual cues from their articulation. The second experiment measured the McGurk effect in Japanese with cross-modal matched and mismatched vowels, and showed that, except with the /u/ sound, the effect was larger when the vowels were matched than when they were mismatched. These results showed, again, that the extent of McGurk effect depends on vowel context and that auditory information processing before phonetic judgment plays an important role in cross-modal feature integration. [source] The physiology of insect auditory afferentsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2004Andrew C. Mason Abstract This review presents an overview of the physiology of primary receptors serving tympanal hearing in insects. Auditory receptor responses vary with frequency, intensity, and temporal characteristics of sound stimuli. Various insect species exploit each of these parameters to differing degrees in the neural coding of auditory information, depending on the nature of the relevant stimuli. Frequency analysis depends on selective tuning in individual auditory receptors. In those insect groups that have individually tuned receptors, differences in physiology are correlated with structural differences among receptors and with the anatomical arrangement of receptors within the ear. Intensity coding is through the rate-level characteristics of tonically active auditory receptors and through variation in the absolute sensitivities of individual receptors (range fractionation). Temporal features of acoustic stimuli may be copied directly in the timing of afferent responses. Salient signal characteristics may also be represented by variation in the timing of afferent responses on a finer temporal scale, or by the synchrony of responses across a population of receptors. Microsc. Res. Tech. 63:338,350, 2004. © 2004 Wiley-Liss, Inc. [source] Basic auditory dysfunction in dyslexia as demonstrated by brain activity measurementsPSYCHOPHYSIOLOGY, Issue 2 2000Teija Kujala Although the generality of dyslexia and its devastating effects on the individual's life are widely acknowledged, its precursors and associated neural mechanisms are poorly understood. One of the two major competing views maintains that dyslexia is based primarily on a deficit in linguistic processing, whereas the other view suggests a more general processing deficit, one involving the perception of temporal information. Here we present evidence in favor of the latter view by showing that the neural discrimination of temporal information within complex tone patterns fails in dyslexic adults. This failure can be traced to early cortical mechanisms that process auditory information independently of attention. [source] Laser stimulation of single auditory nerve fibers,,§¶,THE LARYNGOSCOPE, Issue 10 2010Philip D. Littlefield MD Abstract Objectives/Hypothesis: One limitation with cochlear implants is the difficulty stimulating spatially discrete spiral ganglion cell groups because of electrode interactions. Multipolar electrodes have improved on this some, but also at the cost of much higher device power consumption. Recently, it has been shown that spatially selective stimulation of the auditory nerve is possible with a mid-infrared laser aimed at the spiral ganglion via the round window. However, these neurons must be driven at adequate rates for optical radiation to be useful in cochlear implants. We herein use single-fiber recordings to characterize the responses of auditory neurons to optical radiation. Study Design: In vivo study using normal-hearing adult gerbils. Methods: Two diode lasers were used for stimulation of the auditory nerve. They operated between 1.844 ,m and 1.873 ,m, with pulse durations of 35 ,s to 1,000 ,s, and at repetition rates up to 1,000 pulses per second (pps). The laser outputs were coupled to a 200-,m-diameter optical fiber placed against the round window membrane and oriented toward the spiral ganglion. The auditory nerve was exposed through a craniotomy, and recordings were taken from single fibers during acoustic and laser stimulation. Results: Action potentials occurred 2.5 ms to 4.0 ms after the laser pulse. The latency jitter was up to 3 ms. Maximum rates of discharge averaged 97 ± 52.5 action potentials per second. The neurons did not strictly respond to the laser at stimulation rates over 100 pps. Conclusions: Auditory neurons can be stimulated by a laser beam passing through the round window membrane and driven at rates sufficient for useful auditory information. Optical stimulation and electrical stimulation have different characteristics; which could be selectively exploited in future cochlear implants. Laryngoscope, 2010 [source] Using route and survey information to generate cognitive maps: differences between normally sighted and visually impaired individualsAPPLIED COGNITIVE PSYCHOLOGY, Issue 2 2009Frank J. J. M. Steyvers Visually impaired people (VIP) have to rely on different information to generate a cognitive map of their environment than normally sighted people. This study explored the extent to which a cognitive map could be generated by auditory information of route-type and survey-type descriptions of a fictitious environment. A total of 27 visually impaired and 28 normally sighted participants listened to either a survey-type or a route-type description of a fictitious zoo. They then answered both route-type and survey-type questions. This listening/question-and-answer sequence was repeated twice (total n,=,3). The visually impaired participants showed no difference in error frequency between the two description types, while the normally sighted individuals performed better after listening to the survey-type description. In addition, the learning curve of the normally sighted individuals was steeper than that of the visually impaired and they made fewer errors. The error scores indicated two subgroups in both the normally sighted and the visually impaired groups. These two groups, the ,good' learners and the ,poor' learners, showed marked differences in generating a cognitive map from auditory descriptions of an environment. Copyright © 2008 John Wiley & Sons, Ltd. [source] When auditory presentations should and should not be a component of multimedia instructionAPPLIED COGNITIVE PSYCHOLOGY, Issue 4 2003Wayne Leahy Based on cognitive load theory, two experiments investigated the conditions under which audiovisual-based instruction may be an effective or an ineffective instructional technique. Results from Experiment 1 indicated that visual with audio presentations were superior to equivalent visual-only presentations. In this experiment, neither the auditory nor the visual material could be understood in isolation. Both sources of information were interrelated and were essential to render the material intelligible. In contrast, Experiment 2 demonstrated that a non-essential explanatory text, presented aurally with similar written text contained in a diagram, hindered learning. This result was obtained because when compared to a diagram only format, the aural material was unnecessary and therefore created a redundancy effect. Differences between groups were stronger when information was high in complexity. It was concluded that the effectiveness of multimedia instruction depends very much on how and when auditory information is used. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||