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Acoustic Stimuli (acoustic + stimulus)
Selected AbstractsEnhanced mismatch negativity brain response after binaural word presentationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Tanja Endrass Abstract An oddball paradigm was used to investigate brain processes elicited by spoken words and pseudowords played monaurally, to the left or right ear, or simultaneously to both ears of human subjects instructed to ignore acoustic stimuli but watch a silent video film. The mismatch negativity (MMN), a neurophysiological index of the automatic activation of cortical memory traces, was calculated as the difference between the event-related potential elicited by an infrequent deviant stimulus and the event-related potential to the same item presented as a frequent standard stimulus. Consistent with earlier reports, the MMN to words was larger than that to pseudowords, possibly reflecting the existence of memory traces for spoken words. Bilateral redundant stimulus presentation led to a further increase of the MMN to words relative to both unilateral stimulation modes. This bilateral redundancy gain was absent for pseudowords. We interpret the neurophysiological manifestation of a word-specific bilateral redundancy gain as evidence for interhemispheric cooperation in the automatic access to memory traces for spoken words. Accordingly, word-related cortical networks distributed over both hemispheres allow summation of neural activity between and within hemispheres, thereby potentiating the word-related MMN. [source] Aberrant responses to acoustic stimuli in mice deficient for neural recognition molecule NB-2EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003Hong Li Abstract NB-2, a member of the contactin subgroup in the immunoglobulin superfamily, is expressed specifically in the postnatal nervous system, reaching a maximum level at 3 weeks postnatal. NB-2 displays neurite outgrowth-promoting activity in vitro. To assess its function in the nervous system, we generated mutant mice in which a part of the NB-2 gene was ablated and replaced with the tau-LacZ gene. The general appearance of NB-2-deficient mice and their gross anatomical features were normal. The LacZ expression patterns in heterozygous mice revealed that NB-2 is preferentially expressed in the central auditory pathways. In the audiogenic seizure test, NB-2-deficient mice exhibited a lower incidence of wild running, but a higher mortality rate than the wild-type littermates. c-Fos immunohistochemistry demonstrated that neural excitability induced by the audiogenic seizure test in the NB-2-deficient mice was prominently attenuated in both the dorsal and external cortices of the inferior colliculus, where enhanced neural excitability was observed in the wild-type mice. In response to pure-tone stimulation after priming, NB-2-deficient mice exhibited a diffuse and low level of c-Fos expression in the central nucleus of the inferior colliculus, which was distinctly different from the band-like c-Fos expression corresponding to the tonotopic map in the wild-type littermates. Taken together, these results suggest that a lack of NB-2 causes impairment of the neuronal activity in the auditory system. [source] Netrin-G2 and netrin-G2 ligand are both required for normal auditory responsivenessGENES, BRAIN AND BEHAVIOR, Issue 4 2008W. Zhang Mice in which netrin-G2 has been genetically inhibited do not startle to an acoustic stimulus, but otherwise perform normally through a behavioral test battery. Light microscopic examination of the inner ear showed no obvious structural abnormalities. Brainstem responses to acoustic stimuli (auditory brainstem responses, ABR) were also present, confirming the lack of any overarching defects in the inner ear or auditory nerve. Genetic inhibition of netrin-G2 ligand produced a nearly identical phenotype, that is, no startle with ABR present, and otherwise normal. This similarity confirms that these two proteins act in the same biological pathway. We have also determined that the affinity between the two proteins is strong, around 2.5 nm, similar to that observed between netrin-G1 and netrin-G1 ligand , 2.3 nm in our hands. The combination of equivalent phenotypes when genetically inhibited coupled with evidence of a strong biochemical interaction supports the notion of a receptor,ligand interaction between these two proteins in vivo. This interaction is critical for auditory synaptic responsiveness in the brain. [source] Genetic Correlation Between Innate Alcohol Preference and Fear-Potentiated Startle in Selected Mouse LinesALCOHOLISM, Issue 7 2007Gustavo D. Barrenha Background: There is a high rate of co-occurrence between anxiety and alcohol-use disorders in humans that may arise from the inheritance of common genes that increase the risk for both psychiatric disorders. The purpose of this study was to investigate whether a genetic relationship exists between innate alcohol preference and propensity to develop learned fear, using the fear-potentiated startle (FPS) paradigm, in 2 mouse lines selectively bred for high or low alcohol preference. Methods: Alcohol-naïve, male, and female mice from replicate pairs of lines selectively bred for high alcohol preference and low alcohol preference were randomly assigned to a fear-conditioned or control group. Mice in the fear-conditioned group received 20 pairings of a light stimulus and footshock; the control group received the same number of exposures to light and footshock, except that these stimuli were explicitly unpaired. During testing for FPS, acoustic stimuli were presented both in the presence and in the absence of the light stimulus. Results: In both replicate pairs of lines, mice selectively bred for high alcohol preference showed greater FPS than mice selectively bred for low alcohol preference. No sex differences in FPS were found in any line. Control groups did not show FPS. Conclusion: These findings suggest that common genes mediate both innate alcohol preference and propensity to develop learned fear in these selected mouse lines. [source] Auditory-evoked potentials in general anesthesia monitoring: baseline study of availability in relation to hearing function in awake statusACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2005L. De Siena Background:, It has been confirmed that middle latency auditory-evoked potentials are good indicators of the hypnotic level in patients undergoing general anesthesia. The focal point for the evocation of auditory-evoked potentials is the presence of a serviceable hearing function. The aim of the study was to evaluate the limit of hearing loss above which the test could not be applied. Methods:, To determine the limit of applicability of the technique, 100 subjects were studied. Twenty of them were normally hearing and 80 were affected by sensorineural hearing loss of various degrees. Each subject was submitted to pure tone audiometry, to determine hearing threshold, and then, in awake status, to auditory-evoked potentials recording using acoustic stimuli of 85 dB HL. Results:, All the 20 normally hearing subjects showed a reliable auditory-evoked potentials. Among the 80 subjects affected by hearing loss, only five had no potentials. These five subjects presented a pure tone audiometry threshold greater than 85 dB HL. Conclusion:, The study demonstrated that middle latency auditory-evoked potentials recorded using an A-Line® (software version 1.4) AEP monitor (Danmeter, Odense, Denmark) can be carried out even in presence of hearing loss if the pure tone threshold is less than 85 dB HL. [source] Manganese-enhanced MRI of the mouse auditory pathwayMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Takashi Watanabe Abstract Functional mapping of the lateral lemniscus and the superior olivary complex as part of the auditory pathway was accomplished for the first time in mice in vivo using manganese-enhanced MRI (2.35T, 3D FLASH, 117 ,m isotropic resolution). These and other auditory centers in the brainstem presented with pronounced signal enhancements after systemic administration of manganese chloride when animals were exposed to acoustic stimuli for 48 hr, but not when kept in a quiet environment. The results indicate an activation-dependent accumulation of manganese in the neural circuit composed of the cochlear nucleus, the superior olivary complex, the lateral lemniscus, and the inferior colliculus. The marked enhancement of the lateral lemniscus suggests that the stimulus-related accumulation of manganese reflects not only a regional uptake from extracellular fluid but also a concurrent delivery by axonal transport within the auditory system. Magn Reson Med 60:210,212, 2008. © 2008 Wiley-Liss, Inc. [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] Independence of valence modulation and prepulse inhibition of startlePSYCHOPHYSIOLOGY, Issue 1 2000Larry W. Hawk This study sought to determine whether prepulse inhibition and valence modulation of startle are independent, both within and across individuals. Acoustic probes (105 dB) were delivered as 68 undergraduates viewed pleasant, neutral, and unpleasant pictures. Weak acoustic stimuli (8 dB above background) preceded half of the probes by 120 ms. As expected, startles were larger during unpleasant than during pleasant pictures, and smaller on prepulse than no-prepulse trials. In general, valence modulation and prepulse inhibition of startle were unrelated. That is, prepulse inhibition was consistent across affective states, valence modulation did not differ between no-prepulse and prepulse trials, and valence modulation and prepulse inhibition effects were uncorrelated across individuals. Analysis of raw and percent modification scores generally led to similar conclusions. It is concluded that valence modulation and prepulse inhibition are independent startle modulatory phenomena, although this conclusion is tempered by a finding of poor internal consistency reliability for valence modulation. [source] A comparison of auditory brainstem responses and behavioral estimates of hearing sensitivity in Lemur catta and Nycticebus coucangAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2010Marissa A. Ramsier Abstract Primates depend on acoustic signals and cues to avoid predators, locate food, and share information. Accordingly, the structure and function of acoustic stimuli have long been emphasized in studies of primate behavioral and cognitive ecology. Yet, few studies have addressed how well primates hear such stimuli; indeed, the auditory thresholds of most primate species are unknown. This empirical void is due in part to the logistic and economic challenges attendant on traditional behavioral testing methods. Technological advances have produced a safe and cost-effective alternative,the auditory brainstem response (ABR) method, which can be utilized in field conditions, on virtually any animal species, and without subject training. Here we used the ABR and four methods of threshold determination to construct audiograms for two strepsirrhine primates: the ring-tailed lemur (Lemur catta) and slow loris (Nycticebus coucang). Next, to verify the general efficacy of the ABR method, we compared our results to published behaviorally-derived audiograms. We found that the four ABR threshold detection methods produced similar results, including relatively elevated thresholds but similarly shaped audiograms compared to those derived behaviorally. The ABR and behavioral absolute thresholds were significantly correlated, and the frequencies of best sensitivity and high-frequency limits were comparable. However, at frequencies ,2,kHz, ABR thresholds were especially elevated, resulting in decreased agreement with behavioral thresholds and, in Lemur, the ABR 10-dB range starting points were more than 2 octaves higher than the behavioral points. Finally, a comparison of ABR- and behaviorally-derived audiograms from various animal taxa demonstrates the widespread efficacy of the ABR for estimating frequency of best sensitivity, but otherwise suggests caution; factors such as stimulus properties and threshold definition affect results. We conclude that the ABR method is a promising technique for estimating primate hearing sensitivity, but that additional data are required to explore its efficacy for estimating low-frequency thresholds. Am. J. Primatol. 72:217,233, 2010. © 2009 Wiley-Liss, Inc. [source] Netrin-G2 and netrin-G2 ligand are both required for normal auditory responsivenessGENES, BRAIN AND BEHAVIOR, Issue 4 2008W. Zhang Mice in which netrin-G2 has been genetically inhibited do not startle to an acoustic stimulus, but otherwise perform normally through a behavioral test battery. Light microscopic examination of the inner ear showed no obvious structural abnormalities. Brainstem responses to acoustic stimuli (auditory brainstem responses, ABR) were also present, confirming the lack of any overarching defects in the inner ear or auditory nerve. Genetic inhibition of netrin-G2 ligand produced a nearly identical phenotype, that is, no startle with ABR present, and otherwise normal. This similarity confirms that these two proteins act in the same biological pathway. We have also determined that the affinity between the two proteins is strong, around 2.5 nm, similar to that observed between netrin-G1 and netrin-G1 ligand , 2.3 nm in our hands. The combination of equivalent phenotypes when genetically inhibited coupled with evidence of a strong biochemical interaction supports the notion of a receptor,ligand interaction between these two proteins in vivo. This interaction is critical for auditory synaptic responsiveness in the brain. [source] The dynamics of cardiac defense: From attention to actionPSYCHOPHYSIOLOGY, Issue 5 2010Isabel Ramírez Abstract The attentional and motivational significance of cardiac defense is examined in two studies. In Study 1, cardiac defense was evoked by an intense acoustic stimulus in the context of either a visual search or a memory search task using letters as stimuli. Results showed a potentiation of the long latency acceleration of cardiac defense in the visual search task. In Study 2, participants performed the same visual search task using pleasant, neutral, and unpleasant pictures as stimuli. Results showed a further potentiation of the long latency acceleration of cardiac defense when the visual search task was performed with unpleasant, compared to pleasant or neutral pictures. These results indicate that cardiac defense has both attentional and motivational contributions, where the attentional significance is related to increased sensory processing, whereas the motivational significance is associated with preparation for active defense. [source] Precues enable multiple response preprogramming: Evidence from startlePSYCHOPHYSIOLOGY, Issue 2 2009Anthony N. Carlsen Abstract When one or more response dimensions in a choice reaction time (RT) task are provided beforehand (or precued), RT decreases, indicating that the precued part of a response was prepared in advance. In this study, a startling acoustic stimulus was used to investigate the amount of preprogramming that occurs when part of the response is precued because a startling stimulus has been shown to directly trigger preprogrammed responses. Participants performed wrist flexion/extension movements in a precued one to four choice RT paradigm. A control auditory stimulus (82 dB) or a startling acoustic stimulus (124 dB) accompanied the visual "go" signal on each trial. Although RT latencies were significantly reduced by the startle, many more errors were observed in the startled conditions. Importantly, the errors seen at short RT latencies largely reflected multiple movements to the cued response alternatives, suggesting that multiple responses were preprogrammed. [source] Effect of positive and negative emotion on stimulus-preceding negativity prior to feedback stimuliPSYCHOPHYSIOLOGY, Issue 6 2001Yasunori Kotani Stimulus-preceding negativity (SPN) was recorded to investigate the effect of positive and negative emotion on the SPN preceding feedback stimuli. In the time-estimation task in which an acoustic stimulus was presented 3 s after a voluntary movement, (1) the negative valence (aversive band noise and pure tone) and (2) the positive valence (reward and no-reward) of feedback stimuli were manipulated. During noise conditions, participants received the band noise as a feedback stimulus except when their time estimations were accurate. They received a monetary reward for accurate time estimations under the reward conditions. The prefeedback SPN was larger under reward than no-reward conditions. In addition, the prefeedback SPN in the noise condition was larger compared with the pure tone condition. Our results appear to suggest that emotional anticipation is important in eliciting the prefeedback SPN. [source] | |||||||||||||