Latency Of Auditory Evoked Potential Research Articles

Adjunct Methods for Alzheimer's Disease Detection: A Review of Auditory Evoked Potentials.

The auditory afferent pathway as a clinical marker of Alzheimer's disease (AD) has sparked interest in investigating the relationship between age-related hearing loss (ARHL) and AD. Given the earlier onset of ARHL compared to cognitive impairment caused by AD, there is a growing emphasis on early diagnosis and intervention to postpone or prevent the progression from ARHL to AD. In this context, auditory evoked potentials (AEPs) have emerged as a widely used objective auditory electrophysiological technique for both the clinical diagnosis and animal experimentation in ARHL due to their non-invasive and repeatable nature. This review focuses on the application of AEPs in AD detection and the auditory nerve system corresponding to different latencies of AEPs. Our objective was to establish AEPs as a systematic and non-invasive adjunct method for enhancing the diagnostic accuracy of AD. The success of AEPs in the early detection and prediction of AD in research settings underscores the need for further clinical application and study.

Comparison of evoked potentials across four related developmental encephalopathies

BackgroundDeveloping biomarkers is a priority for drug development for all conditions, but vital in the rare neurodevelopmental disorders where sensitive outcome measures are lacking. We have previously demonstrated the feasibility and tracking of evoked potentials to disease severity in Rett syndrome and CDKL5 deficiency disorder. The aim of the current study is to characterize evoked potentials in two related developmental encephalopathies, MECP2 duplication syndrome and FOXG1 syndrome, and compare across all four groups to better understand the potential of these measures to serve as biomarkers of clinical severity for the developmental encephalopathies.MethodsVisual and auditory evoked potentials were acquired from participants with MECP2 duplication syndrome and FOXG1 syndrome across five sites of the Rett Syndrome and Rett-Related Disorders Natural History Study. A group of age-matched individuals (mean = 7.8 years; range = 1–17) with Rett syndrome, CDKL5 deficiency disorder, and typically-developing participants served as a comparison group. The analysis focused on group-level differences as well as associations between the evoked potentials and measures of clinical severity from the Natural History Study.ResultsAs reported previously, group-level comparisons revealed attenuated visual evoked potentials (VEPs) in participants with Rett syndrome (n = 43) and CDKL5 deficiency disorder (n = 16) compared to typically-developing participants. VEP amplitude was also attenuated in participants with MECP2 duplication syndrome (n = 15) compared to the typically-developing group. VEP amplitude correlated with clinical severity for Rett syndrome and FOXG1 syndrome (n = 5). Auditory evoked potential (AEP) amplitude did not differ between groups, but AEP latency was prolonged in individuals with MECP2 duplication syndrome (n = 14) and FOXG1 syndrome (n = 6) compared to individuals with Rett syndrome (n = 51) and CDKL5 deficiency disorder (n = 14). AEP amplitude correlated with severity in Rett syndrome and CDKL5 deficiency disorder. AEP latency correlated with severity in CDKL5 deficiency disorder, MECP2 duplication syndrome, and FOXG1 syndrome.ConclusionsThere are consistent abnormalities in the evoked potentials in four developmental encephalopathies some of which correlate with clinical severity. While there are consistent changes amongst these four disorders, there are also condition specific findings that need to be further refined and validated. Overall, these results provide a foundation for further refinement of these measures for use in future clinical trials for these conditions.

Sensorimotor rhythm neurofeedback training and auditory perception

Background/Aim. In everyday communication, people are exposed to a myriad of sounds that need to be sorted and relevant information extracted. The ability of a person to concentrate on certain sounds in a noisy background environment, perform selective attention, and focus their auditory attention is crucial for everyday functioning and communication. The aim of this study was to investigate the effect of the sensorimotor rhythm (SMR) (12?15 Hz) neurofeedback (NFB) training to improve auditory cognition measured by the achievements in the Quick speech-in-noise (QuickSIN) test, changes in the amplitudes and latencies of components of auditory evoked potentials (AEP) N100, N200, and P300 in the auditory oddball discrimination task, and changes in the spectral power of the SMR. Methods. The study included 16 healthy participants aged 25?40 years (8 males and 8 females). Each participant had 20 daily sessions of SMR NFB training. Auditory cognitive functions and electrophysiological correlates of cognitive processing were recorded 5 times ? before NFB, after 5, 10, and 20 sessions, and one month after the last session of NFB. Re-sults. The results showed a statistically significant decrease in N200 and P300 latencies at frontal midline (Fz), central midline (Cz), and parietal midline (Pz) regions, an improvement on the QuickSIN test, and an increase in electroencephalogram SMR rhythm spectral power in the Cz region as a result of the NFB SMR training. No significant effect of the NFB training on the N100, N200, and P300 amplitudes on Fz, Cz, and Pz was found. Conclusion. The obtained results suggest that SMR NFB affects auditory perception in terms of shorter latencies of AEP and better performance on the QuickSIN test.

Comparison of auditory evoked potential changes with the duration of diabetes mellitus

Background: Type II diabetes is typically a chronic disease associated with decreasing life expectancy. This is partly due to the number of complications with which it is associated. With increasing duration, the glycemic control in Diabetes Mellitus is also closely associated with hearing loss. Aim and Objective: This study aims to compare the auditory evoked potential (AEP) changes with the duration of Type II diabetic mellitus. Materials and Methods: A total of 135 diabetic patients were involved. They were divided into three groups depending on the duration of the disease: Group-I: 0–5 years; Group-II: 5–10 years; and Group-III: 10–15 years. Blood investigation such as glycosylated hemoglobin (HbA1c) level and fasting blood sugar (FBS) levels was done in all the patients. AEP was done in all the participating diabetic patients. Results: The FBS and HbA1c level values were increased as disease progressed up to 5–10 years of duration. Further, disease progression that is more than 10–15 years of FBS and HbA1c levels was reduced. The results of the study showed that a significant delay in AEP latencies (wave I, wave III, and wave V) and interpeak latencies (IPL I-III and IPL III-V) was prolonged in Group A-II when compared with the other two groups. The results were analyzed by mean standard deviation and using ANOVAs. Conclusion: According to our study, the AEP latencies were prolonged in increased duration of diabetes mellitus patients. This gives a clear idea in managing the disease progress and pathological changes taking place to have a better life.

Position of an acoustic window in a beluga whale: Computation based on auditory evoked potential latencies.

In a beluga whale, the positions of sound receiving areas on the head surface were determined by comparing the acoustic delays from different sound source positions. For this investigation, auditory evoked potentials (AEPs) in response to short tone pips were recorded. Latencies of the first AEP wave that presumably reflected the activity of the auditory nerve were measured at different sound source azimuths. For AEPs of equal amplitudes, the difference in AEP latencies was attributed to the difference in the acoustic delays. These delay differences were used to compute the azimuths of sound receiving points. Measurements were conducted at frequencies from 22.5 to 90 kHz in half-octave steps. At all stimulus frequencies, the receiving points were located 24-38 cm caudal of the melon tip, which is near a proximal part of the lower jaw. Thus, the results indicated the latero-mandibular acoustic window. Possible causes for not finding a lateral or ventro-mandibular window are discussed.

Characteristics of short-patent auditory evoked potentials in children with cerebral palsy

Background. In children with cerebral palsy, high risk of cognitive impairments connected with sensory disintegration – delayed visual and auditory perception.The objective – assessment of temporary and amplitude characteristics brainstem auditory evoked potentials of children with cerebral palsy.Materials and methods. Neurological examination, retrospective analysis of magnetic resonance imaging data of brain and 2-channel brainstem auditory evoked potentials registration with left- and right-ear stimulation and analysis was performed for 60 children aged 4–17 years, with mean age 11.80 ± 0.56 years.Results. There are no significant difference in brainstem auditory evoked potentials latencies of children’s with cerebral palsy age subgroups. A significantly increasing of III–V peak latencies of brainstem auditory evoked potentials and also I–III and I–V interpeak latencies was observed in children with cerebral palsy in comparison of control group. Latencies of different brainstem auditory evoked potentials peaks were significantly higher in children with uni- and bilateral form of cerebral palsy and speech impairment. Group with periventricular leucomalation (on magnetic resonance imaging) is characterized by significantly increased brainstem auditory evoked potentials latencies and normal interpeak intervals. These abnormalities may be linked to non-progressive impairment of brainstem acoustic afferentation.Conclusion. Impairment of brainstem auditory evoked potentials maturation and it’s difference in various cerebral palsy forms may be potentially clinical applicable for assessment of the children and early detection of sensory impairment.

No Effect of Transcranial Direct Current Stimulation of the Auditory Cortex on Auditory-Evoked Potentials.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to change cortical excitability. Its effects are shown for cognitive processing, and behavior in the motor and perceptual domains. However, evidence of tDCS effects in the perceptual domain particularly for auditory processing is rare. Therefore, and in the context of disturbances in auditory processing in psychiatric populations, e.g., in patients with auditory verbal hallucinations, we aimed to investigate the potential modulatory effect of tDCS on the excitability of left posterior temporal cortex in detail. We included 24 healthy participants in a crossover design, applying sham and anodal stimulation in two measurement sessions 1 week apart. Electroencephalography (EEG) was recorded while participants listened to tones before, during, and after stimulation. Amplitudes and latencies of P50, N100, and P200 auditory-evoked potentials (AEP) were compared between anodal and sham stimulation, and between time points before, during, and after tDCS. In contrast to previous studies, results demonstrate no significant differences between stimulation types or time points for any of the investigated AEP amplitudes or latencies. Furthermore, a topographical analysis did not show any topographical differences during peak time periods of the investigated AEP for stimulation types and time points besides a habituation effect. Thus, our results suggest that tDCS modulation of excitability of the left posterior temporal cortex, targeting the auditory cortex, does not have any effect on AEP. This is particularly interesting in the context of tDCS as a potential treatment for changed electrophysiological parameters and symptoms of psychiatric diseases, e.g., lower N100 or auditory verbal hallucinations in schizophrenia.

Behavioral and Auditory Electrophysiological Rebound as a Compensatory Response to the Reinforcing Effects of Morphine

Auditory-evoked potentials (AEPs) can be modified by associative learning, where the appearance of learned compensatory responses (CCRs) may result in the emergence of drug withdrawal symptoms and relapse. Although CCRs’ influence on later attentive and cognitive domains has been extensively examined, contextual conditioned tolerance occurring in preattentive mechanisms operating at earlier stages of information processing has remained largely unexplored. To extend our knowledge on this subject, compensatory changes on the motor and emotional aspects of behavior evoked by contextual cues were investigated with an electronic open field in morphine-pretreated rats challenged with two morphine overdoses (40 and 80 mg/kg). CCRs influence on the AEPs recorded in the central nucleus of the inferior colliculus (CIC) was analyzed with the help of a field potential recording device and a two-chamber shuttle box placed inside a Faraday cage system. The emergence of electrophysiological CCRs was analyzed by recording AEP latency and amplitude elicited in the central nucleus of the IC (CIC) with the aid of a field potential recording device and a two-chamber shuttle box placed inside a Faraday cage system. Behavioral analysis indicated that CCRs ensue in non-familiar contexts. Electrophysiological data revealed increases in the amplitude of AEPs evoked in a non-familiar context. Our results indicate that behavioral learning responses emerge following Pavlovian conditioning even with the use of low and regular doses of morphine over a short-term treatment. Changes in the CIC electrophysiology may indicate that the development of drug dependence occurs covertly in the early stages of sensory information processing.

Short-term 2.1 GHz radiofrequency radiation treatment induces significant changes on the auditory evoked potentials in adult rats

Purpose: There is a growing interest in the usage of radiofrequency radiation (RF) as a noninvasive brain stimulation method. Previously reported data demonstrated that RF exposure caused a change in brain oscillations. Therefore, we aimed to investigate effects of RF on brain oscillation by measuring the auditory response of different brain regions in rats.Materials and methods: Rats were randomly divided into three groups (n = 12 per each group): Cage control (C), sham rats (Sh), and rats exposed to 2.1 GHz RF for 2 h/day for 7 days. At the end of the exposure, auditory evoked potentials (AEPs) were recorded at different locations in rats. Latencies and amplitudes of AEPs, evoked power, inter-trial phase synchronization, and auditory evoked gamma responses were obtained in response to an auditory stimulus. Furthermore, TBARS levels and 4-HNE, GFAP, iNOS, and nNOS expressions were evaluated in all groups.Results: Peak-to-peak amplitudes of AEPs were significantly higher in the RF group compared with the Sh group. There is no significant difference in peak latencies of AEPs between groups. Beside, evoked power, inter-trial phase synchronization, and auditory evoked gamma responses were significantly higher in the RF group compared with the Sh group. In addition, the RF group had significantly lower TBARS and 4-HNE levels than the Sh group. There were no significant differences between groups for GFAP, nNOS, and iNOS levels, and between the C and RF groups for all parameters.Conclusions: Our present findings suggest that short-term RF treatment under chosen experimental conditions have statistically significant effect on neuronal networks of rats by probably reducing oxidative damage. However, this effect must be further studied for possible noninvasive brain stimulation.

Histological correlates of N40 auditory evoked potentials in adult rats after neonatal ventral hippocampal lesion: animal model of schizophrenia

The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.

Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz tone pips

Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulation and by conducting a source analysis of the resulting evoked potentials of short and long latency. Ten healthy, right-handed subjects were recruited and evoked potentials were recorded to both left- and right-ear sound stimulation, above and below vestibular threshold. Below VEMP threshold, typical AEPs were recorded, consisting of mid-latency (MLR) waves Na and Pa followed by long latency AEPs (LAEPs) N1 and P2. In the supra-threshold condition, the expected changes in morphology were observed, consisting of: (1) short-latency vestibular evoked potentials (VsEPs) which have no auditory correlate, i.e. the ocular VEMP (OVEMP) and inion response related potentials; (2) a later deflection, labelled N42/P52, followed by the LAEPs N1 and P2. Statistical analysis of the vestibular dependent responses indicated a contralateral effect for inion related short-latency responses and a left-ear/right-hemisphere advantage for the long-latency responses. Source analysis indicated that the short-latency effects may be mediated by a contralateral projection to left cerebellum, while the long-latency effects were mediated by a contralateral projection to right cingulate cortex. In addition we found evidence of a possible vestibular contribution to the auditory T-complex in radial temporal lobe sources. These last results raise the possibility that acoustic activation of the otolith organs could potentially contribute to auditory processing.

Neural Adaptation and Behavioral Measures of Temporal Processing and Speech Perception in Cochlear Implant Recipients

The objective was to determine if one of the neural temporal features, neural adaptation, can account for the across-subject variability in behavioral measures of temporal processing and speech perception performance in cochlear implant (CI) recipients. Neural adaptation is the phenomenon in which neural responses are the strongest at the beginning of the stimulus and decline following stimulus repetition (e.g., stimulus trains). It is unclear how this temporal property of neural responses relates to psychophysical measures of temporal processing (e.g., gap detection) or speech perception. The adaptation of the electrical compound action potential (ECAP) was obtained using 1000 pulses per second (pps) biphasic pulse trains presented directly to the electrode. The adaptation of the late auditory evoked potential (LAEP) was obtained using a sequence of 1-kHz tone bursts presented acoustically, through the cochlear implant. Behavioral temporal processing was measured using the Random Gap Detection Test at the most comfortable listening level. Consonant nucleus consonant (CNC) word and AzBio sentences were also tested. The results showed that both ECAP and LAEP display adaptive patterns, with a substantial across-subject variability in the amount of adaptation. No correlations between the amount of neural adaptation and gap detection thresholds (GDTs) or speech perception scores were found. The correlations between the degree of neural adaptation and demographic factors showed that CI users having more LAEP adaptation were likely to be those implanted at a younger age than CI users with less LAEP adaptation. The results suggested that neural adaptation, at least this feature alone, cannot account for the across-subject variability in temporal processing ability in the CI users. However, the finding that the LAEP adaptive pattern was less prominent in the CI group compared to the normal hearing group may suggest the important role of normal adaptation pattern at the cortical level in speech perception.

Effects of Propofol, Sevoflurane, Remifentanil, and (S)-Ketamine in Subanesthetic Concentrations on Visceral and Somatosensory Pain–evoked Potentials

Although electroencephalographic parameters and auditory evoked potentials (AEP) reflect the hypnotic component of anesthesia, there is currently no specific and mechanism-based monitoring tool for anesthesia-induced blockade of nociceptive inputs. The aim of this study was to assess visceral pain-evoked potentials (VPEP) and contact heat-evoked potentials (CHEP) as electroencephalographic indicators of drug-induced changes of visceral and somatosensory pain. Additionally, AEP and electroencephalographic permutation entropy were used to evaluate sedative components of the applied drugs. In a study enrolling 60 volunteers, VPEP, CHEP (amplitude N2-P1), and AEP (latency Nb, amplitude Pa-Nb) were recorded without drug application and at two subanesthetic concentration levels of propofol, sevoflurane, remifentanil, or (s)-ketamine. Drug-induced changes of evoked potentials were analyzed. VPEP were generated by electric stimuli using bipolar electrodes positioned in the distal esophagus. For CHEP, heat pulses were given to the medial aspect of the right forearm using a CHEP stimulator. In addition to AEP, electroencephalographic permutation entropy was used to indicate level of sedation. With increasing concentrations of propofol, sevoflurane, remifentanil, and (s)-ketamine, VPEP and CHEP N2-P1 amplitudes decreased. AEP and electroencephalographic permutation entropy showed neither clinically relevant nor statistically significant suppression of cortical activity during drug application. Decreasing VPEP and CHEP amplitudes under subanesthetic concentrations of propofol, sevoflurane, remifentanil, and (s)-ketamine indicate suppressive drug effects. These effects seem to be specific for analgesia.

Effectiveness of steady versus varied-color/varied-pattern visual tasks during acquisition of late auditory evoked potentials

Instructions for late auditory evoked potential (LAEP) testing include a need for the subject to remain alert (not go to sleep). Previous studies show an inverse relationship between alertness level and waveform morphology. Thus, a need exists to maintain alertness during LAEP testing. If not maintained, a wide range of alertness, and thus waveform morphology, may exist from one run to the next. Therefore, if alertness level is not controlled, any variations in waveform morphology may be due to variations in alertness rather than auditory system integrity. Previous investigators have implemented visual tasks consisting of still or action images in an attempt to maintain alertness. In these visual tasks, a subject is typically instructed to attend to a video screen during LAEP testing. This project investigated the effectiveness of two visual task screens: unvaried blue with no pattern, versus varied colors-patterns occurring in 1-3 second random intervals. LAEPs were gathered on twenty-five young adult subjects who were instructed to attend to a video display of one of the screens during LAEP testing. Six replicates were obtained for each screen in counter-balanced order. Results showed no significant (p>.05) differences in mean P1 or P2 latency or amplitude for the two screens.

Acceptance of Background Noise, Working Memory Capacity, and Auditory Evoked Potentials in Subjects with Normal Hearing

The acceptable noise level (ANL) test is a method for quantifying the amount of background noise that subjects accept when listening to speech. Large variations in ANL have been seen between normal-hearing subjects and between studies of normal-hearing subjects, but few explanatory variables have been identified. To explore a possible relationship between a Swedish version of the ANL test, working memory capacity (WMC), and auditory evoked potentials (AEPs). ANL, WMC, and AEP were tested in a counterbalanced order across subjects. Twenty-one normal-hearing subjects participated in the study (14 females and 7 males; aged 20-39 yr with an average of 25.7 yr). Reported data consists of age, pure-tone average (PTA), most comfortable level (MCL), background noise level (BNL), ANL (i.e., MCL - BNL), AEP latencies, AEP amplitudes, and WMC. Spearman's rank correlation coefficient was calculated between the collected variables to investigate associations. A principal component analysis (PCA) with Varimax rotation was conducted on the collected variables to explore underlying factors and estimate interactions between the tested variables. Subjects were also pooled into two groups depending on their results on the WMC test, one group with a score lower than the average and one with a score higher than the average. Comparisons between these two groups were made using the Mann-Whitney U-test with Bonferroni correction for multiple comparisons. A negative association was found between ANL and WMC but not between AEP and ANL or WMC. Furthermore, ANL is derived from MCL and BNL, and a significant positive association was found between BNL and WMC. However, no significant associations were seen between AEP latencies and amplitudes and the demographic variables, MCL, and BNL. The PCA identified two underlying factors: One that contained MCL, BNL, ANL, and WMC and another that contained latency for wave Na and amplitudes for waves V and Na-Pa. Using the variables in the first factor, the findings were further explored by pooling the subjects into two groups according to their WMC (WMClow and WMChigh). It was found that the WMClow had significantly poorer BNL than the WMChigh. The findings suggest that there is a strong relationship between BNL and WMC, while the association between MCL, ANL, and WMC seems less clear-cut.

Semi-automatic attenuation of cochlear implant artifacts for the evaluation of late auditory evoked potentials

Electrical artifacts caused by the cochlear implant (CI) contaminate electroencephalographic (EEG) recordings from implanted individuals and corrupt auditory evoked potentials (AEPs). Independent component analysis (ICA) is efficient in attenuating the electrical CI artifact and AEPs can be successfully reconstructed. However the manual selection of CI artifact related independent components (ICs) obtained with ICA is unsatisfactory, since it contains expert-choices and is time consuming.We developed a new procedure to evaluate temporal and topographical properties of ICs and semi-automatically select those components representing electrical CI artifact. The CI Artifact Correction (CIAC) algorithm was tested on EEG data from two different studies. The first consists of published datasets from 18 CI users listening to environmental sounds. Compared to the manual IC selection performed by an expert the sensitivity of CIAC was 91.7% and the specificity 92.3%. After CIAC-based attenuation of CI artifacts, a high correlation between age and N1–P2 peak-to-peak amplitude was observed in the AEPs, replicating previously reported findings and further confirming the algorithm's validity.In the second study AEPs in response to pure tone and white noise stimuli from 12 CI users that had also participated in the other study were evaluated. CI artifacts were attenuated based on the IC selection performed semi-automatically by CIAC and manually by one expert. Again, a correlation between N1 amplitude and age was found. Moreover, a high test–retest reliability for AEP N1 amplitudes and latencies suggested that CIAC-based attenuation reliably preserves plausible individual response characteristics.We conclude that CIAC enables the objective and efficient attenuation of the CI artifact in EEG recordings, as it provided a reasonable reconstruction of individual AEPs. The systematic pattern of individual differences in N1 amplitudes and latencies observed with different stimuli at different sessions, strongly suggests that CIAC can overcome the electrical artifact problem. Thus CIAC facilitates the use of cortical AEPs as an objective measurement of auditory rehabilitation.

Physiological correlates for categorical perception of species-specific communication sounds of Mongolian gerbils: Mismatch negativity in the auditory evoked potential

Physiological correlates for categorical perception of species-specific communication sounds of Mongolian gerbils: Mismatch negativity in the auditory evoked potential

Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities

Event Abstract Back to Event Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities Naoya Akiyama1, Kohta I. Kobayasi2 and Hiroshi Riquimaroux1, 2* 1 Doshisha University, Department of Biomedical Engineerling and Biomedical Infomation, Graduate School of Life and Medical Science, Japan 2 Doshisha University, Biomedical Information, Japan The laser irradiation with a near-infrared wavelength (830nm) has been recently developed to reversibly inactivate neural activities. Irradiation of near-infrared laser (NIRL) has advantages over other methods for neural suppression (i.e., physical ablation or pharmacological method). The advantages of NIRL are as follows: 1) it may irradiate a small focal area, 2) its inactivation is reversible and 3) inactivation and recovery occurs immediately. Previous studies irradiated NIRL directly to the brain with craniotomy. The NIRL irradiation through the skull without craniotomy is much less invasive and well suited for behavioral studies. The purpose of this study was to evaluate the method of reversible inhibition of neural activity by transcranial irradiation. Five male gerbils (Meriones unguiculatus) were used as subjects. Animal was anesthetized by ketamine and xylazine. We made a hole near the parietal region and silver electorode, tip of which was loop-shaped, was placed on epidula over the primary auditory cortex. We recorded auditory evoked potential (AEP) to clicks and compared the difference in potential before, during and after NIRL irradiation. In addition, we presented light flash to record visual evoked potential (VEP) from the identical location for comparison with AEP. We alternately presented clicks and light flashes to record AEP and VEP. Delay between visual and auditory stimuli was 1 s. All stimulus duration was set at 100 µs. The recordings were made in a soundproof box. Light-emitting diode (LED), loud speaker and optical fiber for laser irradiation were installed in the soundproof box. The first 10 minutes was used for recordings without irradiation. The next 10 minutes was dedicated for recordings during laser irradiation. Then, we continued recordings for 50 minutes after stopping irradiation for examining the recovery process. With irradiation level of 70 mW/mm2 or lower, AEPs did not change during laser irradiation. However, with of irradiation level of 100 mW/mm2 or more, AEP (middle latency responses) was altered. The AEP recovered within 2 minutes after laser irradiation was terminated. On the other hand, the VEP was not altered, regardless of the laser irradiation on auditory cortex. Results indicate that the middle latency AEP (10-50 ms after the sound stimulus) originated in the primary auditory cortex, was possibly suppressed by transcranial NIRL irradiation to the primary auditory cortex. Successful alteration of the AEP by tranxcranial laser irradiation suggests possible application of this methods to free moving or awake behaving animals. Keywords: auditory evoked potential (AEP), visual evoked potential (VEP) Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for participant symposium and student poster award) Topic: Novel Tools and Methods Citation: Akiyama N, Kobayasi KI and Riquimaroux H (2012). Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00374 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Prof. Hiroshi Riquimaroux, Doshisha University, Department of Biomedical Engineerling and Biomedical Infomation, Graduate School of Life and Medical Science, Kyotanabe, Kyoto, 610-0321, Japan, hrikimar@mail.doshisha.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Google Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Google Scholar Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux PubMed Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Interactions between “What” and “When” in the Auditory System: Temporal Predictability Enhances Repetition Suppression

Neural activity in the auditory system decreases with repeated stimulation, matching stimulus probability in multiple timescales. This phenomenon, known as stimulus-specific adaptation, is interpreted as a neural mechanism of regularity encoding aiding auditory object formation. However, despite the overwhelming literature covering recordings from single-cell to scalp auditory-evoked potential (AEP), stimulation timing has received little interest. Here we investigated whether timing predictability enhances the experience-dependent modulation of neural activity associated with stimulus probability encoding. We used human electrophysiological recordings in healthy participants who were exposed to passive listening of sound sequences. Pure tones of different frequencies were delivered in successive trains of a variable number of repetitions, enabling the study of sequential repetition effects in the AEP. In the predictable timing condition, tones were delivered with isochronous interstimulus intervals; in the unpredictable timing condition, interstimulus intervals varied randomly. Our results show that unpredictable stimulus timing abolishes the early part of the repetition positivity, an AEP indexing auditory sensory memory trace formation, while leaving the later part (≈ >200 ms) unaffected. This suggests that timing predictability aids the propagation of repetition effects upstream the auditory pathway, most likely from association auditory cortex (including the planum temporale) toward primary auditory cortex (Heschl's gyrus) and beyond, as judged by the timing of AEP latencies. This outcome calls for attention to stimulation timing in future experiments regarding sensory memory trace formation in AEP measures and stimulus probability encoding in animal models.

Effects of Temperature on Sound Production and Auditory Abilities in the Striped Raphael Catfish Platydoras armatulus (Family Doradidae)

BackgroundSound production and hearing sensitivity of ectothermic animals are affected by the ambient temperature. This is the first study investigating the influence of temperature on both sound production and on hearing abilities in a fish species, namely the neotropical Striped Raphael catfish Platydoras armatulus.Methodology/Principal FindingsDoradid catfishes produce stridulation sounds by rubbing the pectoral spines in the shoulder girdle and drumming sounds by an elastic spring mechanism which vibrates the swimbladder. Eight fish were acclimated for at least three weeks to 22°, then to 30° and again to 22°C. Sounds were recorded in distress situations when fish were hand-held. The stridulation sounds became shorter at the higher temperature, whereas pulse number, maximum pulse period and sound pressure level did not change with temperature. The dominant frequency increased when the temperature was raised to 30°C and the minimum pulse period became longer when the temperature decreased again. The fundamental frequency of drumming sounds increased at the higher temperature. Using the auditory evoked potential (AEP) recording technique, the hearing thresholds were tested at six different frequencies from 0.1 to 4 kHz. The temporal resolution was determined by analyzing the minimum resolvable click period (0.3–5 ms). The hearing sensitivity was higher at the higher temperature and differences were more pronounced at higher frequencies. In general, latencies of AEPs in response to single clicks became shorter at the higher temperature, whereas temporal resolution in response to double-clicks did not change.Conclusions/SignificanceThese data indicate that sound characteristics as well as hearing abilities are affected by temperatures in fishes. Constraints imposed on hearing sensitivity at different temperatures cannot be compensated even by longer acclimation periods. These changes in sound production and detection suggest that acoustic orientation and communication are affected by temperature changes in the neotropical catfish P. armatulus.