Auditory Evoked Potentials Research Articles

Relationship between Loudness Dependence of Auditory-evoked Potentials and Suicidality.

: Serotonin concentration is associated with suicide in patients with major depressive disorder. Loudness dependence of auditory-evoked potentials (LDAEPs), a representative neurophysiological indicator, is related to serotonin activity. Therefore, this study aimed to investigate the relationship between LDAEPs and suicidal ideation, suicide attempts, and the severity of depression. : We evaluated the scalp N1, P2, and N1/P2 LDAEPs along with standardized low-resolution brain electromagnetic tomography (sLORETA)-localized N1, P2, and N1/P2 LDAEPs of 221 patients with major depressive disorder. The demographic and clinical data of the patients, including data on suicidal ideation and previous suicide attempts, were obtained from clinical interviews and medical records. The severity of depression was assessed using the Beck Depression Inventory and Hamilton Depression Rating Scale, whereas suicidal ideation was evaluated using the Beck Scale for Suicidal Ideation (BSS). : The total BSS score was associated with low N1/P2 LDAEP (p = 0.045), whereas P2 sLORETA-LDAEP was associated with lower previous suicide attempts (p = 0.043). In addition, suicide attempt was correlated with an elevated P2 left sLORETA-LDAEP (coefficient = 4.638, p = 0.038). : These findings suggest that suicidal ideation is associated with decreased LDAEP, whereas suicide attempt is associated with increased LDAEP.

Liquid Metal-Based Electrode Array for Neural Signal Recording.

Neural electrodes are core devices for research in neuroscience, neurological diseases, and neural-machine interfacing. They build a bridge between the cerebral nervous system and electronic devices. Most of the neural electrodes in use are based on rigid materials that differ significantly from biological neural tissue in flexibility and tensile properties. In this study, a liquid-metal (LM) -based 20-channel neural electrode array with a platinum metal (Pt) encapsulation material was developed by microfabrication technology. The in vitro experiments demonstrated that the electrode has stable electrical properties and excellent mechanical properties such as flexibility and bending, which allows the electrode to form conformal contact with the skull. The in vivo experiments also recorded electroencephalographic signals using the LM-based electrode from a rat under low-flow or deep anesthesia, including the auditory-evoked potentials triggered by sound stimulation. The auditory-activated cortical area was analyzed using source localization technique. These results indicate that this 20-channel LM-based neural electrode array satisfies the demands of brain signal acquisition and provides high-quality-electroencephalogram (EEG) signals that support source localization analysis.

Brain-derived neurotrophic factor and matrix metalloproteinase-9 activity during rehabilitation therapy of schizophrenic patients - environmental pilot study.

The aim of the study was to evaluate the peripheral level of brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) during rehabilitation therapy, combined with neurofeedback in schizophrenic patients, and to investigate whether these biomarkers are related to psychopathological symptoms, changes in auditory evoked potentials (AEPs), and quantitative EEG (QEEGs) mapping. The study involved two groups of patients diagnosed with paranoid schizophrenia in partial remission who participated in a 3-month structured rehabilitation programme combined with neurofeedback (REH group) and a standard support group (CON group). The following parameters were assessed: BDNF and MMP-9 serum levels, AEPs, QEEGs, and psychopathological symptoms (PANSS). A clinical improvement within the 3-month rehabilitation therapy course was correlated with the increase in BDNF and MMP-9 serum level. Despite the increase in BDNF and MMP-9 during the 3-month rehabilitation therapy, it was not possible to demonstrate any strong and significant correlation between the 2 examined neuropeptides. During the 3-month rehabilitation therapy, the theta waveform share reduction in QEEG, P50 latency reduction and amplitude increase correlated with PANSS Total and MMP-9 results. All clinical (PANSS Positive, Negative, General, Total) and biochemical results (BDNF, MMP-9) of the REH group changed significantly over the 3-month period. Positive symptoms improved only in the CON group.

A cross-sectional study of severe acute malnutrition impact on auditory evoked potentials in children age 6–59 months

Background: Malnutrition is a public health concern in India. According to NFHS-5, the number of children under 5 years who are stunted (less height-for-age) and underweight (less weight-for-age) in India, are 35.5% and 32.1%, respectively. Many researchers reported that malnutrition affects myelination and neural maturation of the auditory brainstem pathway. Aims and Objectives: In this study, auditory evoked potential (AEP) parameters were studied in severly acute malnutrition (SAM) children of 6 months to <5 years of age. Materials and Methods: Fifty children, with severely malnourished (Their weighted age was 51–60% of the expected weight, and height for age <85% of the expected height) and 50 healthy children (with weight >80% of expected with normal height for their age), aged 6–59 months were included in the study. The parameters of AEPs were recorded using RMS-EMG EP MARK II, a 4-channel machine. Results: In our study, 30 (60%) males and 20 (40%) females had severe acute malnutrition. There were significant differences in the mean latencies of the waves I to V and the mean interpeak latencies (IPLs) of the waves I-III and I-V on the right and left ears between the study and control groups (P<0.05). The mean IPLs of I-III and I-V on the right side were found to be longer in the SAM group than in the control group (P<0.05. While the mean absolute peak latencies of wave, I found prolonged on both ears in the children with SAM (P<0.05). Conclusion: In the present study, severely acute malnourished children showed changes in AEPs characterized by absolute wave prolonged latencies and interpeak intervals compared with normally nourished children.

Electrophysiological Testing for an Auditory Processing Disorder and Reading Performance in 54 School Students Aged Between 8 and 12 years.

BACKGROUND Learning to read and write depends on the effective functioning of various sensory systems, including the auditory system. Auditory information processing involves behavioral and electrophysiological processes. Electrophysiological procedures are used to investigate activity in the auditory pathway in response to sound stimuli, and the associated cortical activity in discrimination, integration, and attention. The study evaluated electrophysiological testing for an auditory processing disorder and reading performance in 54 school students aged between 8 and 12 years. MATERIAL AND METHODS The study involved 54 public school students aged between 8 and 12 years, who were divided into a study group and control group. All children underwent basic audiological assessment, rating of reading and writing ability, non-verbal intelligence, auditory brainstem response, long-latency auditory-evoked potentials (LLAEP), frequency following responses (FFR), and auditory training (AT). RESULTS The basic audiological evaluation showed a statistically significant difference between groups only for the frequency of 6 kHz. The LLAEP response had a statistically significant difference between groups for N1 latency, P300 latency, and amplitude. Finally, there was a statistically significant difference between pre-AT and post-AT to LLAEP for latencies of P2, N2, and P300 and amplitudes of N2 and P300, and to FFR for latency of wave C. CONCLUSIONS This study showed that electrophysiological tests are sensitive tools for identifying deficits in the auditory pathway. Moreover, latency measures can detect improvements from an auditory training program. In this way, an auditory intervention program might help children with reading and writing difficulties.

Hearing in catfishes: 200 years of research.

Ernst Weber stated in 1819, based on dissections, that the swimbladder in the European wels (Silurus glanis, Siluridae) and related cyprinids serves as an eardrum and that the ossicles connecting it to the inner ear function as hearing ossicles similar to mammals. In the early 20th century, K. von Frisch showed experimentally that catfishes and cyprinids (otophysines) indeed hear excellently compared to fish taxa lacking auxiliary hearing structures (ossicles, eardrums). Knowledge on hearing in catfishes progressed in particular in the 21st century. Currently, hearing abilities (audiograms) are known in 28 species out of 13 families. Recent ontogenetic and comparative studies revealed that the ability to detect sounds of low-level and high frequencies (4-6 kHz) depends on the development of Weberian ossicles. Species with a higher number of ossicles and larger bladders hear better at higher frequencies (>1 kHz). Hearing sensitivities are furthermore affected by ecological factors. Rising temperatures increase, whereas various noise regimes decrease hearing. Exposure to high-noise levels (>150 dB) for hours result in temporary thresholds shifts (TTS) and recovery of hearing after several days. Low-noise levels reduce hearing abilities due to masking without a TTS. Furthermore, auditory evoked potential (AEP) experiments reveal that the temporal patterns of fish-produced pulsed stridulation and drumming sounds are represented in their auditory pathways, indicating that catfishes are able to extract important information for acoustic communication. Further research should concentrate on inner ears to determine whether the diversity in swimbladders and ossicles is paralleled in the inner ear fine structure.

889 Significance of Cortico-Bulbar Motor Evoked Potential (CoMEP) Monitoring in Vestibular Schwannoma Surgery for Prediction of Postoperative Facial Nerve Palsy

INTRODUCTION: Direct facial nerve stimulation during vestibular schwannoma surgery (VSS) allows preservation of the nerve in its continuity. However, prognostication of post- operative nerve function remains challinging. METHODS: In total, 51 patients (median age 52yrs; 19-84) with unilateral VS (median size 20mm;10-50) were included. Intraoperative neuromonitoring consisted of auditory evoked potentials (AEPs), direct facial nerve stimulation and CoMEPs. An anodal stimulation via subdermal corkscrew electrodes on position C3 or C4 and a cathode near Cz with a train of 6 pulses, each with a duration ono 500us, at a frequency of 5000 Hz and an interstimulus-interval of 2 ms was used. RESULTS: Complete resection was achieved in >90% of patients. Preoperative hearing was preserved in 78% (40/51) patients and postoperative serviceable hearing was preserved in 35% (18/49) patients and was closely related to preserved wave V of the AEPs. Additionally, MEPs were successfully monitored in every patient for the entire duration of the surgery. In 16% of the patients, more than 50% reduction of MEP baseline amplitude was recorded, correlating directly with moderate to severe postoperative facial palsy (House Brackman 3-5). No facial palsy without MEP amplitude reduction was observed. During 6 months FU, recovery of 1-2 HB Grades was observed in all cases. All patients with intraoperative MEP amplitude reduction had significant larger VS than patients without MEP amplitude reduction (27 vs 22 mm, p = 0.02) CONCLUSIONS: In addition to direct facial nerve stimulation, intraoperative CoMEP monitoring during VSS seems to be of high significance and value for intraoperative facial nerve preservation and prognosis estimation of postoperative short- and long-term facial palsy.

The Effect of Different Stimulation Rates on Brainstem Auditory-Evoked-Potential Responses.

Introduction Auditory-evoked potentials are influenced by several factors, including polarity, filter, stimulus intensity and stimulation rate. The presentation of higher rates of stimuli per second enables the collection of a greater number of responses in a given period of time, promoting a shorter testing time; however, the collected recordings are subject to changes related to wave morphology. Objectives To compare the brainstem auditory-evoked-potential responses with click stimulus with the most commonly used stimulation rates in the clinical practice. Methods The present cross-sectional analytical study was performed with fifteen participants of both genders and normal hearing thresholds. The brainstem auditory-evoked potential was performed at four different stimulation rates (21.1, 26.7, and 27.7 stimuli/s, and a rate determined based on a mathematical calculation using the a measurement of the transmission frequency of the power grid at the time of the examination). Results We observed that the rate of 21.1 stimuli/s showed the highest amplitudes for waves I, III, and V when compared with the other rates. The rate of 26.7 stimuli/s, when compared with 27.7 stimuli/s, showed a higher amplitude for wave V. The latency if wave V was significantly lower with the rate of 21.1 stimuli/s than with 27.7 stimuli/s. Conclusions The stimulation rate interferes with wave latencies and amplitudes; its decrease from 27.7 to 21.1 stimuli/s decreases the latency of wave V and increases the amplitues and improves the morphology of waves I, III and V. In addition, we found evidence that suggests an improvement in the visualization of wave III by adjusting the stimulation rate based on a measurement of the local transmission frequency of the power grid.

Endocannabinergic modulation of central serotonergic activity in healthy human volunteers

BackgroundThe serotonergic and the endocannabinoid system are involved in the etiology of depression. Depressive patients exhibit low serotonergic activity and decreased level of the endocannabinoids anandamide (AEA) and 2-arachidonylglycerol (2AG). Since the cannabinoid (CB) 1 receptor is activated by endogenous ligands such as AEA and 2AG, whose concentration are controlled by the fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase, respectively, we investigated the effects on serotonergic utilization. In this study, we investigated the impact of the rs1049353 single-nucleotide polymorphism (SNP) of the cannabinoid receptor 1 (CNR1) gene, which codes the endocannabinoid CB1 receptor, and the rs324420 SNP of the FAAH gene on the serotonergic and endocannabinoid system in 59 healthy volunteers.MethodsSerotonergic activity was measured by loudness dependence of auditory-evoked potentials (LDAEP). Plasma concentrations of AEA, 2AG and its inactive isomer 1AG were determined by mass spectrometry. Genotyping of two SNPs (rs1049353, rs344420) was conducted by polymerase chain reaction (PCR) and differential enzymatic analysis with the PCR restriction fragment length polymorphism method.ResultsGenotype distributions by serotonergic activity or endocannabinoid concentration showed no differences. However, after detailed consideration of the CNR1-A-allele-carriers, a reduced AEA (A-allele-carrier M = 0.66, SD = 0.24; GG genotype M = 0.72, SD = 0.24) and 2AG (A-allele-carriers M = 0.70, SD = 0.33; GG genotype M = 1.03, SD = 0.83) plasma concentration and an association between the serotonergic activity and the concentrations of AEA and 2AG has been observed.ConclusionsOur results suggest that carriers of the CNR1-A allele may be more susceptible to developing depression.

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.

Learning to detect auditory signals in noise: Active top-down selection and stable change in signal representations.

Training can improve detection of auditory signals in noise. This learning could potentially occur through active top-down selection mechanisms or stable changes in signal representations. Here, participants were trained and tested (pretest vs. posttest design) on abilities to detect pure tone signals in noise. Auditory evoked potentials (AEPs) to tones were gathered under dichotic listening conditions where participants attended to nontonal stimuli in the opposite ear. Improvements in detection sensitivity were observable regardless of tested tone frequency. This was true in generalization between 861 Hz and 1058-Hz tones (Experiment 1a), and when testing a frequency range > 1 octave (Experiment 2). Such learning was not apparent without training (Experiment 1b). In contrast to behavior, AEP amplitude increases from pre- to posttest were partially specific to trained tone frequencies, even when selective attention was diverted to the opposite ear of tone presentation. Placed in the context of previous work, results suggest that changes in active top-down selection mechanisms and stable signal representations both play a role in auditory detection learning. The mismatch between AEP and behavioral effects suggests a need to consider how these different learning processes can impact detection performance in the variety of listening scenarios a listener may face. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

EEG study of attention on an auditory target detection task in dolphins and humans

How do dolphins attend to echos and ignore background noise? Is the process similar to how humans attend to conversations in a crowded room? Studies of human selective attention have highlighted endogenous brain processes modulating the magnitude of early responses to sounds in auditory evoked potentials (AEPs), yet these rely on task-specific instructions difficult to employ in animal studies. We trained an adult male dolphin (Tursiops truncatus) to attend to a stream of rapidly presented tones, and provide a whistle response to a “target” tone while withholding responses to “background” tones in an amplitude discrimination task. The background sounds were designed to function as a tonal mismatch negativity paradigm with two frequencies: a standard tone presented 80% of the time, and a deviant presented 20% of the time. Depending on condition, the target could be the same frequency as the standard or the deviant. We observed an enhanced AEP response to a deviant of the same frequency as the target, while the AEP response to the standard-target condition was reduced. This was not predicted by previous human experiments, and we are currently following up with a pilot a human task modeled after the dolphin implicit target detection task.

“Nacho”—A willing and adventurous dolphin with diverse research accomplishments

The bottlenose dolphin, WEN (also known as “Nacho”), worked in the swimmer interdiction system of the United States Navy Marine Mammal Program (MMP) before being transferred to MMP research in the mid-2000s. During his time away from systems work, WEN participated in diverse research projects that benefited our understanding of dolphin hearing, bioacoustics, and auditory physiology. His contributions include several ground-breaking studies: (1) he demonstrated that dolphins could remain vigilant at an acoustic target detection task for days without rest or performance decrement, (2) participated in the first study matching dolphin structural (MRI) and functional imaging (SPECT, PET) with an emphasis on the anatomy of sound-reception and transmission, (3) performed open-ocean work to investigate the target strength of dolphins at depth and the potential for intravascular bubble formation during diving, (4) was instrumental in the development of auditory evoked potential (AEP) methods for use in MMP dolphins, and (5) performed the first direct comparison of AEP and behavioral thresholds to the same acoustic stimulus in a marine mammal. Not only have WEN’s contributions significantly advanced marine mammal science, but with his return to systems work, he continues to contribute to the national security of the United States.

Evidence for rapid divergence of sensory systems between Texas populations of the Mexican tetra (Astyanax mexicanus)

Population divergence is often quantified using phenotypic variation. However, because sensory abilities are more difficult to discern, we have little information on the plasticity and rate of sensory change between different environments. The Mexican tetra (Astyanax mexicanus) is a fish distributed throughout Southern Texas and Northern Mexico and has evolved troglomorphic phenotypes, such as vestigial eyes and reduced pigmentation, when surface ancestors invaded caves in the past several hundred thousand years. In the early 1900s, surface A. mexicanus were introduced to the karstic Edwards-Trinity Aquifer in Texas. Subsequent cave colonization of subterranean environments resulted in fish with phenotypic and behavioral divergence from their surface counterparts, allowing examination of how new environments lead to sensory changes. We hypothesized that recently introduced cave populations would be more sensitive to light and sound when compared to their surface counterparts. We quantified divergence using auditory evoked potentials (AEPs) and particle acceleration levels (PALs) to measure differences in sound sensitivity, and electroretinography (ERGs) to measure light sensitivity. We also compared these results to measurements taken from native populations and lab-born individuals of the introduced populations. Honey Creek Cave fish were significantly more sensitive than proximate Honey Creek surface fish to sound pressure levels between 0.6 and 0.8 kHz and particle acceleration levels between 0.4 and 0.8 kHz. Pairwise differences were found between San Antonio Zoo surface and the facultative subterranean San Pedro Springs and Blue Hole populations, which exhibited more sensitivity to particle acceleration levels between 0.5 and 0.7 kHz. Electroretinography results indicate no significant differences between populations, although Honey Creek Cave fish may be trending toward reduced visual sensitivity. Auditory thresholds between wild-caught and lab-raised populations of recently invaded fish show significant differences in sensitivity, suggesting that these traits are plastic. Collectively, while these results may point to the rapid divergence of A. mexicanus in cave habitats, it also highlights the responsive plasticity of A. mexicanus auditory system to disparate environments.

Multi-channel and multi-harmonic analysis of Auditory Steady-State Response detection

The Auditory Steady-State Response (ASSR) is a type of auditory evoked potential (AEP) generated in the auditory system that can be automatically detected by means of objective response detectors (ORDs). ASSRs are usually registered on the scalp using electroencephalography (EEG). ORD are univariate techniques, i.e. only uses one data channel. However, techniques involving more than one channel – multi-channel objective response detectors (MORDs) - have been showing higher detection rate (DR) when compared to ORD techniques. When ASSR is evoked by amplitude stimuli, the responses could be detected by analyzing the modulation frequencies and their harmonics. Despite this, ORD techniques are traditionally applied only in its first harmonic. This approach is known as one-sample test. The q-sample tests, however, considers harmonics beyond the first. Thus, this work proposes and evaluates the use of q-sample tests using a combination of multiple EEG channels and multiple harmonics of the stimulation frequencies and compare them with traditional one-sample tests. The database used consists of EEG channels from 24 volunteers with normal auditory threshold collected following a binaural stimulation protocol by amplitude modulated (AM) tone with modulating frequencies near 80 Hz. The best q-sample MORD result showed an increase in DR of 45.25% when compared with the best one-sample ORD test. Thus, it is recommended to use multiple channels and multiple harmonics, whenever available.

Latencies of click-evoked auditory responses in a harbor porpoise exceed the time interval between subsequent echolocation clicks.

Most auditory evoked potential (AEP) studies in echolocating toothed whales measure neural responses to outgoing clicks and returning echoes using short-latency auditory brainstem responses (ABRs) arising a few ms after acoustic stimuli. However, little is known about longer-latency cortical AEPs despite their relevance for understanding echo processing and auditory stream segregation. Here, we used a non-invasive AEP setup with low click repetition rates on a trained harbor porpoise to test the long-standing hypothesis that echo information from distant targets is completely processed before the next click is emitted. We reject this hypothesis by finding reliable click-related AEP peaks with latencies of 90 and 160 ms, which are longer than 99% of click intervals used by echolocating porpoises, demonstrating that some higher-order echo processing continues well after the next click emission even during slow clicking. We propose that some of the echo information, such as range to evasive prey, is used to guide vocal-motor responses within 50-100 ms, but that information used for discrimination and auditory scene analysis is processed more slowly, integrating information over many click-echo pairs. We conclude by showing theoretically that the identified long-latency AEPs may enable hearing sensitivity measurements at frequencies ten times lower than current ABR methods.

Cetacean evoked potential audiometry by stranding networks enables more rapid accumulation of hearing information in stranded odontocetes

Knowing the hearing range and sensitivity of a marine mammal is fundamental to determining its potential for being impacted by ocean noise. Enabling stranding responders to perform hearing tests on stranded odontocetes is the most likely means by which most odontocete species will be tested and by which population-level variability in hearing will be determined. A portable auditory evoked potential (AEP) system was modified for use by stranding response teams and optimised to test odontocete hearing. Stranding responders were trained on the system and deployed it to strandings from 2010–2013. Eighteen partial or complete audiograms from common dolphins (n = 15) and Atlantic white-sided dolphins (n = 3) were obtained. Both species demonstrated typically delphinid audiograms with upper frequency limits of hearing between 113–160kHz; however, the region of best sensitivity in the Atlantic white-sided dolphin (28–56kHz) was 18–28 dB less sensitive than that of the common dolphin. A single common dolphin presented with severe hearing loss consistent with presbycusis in delphinids, but with undefined etiology. The number of audiograms obtained during the study greatly increases our knowledge about hearing in these species, neither of which are common to managed care facilities. In the case of the common dolphin, the number of animals tested allows a first estimate of population-level variability. Continued use of AEP systems by stranding responders will expedite the collection of audiometric information for previously untested species and permit sufficient sample sizes to determine population-level variability in the hearing of tested species.

Auditory Fine-Tuned Suppressor of TMS-Clicks (TMS-Click AFTS): A Novel, Perceptually Driven/Tuned Approach for the Reduction in AEP Artifacts in TMS-EEG Studies

TMS contaminates concurrent EEG recordings with Auditory Evoked Potentials (AEPs), which are caused by the perceived impulsive acoustic noise of the TMS coils. We hereby introduce a novel and perceptually motivated/tuned method for the suppression of auditory evoked EEG artifacts of rTMS under the name of “Auditory Fine-Tuned Suppressor of TMS-Clicks” (TMS-click AFTS). The proposed method is based on the deployment of a psychophysically-matched wide-band noise (WBN) masking stimulus, whose parametric synthesis and presentation are based upon adaptive psychophysical optimization. The masking stimulus is constructed individually for each patient/subject, thus facilitating aspects of precision medicine. A specially designed automation software is used for the realization of an adaptive procedure for optimal parameterization of masking noise level, optimizing both the subject’s comfort and the degree of AEP reduction. The proposed adaptive procedure also takes into account the combined effect of TMS intensity level and can as well account for any possibly available subject’s hearing acuity data. To assess the efficacy of the proposed method in reducing the acoustic effects of TMS, we performed TMS-EEG recordings with a 60 channel TMS-compatible EEG system in a cohort of healthy subjects (n = 10) and patients with epilepsy (n = 10) under four conditions (i.e., resting EEG with and without acoustic mask and sham TMS-EEG with and without acoustic mask at various stimulus intensity levels). The proposed approach shows promising results in terms of efficiency of AEP suppression and subject’s comfort and warrants further investigation in research and clinical settings.

Patološki nalaz slušnih evociranih potencijala kod pacijenata sa hipoplazijom vertebralne arterije udruženom sa moždanim udarom posteriorne cirkulacije

The aim of the paper was to determine clinical significance of pathological finding and characteristics of auditory evoked potentials (AEP) in patients with posterior circulation stroke caused by vertebral artery hypoplasia (VAH). The study enrolled 71 patients, 31 of them had posterior circulation stroke. The results of the examinations showed that pathological AEP finding was statistically significantly correlated with posterior circulation stroke (PCS) finding. Changes in AEP amplitude presented a prominent feature of stroke caused by vertebral artery hypoplasia and require further clinical investigations.

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.