Application of evoked response audiometry for specifying aberrant gamma oscillations in schizophrenia

Gamma oscillations probed using auditory steady-state response (ASSR) are promising clinical biomarkers that may give rise to novel therapeutic interventions for schizophrenia. Optimizing clinical settings for these biomarker-driven interventions will require a quick and easy assessment system for gamma oscillations in psychiatry. ASSR has been used in clinical otolaryngology for evoked response audiometry (ERA) in order to judge hearing loss by focusing on the phase-locked response detectability via an automated analysis system. Herein, a standard ERA system with 40- and 46-Hz ASSRs was applied to evaluate the brain pathophysiology of patients with schizophrenia. Both ASSRs in the ERA system showed excellent detectability regarding the phase-locked response in healthy subjects and sharply captured the deficits of the phase-locked response caused by aberrant gamma oscillations in individuals with schizophrenia. These findings demonstrate the capability of the ERA system to specify patients who have aberrant gamma oscillations. The ERA system may have a potential to serve as a real-world clinical medium for upcoming biomarker-driven therapeutics in psychiatry.

P300 Evoked Response Potentials Patterns in Different Complex Concussion Phenotypes

ObjectiveDetermine the utility of P300 Evoked Response Potentials (ERP) voltage patterns in predicting phenotypical sequelae of patients with complex concussions or Persistent Post Concussive Symptoms (PPCS).BackgroundERPs have been used to aid in the diagnosis of multiple neurologic disorders. They have also been recently used in the evaluation of concussions.Design/MethodsA retrospective study of 54 patients, 10–71 year (mean age 29.6 yrs), with PPCS were tested between 6 and 12 weeks post-injury using the standard oddball audio P300 ERP protocol with measures extracted including best central parietal P300 ERP. PPCS Phenotyping was completed in each patient using a standardized post-concussive questionnaire and Rivermead method for 5 primary phenotypes and mixed type.ResultsP300 average Voltage for the entire group was 11.6 mV. Overall, these were significantly lower than age-matched non concussed controls whose average voltage was 16.3 mV (p < 0.0001). Average P300 voltages for each phenotype: Cognition- 14.1 mV, Vestibular- 8.6 mV, Headache- 11.1 mV, Mood- 13.6 mV, Neck Pain- 9.6 mV, Visual- 9.8 mV, Mixed- 6.9 mV, Mixed and Vestibular phenotypes demonstrated the lowest average voltage potentials (6.9 mV and 8.6 mV respectively) which coincided with higher average symptom scores (70.5 and 54.5 respectively). Cognition and Mood demonstrated the highest average voltage potentials (14.1 mV and 13.6 nV respectively), which coincided with lower average symptom scores (40.3 and 48.7, respectively). Mood (13.6 mV) was the lowest average symptom score in the group at 40.3 and Mixed (6.9 mV) was highest at 70.5. Comparing phenotypes against one other, mixed vs mood (p = 0.03), cognition vs vestibular (p = 0.02), and cognition vs mixed (p = 0.009) showed statistical significance.ConclusionsP300 ERPs may help identify persistent abnormal complex concussion neurophysiology. ERPs can also potentially exhibit phenotype specific patterns and be a useful tool in helping differentiate more somatic/physiologic vs mood-based phenotypes. This can ultimately lead in the aid in diagnosis, prognosis, subtyping, and targeted phenotype management.

Application of otoacoustic emissions and brainstem evoked response audiometry in newborn hearing screening

<p class="abstract"><strong>Background: </strong>Newborn hearing screening was conducted in a tertiary care hospital in a step by step manner using otoacoustic emissions (OAE) and brainstem evoked response audiometry (BERA) and details were recorded.</p><p class="abstract"><strong>Methods:</strong> A prospective institutional based study was conducted. All the newborns born in the hospital over a period of 18 months from December 2018 to May 2020 were considered in the study. Healthy newborns were screened bedside within 24 hours of delivery and NICU (Neonatal Intensive Care Unit) babies were screened in the NICU. Handheld OAE apparatus was used as the initial screening tool. A total of 3 OAEs were done for babies with a “refer” result in the OAEs, which were done 1 month apart. Babies with a “refer” in the third OAE were subjected for BERA.</p><p class="abstract"><strong>Results:</strong> A total of 14226 babies were screened at 24-48 hours of birth. Among them, 13,069 babies passed the first OAE screening in both ears. Remaining babies were referred for further follow-up. After subsequent follow-ups and successive testing, 11 babies were found to have hearing loss, which was diagnosed within 4-5 months of the child’s birth.</p><p class="abstract"><strong>Conclusions: </strong>Universal newborn hearing screening is the need of the day. OAE is an effective screening tool for newborn hearing loss. When complemented by BERA, majority of congenitally deaf babies can be diagnosed at a very early age. This helps in early intervention.</p>

Study of brainstem auditory evoked response and biochemical markers in patients of alcohol use disorder

Objectives: Data available on brainstem auditory evoked response (BAER) and its correlation with biochemical parameters in patients of alcohol use disorder (AUD) in Indian population is scanty. Therefore, this study was undertaken to focus on the effects of AUD on BAER and liver enzymes. Materials and Methods: This case-control study included 40 males in the study group who had AUD and 40 healthy males in the control group in the age group of 20–60 years. The BAER was performed using octopus NCS/ EMG/EP (Clarity) machine. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase and serum bilirubin were estimated in all the subjects. Results: We observed a highly significant increase in the absolute latencies of waves III and V and interpeak latencies (IPL) I-III and I-V of BAER in the patients of AUD in this study. Significant increase in the liver enzymes and especially AST/ALT ratio of patients of AUD was seen which indicated towards subclinical alcoholic hepatitis. The latencies of waves of EPs (waves III, V, IPL I-III and IPL I-V) were positively correlated with the biochemical parameters and duration of AUD. Conclusion: Our findings indicated that AUD lead to the increase in brainstem transmission time and also lead to subclinical alcoholic hepatitis which is reflected by the increase in the liver enzymes. We concluded that chronic alcohol consumption affected the auditory pathways and delayed the auditory transmission time which was suggestive of possible demyelination of auditory tracts.

Comparative study of brainstem evoked response audiometry in diabetic patients and non-diabetic subjects to assess the involvement of central auditory pathway

<p><strong>Background: </strong>Diabetes mellitus (DM) which is prevalent in world is associated with sensorineural hearing loss. Brainstem evoked response audiometry (BERA) is a simple, non-invasive procedure to detect early impairment of acoustic nerve and auditory pathway. The present study is under taken to evaluate the impact of DM on BERA parameters. Aim of the study was to compare the BERA of diabetic patients to those of age and gender matched controls to assess the involvement of central auditory pathway.</p><p><strong>Methods</strong>: A cross sectional study was conducted on 35 diabetic patients, aged 35 to 55 years, who were on treatment for at least 2 years, and 35 age and sex matched control participants, were subjected for BERA at 70,80 and 90 dB. The waveforms, absolute latency of wave I, wave III, wave V and interwave/ inter peak latency of I-III, III-V and I-V were analyzed with respect to both groups.</p><p><strong>Results</strong>: The absolute latency of wave III and wave V, interpeak/ interwave latency of I-III, interpeak/ interwave latency of I-V, III-V and absolute latency of wave V were highly significant at corresponding tested stimuli in the diabetic group compared to the control group.</p><p><strong>Conclusions</strong>: Early involvement of central auditory pathway in diabetic patients, can be detected with fair accuracy with auditory evoked potential studies; if done on a regular basis warrants meticulous glycemic control and prevents further damage.</p>

Characterizing the short-latency evoked response to intracortical microstimulation across a multi-electrode array

Objective: Persons with tetraplegia can use brain-machine interfaces to make visually guided reaches with robotic arms. Without somatosensory feedback, these movements will likely be slow and imprecise, like those of persons who retain movement but have lost proprioception. Intracortical microstimulation (ICMS) has promise for providing artificial somatosensory feedback. If ICMS can mimic naturally occurring neural activity, afferent interfaces may be more informative and easier to learn than interfaces that evoke unnaturalistic activity. To develop such biomimetic stimulation patterns, it is important to characterize the responses of neurons to ICMS. Approach: Using a Utah multi-electrode array, we recorded activity evoked by single pulses, and short (~0.2 s) and long (~4 s) trains of ICMS at a wide range of amplitudes and frequencies. As the electrical artifact caused by ICMS typically prevents recording for many milliseconds, we deployed a custom rapid-recovery amplifier with nonlinear gain to limit signal saturation on the stimulated electrode. Across all electrodes after stimulation, we removed the remaining slow return to baseline with acausal high-pass filtering of time-reversed recordings. With these techniques, we could record ~0.7 ms after stimulation offset even on the stimulated electrode. Main results: We recorded likely transsynaptically-evoked activity as early as ~0.7 ms after single pulses of stimulation that was immediately followed by suppressed neural activity lasting 10-150 ms. Instead of this long-lasting inhibition, neurons increased their firing rates for ~100 ms after trains. During long trains, the evoked response on the stimulated electrode decayed rapidly while the response was maintained on non-stimulated channels. Significance: The detailed description of the spatial and temporal response to ICMS can be used to better interpret results from experiments that probe circuit connectivity or function of cortical areas. These results can also contribute to the design of stimulation patterns to improve afferent interfaces for artificial sensory feedback.