The Role of the SLP and Assistive Technology in Life Care Planning
Roger O. Weed, Debra E. Berens in Life Care Planning and Case Management Handbook, 2018
Evoked potentials refer to normal electrical activities of the central nervous system that occur in response to specific and controlled sensory stimulation. Whether the sensory stimulus is visual, somatosensory, or auditory, evoked brain responses are recorded using electrodes referred to the spinal cord, brain stem, and scalp. Visual evoked potentials are used to evaluate electrical conduction along the optic nerve, optic tract, lateral geniculate, optic radiations, and visual cortex. Somatosensory evoked responses are elicited by simulation of contralateral peripheral nerves. Clinical conditions in which somatosensory evoked potentials are of diagnostic value include multiple sclerosis, brain injuries, brain death, posterior column spinal cord lesions, and lesions of the peripheral nerves. Evoked response audiometry is the electrophysiological assessment of auditory functions. It measures changes in neural activity that occur in the auditory acoustic stimuli. Evoked response audiometry is used for assessing the functioning of the auditory neural pathway to predict hearing thresholds in patient populations that are difficult to test. In evoked response audiometry, the most commonly measured responses are the auditory brain stem responses (brain stem auditory evoked response).
Giga-Ohm High-Impedance FET Input Amplifiers for Dry Electrode Biosensor Circuits and Systems
Iniewski Krzysztof in Integrated Microsystems, 2017
The serial comparison experiment involved recording a visual-evoked response. The visual-evoked potential is a transient response elicited by specific visual stimuli. It is used in combination with continuous EEG recordings to document the integrity of neural pathways and does not require a motor response. An example of such elicited responses is the FVEP. Despite the fact that FVEPs are very variable, they are often used in general medical practice to assess the eyes to cortex pathway integrity [48,49]. In this experiment, we compare the test EEG system configured with dry electrodes with a reference system referred to as the g.BSamp system which used standard brass golden cup electrodes. The g.BSamp system is in use at the biomedical lab at the University of Naples. Once again, as previously mentioned, both systems were first tested using a signal generator. Also, as previously mentioned, the EEG signals recorded with both systems were filtered using a software band-pass filter, 0.05–100 Hz (50th-order FIR) and an additional 50th-order IIR notch filter at 50 Hz was applied.
Hearing Aids for the Pediatric Population
Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm in Advances in Audiology and Hearing Science, 2020
The auditory evoked potentials are waveform representing activity generated at several levels of the central auditory nervous system in response to an acoustic stimulus. They are classified according to latency that is the interval of time between the presentation of the sound stimulus and the generation of waveforms. Evoked potentials are essentially classified into three groups: Short-latency potentials occurring in the first 10–12 ms; middle-latency potentials occurring between 12 and 50 ms; and long-latency potentials, also called cortical auditory evoked potentials (CAEPs) occurring between 50 and 600 ms (Hall, 2007). The most common exogenous CAEPs are P1, N1, P2. These components provide information concerning the arrival of sound information to the auditory cortex (Näätänen and Picton, 1987). For an adult, the P1 wave is characterized by a small positive peak, with a latency value of approximately 50 ms; then a significant negative peak (N1) at 100 ms and, lastly, a second large positive peak (P2) occurring at about 200 ms. In infants and young children, the evoked response is dominated by a large positivity (P1) at 100–250 milliseconds followed by late negativity at 250–400 ms (Guilley et al., 2005). CAEPs can be evoked using auditory stimuli that are relatively long in duration and can be reliably recorded in infants and young children.
Developing therapeutic strategies to promote myelin repair in multiple sclerosis
Published in Expert Review of Neurotherapeutics, 2019
Laura E. Baldassari, Jenny Feng, Benjamin L.L. Clayton, Se-Hong Oh, Ken Sakaie, Paul J. Tesar, Yanming Wang, Jeffrey A. Cohen
Evoked potentials are objective, noninvasive, in vivo electrophysiological measures that assess the function of the CNS sensory and motor pathways. Many of the symptoms in MS result from abnormal nerve impulse generation and axonal conduction resulting from demyelination [73]. Therefore, evoked potentials have been used as outcome measures in several recent remyelination trials. After standardized repetitive stimulus administration, the amplitude and latency of the resultant summated response in the corresponding tract can be quantified. Reduced amplitude reflects a decreased number of functional axons. Axonal demyelination results in both conduction delay (increasing latency) and block (reducing amplitude). Several evoked potential modalities can be measured in MS. VEPs assess functional integrity of the afferent visual pathways from the optic nerve to occipital cortex. Somatosensory evoked potentials (SSEPs) assess functional integrity of the sensory pathways from the upper or lower limbs to parietal cortex. Brainstem auditory evoked potentials assess conduction from the cochlea to temporal cortex. Motor evoked potentials (MEPs) assess motor pathways from motor cortex to target muscles.
Transverse myelitis associated with primary biliary cirrhosis: clinical, laboratory, and neuroradiological features
Published in International Journal of Neuroscience, 2022
Mangsuo Zhao, Mingjie Zhang, Shimei Zhou, Bingxin Shi, Yan Wei, Fangjie Huang, Jing Wang, Jingfeng Huang, Liyan Qiao
On laboratory workup, the results of routine blood tests, urine test, stool analysis, and measurements of liver, renal, and thyroid functions, homocysteine, folic acid, and vitamin B12 levels, and the erythrocyte sedimentation rate (ESR) were all within the normal limits. Anti-nuclear (ANA), anti-double-stranded DNA, anti-extractable nuclear antigen, and anti-neutrophil cytoplasmic antibodies were not found in the serum. The results of routine and biochemical tests of the cerebrospinal fluid (CSF) were normal. Oligoclonal bands (OB) were positive. Anti-AQP4 IgG was not detected in serum or CSF. Serum and CSF were negative for the following antibodies: anti-N-methyl-d-aspartic acid receptor, anti-contactin-associated protein-like 2, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1 and 2, anti-leucine-rich glioma-inactivated 1, anti-gamma-aminobutyric acid B receptor, and anti-dipeptidyl-peptidase-like protein 6 for autoimmune encephalitis. As biomarkers of paraneoplastic syndromes, Hu (anti-neuronal nuclear antibody 1), Yo (Purkinje cell autoantibody, PCA1), Ri (anti-neuronal nuclear antibody 2), Ma2, CV2/CRMP5, and amphiphysin were not detected in serum or CSF. Magnetic resonance imaging (MRI) studies of the brain and spinal cord were performed. Abnormal enhancement of the spinal cord was observed at T8–T9, suggestive of incomplete TM (Figure 1). Brain MRI showed no obvious abnormalities. Visual evoked potential and brainstem auditory evoked potential were within the respective normal ranges. The P40 wave of the somatosensory evoked potential disappeared bilaterally.
Cortical auditory evoked potentials in cochlear implant listeners via single electrode stimulation in relation to speech perception
Published in International Journal of Audiology, 2018
Tim Liebscher, Katrin Alberter, Ulrich Hoppe
Many individuals who suffer from severe to profound hearing loss can restore speech recognition in quiet and to some degree in noisy situations with a cochlear implant (CI). Performance outcomes are typically evaluated with speech recognition tests in different listening environments, while objective tests can provide helpful information from auditory nerve fibres. A number of paradigms for electrophysiological measurements have been developed to assess the functional integrity of the auditory nerve, auditory brainstem processing and cortical processing in CI recipients (Kileny 2007). Cortical evoked potentials are assumed to provide the auditory perception of the electrical stimuli, since the auditory cortex processes the cochlea’s signals. Hence, by measuring cortical evoked action potentials (CAEPs) at the “final stage” of the auditory pathway, we can quantify acoustic processes.
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