-
JPMA. the Journal of the Pakistan... Sep 2021Evoked Potentials are electrical potentials that occur in a group of neurons in response to stimulation of a sensory organ which can be recorded by surface electrodes.... (Review)
Review
Evoked Potentials are electrical potentials that occur in a group of neurons in response to stimulation of a sensory organ which can be recorded by surface electrodes. Testing evoked potentials is useful in assessing the integrity of neuronal pathways both at sensory and motor levels of neural control. Early auditory evoked potentials include cochlear and brainstem auditory-evoked potentials, popularly known as electrocochleogram, and auditory brainstem response. Evoked potential audiometry is a neurophysiogical test to assess auditory pathway function in response to auditory stimuli. Auditory brainstem response mainly assesses brainstem functions and integrity. These evoked potentials are widely used for assessment of the cochlear functions, auditory nerve and the brainstem. Most common indications for auditory evoked potentials include routine newborn hearing screening for auditory pathway deficits, detecting retrocochlear pathologies, intraoperative and intensive care monitoring, frequency-related measurement of auditory sensitivity and for diagnosing some demyelinating disorders in initial stages. The current narrative review was planned to highlight auditory brainstem response recording's basic principles, uses and methods of interpretation in health and disease phases.
Topics: Brain Stem; Cochlea; Cochlear Nerve; Evoked Potentials, Auditory, Brain Stem
PubMed: 34580520
DOI: 10.47391/JPMA.03-432 -
Neuron Jul 2007Transcranial magnetic stimulation (TMS) is a technique for noninvasive stimulation of the human brain. Stimulation is produced by generating a brief, high-intensity... (Review)
Review
Transcranial magnetic stimulation (TMS) is a technique for noninvasive stimulation of the human brain. Stimulation is produced by generating a brief, high-intensity magnetic field by passing a brief electric current through a magnetic coil. The field can excite or inhibit a small area of brain below the coil. All parts of the brain just beneath the skull can be influenced, but most studies have been of the motor cortex where a focal muscle twitch can be produced, called the motor-evoked potential. The technique can be used to map brain function and explore the excitability of different regions. Brief interference has allowed mapping of many sensory, motor, and cognitive functions. TMS has some clinical utility, and, because it can influence brain function if delivered repetitively, it is being developed for various therapeutic purposes.
Topics: Brain Mapping; Cerebral Cortex; Electric Stimulation; Evoked Potentials; Humans; Motor Cortex; Transcranial Magnetic Stimulation
PubMed: 17640522
DOI: 10.1016/j.neuron.2007.06.026 -
Clinical Neurophysiology : Official... Oct 2007The empirical and theoretical development of the P300 event-related brain potential (ERP) is reviewed by considering factors that contribute to its amplitude, latency,... (Review)
Review
The empirical and theoretical development of the P300 event-related brain potential (ERP) is reviewed by considering factors that contribute to its amplitude, latency, and general characteristics. The neuropsychological origins of the P3a and P3b subcomponents are detailed, and how target/standard discrimination difficulty modulates scalp topography is discussed. The neural loci of P3a and P3b generation are outlined, and a cognitive model is proffered: P3a originates from stimulus-driven frontal attention mechanisms during task processing, whereas P3b originates from temporal-parietal activity associated with attention and appears related to subsequent memory processing. Neurotransmitter actions associating P3a to frontal/dopaminergic and P3b to parietal/norepinephrine pathways are highlighted. Neuroinhibition is suggested as an overarching theoretical mechanism for P300, which is elicited when stimulus detection engages memory operations.
Topics: Animals; Brain Chemistry; Cortical Synchronization; Electroencephalography; Event-Related Potentials, P300; Evoked Potentials; Humans; Neurotransmitter Agents
PubMed: 17573239
DOI: 10.1016/j.clinph.2007.04.019 -
Clinical Neurophysiology : Official... Dec 2021This is the second chapter of the series on the use of clinical neurophysiology for the study of movement disorders. It focusses on methods that can be used to probe... (Review)
Review
This is the second chapter of the series on the use of clinical neurophysiology for the study of movement disorders. It focusses on methods that can be used to probe neural circuits in brain and spinal cord. These include use of spinal and supraspinal reflexes to probe the integrity of transmission in specific pathways; transcranial methods of brain stimulation such as transcranial magnetic stimulation and transcranial direct current stimulation, which activate or modulate (respectively) the activity of populations of central neurones; EEG methods, both in conjunction with brain stimulation or with behavioural measures that record the activity of populations of central neurones; and pure behavioural measures that allow us to build conceptual models of motor control. The methods are discussed mainly in relation to work on healthy individuals. Later chapters will focus specifically on changes caused by pathology.
Topics: Central Nervous System; Electroencephalography; Evoked Potentials; Evoked Potentials, Motor; Humans; Motor Cortex; Movement Disorders; Reaction Time; Transcranial Direct Current Stimulation; Transcranial Magnetic Stimulation
PubMed: 34717225
DOI: 10.1016/j.clinph.2021.09.013 -
NeuroImage Sep 2021Our perception of the external world is influenced by internal bodily signals. For example, we recently showed that timing of stimulation along the cardiac cycle and...
Our perception of the external world is influenced by internal bodily signals. For example, we recently showed that timing of stimulation along the cardiac cycle and spontaneous fluctuations of heartbeat-evoked potential (HEP) amplitudes influence somatosensory perception and the associated neural processing (Al et al., 2020). While cardiac phase affected detection sensitivity and late components of the somatosensory-evoked potentials (SEPs), HEP amplitudes affected detection criterion and both early and late SEP components. In a new EEG study, we investigate whether these results are replicable in a modified paradigm, which includes two succeeding temporal intervals. In one of the intervals, subjects received a weak electrical finger stimulation and reported first whether they detected any stimulation and then allocated the stimulus to one of the two intervals. Our results confirm the previously reported cardiac cycle and prestimulus HEP effects on somatosensory perception and evoked potentials. In addition, we obtained two new findings. Source analyses in this and our original study show that the increased likelihood of conscious perception goes along with HEP fluctuations in parietal and posterior cingulate regions, known to play important roles in interoceptive processes. Furthermore, HEP amplitudes were shown to decrease when subjects engaged in the somatosensory task compared to a resting state condition. Our findings are consistent with the view that HEP amplitudes are a marker of interoceptive (versus exteroceptive) attention and provide a neural underpinning for this view.
Topics: Adult; Awareness; Consciousness; Electroencephalography; Evoked Potentials; Evoked Potentials, Somatosensory; Female; Heart Rate; Humans; Interoception; Male; Somatosensory Cortex; Touch Perception; Young Adult
PubMed: 34111514
DOI: 10.1016/j.neuroimage.2021.118247 -
Vision Research Sep 2020To study the physiology of the primate visual system, non-invasive electrophysiological techniques are of major importance. Two main techniques are available: the... (Review)
Review
To study the physiology of the primate visual system, non-invasive electrophysiological techniques are of major importance. Two main techniques are available: the electroretinogram (ERG), a mass potential originating in the retina, and the visual evoked potential (VEP), which reflects activity in the primary visual cortex. In this overview, the history and the state of the art of these techniques are briefly presented as an introduction to the special issue "New Developments in non-invasive visual electrophysiology". The overview and the special issue can be used as the starting point for exciting new developments in the electrophysiology of primate and mammalian vision.
Topics: Animals; Electroretinography; Evoked Potentials, Visual; Retina; Vision, Ocular; Visual Cortex
PubMed: 32540518
DOI: 10.1016/j.visres.2020.05.003 -
Brazilian Journal of Otorhinolaryngology 2020Cortical auditory evoked potentials have been increasingly used in research and audiological routines. However, there is a lack of studies with a large number of...
INTRODUCTION
Cortical auditory evoked potentials have been increasingly used in research and audiological routines. However, there is a lack of studies with a large number of children who are stratified by age group. These would help clarify the variations in latency and amplitude of cortical auditory evoked potentials, and thus help establish reference values in children of different ages.
OBJECTIVE
To identify the variation in latency and amplitude of the cortical auditory evoked potentials and to establish reference values for the pediatric population.
METHODS
This was a cross-sectional study. Subjects were born at term and presented with no auditory complaints. A total of 105 children, of up to 6 years and eleven months old, who were divided into 7 age groups, named 1, 2, 3, 4, 5, 6 and 7, participated in the study. The tests were carried out using Biologic Navigator Pro. Initially, brainstem auditory evoked potential testing was performed in order to investigate the electrophysiological threshold of the subjects. Then, cortical auditory evoked potentials were elicited through oddball paradigm with tone burst differing in frequency, 750Hz (frequent) and 1000Hz (rare), and stimuli differing in speech: /ba/ (frequent) and /da/ (rare). In this study, descriptive and comparative analyzes of tonal and speech stimuli were performed for the age groups.
RESULTS
Significant differences were observed when comparing cortical auditory evoked potentials with speech stimulus in the right ear for P2 amplitude, for P1 latency the left ear, for P2 amplitude of the left ear; and for P1 amplitude of the left ear when performed with tonal stimuli.
CONCLUSION
The obtained results can be considered as reference values of latency and amplitude of cortical auditory potentials in infants and children, and be used for monitoring their cortical auditory development.
Topics: Acoustic Stimulation; Auditory Cortex; Child; Cross-Sectional Studies; Evoked Potentials, Auditory; Humans; Infant; Speech; Speech Perception
PubMed: 30926456
DOI: 10.1016/j.bjorl.2019.01.007 -
Journal of Neuroscience Methods Jan 2021Compared to conventional transcranial magnetic stimulation (TMS), the triple stimulation technique (TST) strongly decrease the effects of desynchronization of descending... (Review)
Review
BACKGROUND
Compared to conventional transcranial magnetic stimulation (TMS), the triple stimulation technique (TST) strongly decrease the effects of desynchronization of descending discharges and accompanying phase cancellation that follow TMS and offers a more sensitive method to quantify motor evoked potentials (MEPs).
NEW METHOD
Using the TST, we explored as to whether sub-threshold TMS evokes peripheral motor neuron discharges (MNs). We compared the number of MEPs elicited by TMS and by TST in fifteen healthy participants. We used the subthreshold intensity of 80 % resting motor threshold. To control the TST assessment of the corticospinal tract, we included a peripheral stimulation control condition, which consisted of peripheral stimulation alone, in a subgroup of five volunteers.
RESULTS
Compared to TMS, TST at sub-threshold intensities did not detect significantly more responses unequivocally attributable to the cortical stimulation. In contrast, the peripheral supra-maximal stimuli produced confounding effects in the TST condition that were, in part, indistinguishable from cortical responses.
COMPARISON WITH EXISTING METHODS
At subthreshold TMS intensities, the TST does not detect more discharges of spinal MNs than conventional TMS and, in addition, it is confounded by effects from peripheral stimulation.
CONCLUSION
The TST can be useful in assessing the integrity of the MN pool and of the corticospinal tract. However, if used at near threshold intensity, the confounding effects of peripheral stimulation need to be considered; for instance, in paired-pulse stimulation paradigms assessing the cortical physiology.
Topics: Evoked Potentials, Motor; Humans; Motor Neurons; Pyramidal Tracts; Rest; Transcranial Magnetic Stimulation
PubMed: 33002507
DOI: 10.1016/j.jneumeth.2020.108959 -
Brazilian Journal of Otorhinolaryngology 2017Stuttering is a speech fluency disorder, and may be associated with neuroaudiological factors linked to central auditory processing, including changes in auditory... (Comparative Study)
Comparative Study
INTRODUCTION
Stuttering is a speech fluency disorder, and may be associated with neuroaudiological factors linked to central auditory processing, including changes in auditory processing skills and temporal resolution.
OBJECTIVE
To characterize the temporal processing and long-latency auditory evoked potential in stutterers and to compare them with non-stutterers.
METHODS
The study included 41 right-handed subjects, aged 18-46 years, divided into two groups: stutterers (n=20) and non-stutters (n=21), compared according to age, education, and sex. All subjects were submitted to the duration pattern tests, random gap detection test, and long-latency auditory evoked potential.
RESULTS
Individuals who stutter showed poorer performance on Duration Pattern and Random Gap Detection tests when compared with fluent individuals. In the long-latency auditory evoked potential, there was a difference in the latency of N2 and P3 components; stutterers had higher latency values.
CONCLUSION
Stutterers have poor performance in temporal processing and higher latency values for N2 and P3 components.
Topics: Acoustic Stimulation; Adolescent; Adult; Auditory Perception; Educational Status; Event-Related Potentials, P300; Evoked Potentials, Auditory; Female; Humans; Male; Middle Aged; Reaction Time; Stuttering; Young Adult
PubMed: 27233690
DOI: 10.1016/j.bjorl.2016.02.015 -
Tidsskrift For Den Norske Laegeforening... May 2013Evoked potentials are used to detect conduction disturbances in the central nervous system. This paper provides an overview of the areas in which evoked potentials are... (Review)
Review
BACKGROUND
Evoked potentials are used to detect conduction disturbances in the central nervous system. This paper provides an overview of the areas in which evoked potentials are used in clinical neurophysiological diagnostics, with the emphasis on coma and demyelinating disease.
METHOD
The article is based on a literature search in PubMed and the authors' long experience of neurological and neurophysiological diagnostics.
RESULTS
Somatosensory evoked potential (SEP) can be a reliable predictor of failure to regain consciousness as early as 24 hours after anoxic coma has occurred. If coma is caused by a brain trauma, cerebrovascular episode or other neurological disease, information about which sensory brainstem pathways are damaged can be obtained from somatosensory evoked potentials and brainstem auditory evoked potentials (BAEP), which can also be useful for planning rehabilitation. Normal SEP and BAEP findings in cases of coma caused by trauma are associated with a favourable prognosis. Visually evoked potential (VEP) can often reveal signs of a history of optic neuritis. SEP and BAEP can also reveal subclinical lesions in the central nervous system and be a supplementary diagnostic test for multiple sclerosis.
INTERPRETATION
The clinical value of SEP and BAEP is high in coma cases. Evoked potentials are also important in intraoperative monitoring. The clinical value of VEP is high when a history of optic neuritis is a deciding factor for a multiple sclerosis diagnosis. Some selected patients who are being assessed for demyelinating disease will benefit from a full EP study.
Topics: Coma; Demyelinating Diseases; Evoked Potentials; Humans; Monitoring, Intraoperative; Optic Neuritis
PubMed: 23652144
DOI: 10.4045/tidsskr.12.1176