An Electrophysiological Correlate of Phonemic Discrimination

1981 ◽  
Vol 20 (6) ◽  
pp. 480-487 ◽  
Author(s):  
Gary P. Jacobson ◽  
Donald P. Gans
2019 ◽  
Author(s):  
Henry Railo ◽  
Niklas Nokelainen ◽  
Saara Savolainen ◽  
Valtteri Kaasinen

AbstractObjectiveSpeech deficits are common in Parkinson’s disease, and behavioural findings suggest that the deficits may be due to impaired monitoring of self-produced speech. The neural mechanisms of speech deficits are not well understood. We examined a well-documented electrophysiological correlate of speech self-monitoring in patients with Parkinson’s disease and control participants.MethodsWe measured evoked electroencephalographic responses to self-produced and passively heard sounds (/a/ phonemes) in age-matched controls (N=18), and Parkinson’s disease patients who had minor speech impairment, but reported subjectively experiencing no speech deficits (N=17).ResultsDuring speaking, auditory evoked activity 100 ms after phonation (N1 wave) was less suppressed in Parkinson’s disease than controls when compared to the activity evoked by passively heard phonemes. This difference between the groups was driven by increased amplitudes to self-produced phonemes, and reduced amplitudes passively heard phonemes in Parkinson’s disease.ConclusionsThe finding indicates that auditory evoked activity is abnormally modulated during speech in Parkinson’s patients who do not subjectively notice speech impairment. This mechanism could play a role in producing speech deficits in as the disease progresses.


2016 ◽  
pp. 693-699
Author(s):  
Rene L. Utianski ◽  
John N. Caviness

Movement-related cortical potentials (MRCPs) are EEG potentials that occur with movement and are recorded using surface scalp electrodes. A technique termed “EEG-EMG back-averaging” is used to obtain MRCPs. The earliest recordable MRCP is the Bereitschaftspotential or readiness potential. Special EEG averaging techniques may also be used to study the cortical processes underlying cognition. Event-related potentials (ERPs) record the cortical activity evoked by a stimulus charged with cognitive significance. The P300 is the most commonly recorded ERP, elicited in an oddball technique of auditory stimulation; the subject is instructed to attend to a rare stimulus presented among a string of frequent stimuli. Only trials triggered by this rare event are averaged. The P300 may be the electrophysiological correlate of selected attention. The N400, another ERP, is assessed during semantic comprehension of language. The chapter discusses normal variants of MRCPs and ERPs, as well as disruptions secondary to neurological disease.


Author(s):  
Taimour Alam ◽  
Alexander StJ.E. Barker ◽  
James J.P. Alix ◽  
Marios Hadjivassiliou ◽  
Dasappaiah G. Rao

AbstractBackground: Sensory ganglionopathy (SG) is characterised by asymmetrical sensory fibre degeneration, with the primary pathology occurring at the level of the dorsal root ganglion. It is seen in the context of autoimmune, paraneoplastic, and degenerative disorders. There is limited literature examining the electrophysiological correlate of the trigeminal ganglion and associated pathways, the blink reflex (BR), in cases of SG. Previous work has suggested that the BR is preserved in cases of SG associated with paraneoplasia. Methods: The local clinical neurophysiology database was searched for patients diagnosed with SG from peripheral nerve conduction studies in whom the BR was performed. Twenty-six patients were included in the final analysis. Results: Sjögren’s syndrome constituted the most common SG aetiology (8/26), followed by idiopathic cases (7/26) and paraneoplasia (5/26). BR abnormalities were seen in 9 of the 26 patients (34.6%) across all aetiologies. No patients reported sensory disturbance in the distribution of the trigeminal nerve, indicating that the changes noted are subclinical. Three patients showed abnormality of the R1 response; in the remaining six patients, only R2 responses were affected. Conclusions: Subclinical abnormalities of both R1 and R2 can be seen in the context of SG of varying aetiologies, including paraneoplasia. Performing the BR in patients with suspected of having SG may be helpful in providing additional evidence of patchy sensory fibre involvement that is characteristic of the disease.


2009 ◽  
Vol 23 (2) ◽  
pp. 43-51 ◽  
Author(s):  
Andrea Schankin ◽  
Dirk Hagemann ◽  
Edmund Wascher

Changes between two successively presented pictures are hard to detect when their presentation is interrupted by a blank (change blindness). This task is well established for investigating the neural correlates of visual awareness. It allows the comparison of electrophysiological activity evoked by physically identical trials in which the change was detected versus trials in which the change remained unnoticed. One possible correlate of aware processing is the N2pc component, an increased negative activity, contralateral to a processed stimulus between 200–300 ms after stimulus onset. However, this component has been also assigned to the allocation of attention. In two experiments, an N2pc was observed for detected changes. This component was markedly reduced for undetected changes and even more if participants reported a change that was not present (imagined change). These results suggest that the N2pc rather reflects attentional processing of stimuli in visual cortical areas than the actual aware representation.


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