P300 reflects the degree of cognitive decline in dementing illness
Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093 U.S.A.Electroencephalography and Clinical Neurophysiology 03/1986; 63(2):138-144. DOI: 10.1016/0013-4694(86)90007-6
An auditory discrimination paradigm was employed to elicit the P3 component of the event-related brain potential (ERP) from 39 demented patients (mean age = 71 years). Component latency was longer in patients who were diagnosed as having primary degenerative dementia and other cognitive impairment disorders compared to age-matched controls. Neurologist ratings of cognitive impairment were significantly correlated with P3 latency values, although no differences in mean latency were obtained between the various categories of dementia. ERP measurement techniques and the interpretation of P3 latency as an index of dementing illness are discussed.
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- "In particular, measurement of latency 1 is key to determining the order in which cognitive processes are performed, and plays a pivotal role in mental chronometry (Coles, Smid, Scheffers, & Otten, 1995). There are numerous factors that can influence the latency of an ERP component, making the measurement of particular interest for clinical studies (Bruder et al., 1991; Polich, Ehlers, Otis, Mandell, & Bloom, 1986; Todd et al., 2008). "
ABSTRACT: Methods for measuring onset latency contrasts are evaluated against a new method utilizing the dynamic time warping (DTW) algorithm. This new method allows latency to be measured across a region instead of single point. We use computer simulations to compare the methods’ power and Type I error rates under different scenarios. We perform per-participant analysis for different signal-to-noise ratios and two sizes of window (broad vs. narrow). In addition, the methods are tested in combination with single-participant and jackknife average waveforms for different effect sizes, at the group level. DTW performs better than the other methods, being less sensitive to noise as well as to placement and width of the window selected.
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- "Cerebral differences associated to the presence / absence of auditory stimuli Classical auditory N1 - P2 - N2 - P3 components were observed for cate - gorized stimuli , but not for uncategorized stimuli or silences . This result is not surprising as ERP amplitudes decrease when intensity is reduced ( Hillyard et al . , 1971 ; Polich et al . , 1986 ) to the psychophys - ical threshold or near it ( Suzuki et al . , 1976 ; Musiek et al . , 2005 ) . The increase in theta power for categorized stimuli may be associated with the evoked responses , as Klimesch et al . ( 2007 ) have shown that ERPs reflect the superposition of an increase in evoked theta fre - quency band over a decrease"
ABSTRACT: Recent human behavioral studies have shown semantic and/or lexical processing for stimuli presented below the auditory perception threshold. Here, we investigated electroencephalographic responses to words, pseudo-words and complex sounds, in conditions where phonological and lexical categorizations were behaviorally successful (categorized stimuli) or unsuccessful (uncategorized stimuli). Data showed a greater decrease in low-beta power at left-hemisphere temporal electrodes for categorized non-lexical sounds (complex sounds and pseudo-words) than for categorized lexical sounds (words), consistent with the signature of a failure in lexical access. Similar differences between lexical and non-lexical sounds were observed for uncategorized stimuli, although these stimuli did not yield evoked potentials or theta activity. The results of the present study suggest that behaviorally uncategorized stimuli were processed at the lexical level, and provide evidence of the neural bases of the results observed in previous behavioral studies investigating auditory perception in the absence of stimulus awareness.
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- "As age advances, the latencies of P300 and N100 components increase [9, 10, 29], whereas the amplitudes of these two components are decreased [12, 29]. Changes in both parameters have been reported to be associated with decreased memory function [30–32]. A profile of evidence during the past decade has also shown that the alteration of N100, which reflects attention, and the alteration of P300, which reflects both attention and memory operation or cognitive processing, are associated with the function of cholinergic system [33, 34]. "
ABSTRACT: At present, the scientific evidence concerning the effect of Bacopa monnieri on brain activity together with working memory is less available. Therefore, we aimed to determine the effect of B. monnieri on attention, cognitive processing, working memory, and cholinergic and monoaminergic functions in healthy elderly. A randomized double-blind placebo-controlled design was utilized. Sixty healthy elderly subjects (mean age 62.62 years; SD 6.46), consisting of 23 males and 37 females, received either a standardized extract of B. monnieri (300 and 600 mg) or placebo once daily for 12 weeks. The cholinergic and monoaminergic systems functions were determined using AChE and MAO activities. Working memory was assessed using percent accuracy and reaction time of various memory tests as indices, whereas attention and cognitive processing were assessed using latencies and amplitude of N100 and P300 components of event-related potential. All assessments were performed before treatment, every four weeks throughout study period, and at four weeks after the cessation of intervention. B. monnieri -treated group showed improved working memory together with a decrease in both N100 and P300 latencies. The suppression of plasma AChE activity was also observed. These results suggest that B. monnieri can improve attention, cognitive processing, and working memory partly via the suppression of AChE activity.
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