Biomedical subjects

N E Noldy

Publications and source records attributed to N E Noldy.

6 recordsLinked to original sources

PubMed1992

Molecular and prospective phenotypic characterization of a pedigree with familial Alzheimer's disease and a missense mutation in codon 717 of the beta-amyloid precursor protein gene.

We present prospective clinical and neuropathologic details of a pedigree segregating familial Alzheimer's disease (FAD) associated with a mutation (G----A substitution) at nucleotide 2149 in exon 17 of the amyloid precursor protein (APP) gene. This mutation, which is predicted to cause the missense substitution of isoleucine for valine at codon 717 of APP, cosegregated perfectly with the FAD trait (lod score = 3.49 at theta = 0.00). The earliest clinical manifestations of the disease relate to deficits in memory function, cognitive processing speed, and attention to complex cognitive sets. These changes occurred in the absence of changes in nonmemory language and visuospatial functions. The neuropathologic features of FAD associated with the APP717 mutation in this family include severe neuronal loss, abundant neurofibrillary tangles, amyloid plaques, and amyloid angiopathy. These results provide independent confirmation that mutations in the APP gene are linked to the FAD trait in some families.

Adult↗

PubMed1991

Late auditory evoked potentials in alcoholics. Identifying those with a history of epileptic seizures during withdrawal.

The N1-P2 wave of the auditory evoked potential was studied in 19 alcoholics, six of whom had withdrawal seizures on previous admissions. The recordings were made at 1 and 5 days after cessation of drinking. Eight nonalcoholic volunteers were used as controls. The latencies of N1 and P2 were slightly prolonged in alcoholics, but during the detoxification period they frequently shortened (p less than 0.05), occasionally attaining the values of the controls. One day after withdrawal, the amplitude of N1-P2 was consistently reduced in the alcoholics compared to the controls (p less than 0.05 and p less than 0.01), but higher in alcoholics with a seizure history compared to alcoholics without seizures (p less than 0.05 and p less than 0.001). Five days after cessation of drinking, the amplitude in the alcoholic groups always increased from the admission values (p less than 0.05 and p less than 0.01). By that time, the alcoholics with a history of withdrawal seizures had significantly (p less than 0.05 and p less than 0.01) higher amplitudes than those of the controls or the alcoholics without seizures. Large N1-P2 amplitude during alcohol withdrawal may reflect increased cerebral excitability and contribute to the identification of alcoholics with high risk for withdrawal seizures.

Adult↗

PubMed1990

Event-related potentials and recognition memory for pictures and words: the effects of intentional and incidental learning.

Event-related potentials were recorded under conditions of intentional or incidental learning of pictures and words, and during the subsequent recognition memory test for these stimuli. Intentionally learned pictures were remembered better than incidentally learned pictures and intentionally learned words, which, in turn, were remembered better than incidentally learned words. In comparison to pictures that were ignored, the pictures that were attended were characterized by greater positive amplitude frontally at 250 ms and centro-parietally at 350 ms and by greater negativity at 450 ms at parietal and occipital sites. There were no effects of attention on the waveforms elicited by words. These results support the view that processing becomes automatic for words, whereas the processing of pictures involves additional effort or allocation of attentional resources. The N450 amplitude was greater for words than for pictures during both acquisition (intentional items) and recognition phases (hit and correct rejection categories for intentional items, hit category for incidental items). Because pictures are better remembered than words, the greater late positive wave (600 ms) elicited by the pictures than the words during the acquisition phase is also consistent with the association between P300 and better memory that has been reported.

Adult↗

PubMed1990

Late auditory evoked potentials: a method for monitoring drug effects on the central nervous system.

An auditory event-related potential paradigm was designed to objectively quantify the effects of drugs on the central nervous system (CNS). A series of tones was presented at three random interstimulus intervals (ISI). The amplitude of N1-P2 and the recovery of this complex across ISI appear to be rapid, reliable and sensitive measures of changes in brain function associated with drug intake. To illustrate, an acute dose of diazepam was administered orally to a small group of normal subjects. The amplitude of N1-P2 was reduced and the slope of recovery flattened, indicating a decrease in CNS excitability concomitantly with the established pharmacokinetics of the drug.

Acoustic Stimulation↗

PubMed1990

Acute, withdrawal, and chronic alcohol effects in man: event-related potential and quantitative EEG techniques.

The results presented here strongly suggest that quantitative electroencephalography and event-related potentials are excellent research tools and may be clinically useful as non-invasive monitors of psychotropic drug action and encephalopathies. Our initial data with acute mild alcohol intoxication show that acute tolerance may be reflected in qEEG but not in P3 latency. Since predictably some brain functions may show tolerance, and others not, these approaches may be useful probes. The amplitude of N1-P2 appears to differentiate alcoholics with and without a history of withdrawal seizures. This technique may thus prove useful in determining treatment and monitoring treatment effects in alcohol withdrawal. P3 latency appears to be normal in Korsakoff's syndrome, unlike in Alzheimer's disease. The combination of the event-related potentials with neuropsychology and magnetic resonance imaging scans should be invaluable for future research in these patient groups. Many patients with severe liver disease superficially appear mentally intact. The event-related potential and quantitative electroencephalography findings we have demonstrated may indicate those at greater risk for alterations in brain functioning. These techniques may also prove useful in diagnosing other "subclinical" encephalopathies and further our understanding of the underlying brain pathophysiology.

Aged↗

PubMed1988

A peak detector program for event-related potentials.

A computer program, developed for peak detection of averaged evoked potential waveforms, is described. The program is able to automatically score up to 200 data files in a single session. The user is asked to define intervals (windows) in which a maximum peak is to be detected. The program can optionally search each EEG channel or a single 'reference' channel from which all other channels will be compared. The mean amplitude of several data points can also be computed within a particular window. When evoked potentials are particularly noisy, it is possible to estimate the 'signal' in the higher frequency background 'noise'. Because the program is written in BASIC, it can be readily transferred to many different computer systems.

Arousal↗