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Biomedical subjects

E A Salzen

Publications and source records attributed to E A Salzen.

At least 19 recordsLinked to original sources
PubMed1992

Event related potentials, reaction time, and cognitive performance in idiopathic Parkinson's disease.

Sixteen non-demented patients with idiopathic Parkinson's disease (PD) with varying degrees of cognitive impairment and sixteen age-, sex- and education-matched normal controls were examined with (1) an auditory oddball paradigm requiring counting or a motor response in separate determinations, (2) a reaction time task with movement time component and (3) a detailed clinical and neuropsychological test battery. Patients were impaired on a number of neuropsychological tests. They also showed an increased P2 and N2 latency, but no significant increase in P3 latency. Their response initiation times and reaction times during the oddball experiment were not different from controls, whereas movement time was significantly increased. Increased peak latencies, particularly for N2, were moderately associated with Parkinsonian motor impairment in patients and with the Benton Multiple Choice Visual Retention Test in patients and controls. Movement time was associated with P3 latency only in controls and in both groups with the Benton Multiple Choice Visual Retention Test. The observed pattern of results suggests that in non-demented PD patients ERP peak latencies, visuo-spatial task performance and Parkinsonian motor impairment share a significant degree of variance. While impairments in neuropsychological tests and delay in the earlier peaks P2 and N2 do not appear to be sensitive to medication with L-DOPA, normal P3 latencies might indicate good pharmacological symptom control in the absence of dementia.

Aged↗
PubMed1990

P300 and smooth eye pursuit: concordance of abnormalities and relation to clinical features in DSM-III schizophrenia.

Twenty-five DSM-III-diagnosed schizophrenics and 37 normal and age-matched controls were examined using an oddball paradigm for the generation of P300 and smooth eye-pursuit tasks. Results were compared between groups and related to clinical characteristics, including a family history of psychiatric illness. Group differences were found for P300 amplitudes, latencies and eye-tracking. A family history of psychiatric illness was associated with normal eye-tracking in patients. Small P300 amplitudes alone and in combination with long P300 latencies were associated with a family history in controls.

Adult↗
PubMed1982

The early wave of the visual evoked potential to sinusoidal gratings: responses to quadrant stimulation as a function of spatial frequency.

VEPs were elicited by sinusoidal grating patterns of differing spatial frequencies presented in each of the 4 quadrants of the visual field. Analysis of the early wave of the VEP indicated a pattern of polarity inversions when wave forms were compared across the horizontal meridian of the visual field. With the exception of low spatial frequencies, clear polarity inversions also occurred across the vertical meridian of the visual field in the case of laterally placed electrodes. Comparison of the clearly identifiable early peak with records for the same subject using central field stimulation showed the complexity of the latter records and the inherent difficulty of isolating and interpreting specific component waves of the VEP without adequate topographical data from quadrant stimulation.

Brain Mapping↗
PubMed1982

Visual-evoked responses elicited by the onset and offset of sinusoidal gratings: latency, waveform, and topographic characteristics.

Transient evoked potentials (VERs) elicited by the onset and offset of sinusoidal gratings have been investigated. Results indicated that an increase in amplitude and a decrease in latency characteristics of VER occur as monotonic functions of increasing contrast. The latencies were shorter for low than for medium spatial frequency gratings up to contrasts of 0.51. Previous reports of the latency of the VER increasing as a monotonic function of increasing spatial frequency are confirmed. Topographic studies of the scalp distribution of VERs indicated that the site of maximal response were similar for low and medium spatial frequencies and that potentials elicited by stimulus offset had a similar distribution to the early onset response. These results indicate that the same cortical region may be responsible for generating these potentials despite their different latency and trigger features. Additional data are presented to illustrate the likely effects of differential recording on the waveform of the VER.

Adult↗
PubMed1978

Forebrain lesions and retention of imprinting in domestic chicks.

Newly-hatched domestic chicks were reared separately with one of two types of imprinting object hanging in their cages. On the 5th day discrimination tests demonstrated strong preferences for the familiar object. On the 6th day the chicks were subjected to bilateral aspiration lesions of either the anterior or the lateral forebrain and their imprinting objects removed from the cage. Discrimination tests were made on the 9th and 12th days, the imprinting objects replaced, and a final relearning test given on the 14th day. The anterior lesion group was slightly impaired in the retention and relearning tests while the lateral lesion group was drastically affected, being significantly worse than the anterior group and with choices only just significantly above random expectation in the retention tests and no different from random choice in the relearning test. It was concluded that a lateral forebrain region is necessary for retention and relearning of a previously acquired imprinted preference.

Animals↗
PubMed1978

Facial expressions in captive squirrel monkeys (Saimiri sciureus).

The facial expressions of captive, group-living squirrel monkeys are described. Elements of facial expressions, the occurrence of these expressions and accompanying vocalizations are detailed. The range of facial expressions recorded for this species is similar to that previously reported for other simian primates.

Aggression↗
PubMed1977

The spatial selectivity of early and late waves within the human visual evoked response.

Two studies on the amplitude, latency, and waveform of human visual evoked responses to the onset of sine-wave grating patterns were made. Results indicated that the peak latencies of both early and late waves were a function of the spatial frequency of the stimulus. The amplitude of the early wave (N1-P1) was consistently greatest at low spatial frequenciies while the late wave (N2-P2) showed consistent attenuation at low spatial frequencies. In addition the location of the peak amplitude response of the late, but not the early, wave depended on the location (macular versus extramacular) and area(small versus large stimulus field) of retina stimulated. These findings are discussed in the light of evidence for separate transient and sustained systems within the human visual system.

Evoked Potentials↗
PubMed1975

A forebrain lesion preventing imprinting in domestic chicks.

Newly hatched domestic chicks were subjected to bilateral aspiration lesions of the anterior, dorsal, posterior or lateral regions of the forebrain and then were reared separately with one of two types of imprinting object. Between 3 and 10 days later they were tested for imprinting, pecking accuracy, visual looming and auditory startle responses. Lateral and dorsal lesion groups differed from a control group in the number of successful discriminations of their imprinting object and the lateral group was not significantly different from a random expectancy. All groups were impaired in pecking accuracy but the lateral group was the most severely affected. Looming responses and post startle freezing behaviour were reduced only in the posterior and dorsal groups which were also the least responsive in the imprinting tests. It was concluded that the lateral forebrain area is critically and specifically involved in the visual learning of imprinting being necessary for the discrimination of, but not for approach responsiveness to, imprinting objects.

Animals↗