PubMed Health⌕ Search

Biomedical subjects

W Miltner

Publications and source records attributed to W Miltner.

7 recordsLinked to original sources
PubMed1995

Pain-related cerebral potentials in patients with frontal or parietal lobe lesions.

The present study investigated the processing of painful electrical stimuli in patients with unilateral frontal or parietal lobe damage and matched control subjects. Patients with frontal lesions showed increased pain thresholds when the stimuli were administered contralateral to the lesion. While the peak-to-peak amplitudes of the N150/P250 components of the somatosensory potentials increased linearly with stimulus intensity in the control subjects, the responses in the frontal group did not change significantly between stimulation at pain and tolerance threshold. There was no evidence for altered pain processing in patients with parietal lobe lesions. The findings of the present study support the hypothesis of an involvement of the frontal cortex in pain perception in humans.

Adult↗
PubMed1994

A test of brain electrical source analysis (BESA): a simulation study.

The present report summarizes the results of a simulation study on the accuracy of Scherg's implementation of spatio-temporal analysis (BESA) for estimating the parameters (wave shape, location, orientation) of the intracranial sources of event-related brain potentials (ERPs) recorded from the scalp. In view of the subjective factors that might influence a solution, 10 subjects, ranging from those with much experience with ERPs and extensive background in the use of BESA to those with little experience with BESA and/or no knowledge of ERPs, independently analyzed a set of simulated somatosensory ERP data. The simulation contained wave forms from 32 electrode sites generated by a combination of 10 dipole sources. The primary question was how faithfully the different subjects would depict the source wave shapes, locations and orientations. Based on the 9 subjects who were familiar with ERPs, the grand-average cross-correlation coefficient between subjects' estimated and actual source wave shapes was 0.89 (standard deviation (S.D.) = 0.17). The grand-average location error, based upon a head diameter of 17 cm, was 1.4 cm (S.D. = 1.0 cm). The grand-average orientation error was 24.4 degrees (S.D. = 20 degrees).

Brain↗
PubMed1994

Neurophysiological differences between perception and imagery.

The present study was designed to examine brain activity underlying mental imagery is conceptualized as behavior guided by internal representation only, the activity of the prefrontal lobes was assumed to be a measure of differentiation of imagery from perception. Twenty-one subjects were requested to observe and imagine a swinging pendulum and to touch and imagine a coshball in separate trials. The EEG was recorded from 15 standard electrode sites and analyzed with (1) traditional alpha power and (2) an estimation of dimensional complexity (a measure derived from nonlinear dynamics). Both EEG measures revealed expected object-related differences during perception as well as during imagery. The visual pendulum showed relative to the tactile coshball increased dimensional complexity and less alpha power at parietal and frontal sites. However, only the EEG dimension supported the main hypothesis: Imagery resulted in increased prefrontal dimensional complexity in comparison to perception independent of the modality of the image. In contrast, for alpha power the difference between imagery and perception was due to stimulus modality.

Adolescent↗
PubMed1994

Emotional qualities of odors and their influence on the startle reflex in humans.

Recent human and animal research suggests that the startle reflex might serve as a psychophysiological indicator of the emotional valence of foreground stimulation. The present experiment was designed to evaluate the emotional effects of positive and negative odorant stimuli. We examined the effects of continuous hydrogen sulphide (H2S) and vanillin stimulation on the magnitude of the acoustic startle reflex (measured at the M. orbicularis oculi) and on ratings of subjective valence in 16 healthy subjects. In accordance with the view that odors have emotional qualities, we found that H2S, a presumed negative foreground stimulus, significantly enhanced the startle-reflex amplitude relative to neutral air stimulation, whereas vanillin, a positive foreground stimulus, tended to reduce the reflex amplitude compared with neutral air stimulation. Both odorant stimuli were rated as equally intense by the subjects, and heart rate and electrodermal activity were not affected differentially by the two odorants.

Acoustic Stimulation↗
PubMed1994

Classical conditioning of pain responses.

Classical conditioning is involved in the acquisition of chronic pain. The present study investigated whether experimental pain responses can be conditioned using auditory stimuli in a differential trace conditioning paradigm. 16 healthy subjects served as paid volunteers. The UCS was an intracutaneous electrical stimulus applied to the left middle-finger (10 ms duration). Tones of 1000 and 1400 Hz (both 80 dB SPL, 50 ms) were used as CS+ and CS-, respectively. A trace conditioning paradigm was used with an 800 ms interval between CS and UCS. Somatosensory event related potentials (SEP) and auditory event related potentials (AEP) were recorded from 29 electrode sites. Subjective pain reports were measured with an adjective list that allowed a detailed description of subjects' sensations elicited by painful and auditory stimuli. Data revealed significant differences of the subjective sensations between the CS+ and CS-, but no differences in the amplitudes and latencies of the P50, N100, P200, and P300 AEP components. No changes in the topographical organization of the CS+ and CS- were found. A significant differential negativity in the brain sites responsible for processing the UCS was obtained, which is attributed to the anticipation of the UCS after CS+ presentation.

Acoustic Stimulation↗
PubMed1986

Biofeedback of visual evoked potentials.

The present study investigated the operant conditioning of visual evoked potentials within a latency range between 200 and 600 ms using a visual discrimination task, and scrutinized whether biofeedback-induced potential shifts covaried with behavioral responses (reaction time, RT). It could be demonstrated that subjects were able to modify their ERPs towards more or less positivity according to the instruction given. In addition, in could be shown that a biofeedback-induced greater positivity of the P300-complex was highly correlated with a decrease of reaction time. It is hypothesized that this could be due to a modification of P300-components reflecting information processing.

Adult↗