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D Brenner

Publications and source records attributed to D Brenner.

30 records · Page 2Linked to original sources
PubMed1982

Modulation transfer functions of the human visual system revealed by magnetic field measurements.

Properties of a neural source of magnetic field localized in the occipital lobe was measured in a steady-state paradigm using contrast reversing gratings. Comparisons with scalp potentials provided evidence that the evoked field was associated with intracellular currents. Its modulation transfer functions were similar to the analogous functions for the scalp potential and the detection of a grating. Moreover, the amplitude of the evoked field was linearly related to the potential amplitude and their phases were nearly identical. An analysis of the results in terms of theoretical relations between evoked field and potential led us to conclude that these two measures may yield a similar characterization of the source when one dipolar source predominantly gives rise to both measures, but they may yield complementary information when multiple sources contribute to the measures.

Evoked Potentials, Visual↗
PubMed1981

On the relation between somatic evoked potentials and fields.

Recently Okada et al. (1981) reported that stimulation of the median nerve with a brief electrical impulse at the wrist evoked a transient change in the brain's magnetic field. This somatic evoked field (SEF) is similar in its temporal waveform to the response to the same stimulus reported for the electrical potential recorded on the pial surface of the exposed brain. Moreover, both measures differ substantially from the somatic evoked potential (SEP) recorded at the scalp. The present paper describes a more detailed account of the SEF as well as an analysis of its relation to the SEP and to the somatic pial response (SPR). Its purpose of the use the three measures in clarifying our understanding of the nature and locations of sources of the SEF. This paper is divided into three sections. The first is a background section which reviews basic principles and models that are widely used in deducing the locations of sources of evoked potentials and fields. It indicates the types of currents which may give rise to the SEF, and distinguishes between them and the current which is associated with the SEP. It concludes with a rationale for the experiments described in the next section. The experiments described in the second section determined how the SEF varies with the position from which it is recorded at the scalp. These variations turn out to be essential to our understanding of the nature and location of the sources of the SEF. The third section summarizes the results of the experiments and makes clear how they affect theories of the origin of the SEF. The findings also have implications for our understanding of the SEP and SPR. The most salient findings are: (1) The SEF recorded normal to the head provides essentially the same information as that provided by reported potential recordings from the exposed surface of the brain (the SPR). (2) The SEF originates in the cortex of the cerebrum in the vicinity of the central sulcus. (3) The currents that account for identifiable components of the SEF are opposite in direction to those that account for corresponding components of the SPR. This result is consistent with models that ascribe the detected field normal to the scalp to intracellular currents, whereas the VEP is associated with extracellular currents flowing in the opposite direction.

Brain↗
PubMed1978

Body build stereotypes and self-identification in three age groups of females.

Body build stereotypes of three age groups (6, 15, and 19 years old) of average weight and "heavy" female students were studied. First, the students were asked to circle one adjective from each of 28 antonym pairs, which was "most like" themselves. Concurrently, side-view figures of a female endormorph, an ectomorph, and a mesomorph were shown to each student. The figures were of the approximate age of the student. She was asked to point to one of the figures which "best fit" the adjectives in each of the 18 antonym pairs as they were read aloud. Lastly, each student was asked to choose one of the figures which "most looked" like themselves and the one which they would most want to "look like". Thus, discrepancies could be detected between one's self description and one's description of others with a very similar physique. The hypothesis that females would have similar physique preferences and aversions as those of males in a previous study (3) was confirmed. Females preferred the mesomorph figure (p less than .001) and at least favored the endomorph figure (p less than .001). The ectomorph figure was viewed less negatively than the endomorph figure (p less than .01). The youngest group showed more preference towards the endomorph and ectomorph figures then did the two older groups. "Heavy" physique students rejected the behavioral stereotypes descriptive of themselves even though they earlier had associated the very same stereotypes to the physique most like their own.

Adolescent↗
PubMed1976

Decreased prevalence of immediate hypersensitivity (atopy) in a cancer population.

It has been suggested that the atopic population has decreased risk of cancer. This investigation examined the cumulative prevalence of atopy in a population with neoplastic disease and compared this with the prevalence of atopy in an age-matched control group and with published estimates of atopy in the general peopulation. Seventy-four patients with neoplastic disease and 86 patients without cancer were evaluated. The subjects were given a standard allergic questionnaire which evaluated them with regard to a history of allergic symptoms, hives, eczema, frequent colds, frequent unexplained rashes, hay fever, and asthma. All were skin tested with a representative group of regionally significant allergens. There was a 15-fold decrease in prevalence of atopy in the cancer population, compared with the control group and compared with published estimates of atopy in the general population.

Adult↗
PubMed1975

Visually evoked magnetic fields of the human brain.

Magnetic field variations from the human brain produced by visual stimulation have been observed in a normal laboratory setting with a superconducting quantum interference device and no magnetic shielding of the subject. Previously unknown temporal and spatial features of the field near the scalp are reported.

Brain↗
PubMed1975

Analysis of the components of bile flow in the rhesus monkey.

Bile flow studies were performed in three groups of awake rhesus monkeys. In the first group, the increase in bile flow stimulated by secretin was not accompanied by an increase in erythritol-14C clearance. Resection of the gastric antrum and small intestine in the second group resulted in stable bile flow at fixed bile salt secretion rates. Linear regression lines for bile flow versus bile salt secretion rate and erythritol-14C clearance versus bile salt secretion rate were parallel, and the Y-axis intercept for the latter was consistently higher than for the former. We concluded that erythritol-14C clearance equals canalicular flow, and ductular reabsorption is constant at all bile salt secretion rates in this species. Bile flow was studied during fasting and feeding, over 6 days, in the third group. A model incorporating four bile flow components was developed and tested by multivariate regression analysis. The data fit the model quite well, explaining greater than 90% of the variation in bile flow. A method of measuring the contribution to bile flow of each of the four components is provided.

Animals↗
PubMedDate not supplied

Use of the computed tomographic whole body scanner to stage and follow patients with advanced ovarian carcinoma.

Advanced ovarian carcinoma continues to be a difficult tumor to evaluate noninvasively. Recent developments in chemotherapy have enhanced response rates in this disease, thus improving the likelihood of tumor regression. Computed Tomography (CT) allows the noninvasive estimation of tumor extent in patients with ovarian carcinoma. Seventeen patients with epithelial ovarian carcinoma had 22 whole body CT scans performed either just prior to or following laparotomy. For determination of tumor involvement, when the CT was positive, a high pathologic correlation was found at liver, ascitic, peritoneal, mesenteric, and omental sites (sensitivity). When the cT was negative, high pathologic correlation was found at ascitic and mesenteric sites (specificity). Lower and negative correlation at other disease sites is attributed to difficulty of CT detection of small (1 cm) tumor nodules on visceral surfaces. Eighteen patients with advanced ovarian carcinoma were followed prospectively during treatment with repetitive CT scans. CT results were compared with physical examination, other radiologic studies, and clinical status. In 83% (15/18) of patients and 88% (59/67) of CT scans performed, CT was found to contribute useful management information. Clinical decisions were made on the basis of CT alone in 43% (29/67) of scans performed. These data suggest that CT scanning is very useful in the staging and follow-up of patients with ovarian carcinoma and can replace other radiologic procedures, but it is not completely accurate and needs to be correlated with physical examination and in cases without tumors visible with CT, with laparotomy.

Female↗