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Biomedical subjects

C Senior

Publications and source records attributed to C Senior.

27 records · Page 2Linked to original sources
PubMed1999

The functional anatomy of the McCollough contingent colour after-effect.

We report two functional magnetic resonance imaging (fMRI) experiments which reveal a cortical network activated when perceiving coloured grids, and experiencing the McCollough effect (ME). Our results show that perception of red-black and green-black grids activate the right fusiform gyrus (area V4) plus the left and right lingual gyri, right striate cortex (V1) and left insula. The ME activated the left anterior fusiform gyrus as well as the ventrolateral prefrontal cortex, and in common with colour perception, the left insula. These data confirm the critical role of the fusiform gyrus in actual and illusory colour perception as well as revealing localized frontal cortical activation associated with the ME, which would suggest that a 'top-down' mechanism is implicated in this illusion.

Adult↗
PubMed1999

An investigation into the perception of dominance from schematic faces: a study using the World-Wide Web.

The World-Wide Web (WWW) is considered to be a viable tool for scientific research, and several investigators have already made use of it in their studies. Although the WWW allows researchers to access a vast subject pool, questions of reliability and validity need to be addressed before it is incorporated into mainstream research. By replicating, on the Internet, an existing study (Keating, Mazur, & Segall, 1977) on the perception of schematic faces, we were able to conclude that experimental work carried out in this manner is not necessarily biased by the medium. One difference from previous work was the effect of a smiling versus a nonsmiling face on the perception of dominance, given an identical brow position for the two faces. This was replicated on a different occasion with different subjects, which may represent a shift in attitudes to this facial configuration since the original study was conducted. Young North American males were overrepresented in our sample, but comparison with other surveys indicates that the population sampled by the Internet is becoming more representative.

Facial Expression↗
PubMed1998

A pilot investigation into the neuroendocrine correlates of personality in the workplace.

Pilot data are reported on the relation rate of adaptation to a change in usual patterns of circadian behaviour by personality scores. Personality was defined through scores on the Eysenck Personality Inventory and change in circadian behavior as working a random day shift in a predominately night shift work schedule. The rate of adaptation to change in circadian behavior pattern was recorded by levels of salivary Cortisol for each subject. 4 persons scoring high on Extraversion produced more Cortisol during the day shift, while the 2 scoring high on Intraversion produced more during the night shift.

Circadian Rhythm↗
PubMed1997

A specific neural substrate for perceiving facial expressions of disgust.

Recognition of facial expressions is critical to our appreciation of the social and physical environment, with separate emotions having distinct facial expressions. Perception of fearful facial expressions has been extensively studied, appearing to depend upon the amygdala. Disgust-literally 'bad taste'-is another important emotion, with a distinct evolutionary history, and is conveyed by a characteristic facial expression. We have used functional magnetic resonance imaging (fMRI) to examine the neural substrate for perceiving disgust expressions. Normal volunteers were presented with faces showing mild or strong disgust or fear. Cerebral activation in response to these stimuli was contrasted with that for neutral faces. Results for fear generally confirmed previous positron emission tomography findings of amygdala involvement. Both strong and mild expressions of disgust activated anterior insular cortex but not the amygdala; strong disgust also activated structures linked to a limbic cortico-striatal-thalamic circuit. The anterior insula is known to be involved in responses to offensive tastes. The neural response to facial expressions of disgust in others is thus closely related to appraisal of distasteful stimuli.

Adult↗
PubMed1984

The effect of intra-amniotic injection of triiodothyronine on pulmonary maturity in lambs at 130 days gestation.

Saline or triiodothyronine (T3) (50-1000 micrograms) was injected into the amniotic sac of 17 pregnant ewes under general anesthesia at 130 days gestation. Forty-eight h later, the lambs were delivered by hysterotomy. Cord plasma T3 and cortisol and amniotic fluid T3 were assayed, and the maturity of the fetal lung was assessed in terms of its pressure-volume response and its surfactant (lamellar body phospholipid) content. With the highest dose of T3, cord plasma T3 and cortisol were raised, and lung maturity was enhanced compared with saline-treated controls; the pressure-volume curve showed increased hysteresis on inflation and deflation, and the lung retained air on return to zero pressure. There was also an apparent, but not statistically significant, increase in the lamellar body phospholipid content of the lung. Irrespective of treatment, lungs which were more mature, in terms of their pressure-volume characteristics, tended to contain a higher proportion of lamellar body phospholipid relative to total phospholipid.

Amnion↗
PubMed1972

An alternative approach to the study of new enzymatic reactions involving DNA (DNA-dependent ATPases-purification-properties-E. coli).

Ordinarily, enzymes that catalyze bimolecular reactions involving DNA and nucleoside triphosphates are assayed in terms of the predicted changes in DNA. However, by assay of the enzymes by changes in nucleoside triphosphates, new enzymes may be sought without prior knowledge of the role of DNA in the reaction. This approach was used to isolate two new enzymes from Escherichia coli and one from T4 phage-infected E. coli. In this communication, the general application of this technique and its specific use in the isolation of two DNA-dependent ATPases from E. coli are described. Both enzymes catalyze a DNA-dependent cleavage of ATP to ADP and Pi. The two enzymes can be distinguished by their characteristic activities with different DNAs and synthetic polydeoxynucleotides. Neither of the enzymes shows endonuclease or exonuclease activity in conventional assays. These reactions were studied by isotope-exchange experiments. The discovery of these enzymes attests to the effectiveness of this method to seek new reactions involving nucleic acids. Moreover, our results suggest that other enzymes of nucleic acid metabolism may be found and purified by this new approach.

Adenosine Diphosphate↗
PubMedDate not supplied

Visual imagery and depersonalisation.

Twenty-eight people diagnosed with depersonalisation disorder (DD) were assessed using self-report measures of imagery ability in relation to a range of symptoms and in comparison with age- and sex-matched controls. It was found that symptoms of depersonalisation as well as other dissociative symptoms and depressed mood correlated with impaired ability to generate visual images. This was particularly evident with images pertaining to the self and other people as opposed to objects. A subgroup of 10 patients was tested on a neuropsychological battery of visual perception tests and found to be unimpaired compared with normal controls and patients with obsessive compulsive disorder, despite subjective impairments in imagery and high symptom scores. The findings add further weight to the distinctions made between imagery and perceptual processes.

Adult↗