Spectral characteristics of blink suppression in normal observers

Previous studies of the characteristics of suppression occurring under various visual conditions show similarities and differences which may indicative of the mechanism of suppression. The primary purpose of this study was to determine if the suppression that occurs in response to an eyelid blink (blink suppression) is similar to that which occurs during a saccade (saccadic suppression). In addition, the characteristics of blink suppression and other forms of suppression (i.e. permanent and binocular rivalry suppression) are compared. A test probe paradigm was utilized to determine the effect of blink suppression on the spectral sensitivity function in three normal observers. Employing a two alternative forced choice technique, thresholds were determined for wavelengths from 420 to 680 nm in 20 nm steps. At each wavelength, the threshold was determined at 0 and 400 msec after the onset of a voluntary blink. The magnitude of suppression was taken as the difference between the 0 and 400 msec thresholds. Similar to saccadic suppression, the magnitude of blink suppression increased as the stimuli biased detection towards the luminance channel. These results suggest that blink suppression and saccadic suppression are the result of a single mechanism. Similarities between blink suppression and other forms of visual suppression are also considered.     

Interhemispheric relations in processing hierarchical patterns: Evidence from normal and commissurotomized subjects.

On the basis of a review of neuropsychological evidence for several component processes of responding to global and local levels of hierarchically structured patterns, L. C. Robertson and M. R. Lamb (see record 1991-24938-001) hypothesized that interhemispheric communication between posterior cortexes would disrupt the typically interfering effects of global patterns on local response. These studies confirmed this hypothesis in 3 commissurotomized Ss. The normal interaction between visual field presentation and global or local level was present in normal Ss and all 3 patients, but global interference was absent or even reversed in patients. These data are discussed as they relate to the function of the corpus callosum and functional hemisphere asymmetries in responding to global and local levels of hierarchical forms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Circulating basophils in normal subjects and in subjects with hay fever

The relationship of hay fever symptoms and changes in the number of circulating basophils was studied in 12 subjects clinically sensitive only to ragweed and in 10 nonatopic subjects before, during, and after the ragweed season. Total white blood counts, absolute basophil counts, and symptom scores were recorded twice weekly from mid-June through October, 1974, and compared with the ragweed pollen count. The results indicated that the absolute and relative number of basophils were significantly elevated (p less than 0.001) in the hay fever group when symptoms occurred. As the symptom score of the allergic group increased during the ragweed season, the number of basophils also increased, only to decrease to control values when symptoms subsided. The basophil counts of the atopic group were significantly higher than those of the nonatopic group during the control periods. The nonatopic group also showed a significant elevation of basophils during the ragweed season, but to a much lesser extent than the atopic group. It is concluded that: (1) subjects with symptomatic hay fever have a significantly elevated absolute and relative basophil count which correlates with the exacerbation and remission of symptoms; (2) nonatopic subjects also have a small but significant elevation of basophils during the ragweed season; and (3) the elevation of basophils in the atopic group during symptoms is significantly greater than in the nonatopic group during the ragweed season.     

Bone conduction speech audiometry in normal subjects

The present study was designed to investigate: (1) the relationship among bone conduction (BC) pure tone averages, BC speech reception thresholds (SRTs), and BC speech detection thresholds for normal subjects; (2) short term reliability of BC SRTs; and (3) characteristics of the articulation functions for spondees obtained by bone conduction. Twenty-five normal-hearing young adults participated. The data revealed that BC SRT-pure tone average and SRT-speech detection threshold relationships are essentially the same as for air conduction. A comparison of the articulation functions for air conduction and BC revealed no practical difference between the two modes of stimulus presentation.     

Inducing schizophrenic associations in normal subjects.

L. S. Levitz and L. P. Ullmann (see record 1970-03762-001) found that normal Ss can increase their number of uncommon associations in response to instructions and reinforcement. Using 40 college students, the present study replicated this finding with a concurrent measure of response latency, and as predicted, the increase in uncommon associations was accompanied by an increase in response latency. Results are consistent with the theory that instructions induce normals to change their responses by means of an editing process, and it is suggested that such editing of responses is a "symptom" of normal flexibility rather than a model of the development of schizophrenic thought disorder. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface activity of tear fluid in normal subjects

BACKGROUND: Microsporum-canis-infected cats, especially the asymptomatic infected ones, are mainly responsible for the zoonotic disease. The important variability of the clinical signs in cats is poorly understood. Recently, a 31.5-kD keratinolytic subtilase was found to be a putative virulence factor. OBJECTIVE: To investigate the possible relationship between the clinical status of dermatophytic cats and the production of the keratinase. METHODS: Seven M. canis strains isolated either from clinically affected, asymptomatic infected or mechanical carrier cats were tested for the in vitro production of the enzyme. The immunohistochemical detection of the enzyme was also assessed in skin biopsies of 4 symptomatic and 7 asymptomatic naturally infected cats. RESULTS: All the strains produced in vitro a 31.5-kD keratinolytic subtilase. The enzyme was present in all but 1 of the infected cats. CONCLUSION: The production of the keratinase is not a factor directly responsible for the clinical picture seen in M.-canis-infected cats.     

Gender-related dissociations of categorical fluency in normal subjects and in subjects with Alzheimer's disease.

Semantic fluency tasks, with the categories of birds and furniture as stimuli, were administered to normal subjects and patients with Alzheimer's disease (AD). Normal subjects showed a gender-related double dissociation consistent with the literature data because men were more fluent with the birds category and women with the furniture category. Also, patients with AD showed a Gender × Category interaction, but the double dissociation between birds and furniture was not present because of a prevalent impairment of the living category birds that was irrespective of gender. This pattern of impairment in patients with AD was independent from the disease stage. The authors conclude that (a) gender-related categorical effects cannot be considered as inborn, sex-related cognitive differences but as familiarity effects and (b) both lesion-related and familiarity-related factors must be taken into account to explain category-specific effects of patients with brain damage and patients with AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Limited conscious monitoring of motor performance in normal subjects

Normal subjects traced sagittal lines on a graphic tablet using a stylus held in their right hand. The hand was hidden by a mirror in which they saw the lines projected from a computer screen. In normal trials, the line seen in the mirror exactly corresponded to the traced line. In perturbed trials, a bias was introduced by the computer, so that the line appeared to deviate in one direction (right or left) by a variable angle (2, 5, 7 or 10 degrees). Subjects consistently displaced their hand in the opposite direction for producing a visually sagittal line. After each trial, they were asked in which direction they thought their hand had moved. In perturbed trials, they grossly underestimated the hand deviation. In addition, a post-hoc analysis revealed that one group of subjects misperceived the direction of their hand movement in the direction opposite to the perturbation (Group 1, including 9 Ss), whereas the other group gave responses in the correct direction (Group 2, including 4 Ss). In a second session using the same experimental paradigm, a motor response was asked for: subjects had to indicate the perceived direction of their hand during each trial by drawing a line with their eyes closed. Again, responses indicated a poor conscious monitoring of motor performance. These results suggest that normal subjects are not aware of signals generated by their own movements.     

Topographical distribution of spindles and K-complexes in normal subjects

To assess the topographical distribution of sleep spindles and K-complexes, four 15-minute samples of stage 2 sleep in a group of eight healthy young adults were analyzed. Results show that a majority of spindles generated are detected over central regions, and that K-complexes are markedly predominant over prefrontal and frontal regions. These findings are consistent with the single-spindle generator hypothesis and raise questions concerning the Rechtschaffen and Kales rules for scoring K-complexes.     

Perception of the upright in normal and schizophrenic subjects

To see the effects of a large angle of frame-tilt, movement of the rod in the clockwise direction, and the difference between the normal and schizophrenic subjects in the perception of the upright, a mixed design (subjects X angle X presentation X trial) was used. 24 normal and 24 schizophrenic subjects were tested in a darkroom with a rod-and-frame test. The results showed a small error with a clockwise movement of the rod, when the frame also was tilted clockwise, and no difference in perception of the upright between the normal and schizophrenic subjects.     

Variability of hepatic vein Doppler tracings in normal subjects

A prospective study was undertaken to determine the variability of hepatic vein Doppler waveforms in normal subjects. Seventy-five patients without liver or heart disease underwent Doppler examination of the middle hepatic vein. Normal triphasic tracings were observed in 68 subjects, while flattened tracings were observed in seven subjects. In addition, in four of the seven subjects with flattened tracings, an increase in pulsatility was seen during prolonged inspiration. We conclude that there is variability of hepatic vein tracings in normal subjects and that respiratory maneuvers can alter these tracings.     

Intraseptal scopolamine has differential effects on Pavlovian eye blink and heart rate conditioning.

Evaluated the effects of intraseptal scopolamine hydrobromide (40 μg) injections on Pavlovian (classical) conditioning, with tones used as the CS and a periorbital electric shock train as the UCS, using New Zealand albino rabbits. Eyeblink (EB) and heart rate (HTR) CRs were concomitantly recorded. Although injections of scopolamine into the medial septum impaired the acquisition of the Pavlovian conditioned eyelid reflex, these injections enhanced the magnitude of accompanying Pavlovian conditioned HTR decelerations. However, scopolamine applied to the lateral septal area had no effect on EB conditioning, relative to the vehicle; like medial injections, scopolamine also enhanced the magnitude of the accompanying HTR decelerations. Results are compatible with those of previous investigations indicating that medial septal dysfunction impairs somatomotor conditioning but leaves autonomic conditioning intact and that septal dysfunction produces a parasympathetic bias of the cardiovascular system. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manipulation of indications of disturbed thinking in normal subjects.

Presents data to support a behavioral model of schizophrenia which predicts that "normal" people emit indications of disturbed thinking (IDT) and that the rate of emitted IDT will be affected by environmental manipulations. 2 2 * (presence or absence of reinforcement; use or nonuse of instructions) experiments were conducted with 48 undergraduates. In Exp. I, Holtzman inkblots (HIT) served as the pretest-posttest measure and a word association test (WAT) was used for training; in Exp.II, the WAT was the pretest-posttest measure and HIT was used for training. Results indicates that: (a) both reinforcement and instructions affected IDT rates on both HIT and WAT during training; (b) training results generalized to the pretest-posttest task; and (c) compared to reinforcement, instruction led to a more rapid but less durable increase in IDT. (36 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fructosamine in obese normal subjects and type 2 diabetes

Occult coronary artery disease often accompanies symptomatic peripheral vascular disease and has an important effect on survival. Most perioperative and late fatalities after peripheral vascular operations are due to cardiac causes. Noninvasive cardiac testing can identify patients at increased risk for postoperative cardiac complications, although controversy exists regarding the optimal preoperative evaluation. Risk reduction strategies for patients known to be at high risk are also controversial. Some authors advocate coronary revascularization with coronary artery bypass grafting or percutaneous transluminal coronary angioplasty before the vascular procedure. Others believe that the combined morbidity and mortality of 2 operations exceed those of a peripheral vascular operation performed with aggressive monitoring and medical therapy. Continuous electrocardiographic monitoring after an operation has identified silent myocardial ischemia as a powerful predictor of cardiac complications. Ongoing research is likely to provide insights into the pathogenesis of postoperative cardiac complications and may lead to specific therapeutic interventions. Few prospective studies have been done in this area, and the threshold for preoperative and postoperative intervention is unknown. I review the literature and present an algorithm to guide cardiac testing and risk reduction in patients undergoing elective vascular surgical procedures.     

Characterization of multi-input electroretinogram using normal control subjects

BACKGROUND: The multi-input electroretinogram (ERG) has recently been developed to analyze focal retinal responses in the central region and is expected to become a powerful tool for management of retinal diseases. The relationship between the obtained ERG response and retinal neuronal functions is not yet fully understood. METHOD: In the present study, in order to study the spatial retinal functions; multi-input ERGs were recorded from 14 healthy subjects under several illumination conditions modulating photoreceptor functions. RESULTS: The first-order kernel amplitudes were changed in correspondence to the cone photoreceptor adaptation states under different background illuminations. A strong flash exposure significantly lowered the amplitude (approximately 70%) within the central 15 deg but lowered it only slightly (10-20%) in the peripheral areas outside the central 15 deg. Similar effects were observed when the stimulus luminance was lowered by neutral density filters. CONCLUSION: Our data suggest that a newly developed multi-input measurement of ERGs represents signals within the firing of postreceptor neurons from cone photoreceptors at specific areas. Thus, this analysis is a useful tool for mapping the spatial network of neurons in the central region.     

The masculinity-femininity dimension in normal and psychotic subjects.

A research was designed to test hypotheses derived from psychoanalytic theory that psychotic and normal women differ in their responses to measures of different levels of masculinity organization. "On the DC (Drawing Completion Test), the psychotic women obtain more masculine scores than do normals. However, using the DAP (Draw-A-Person Test) as a measure of body image, only two of four measures yielded significant differences, and these did not hold up on cross-validation. The verbal statements of normal women concerning masculinity-femininity status correspond more closely to their respective measures of body image status than do those of psychotic women." Theoretical implications of findings and areas for future research are discussed. 22 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenic-like responses in normal subjects under time pressure.

"It was hypothesized that the conceptual performance of normal Ss working under time pressure would deteriorate as a result of an increase in associative intrusions, and would thus more nearly resemble the performance of schizophrenics. Twenty-eight Ss were given a conceptual card sorting task in which for each sorting choice there were three alternatives, one of which was the correct conceptual response, one an associative distracter, and one which was neither, called… the irrelevant response… . increasing the speed of response produced an increase in an schizophrenic-like kind of error." (PsycINFO Database Record (c) 2010 APA, all rights reserved)