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PubMed1991

Social network and social support deficits in depressed patients: a result of distorted perception?

Many studies have indicated that depressed individuals show deficits in social network/social support. However, little attention has been paid to the extent to which the illness itself causes these deficits that, owing to the distortion of perception of depressed patients, might be experienced subjectively, but do not necessarily exist objectively. To examine this question, a prospective study was conducted with hospitalized depressed patients. In accordance with the assumption that the duration of illness has a special impact on social resources, the sample was divided into two groups: individuals with single episodes of depression (n = 25) and with recurrent depression (n = 25). At the beginning of hospitalization both groups showed massive deficits in social network/social support. Depressed individuals with single episodes showed fewer deficits, the more the depression improved. In contrast, such a covariation of severity of depression and the amount of experienced deficits was not found among the individuals with recurrent depression.

Adult↗
PubMed1987

Intravenous procaine as a probe of limbic system activity in psychiatric patients and normal controls.

Evidence from animal and human studies suggests that procaine hydrochloride may selectively activate limbic system structures and suppress neocortical structures. We administered a series of intravenous bolus doses of procaine hydrochloride to 31 subjects (7 with affective disorders, 17 with borderline personality disorder, and 7 healthy normal volunteers). Dose-related cognitive and sensory distortions and illusions were observed; affective experiences ranged widely from euphoric to dysphoric. Topographic electroencephalogram (EEG) analysis indicated selective increases in fast activity (26-45 Hz) over the temporal lobes; the degree of increase in this activity correlated with degree of dysphoria experienced. Procaine was associated with increases in secretion of cortisol, adrenocorticotrophic hormone (ACTH), and prolactin, but not with growth hormone. These preliminary data are consistent with the possibility that procaine might serve as a clinically useful probe of psychosensory, affective, electrophysiological, and endocrine effects referable to the limbic system.

Adrenocorticotropic Hormone↗
PubMed2003

Neuronal activity changes and body image distortion in anorexia nervosa.

Body image distortion is a major and often persistent symptom in anorexia nervosa. During a functional imaging investigation we confronted female anorectic patients and healthy controls with their own digitally distorted body images using a computer-based video-technique. Our findings indicate activation of the attention network as well as of structures involved in visuo-spatial processing and self-reflection in both groups. Anorectic patients showed a greater activation in the prefrontal cortex (BA 9) and the inferior parietal lobule (BA 40), including the anterior intraparietal sulcus, than did controls. However, an analysis of the BOLD-response in the IPL area revealed that anorectic patients showed only a specific increase in activation to their own pictures than to others indicating different visuo-spatial processing, while controls did not differentiate.

Adolescent↗
PubMed2003

Thapsigargin suppresses cochlear potentials and DPOAEs and is toxic to hair cells.

Thapsigargin, a drug that inhibits sarco-endoplasmic reticulum Ca(2+) ATPases (SERCAs), was infused into the perilymph compartment of the guinea pig cochlea in increasing concentrations (0.1-10 microM) while sound evoked cochlear potentials were monitored. Thapsigargin significantly suppressed the compound action potential of the auditory nerve, cochlear microphonics, and increased N(1) latency at low (56 dB SPL) and high intensity (92 dB SPL) levels of sound, suppressed low intensity sound evoked summating potential (SP) and greatly increased the magnitude of the high intensity sound evoked SP. At 10 microM, the drug suppressed the cubic distortion product otoacoustic emissions (2f(1)-f(2)=8 kHz, f(2)=12 kHz) evoked by both high and low intensity primaries (45, 60, 70 dB SPL). Thapsigargin (10 microM; 30 min) increased the endocochlear potential slightly (5 mV). In chronic animals, thapsigargin (10 microM; 60 min) destroyed many outer hair cells and some inner hair cells, especially in the basal turns. These effects are consistent with the hypothesis that the inhibition of the SERCAs affects the function of the cochlear amplifier and outer hair cells to a greater degree than it affects other functions of the cochlea.

Acoustic Stimulation↗
PubMed1980

Perceived spatial frequency of flickering gratings: a local spatial distortion.

Perceived spatial frequency of a low-frequency grating increases if the grating contrast is temporally modulated at about 4 to 16 Hz. The amount of increase can be up to 50% as estimated by a grating-match technique. It is shown here that the illusion is not a simple spatial-frequency shift phenomenon but also involves local spatial distortions. This was discovered by using the method of distance match, in which the perceived length of a spatial period or its multiples was estimated in a flickering grating. The results indicate that the illusory increase in perceived spatial frequency does not predict the perceived period length of a grating in a simple reciprocal manner. The decrease in the apparent period length is restricted to distances covering only one or two spatial cycles. This points out that care should be taken in interpreting various illusory changes in spatial frequency simply as shifts of frequency. The results are interpreted as demonstrating the operation of a size-analyzing mechanism which has a limited spatial bandwidth and which is sensitive to flicker-induced disturbances.

Humans↗
PubMedDate not supplied

A case study of space-time distortion during a total lunar eclipse following street use of LSD.

Although psychedelics can induce "cosmic" consciousness through severe distortions of time and space perceptions, little attention has been given to examination of this psychopharmacological property. With the hope of providing an impetus to further research in this area, a case of cosmic perception under the influence of LSD is reported which included the apparent movement of consciousness to the lunar surface combined with the experience of remote viewing of the Milky Way galaxy. While the possibility of veridical remote viewing is unlikely, it is speculated that the neurocognitive action of LSD can sensitize the user to focused bright light, associated memories, and creative elaborations during actual eclipse events. Experimenters are urged to adopt precautions to avoid potentially detrimental effects of pharmacologically manipulating the space-time continuum.

Adult↗
PubMed1989

Distorting patient or distorting instrument? Body shape disturbance in patients with anorexia nervosa and bulimia.

Three current techniques for estimating body size (Image Marking, Visual Size Estimation, and Distorting Video techniques) were compared. Anorexia nervosa and bulimic patients and normal control subjects were required to make size judgments of the way they 'knew' they looked, the way they 'felt' they looked, and of the width of an inanimate control object. Results from the three techniques were not the same, thus implying that research findings can no longer be cross-compared. Moreover, while all subjects were similar in the accuracy of their estimation of a control object, anorexia nervosa and bulimic patients overestimated their own body size significantly more than normal controls. This difference was even more marked when affective instructions were compared.

Adolescent↗
PubMed2002

Distortion product otoacoustic emissions in frogs: correlation with middle and inner ear properties.

Four frog species, Rana pipiens, Scaphiopus couchii, Xenopus laevis and Bombina orientalis, were examined for distortion product otoacoustic emissions (DPOAE). These species were chosen for their diverse otic morphologies. Rana has a well-developed caudal extension of the amphibian papilla within the inner ear; Scaphiopus, Xenopus and Bombina do not. Rana and Scaphiopus have a tympanic middle ear, Xenopus has a subcutaneous tympanic disk and Bombina has only an operculum. DPOAEs were present in Rana and Xenopus, with amplitudes up to 55 and 20 dB SPL, respectively. DPOAEs could be detected in neither Scaphiopus nor Bombina. These results show that (1) a well-developed caudal extension is not necessary for generation of DPOAEs, and (2) a tympanic middle ear is neither required nor sufficient to have DPOAEs.

Animals↗
PubMed2006

Distortion product otoacoustic emissions: a time domain analysis.

Distortion product otoacoustic emissions (DPOAEs) provide relatively easily accessible external information about internal properties of the inner ear. A primary result is that the detection of normal DPOAE components is a strong indicator of normal functioning of the cochlear mechanics. The details of amplitude and phase behavior of the DPOAEs, and the development over time (DPOAE delay) are not fully understood and subject of some debate. In this paper, I would like to emphasize the view that precise time domain experiments and time domain model analysis provide a superb tool, the power of which is generally underestimated. Results are presented from a model analysis in which the primary-tone phase variation technique introduced by Whitehead et al. was employed successfully.

Acoustic Stimulation↗
PubMed1992

[Errors of monocular localization in strabismic amblyopia. Two-dimensional distortion].

Spatial distortions, i.e. spatial localization errors, and precision of localization were measured monocularly in the central visual field of 7 normal observers, 17 strabismic amblyopes and 2 anisometropic amblyopes. The task of the subjects was to construct circles of 2 degrees, 4 degrees and 6 degrees radius around a fixation point, using the dominant and the amblyopic eye in turn. Normal observers set distances on the vertical meridian smaller than distances on the horizontal meridian. Anisometropic amblyopes showed localization errors and variances similar to those of normal observers. The amblyopic eyes of strabismic observers with a large angle strabismus and deep amblyopia showed significant, individually different localization errors correlating with the depth of amblyopia. Strabismics with microstrabismus exhibited parallels between monocular localization and dichoptic retinal correspondence.

Amblyopia↗
PubMed1995

Monitoring cochlear function intraoperatively using distortion product otoacoustic emissions.

Distortion product otoacoustic emissions (DPOAEs) elicited by a bitonal stimulus complex are low-level sounds that are generated within the cochlea, and are easily measured by a miniature microphone system placed in the external auditory canal. Under conditions of rapid measurement, DPOAEs have been shown in an animal model to be exquisitely sensitive to interruption of the blood supply to the inner ear. Currently, there is no real-time procedure available for monitoring hearing function intraoperatively during neurotologic surgery. The goal of the present study was to determine the utility of DPOAEs in monitoring cochlear status intraoperatively, particularly during procedures commonly used to remove acoustic neuromas. Distortion product otoacoustic emissions were measured pre- and intraoperatively in 11 patients, who were under general anesthesia for a variety of otolaryngologic procedures, including acoustic neuroma resection. High frequency emissions (i.e., > or = 4 kHz) were less affected by the elevated levels of acoustic noise present in the operating-room environment, thus permitting emitted responses to be updated as quickly as every 2 seconds. However, a number of technical problems were encountered and addressed during development of the emission monitoring technique. Despite these difficulties, overall, DPOAEs appear to be a promising adjunct to the intraoperative monitoring of auditory function.

Acoustic Impedance Tests↗
PubMed1990

Effect of contralateral sound stimulation on the distortion product 2F1-F2: evidence that the medial efferent system is involved.

The mechanical nonlinearity of the cochlea that is associated with normal cochlear function, induces distortion products that can be recorded in the external auditory canal. The acoustic cubic distortion product 2F1-F2 (DP) was measured in the external canal in the presence and in the absence of a contralateral white noise. The experiments were carried out on 20 guinea pigs after a section of the middle ear muscles. They showed that the presence of a contralateral white noise induces a significant reversible reduction of the magnitude of the DPs. This suppressive effect produced by the contralateral white noise was completely canceled out by the midline sagittal section of the brainstem. This report supports the hypothesis that the suppressive effect of a contralateral sound stimulation is mediated by the medial efferent system.

Acoustic Stimulation↗
PubMed2004

Correcting distorted perception of sleep in insomnia: a novel behavioural experiment?

Patients with primary insomnia overestimate their sleep onset latency (SOL) and underestimate their total sleep time (TST). The present study aimed to test the utility of a novel behavioural experiment designed to correct distorted perception of sleep among patients diagnosed with primary insomnia. Individuals with primary insomnia were asked to wear an actigraph and keep a sleep diary for three nights. On the following day, half were shown the discrepancy between the data recorded on the actigraph and their sleep diary (Shown-Discrepancy Group), the other half were not shown the discrepancy (No-Demonstration Group). Participants were then asked to wear the actigraph and keep a sleep diary for three further nights. Following the behavioural experiment, the Shown-Discrepancy Group estimated their SOL more accurately and reported less anxiety and preoccupation about sleep compared to the No-Demonstration Group. The theoretical and clinical implications of these findings are discussed.

Adolescent↗
PubMed2004

Spatial distortions and processing latencies in the onset repulsion and Fröhlich effects.

In the Fröhlich illusion, the first position of a moving target is mis-localized in the direction of motion. In the onset repulsion effect, the opposite error occurs. To reconcile these conflicting error patterns, we improved previous methods by using natural pointing movements and a large range of target velocities. Displacement was found to increase in the direction of motion, but the linear function relating velocity and displacement was shifted opposite to the direction of target motion. The results suggest that onset localization may be determined by two independent factors: first, an (attentional) delay that accounts for the increase of displacement in the direction of motion with increasing velocity. This delay is visible in motor and probe judgments and explains the Fröhlich illusion. Second, motor judgments are offset opposite to the direction of target motion. This bias is unique to motor judgments (pointing) and may be partially explained by attentional repulsion.

Humans↗
PubMed1993

Occlusion and the distortion of alignment in three-dimensional space.

When observers are asked to align two rectangular stimuli oriented at 45 degrees to the visual axis there is a slight tendency to set the more distant stimulus closer to the eye than its true coplanar position. However, when a large rectangular surface is interpolated between the two oblique stimuli and the observer, errors of alignment become relatively much larger. The displacement caused by the interpolated stimulus occurs both when the display is viewed monocularly and when it is viewed binocularly. Reducing the obliquity of the rectangles results in smaller judgment errors and increasing obliquity increases errors; this is true with and without occlusion. The addition of texture elements to the surfaces of the rectangles reduces judgment errors significantly, but only under conditions of occlusion. It is possible that misalignments recorded for three-dimensional displays have something in common with the two-dimensional Poggendorff illusion.

Adult↗
PubMed2004

Body-image dissatisfaction in gay versus heterosexual men: is there really a difference?

BACKGROUND: Gay men are thought to experience body-image concerns or disorders more frequently than heterosexual men. It is unclear, however, whether these putative concerns are due to unrealistic body ideals (aspiring to a body shape that is difficult or impossible to attain), body-image distortion (misperceiving the actual shape of one's body), or both. METHOD: We administered a well-established computerized body-image test, the "somatomorphic matrix," to 37 gay men recruited from the community in April 1999 and compared the results with previous data from 49 community-recruited heterosexual comparison men and 24 clinic-recruited heterosexual men with eating disorders. RESULTS: Gay men were indistinguishable from the community-recruited heterosexual comparison men on measures of both body ideals and body-image distortion. By contrast, eating-disordered men were significantly distinguishable from both other groups on body-image distortion. The lack of differences between community gay and heterosexual men on body-image indices seems unlikely to represent a type II error, since the somatomorphic matrix showed ample power to detect abnormalities in the eating-disordered men, despite the smaller sample size of the latter group. CONCLUSION: Contrary to our hypotheses, gay men did not differ significantly from heterosexual men on measures of body image. These unexpected findings cast doubt on the widespread belief that gay men experience greater body-image dissatisfaction than heterosexual men. If our findings are valid, it follows that some previous studies of body image in gay men may possibly have been influenced by selection bias.

Adult↗
PubMedDate not supplied

Contrast enhancement of the retinal image and image distortion associated with macular degeneration.

An analysis of image distortion in connection with macular degeneration revealed that seeing objects requires brightness contrast enhancement. Thus macular degeneration changes neural interaction controlling bipolar cell responses to light stimulating photoreceptors to reverse spatial brightness contrast enhancement with the consequence that objects cannot be seen. This shows that the contrast of the retinal images is too low for vision without enhancement. However images consisting of randomly arranged small spots of different brightness are seen because of cones enhancing bipolar cell responses to rod input and rods enhancing bipolar cell responses to cone input. This residual vision and the observation that image distortion disappears at low light intensities reveal that macular degeneration is a functional disorder with intact photoreceptor function. The affection may therefore be caused by a reduction of blood flow through the choriocapillaries associated with ageing. The analysis of image distortion associated with the affection led to a simple way to determine the size of the affected retinal area, making it possible to follow the progression of the affection in a direct and simple way. Basic aspects are described of synaptic interaction within the information processing unit that determines the responses of the bipolar cells to photoreceptor input. This unit is the first information processing unit that has been revealed thanks to the extension of the analysis of the nervous system to the nanometer level at which information is processed. The minute size of the information processing unit, the special conditions for synaptic transmission combined with the short distances separating the synapses create special conditions for neural interaction at the nanometer level, establishing conditions for high speed neural communication.

Animals↗
PubMed1991

Memory psychophysics for areas: distortion in natural memory of a school campus.

As the perceived magnitude of a stimulus is related by power function t o the physical magnitude, the remembered visual areas and length are also related by power function to the actual areas and length. The main purpose of this study is to examine whether the power law is also applicable to remembered areas in natural environment, e.g., a school campus, and to its old memory. 31 junior high students and seven university undergraduates who graduated from the same junior high school seven years before were asked to draw a layout of the school campus. The areas of the school facilities and field, and other features of drawings such as the number of recalled facilities and objects, and direction of the sketch were assessed. Analysis showed that the areas remembered by the junior high subjects followed the power law while those remembered by the undergraduates did not. The divergence of exponents observed for undergraduates was accounted for by reconstruction by schema.

Adolescent↗