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PubMed1995

Brief report: thought disorder in Asperger syndrome: comparison with high-functioning autism.

Asperger syndrome (AS) is a pervasive developmental disorder generally regarded as a variant of autism. While it has been included in the ICD-10 and DSM-IV as a distinct diagnostic entity, it is still unclear to what extent it differs from high-functioning autism (HFA). Persons with HFA have been reported to show a variety of deficits of thought processes. Abnormalities such as poor reality testing, perceptual distortions, and areas of cognitive slippage have been described using the Rorschach inkblot test (Dykens, Volkmar, & Glick, 1991). Since AS has been conceptualized as a mild variant of autism, we hypothesized that persons with AS will have fewer abnormalities on the Rorschach test compared to persons with HFA. To test this hypothesis, we compared 12 subjects with AS (ICD-10, 10 male, mean age = 12.2 +/- 3.3 years, mean full-scale IQ = 99.6) with 8 subjects with HFA (ICD-10/DSM-III-R, 7 male, mean age = 12.2 +/- 3.8 years, mean full-scale IQ = 83.4) on the Rorschach test. AS subjects demonstrated a trend towards greater levels of disorganized thinking than the HFA group. They were also more likely to be classified as "Introversive" suggesting that AS subjects may have more complex inner lives involving elaborate fantasies, Also, AS subjects tended to be more focused on their internal experiences. However, overall, the Rorschach test was not found to differentiate the two diagnostic groups on the majority of structural variables. Implications of these findings are discussed with regard to the diagnostic validity of Asperger syndrome.

Adolescent↗
PubMed1991

Though disorder in high-functioning autistic adults.

Examined thought disorder in a sample (n = 11) of high-functioning autistic young adults and older adolescents (mean IQ = 83) utilizing objective ratings from the Thought, Language and Communication Disorder Scale (TLC Scale) and projective data from the Rorschach ink blots. Results from the TLC Scale pointed to negative features of thought disorder in this sample (e.g., Poverty of Speech). Rorschach protocols revealed poor reality testing and perceptual distortions in every autistic subject, and also identified several areas of cognitive slippage (e.g., Incongruous Combinations, Fabulized Combinations, Deviant Responses, Inappropriate Logic). Comparing TLC Scale and Rorschach results to schizophrenic reference groups, autistic subjects demonstrated significantly more Poverty of Speech and less Illogically on the TLC Scale, and on the Rorschach they evidenced features of thought disorder that are encountered also in schizophrenia. Results are discussed in relation to the measures employed, and to areas of similarity and difference between autism and schizophrenia.

Adolescent↗
PubMed2003

Relative contributions of visual and vestibular information on the trajectory of human gait.

Seven healthy individuals were recruited to examine the interaction between visual and vestibular information on locomotor trajectory during walking. Subjects wore goggles that either contained a clear lens or a prism that displaced the visual scene either 20 degrees to the left or right. A 5-s bipolar, binaural galvanic stimulus (GVS) was also applied at three times the subject's individual threshold (ranged between 1.2 to 1.5 mA). Subjects stood with their eyes closed and walked forward at a casual pace. At first heel contact, subjects opened their eyes and triggered the galvanic stimulus by foot switches positioned underneath a board. Reflective markers were placed bilaterally on the shoulders as the walking trajectory was captured using a camera mounted on the ceiling above the testing area. Twelve conditions were randomly assigned that combined four visual conditions (eyes closed, eyes open, left prism, right prism) and three GVS conditions (no GVS, GVS anode left, GVS anode right). As subjects walked forward, there was a tendency to deviate in the direction of the prisms. During GVS trials, subjects deviated towards the anode while walking, with the greatest deviations occurring with the eyes closed. However, when GVS was presented with the prisms, subjects always deviated to the side of the prisms, regardless of the position of the anode. Furthermore, the visual-vestibular conditions produced a larger lateral deviation than those observed in the prisms-only trials. This suggests that the nervous system examines the sensory inputs and takes into account the most reliable and relevant sensory input.

Adult↗
PubMed2005

Face perception: an integrative review of the role of spatial frequencies.

The aim of this article is to reinterpret the results obtained from the research analyzing the role played by spatial frequencies in face perception. Two main working lines have been explored in this body of research: the critical bandwidth of spatial frequencies that allows face recognition to take place (the masking approach), and the role played by different spatial frequencies while the visual percept is being developed (the microgenetic approach). However, results obtained to date are not satisfactory in that no single explanation accounts for all the data obtained from each of the approaches. We propose that the main factor for understanding the role of spatial frequencies in face perception depends on the interaction between the demands of the task and the information in the image (the diagnostic recognition approach). Using this new framework, we review the most significant research carried out since the early 1970s to provide a reinterpretation of the data obtained.

Attention↗
PubMed1994

Neuropsychiatric disorders, myoclonus, and dystonia in calcification of basal ganglia pathways.

Two cases of basal ganglia calcification involving the globus pallidus are presented. Both patients had cognitive dysfunction, temporal lobe-like symptoms (including amnestic state, perceptual distortions, or complex visual hallucinations), and myoclonus. Patient 1 manifested depression, auditory hallucinations, anxiety, paranoia, and postural tremor; patient 2 manifested multifocal dystonia with dystonic tremor. These cases supplement other reports of psychotic features and dementia associated with pallidal pathology. Additionally, the phenomena encountered in these cases are considered in light of recent advances in our understanding of basal ganglia functional pathways. These cases afford a potential pathophysiological window to the possible role of the globus pallidus in these neuropsychiatric conditions. In concert with other recent findings, these cases suggest specific pathway involvement in hallucinations, paranoia, depression, myoclonus, and dystonia. Further research will indicate if these pathways play a role in schizophrenia, mood disorders, and anxiety disorders.

Adult↗
PubMed1977

The effects of phencyclidine on visually evoked potentials of rhesus monkeys.

Phenyclidine (Sernylan) was given intramuscularly to 12 rhesus monkeys and electroencephalograms and visually evoked potentials to photic stimulation were recorded. Phencyclidine has profound effects upon VEP's, particularly a marked enhancement of positive components maximal around 100 msec after stimulus presentation. Most likely these effects are related to the level of surgical anesthesia, Stage III, phase I. A correlation was suggested between the increased amplitude of VEP's and the psychotic clinical manifestations of visual perceptual distortions. Physicians and investigators should be aware of the striking effects of this compound, now widely used as a street drug "angel's mist" of "angel's dust", on neurophysiological functions.

Animals↗
PubMed1991

The problem of feedback in hearing aids.

One of the factors that limits hearing-aid performance is feedback. This paper discusses the problem of feedback in hearing aids, illustrated with examples based on a computer simulation of hearing-aid behavior. The available technology for dealing with the problem of feedback is then reviewed, and new digital signal-processing approaches are described that may finally solve the feedback problem.

Equipment Design↗
PubMed1984

Impaired glycine-serine conversion and increased plasma taurine levels in episodic psychotic patients with psychedelic symptoms.

A disturbance of serine-glycine metabolism has been demonstrated in patients suffering from episodic acute psychosis, characterized by sensory perceptual distortions in whom oral loading with either serine or glycine induced psychedelic symptoms. Fasting plasma amino acid levels in oral serine-responsive patients were compared with those in glycine-responsive and manic-depressive patients. Only serine-responsive patients had a decreased plasma serine and increased plasma taurine concentration, while glycine responsive patients showed decreased alanine and manic-depressive patients an increased plasma glycine level. Amino acid analyses of plasma samples obtained after serine loading in patients and controls suggest that serine-responsive patients had an impaired conversion of glycine into serine. The results suggest that the higher plasma taurine level in serine-responsive patients is caused by an increased synthesis of taurine from homocysteine and serine. The limiting capacity of methyltetrahydrofolate-homocysteine methyltransferase coupled to increased formation of taurine may be responsible for the serine-evoked psychotic syndrome.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1985

Is reduced vernier acuity in amblyopia due to position, contrast or fixation deficits?

Poor vernier acuity, exhibited by amblyopes, may reflect anomalies related to eccentric fixation, deficient position sensitivity, or reduced contour visibility. We have examined these factors by measuring contrast and vernier sensitivities with stimuli consisting of extended sinusoidal gratings of several spatial frequencies. Vernier thresholds were measured using both a classical single step position change and also a grating that was position-modulated sinusoidally along its entire length. For both types of target amblyopes exhibited deficient displacement sensitivity although accurate fixation was not strictly required. The vernier deficits were not critically dependent upon the type of displacement used, and the magnitudes of the vernier and contrast sensitivity deficits were closely related. Both were largest at high spatial frequencies, and those amblyopes with larger contrast sensitivity deficits also had larger vernier acuity deficiencies. Typically, contrast sensitivity and vernier acuity were normal, or nearly so, at very low spatial frequencies. Also, vernier acuities for the amblyopic and non-amblyopic eyes were approximately equal if grating contrast was set at some fixed multiple of detection threshold. We did not find a close relationship between the magnitude of the vernier deficit and reported perceptual distortions.

Amblyopia↗
PubMed1994

Visual loss during interocular suppression in normal and strabismic subjects.

Visual acuity was measured in one eye during monocular vision, and while the fellow eye viewed stimuli not including the acuity target. The aim was to find how acuity in one eye is reduced by going from monocular to binocular viewing. In normal subjects, acuity was at its lowest during the suppressive phase of binocular rivalry, was reduced less when the fellow eye viewed a contoured nonrivalrous stimulus, and was not reduced at all when the stimulus to the fellow eye consisted of a uniformly lit field. In strabismic subjects, by contrast, acuity was markedly reduced in going from monocular to binocular viewing no matter what stimulus was viewed by the fellow eye. Pathological suppression is therefore largely independent of the inducing stimulus. It was also shown that acuity in the nonstrabismic eye of some of the strabismic subjects was improved by allowing the strabismic eye to view; these were the subjects with the greatest depths of amblyopia.

Adolescent↗
PubMed1979

Maternal responsiveness in the squirrel monkey following chronic administration of delta 9-THC.

Mother squirrel monkeys were orally administered gradually increasing doses of delta 9-THC (from 0.5 to 5.0 mg/kg) 5 days/wk from 2 wk to approximately 6 mo after birth. After having received a dose of 5.0 mg/kg for an average of 3.5 mo, drug-treated mothers were then compared with control mothers in terms of theri responsiveness both to their own and to unrelated infants. In contrast to the control mothers whose response pattern clearly showed differentiation of their own and other infants, the mothers that received delta 9-THC responded in much the same manner to the alien infant as they did to their own infant. The results show that the behavior of the THC-exposed mothers was not attributed simply to a general reduction in their responsiveness toward their offspring or to an overall reduction in their own state of arousal. Rather, the results suggest that chronic ingestion of delta 9-THC caused the mothers to be less disturbed by separation from their infants and/or produced degree of perceptual distortion that prevented them from responding selectively to the different infants.

Animals↗
PubMed1983

Serine and glycine-induced catalepsy in porphyric rats: an animal model for psychosis?

It was investigated whether an increased demand for glycine, as postulated to occur in patients who have suffered from episodic psychoses accompanied by multiple perceptual distortions, could evoke psychotic reactions. Catalepsy was used as a measure for psychosis and was observed after injection of serine or glycine in porphyric rats. Catalepsy was was shown to occur after serine as well as glycine administration in 2-allyl-2-isopropylacetamide (AIA) pretreated rats, while in lead (Pb) + phenobarbital pretreated rats only glycine was effective. Administration of AIA to rats resulted in a strongly enhanced excretion of porphobilinogen (PBG) in urine, while Pb + phenobarbital pretreated rats showed increased excretion of delta-aminolevulinic acid (delta-ALA). The Pb + phenobarbital pretreated animals showed elevated serine plasma levels and lowered glycine plasma levels 18 hours after injection, while no significant differences in plasma levels of these amino acids were found 24 hours after AIA administration. In AIA or saline pretreated animals, but not in those pretreated with Pb + phenobarbital, glycine formation from serine was elevated. It is concluded that the present animal model can be used to investigate episodic psychoses.

Allylisopropylacetamide↗
PubMed1986

Self-reported cocaine reactions among social-recreational users: a factor analytic study.

The purpose of the present paper was to examine the latent structure of self-reported cocaine reactions among a purposive sample of 103 social-recreational users. From a set of 24 items, factor analysis yielded seven distinct factors: the first was indicative of minor reactions consistent with intranasal administration; the second was reflective of sensory-perceptual distortions; the third of stimulatory-insomnious effects; the fourth of paranoic-aggressive reactions; the fifth of positive social effects; the sixth of physio-logical-cardiovascular reactions; and the seventh of physical-psychological problems of a chronic nature. Although particular dimensions of cocaine reactions were suggested, future research could focus on the issue of the degree of seriousness of consequences of these underlying dimensions.

Adult↗
PubMed1979

Different behaviour of quadratic and cubic difference tones.

Level and phase of the cubic and quadratic difference tone were measured as a function of the primary tones' level, frequency separation, frequency region as well as of the frequency of an additional simultaneous masker. The results lead to the conclusion that quadratic and cubic difference tones are produced in different nonlinearities although both result in the same kind of adequate stimulus.

Auditory Perception↗
PubMed1985

A case study of monaural diplacusis.

A detailed examination of a case of monaural diplacusis is reported. Low-intensity pure tones presented within a certain frequency range do not sound "pure"; instead, the percept is that of "roughness", "multiple tones" or "beats". In addition, an aftertone is heard upon the cessation of certain tones. Psychophysical experiments (e.g., simultaneous masking, best beats and pitch matching) suggest that the monaural diplacusis results from an interaction between the external tone and an internal tone. The internal tone, however, does not appear to be manifest as a spontaneous oto-acoustic emission.

Acoustic Stimulation↗
PubMed2004

Does handedness influence the strength of phantom limb illusions in the virtual reality box?

Subjects had to judge the size of a tactile stimulus held in the unseen hand, while a visible phantom hand representing that unseen hand held a tactile stimulus of same or different size. No asymmetries in interference effects were found that could be related to hand or handedness. The method lends itself to quantification of virtual reality box illusions and can be used to evaluate the role of experience and sources of variability in the strength of the illusion across subjects.

Computer Simulation↗
PubMed2006

The impact of colour, spatial resolution, and presentation speed on category naming.

Studies of neurological patients with category-specific agnosia have provided important contributions to our understanding of object recognition, although the meaning of such disorders is still hotly debated. One crucial line of research for our understanding of category effects, is through the examination of category biases in healthy normal subjects. This approach has, however, led to contradictory findings with advantages both for natural kinds and for man-made things being documented in healthy subjects. It has been proposed that task conditions may influence the direction of advantage (Gerlach, 2001) and in particular, that sub-optimal viewing conditions underpin natural kinds advantages, while man-made advantages emerge under more optimal viewing conditions. In two experiments with normal subjects, we examined the roles played by spatial resolution (blurring), stimulus type (colour and texture), and speed of presentation in picture naming across category. In both experiments, healthy subjects showed a natural kind advantage for original stimuli and for blurred colour stimuli (at slow and fast presentation speeds), while an advantage for man-made things emerged for line-drawings that were blurred and presented slowly. The implications for category-specific object recognition deficits are discussed.

Adult↗