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Biomedical subjects

M Myslobodsky

Publications and source records attributed to M Myslobodsky.

At least 19 recordsLinked to original sources
PubMed2003

Gourmand savants and environmental determinants of obesity.

Obesity is an embodiment of a multifactorial problem with several intermediates in its casual pathway. Virtually all who have written on obesity have responded to four inter-related factors: genetic, perinatal, environmental, and consumption-expenditure energy imbalance. The message to take home is that while a molecular description of each participant of the obesity machinery seems achievable in principle, a complex model describing all of them is currently beyond our grasp. That is why the eradication of the obesity epidemic is seen in a more precise neuropsychological description of what is wrong with each subset of patients. This review proposes that the neuropsychiatric experience might be the most fundamental for it could help to refocus the view of obesity from 'traditional' environmental factors and lifestyle changes to those dominated by a more 'individual-centred' perspective in which different modes of causal attribution are appropriate. This review advocates the idea of environmental dependency as a determinant of obesity, which has been an important idea in neurosciences for more than 30 years with roots in three important areas: psychological, neuropsychiatric, and experimental. The neuropsychology of obesity is yet to become part of today's agenda of obesity research.

Behavior↗
PubMed2001

Are patients with Parkinson's disease suicidal?

Using the National Center of Health Statistics' mortality statistics databases for 1991 through 1996 (12,430,473 deaths), we isolated 144,364 individuals 40 years of age or older with a primary diagnosis of Parkinson's disease (PD). Of these, 122 died by suicide. The rate of suicide in the general population was about 10 times higher than in patients with PD (0.8% compared with only 0.08%, respectively). These different rates of suicide cannot be attributed to differences in age, gender, race, education, or marital status. Compared with patients with suicidal PD, patients with PD who died from other causes manifested significantly lower rates of affective disorders. The referent population exhibited a higher rate of malignancy and a lower rate of depression. The findings suggest that marital status, mood disorder, and somatic comorbidity provide only a limited understanding of completed suicide.

Adult↗
PubMed1996

Bilateral comparison of occipital lobe sulci: a sulcus identifying algorithm.

A procedure for automatic identification of sulci of cerebral hemispheres in magnetic resonance images is presented. The algorithm departs from information of the spatial location of a given feature (e.g., sulcal contour) in one hemisphere and automatically defines its course in the other hemisphere. The automatic tracing of sulci was successfully performed in the mesial aspect of both hemispheres in 18 normal individuals. The sulcal location in the target hemisphere was first approximated by assuming an affine transformation between hemispheres, and then refined by local edge analysis. The method produced reliable results in comparing the intersulcal areas (the cuneus), sulcal length, their complexity, and the angle between the pariteooccipital and retrocalcarine fissures.

Adolescent↗
PubMed1995

Midline abnormalities and psychopathology: how reliable is the midsagittal magnetic resonance "window" into the brain?

The argument is made that mensuration of midsagittal magnetic resonance (MR) images is plagued with methodological errors due to confusion of the midsagittal MR image and the mesial brain surface. Several examples are given to demonstrate the effects of slice thickness and orientation on the size and shape of mesial structures. The benefits of examining contiguous slices and the necessity of consulting coronal and transaxial cuts in mensuration efforts of midsagittal cuts are emphasized.

Corpus Callosum↗
PubMed1995

"McGurk illusion" to bilateral administration of sensory stimuli in patients with hemispatial neglect.

The illusion of McGurk (Nature 264, 746-748, 1976) refers to the blending of conflicting audio-visual messages. By taking advantage of this phenomenon the study explored whether visual cues (i.e. manner of articulation) in ipsilesional (right) space would help a patient with auditory neglect to mentally reconstruct syllabic sounds voiced in contralesional (left) space. We examined seven patients with clinically detectable visual neglect following right hemisphere damage. All had signs of auditory neglect as documented by the inferior identification of syllables delivered through a loudspeaker on the left side. In contrast, syllabic sounds delivered contralesionally together with visual stimuli in the ipsilesional space significantly increased identification of "neglected" syllabic sounds. Of the increased responses, 23% were classified as illusory blends, thereby suggesting that manner of articulation provides a valuable clue as to the possible "best fit" for a consonant. The susceptibility to the blend illusion was identical in patients and controls. Results indicate that neglected auditory stimuli are retrieved in patients with right hemisphere lesion by the mechanism of the ventriloquist illusion in the presence of a carefully timed sequence of comparisons of auditory signals in the neglected space with visual signals in the attended space. The possibility that neuronal mechanisms that serve audio-visual merger in spatial localization are also utilized for processing speech distinctions is discussed.

Acoustic Stimulation↗
PubMed1985

Prenatal chlordiazepoxide effects on metrazol seizures and benzodiazepine receptors density in adult albino rats.

Adult offsprings of rats treated with daily injection of chlordiazepoxide (10 mg/kg, i.p.) during pregnancy showed a significant decrease in benzodiazepine receptors in the cortex and the cerebellum without apparent changes in receptor affinity. A reduced susceptibility to metrazol-induced epileptogenesis paralleled this change. These findings are discussed in relation to the differential vulnerability of various types of benzodiazepine receptors.

Animals↗
PubMed1984

Tardive dyskinesia--prevalence and subtypes at Valkenberg Hospital, Cape Town.

A survey of 278 White long-term inpatients at Valkenberg Hospital, Cape Town, revealed a 17% incidence of tardive dyskinesia. The heterogeneity of this condition is discussed and the incidence of the various subtypes is given. The relationship between tardive dyskinesia and certain risk variables such as age, duration of hospitalization and concomitant administration of anticholinergics, while clinically suggestive, was found to be not statistically significant.

Aged↗
PubMed1984

Visual evoked potentials and nociceptive thresholds in high and low self-stimulators.

Tail flick latencies (TFL) were examined in order to distinguish between rats from genetically high (HI) and low (LO) self-stimulation lines (LC2-HI and LC2-LO). In addition, slow secondary negative wave (SNW) of the visual evoked potential, which is considered to be a sensitive index of normal and pharmacologically-induced behavioral arousal, was analysed. Small, albeit statistically significant enhancement of SNW was obtained in LO rats. Unlike LO animals, HI rats gained in SNW amplitude during repeated photic stimulation. The difference between the lines was highly significant. TFL assessment yielded slightly reduced (NS) values for HI rats. However, when TFL and SNW data were compared it appeared that TFL vary as a function of SNW amplitude in LO but not in HI rats, (r = 0.9). SNW may be employed as a predictor of the nociceptive threshold in rats.

Animals↗
PubMed1983

Anticonflict action of sodium valproate. Interaction with convulsant benzodiazepine (Ro 5-3663) and imidazodiazepine (Ro 15-1788).

The possibility that Ro 15-1788, a specific benzodiazepine antagonist would reverse the anxiolytic effect of VPA (200 mg/kg) in the Geller-Seifter paradigm was tested, using male albino rats. VPA (200 mg/kg) induced disinhibition which was antagonized by a convulsant benzodiazepine, Ro 5-3663 (1 mg/kg), but not by imidazobenzodiazepine, Ro 15-1788 at doses of 10 mg/kg, or 30 mg/kg. However, Ro 15-1788 (30 mg/kg) did have a short lasting antagonistic effect on VPA when tested in a "condensed" form (see text) of the conflict test. The nature of the anticonflict potency of VPA is discussed.

Animals↗
PubMed1983

A behavioral examination of convulsant benzodiazepine and GABA antagonist, Ro 5-3663, and benzodiazepine-receptor antagonist Ro 15-1788.

The potential "anxiogenic" effects of convulsant benzodiazepine and GABA-antagonist, Ro 5-3663 and specific antagonist of benzodiazepine receptors, Ro 15-1788 were compared in the Geller-Seifter conflict paradigm. Chlordiazepoxide (CDP) (5 mg/kg) was used as a "positive" control. Both Ro 5-3663 (1 mg/kg) and Ro 15-1788 (10 mg/kg) antagonized the anticonflict effect of CDP. However, while Ro 15-1788 had a modest anticonflict potency. Ro 5-3663 had an anxiogenic effect in its own right.

Animals↗
PubMed1982

Benzodiazepine antagonists abolish electrophysiological effects of sodium valproate in the rat.

A hypothesis was considered that anti-epileptic potency of sodium valproate (VPA) may be associated with its action via the benzodiazepine system. The ability of anti-petit mal drugs to suppress the slow secondary negative wave (SNW) of the visually evoked potential was used as a sensitive electrophysiological "tag" for comparison of VPA (200 mg/kg, i.p.) and Diazepam (5 mg/kg, i.p.) effects. Both drugs induced a profound inhibition of the SNW. Benzodiazepine antagonists Ro 5-3663 (2 mg/kg, i.p.) and Ro 15-1788 (5 mg/kg, i.p.) caused recovery of the SNW amplitude within several minutes of injection. Both antagonists abolished immobility and sedation produced by VPA and Diazepam. The possibility should be considered that therapeutic effects of VPA are mediated through the benzodiazepine receptor coupled to GABA.

Animals↗
PubMed1982

Unilateral dopamine deficit and lateral eeg asymmetry: sleep abnormalities in hemi-Parkinson's patients.

The hypothesis was tested that unilateral dopamine deficiency leading to the contralateral extrapyramidal syndrome (hemi-parkinsonism) would cause distinctly asymmetric EEG sleep patterns. In 7 hemi-Parkinson's patients 2 nights of sleep were monitored along with pre-sleep waking periods. No medication was given prior to the first night. The second night followed at least 2 months of L-DOPA medication. Although in all patients sleep architecture was disturbed, no statistically significant asymmetries of sleep patterns were obtained. L-DOPA medication improved the quality of sleep. Delta sleep was most visibly improved. Also, post-treatment enhancement of the mean delta power over the parkinsonian hemisphere was supported statistically. The role of dopamine in slow wave sleep control and mechanisms of contralateral hemisphere involvement are discussed.

Aged↗
PubMed1981

Convulsant-specific architecture of the postictal behavior syndrome in the rat.

The postictal immobility syndrome was examined in five experimental grand mal epilepsy models in an attempt to analyze separately the behavioral and underlying neurochemical aspects of the rigid-catatonic and flaccid-cataleptic states. Catalepsy and analgesia were found in varying degrees after maximal electroshock (MES), metrazol, picrotoxin, and Ro 5-3663 activated seizures. Signs of rigidity were noticed after the MES and picrotoxin seizures. Kindled seizures were followed by explosive behavior without signs of rigidity, catalepsy, and analgesia. Naloxone reduced the duration but not the score (intensity) of catalepsy and failed to selectively antagonize analgesia. The relative representation of the tonic stage of convulsions seemed to be the major determinant of the development of catatonic-cataleptic symptomatology. It is suggested that more than a single neurotransmitter system is involved in the postictal immobility syndrome and each epilepsy model has its unique neurochemical profile.

Animals↗
PubMed1981

Smooth pursuit pattern in schizophrenic patients during cognitive task.

Asymmetries in saccadic pursuit were studied, using EOG, ion 20 schizophrenic patients, as well as in two groups of normal subjects, screened for their patterns of lateral eye movements (LEM). Tracking performance was also examined while subjects were concurrently engaged in performing a cognitive task. Saccadic pursuit among schizophrenic patients was replicated in the present study. No asymmetry was observed in the quality of leftward as compared to rightward tracking. However, solving syllogisms while tracking resulted in further deterioration in tracking performance of the patients, with significantly more saccades and arrests in tracking occurring when following the target to the left as compared to rightward following. Similar asymmetry was observed in one group of controls who are believed to rely more on their left hemisphere on the LEM test, whereas no asymmetry was observed in the performance of the second control group. These results are interpreted as supporting the hypothesis of left hemispheric hyperactivity in schizophrenia. Saccadic pursuit in one subgroup of the normal sample is considered as suggesting that these individuals belong to the high-risk group.

Adolescent↗