Biomedical subjects

S Daigneault

Publications and source records attributed to S Daigneault.

9 recordsLinked to original sources

PubMed2000

Right body side performance decrement in congenitally dyslexic children and left body side performance decrement in congenitally hyperactive children.

OBJECTIVE: Simple and complex visuomotor performance of the right and left sides of the body was investigated in 37 children with left hemisphere lesions, 35 children with right hemisphere lesions, 53 developmentally dyslexic children, 29 developmentally hyperactive children, and 35 "normal" children who had endured a very mild head injury with no sequelae. BACKGROUND: Lateralized soft signs, EEG topography, metabolic brain imaging, and neuropsychological test profiles suggest a predominance of left hemisphere dysfunction in dyslexia and right hemisphere dysfunction in hyperactivity. METHOD: Nine measures of lateralized performance were drawn from the Purdue pegboard, Letter cancellation, Rey complex figure, Wechsler Intelligence Scale for Children (WISC) Mazes, and WISC Picture completion tests. RESULTS: The children with left hemisphere lesions manifested significantly weaker performance on test components involving the right body side, relative to the normal controls, on the Purdue pegboard, Rey complex figure (delayed recall condition), and WISC Picture completion tests, and the dyslexic children on the former two. The children with right hemisphere lesions manifested significantly weaker performance on test components involving the left body side, relative to the normal controls, on the WISC Mazes test, as did the hyperactive children. CONCLUSIONS: We propose that (1) contralateral performance decrement results from a unilateral cortical lesion in children, and (2) developmental dyslexia may comprise a slight predominance of left hemisphere dysfunction and developmental hyperactivity of right hemisphere dysfunction.

Attention↗

PubMed1999

Mania, pseudomania, depression, and pseudodepression resulting from focal unilateral cortical lesions.

OBJECTIVE: This consecutive multiple case study was designed to determine whether cortical lesion sites can predict occurrence of mood or psychomotor disorders in adults and children. BACKGROUND: Most of a large body of research supports the contention that left hemisphere lesions result more often than right ones in depression, and that the inverse occurs in mania. However, it is not clear how psychomotor status fits into this picture, nor whether children respond to the same lesions in a similar manner. METHOD: Published (n = 88) and unpublished (n = 31) cases of school-aged child and adult patients with focal unilateral cortical lesions and psychomotor agitation or lethargy with or without corresponding mania or depression were reviewed systematically to determine whether lesion location relates systematically to any of those psychiatric conditions. No patients had symptoms prior to detection of their lesion. Manic-depressives and agitated depressives were also excluded. RESULTS: Patients with mania and/or psychomotor agitation had predominantly right hemisphere lesions. Postlesion hyperactivity (without mania) in children was common but was not more related to lesions in one or the other hemisphere. Adult and child patients with depression and/or psychomotor lethargy had predominantly left hemisphere lesions. The intrahemispherical site of the lesion did not significantly predict the type of mood or psychomotor disorder. Nevertheless, the nonsignificant trend was for right posterorolandic lesions to predict mania or agitation and for left frontal lesions to predict depression or psychomotor lethargy. CONCLUSIONS: These findings support the neuropsychiatric approach to mood and psychomotor disorder in children and adults.

Adult↗

PubMed1998

Pseudoakathisia from a acquired lesion.

Akathisia, "inability to remain seated", is a common condition in patients medicated with neuroleptics, and also occurs in other medication regimens. Only a few cases of akathisia resulting from focal lesions have been published. These cases suggest that differing lesion sites are sufficient for producing objective or subjective akathisia. The authors present a patient with akathisia who had no subjective complaints, suggesting that a combined basal ganglia and frontal lobe lesion may lead to objective akathisia (pseudoakathisia).

Adolescent↗

PubMed1995

Does so-called interhemispheric transfer time depend on attention?

To our knowledge none of many past attempts to experimentally modulate the crossed-uncrossed differential (CUD) or so-called "interhemispheric transfer time" derived from appropriate visual reaction time experiments has ever succeeded. The present 4 experiments were designed to establish that (a) under normal attentional constraints, significant CUDs would be obtained, but that (b) lateral mobilization of attention by probabilistic (valid and invalid) cuing as to target location would significantly and systematically alter the CUDs. In a baseline experiment, a significant CUD was obtained. In Experiments 2-4, CUDs were rendered nonsignificant by probabilistic cuing. Specific experimental conditions generally did not significantly influence the CUD in a systematic direction. In only one of many analyses of those results did an experimental effect on the CUD reach significance: In Experiment 3 intrasubject mean reaction times yielded a significant complex dissociation of CUDs as a function of type of cuing (valid or invalid) and stimulus onset asynchrony. It was concluded that the CUD can be significantly modulated by target location cuing, but only under very specific conditions. The direction of the trends in all the experiments, and in the significant finding, suggests that the CUD component that is most markedly influenced by such cues is a postcallosal, motor component.

Adult↗

PubMed1994

Zaidel's model of interhemispheric dynamics: empirical tests, a critical appraisal, and a proposed revision.

Zaidel has proposed a model of intra- and interhemispheric dynamics which attempts to explain field and hand effects in visual reaction time experiments. The model includes prototypes of two extreme cases: a "callosal relay" pattern, in which interhemispheric transfer is inferred, and a "direct access" pattern, in which each hemisphere is inferred to execute the task independently. Five visual reaction time experiments were carried out to test six predictions which Zaidel has made within the framework of his model. Some of these predictions were supported but others were rejected. These findings, in conjunction with findings of other researchers, were critically analyzed in view of determining the extent to which Zaidel's model can be revised in order to fit the ensemble of relevant findings. It was concluded that the model can indeed be revised but that this requires a redefinition of conditions indicative of presence or absence of interhemispheric relay. A new model is proposed assuming exclusively excitatory callosal relay and focussing on magnitude and valence of field effects obtained at each hand, considered in their interrelation.

Adult↗

PubMed1993

Working memory and the Self-Ordered Pointing Task: further evidence of early prefrontal decline in normal aging.

Two major lines of investigation are currently clarifying the nature of the impairment of working memory associated with normal aging. Cognitive psychology has formulated the problem in terms such as the balance of impairment of encoding, retrieval, storage and/or attention, whereas neuropsychology has formulated the problem in terms such as the balance of frontal (executive) versus temporal (mnemonic) degeneration. The findings of this study support the contention that the primary impairment of working memory in early normal aging is an active attentional executive processing deficit. Specifically, on the Self-Ordered Pointing Task, there is significantly ineffective exploitation of top-down clustering strategy as a function of aging. On this task, self-organization of encoding and retrieval must occur simultaneously with ongoing responding. The finding cannot be explained as an impairment of encoding, retrieval, storage, or build-up and/or release of proactive interference, since indexes of these did not discriminate young-adult from middle-aged samples.

Adult↗

PubMed1992

An empirical test of two opposing theoretical models of prefrontal function.

The purpose of this study was to compare the validity of two models which contrast with each other in the manner in which they integrate neuropsychological tests into distinct prefrontal constructs. The first prefrontal model consists of five distinct functional constructs drawn from human clinical neuropsychology. The second model, elaborated by Goldman-Rakic, is based primarily on monkey research and postulates a basic prefrontal function, "on-line representational memory," which guides behavior in the absence of, or despite discriminative environmental stimuli. In the latter model, distinct prefrontal functional constructs are primarily defined in terms of various types of representational memory involved in specific tasks. Eleven "prefrontal" measures were obtained from 259 normal adults, stratified for age, education, and sex. Confirmatory factor analyses revealed that the Goldman-Rakic model "fit" the data better than the model derived from human clinical neuropsychology, while several constructs commonly used in human neuropsychology were refuted. It was concluded that new research on brain-damaged humans with a view to understanding prefrontal function might benefit from using the Goldman-Rakic model as a starting point.

Adolescent↗

PubMedDate not supplied

Processing of pragmatic and facial affective information by patients with closed-head injuries.

Although several affective impairments have been demonstrated to occur following closed-head injury (CHI), deficits of the communicative function of language, particularly sentenial and suprasentential pragmatic aspects, have been suggested, but not demonstrated, to occur. This study compared 31 normals and 31 severely closed-head injured patients matched for age, sex and education. The dependent measures consisted of a facial test of emotion (FTE) and a contextual test of emotion (CTE). The former task consisted of 36 slides representing facial expressions of the six emotions demonstrated by Ekman and colleagues to be transcultural, namely, job, sadness, fear, anger, surprise and disgust. The subject was required to name the appropriate emotion for each slide. The latter task consisted of correctly identifying the appropriate emotion for each of 36 brief verbal narratives representing contexts connotative of the same six transcultural emotions. The CHI patients were impaired overall on the FTE but not the CTE. However, the ability to identify anger was significantly impaired on both tasks when considered in isolation from the other emotions. It was concluded that a processing deficit of primary emotional material, particularly anger, does exist following CHI, but that this deficit is not necessarily independent of task and/or modality parameters. It was also concluded that evidence of a pragmatic deficit of the language function following CHI remains to be provided at this time.

Adult↗

PubMedDate not supplied

[Hypothalamic hamartoma: detailed presentation of a case].

We describe a seven year old child with a hypothalamic hamartoma. Classical symptoms of hypothalamic hamartoma include gelastic epileptic laughter, precocious puberty, aggressiveness, and progressively worsening epilepsy. After a normal first few years of life, this case presents all these symptoms except the precocious puberty. He has a markedly morbid personality disorder: he assaults strangers and relatives, bites people, spits in their faces unpredictably, is coprolalic and coprophagic, has gelastic laughter, puts pencils, erasers, and other non-comestible objects in his mouth, chews and ingests them, has tics (plays noisily with his saliva, empty chewing, compulsive spitting) and is self-injurious. None of the medications attempted to date have been of any help. Medical prognosis is somber, and this case is difficult to institutionalize, the more "congenial" institutions being insufficiently equipped to protect him and the beneficiaries and staff from his aggressive behavior. MRI showed the typical profile of hypothalamic hamartoma, and the diagnosis was confirmed with partial resection. This case illustrates that a tiny lesion, the size of a small cherry, can have extremely morbid psychological consequences. Detailed neuropsychological evaluation, certain unusual electroencephalographic traits and neurosurgical issues are discussed.

Child↗