Claude M. J. Braun

Ventral frontal deficits in psychopathy: Neuropsychological test findings

The hypothesis of prefrontal dysfunction in psychopathy has been pursued for many years, without convincing results. It is proposed here that this approach in previous studies was far too global. The present investigation was carried out in order to test a more specific hypothesis of orbitofrontal and/or frontal ventromedial deficits in psychopathy. Psychopathic criminals were compared to non-psychopathic criminals with measures related to orbitofrontal or frontal ventromedial functioning, as well as with control measures more associated with frontodorsolateral and posterorolandic functions. All subjects provided urine samples for drug assay. It was found that, while the two groups performed similarly on all the control measures, including the drug tests, the psychopaths were significantly impaired on all the orbitofrontal-ventromedial tasks. The psychopaths were significantly impulsive on several tests as well as significantly dysosmic [corrected]. The latter finding is particularly important in the sense that it cannot readily be explained socioculturally, thus presenting a new and convincing argument for brain-based etiology of this disorder. The results are discussed in relation to other psychiatric disorders characterized by impulse dyscontrol as well as in relation to other putative neurobiological etiological factors in psychopathy.

Early effects of normal aging on perseverative and non‐perseverative prefrontal measures

Current neuropsychological research supports a model postulating that prefrontal functions are among the first to decline in normal aging, but this model has rarely been empirically tested with subjects of 65 years or less. This study tests the following hypotheses: (a) A significant decline occurs prior to age 65 in a wide ranging set of prefrontal performance measures and (b) a significant increase occurs on measures of perseveration based on the same prefrontal tasks. A group of young adults (n = 70) aged 20 to 35 and a group of elderly adults (n = 58) aged 45 to 65, group‐matched for education and sex, were evaluated by means of six neuropsychological prefrontal tasks: the Self‐Ordered Pointing Task, the Wisconsin Card Sorting Test, the Porteus Mazes, a Verbal Fluency Task, a Design Fluency Task, and the Stroop Test. Four of the six prefrontal scores and four of six measures of perseveration manifested significant declines in the elderly group, suggesting that normal aging prior to age 65 may exhibit ...

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.

Cognitive structure of executive deficits in frontally lesioned head trauma patients performing activities of daily living.

OBJECTIVE Executive functions in activities of daily living (ADL) were investigated in 10 patients with frontal lobe lesions after a mild to severe closed head injury (CHI). METHOD The CHI patients were compared to 12 normal controls with a neuropsychological test battery, a script recitation task and a realistic simulation of complex multitask ADL (planning and preparing a meal). RESULTS Though the CHI patients were significantly slow on one test and subject to interference on an attention test with parametric testing, the groups did not differ on any neuropsychological test with non parametric testing. However, the CHI patients manifested marked anomalies in the meal preparation task. While small sequences of actions were easily produced, large action sets could not be correctly executed. CONCLUSION An outstanding deficit in strategic planning and prospective memory appears to be an important underpinning of the impairment of ADL observed in CHI patients with frontal lobe lesions.

Similar 1H magnetic resonance spectroscopic metabolic pattern in the medial temporal lobes of patients with mild cognitive impairment and Alzheimer disease.

Structures of the medial temporal lobes are recognized to play a central role in memory processing and to be the primary sites of deterioration in Alzheimer disease (AD). Mild cognitive impairment (MCI) represents potentially an intermediate state between normal aging and AD. Proton magnetic resonance spectroscopy (MRS) was used to examine brain metabolic changes in patients with AD and MCI in the medial temporal lobes (MTLs), parietotemporal cortices (PTCs) and prefrontal cortices (PFCs). Fourteen patients with MCI, 14 patients with mild AD and 14 age- and sex-matched control subjects were studied. Patients with AD and MCI demonstrated significant reductions of NAA/H(2)O and Cho/H(2)O in the left MTL relative to control subjects. Patients with AD showed mI/H(2)O increases relative to patients with MCI and control subjects in all six regions investigated, and a statistically significant mI/H(2)O increase was measured in the right PTC. Patients with AD and MCI demonstrated the same metabolic pattern in the left MTL, suggesting a similar pathological process underlying memory impairment. Increased mI signal appears to be a neurochemical abnormality associated mostly with AD and the dementia process. Some interhemispheric metabolite asymmetries were increased in AD patients.

Estimation of interhemispheric dynamics from simple unimanual reaction time to extrafoveal stimuli

This essay reviews research on interhemispheric transfer time derived from simple unimanual reaction time to hemitachistoscopically presented visual stimuli. Part 1 reviews major theoretical themes including (a) the significance of the eccentricity effect on interhemispheric transfer time in the context of proposed underlying neurohistological constraints; (b) the significance of gender differences in interhemispheric transfer time and findings in dyslexics and left-handers in the context of a fetal brain testosterone model; and (c) the significance of complexity effects on interhemispheric transfer time in a context of “dynamic” vs. “hard-wired” concepts of the underlying interhemispheric communication systems. Part 2 consists of a meta-analysis of 49 published behavioral experiments, in view of drawing a portrait of the best set of experimental conditions apt to produce salient, reliable, and statistically significant measures of interhemispheric transfer time, namely (a) index rather than thumb response, (b) low rather than high target luminance, (c) short rather than prolonged target display, and (d) very eccentric rather than near-foveal stimulus location. Part 3 proposes a theoretical model of interhemispheric transfer time, postulating the measurable existence of fast and slow interhemispheric channels. The proposed mechanisms evolutionary adaptive value, the neurophysiological evidence in its support, and favorable functional evidence from studies of callosotomized patients are then presented followed by proposals for critical experimental tests of the model.

Opposed Left and Right Brain Hemisphere Contributions to Sexual Drive: A Multiple Lesion Case Analysis

Brain topographical studies of normal men have have shown that sexual excitation is asymmetric in the brain hemispheres. Group studies of patients with unilateral epileptic foci and other studies of patients with unilateral brain lesions have come to the same conclusion. The present study reviewed previously published single case reports of patients with frank hypo or hypersexuality subsequent to a unilateral brain lesion. Hyposexual patients tended to have left hemisphere lesions (primarily of the temporal lobe), and hypersexual patients tended to have right hemisphere lesions (primarily of the temporal lobe) (p < 0.05). We interpret this double dissociation as part of a more general phenomenon of psychic tone similarly dissociated with regard to hemispheric control, including mood, psychomotor baseline, speech rate, and even immunity. The behavioral significance of this psychic tone is to modulate approach versus avoidance behavior.

Is anorexia nervosa a neuropsychological disease

Evidence for central nervous system, and more particularly cortical, etiology of anorexia nervosa is reviewed. Topics covered are neuropsychiatric comorbidity, inheritance patterns, the neurobiology of body-image disturbance and of the eating function, perinatal and alcoholic insult to the brain, neurochemical and neuroelectric disturbance, anatomic and metabolic brain imaging, and neuropsychological impairment. It is concluded that there is indeed an important neuropsychological etiological dimension to anorexia nervosa. The profile most frequently associated with anorexia nervosa is right posterior hypometabolism, followed by right anterior hypermetabolism, both associated with right-sided abnormal electroencephalogram spiking. It is also proposed that bulimia consists of a “positive” neurological subtype and that restricting anorexia represents a “negative” neurological subtype. Priorities for further research into anorexia nervosa are specified to include twin adoption studies, brain electrical topography studies, postmortem histological studies, and experimentally inspired neuropsychological studies.

Cognitive structure of executive deficits in patients with frontal lesions performing activities of daily living

Objective. Executive function in activities of daily living (ADL) were investigated in 10 patients with excised frontal lobe tumours. Method. The patients with frontal lesions were compared to 10 normal controls with a neuropsychological test battery, a script generation task and a realistic implementation of complex multi-task ADL (planning and preparing a meal). Results. The patients manifested numerous basic executive deficits on the paper-pencil tests, were unimpaired on the script generation task despite an aberrant semantic structure and manifested marked anomalies in the meal preparation task. Conclusion. Frontal lobe deficits in lengthy complex multi-task ADL can be explained by impairment of several executive functions, generalized slowness of performance and paucity of behaviour.

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.