Relationship between sebostatic activity, tolerability and efficacy of three topical drugs to treat mild to moderate acne

BACKGROUND

Acne is a multifactorial disorder in which the sebum plays an important pathogenetic role.

PURPOSE OF THE STUDY

To evaluate the sebostatic effect of three anti-acneic ingredients (azelaic acid, adapalene and benzoyl peroxide) conveyed in cream and to determine whether there is a correlation with the therapeutic results.

MATERIALS AND METHODS

Sixty-five patients with mild or moderate acne localized on the face were divided into three therapy groups at random: 25 applied azelaic acid once a day, 20, benzoyl peroxide and 20, adapalene. All the patients were observed at the time of enrolling and a further four times at fortnightly intervals. At each visit the sebum casual level on the forehead, chin and one cheek was measured using a sebumeter. Furthermore, side-effects and clinical-therapeutic effectiveness were noted.

RESULTS

Four patients did not complete the study. Azelaic acid showed an average reduction of 13.9% in sebum production on the forehead, 14.2% on the chin and 15.2% on the cheek. Benzoyl peroxide caused an increase of 10.5% in sebum production on the forehead, 10.3% on the chin and 25.4% on the cheek. Adapalene reduced sebaceous secretion by 0.2% on the forehead and 6.7% on the cheek whereas sebum production increased by 6.2% on the chin. All three drugs showed a clinical improvement in the acneic lesions with moderate adverse effects.

CONCLUSION

The three topical drugs bring about good therapeutic results with scarce side-effects that do not, however, seem to be correlated with the sebostatic activity.

Preservation of cognitive function in dystonia treated by pallidal stimulation

OBJECTIVE

To assess the effects of bilateral pallidal deep brain stimulation (DBS) on mood and cognitive performance in patients with dystonia before surgery (at baseline, while patients received their usual treatment) and 12 months postoperatively (while patients received neurostimulation and their medications) in a multicenter prospective study.

METHODS

Twenty-two patients with primary generalized dystonia were evaluated with tests focused on executive functions. The authors considered the patients' severe disability and selected the following tests: Raven Progressive Matrices 38, Similarities and Arithmetic subtests of the Wechsler Adult Intelligence Scale-R, Grober and Buschke, Wisconsin Card Sorting Test (WCST), verbal fluency, Trail Making Test, and the Beck Depression Inventory. Median age at surgery was 30 years (range = 14 to 54 years), median duration of disease was 18.5 years (range = 4 to 37 years).

RESULTS

Before surgery, no patients showed cognitive decline or depression. The surgical procedure appeared to be benign cognitively. One year after surgery, free recall improved. There was a significant reduction in the number of errors in the WCST. No behavioral or mood changes were found.

CONCLUSIONS

Bilateral pallidal stimulation has a good benefit-to-risk ratio as it did not negatively affect cognitive performance and mood in primary dystonia, while a significant motor improvement was obtained. Moreover, a significant mild improvement in executive functions was observed, which may have been related either to the surgical treatment or to the marked decrease in anticholinergic drugs.

"Applause sign" helps to discriminate PSP from FTD and PD

The "applause sign" is a simple test of motor control that helps to differentiate PSP from frontal or striatofrontal degenerative diseases. It was found in 0/39 controls, 0 of 24 patients with frontotemporal dementia (FTD), 0 of 17 patients with Parkinson disease (PD), and 30/42 patients with progressive supranuclear palsy (PSP). It discriminated PSP from FTD (p < 0.001) and PD (p < 0.00). The "three clap test" correctly identified 81.8% of the patients in the comparison PSP and FTD and 75% of the patients in the comparison of PSP and PD.

Clinical and neuropathologic variation in neuronal intermediate filament inclusion disease

BACKGROUND

Recently described neuronal intermediate filament inclusion disease (NIFID) shows considerable clinical heterogeneity.

OBJECTIVE

To assess the spectrum of the clinical and neuropathological features in 10 NIFID cases.

METHODS

Retrospective chart and comprehensive neuropathological review of these NIFID cases was conducted.

RESULTS

The mean age at onset was 40.8 (range 23 to 56) years, mean disease duration was 4.5 (range 2.7 to 13) years, and mean age at death was 45.3 (range 28 to 61) years. The most common presenting symptoms were behavioral and personality changes in 7 of 10 cases and, less often, memory loss, cognitive impairment, language deficits, and motor weakness. Extrapyramidal features were present in 8 of 10 patients. Language impairment, perseveration, executive dysfunction, hyperreflexia, and primitive reflexes were frequent signs, whereas a minority had buccofacial apraxia, supranuclear ophthalmoplegia, upper motor neuron disease (MND), and limb dystonia. Frontotemporal and caudate atrophy were common. Histologic changes were extensive in many cortical areas, deep gray matter, cerebellum, and spinal cord. The hallmark lesions of NIFID were unique neuronal IF inclusions detected most robustly by antibodies to neurofilament triplet proteins and alpha-internexin.

CONCLUSION

NIFID is a neuropathologically distinct, clinically heterogeneous variant of frontotemporal dementia (FTD) that may include parkinsonism or MND. Neuronal IF inclusions are the neuropathological signatures of NIFID that distinguish it from all other FTD variants including FTD with MND and FTD tauopathies.

Tourette's syndrome and deep brain stimulation

In this prospective double blind randomised "N of 1" study, a patient with a severe form of Tourette's syndrome was treated with bilateral high frequency stimulation of the centromedian-parafascicular complex (Ce-Pf) of the thalamus, the internal part of the globus pallidus (GPi), or both. Stimulation of either target improved tic severity by 70%, markedly ameliorated coprolalia, and eliminated self injuries. Severe forms of Tourette's syndrome may benefit from stimulation of neuronal circuits within the basal ganglia, thus confirming the role of the dysfunction of limbic striato-pallido-thalamo-cortical systems in this disorder.

Does bilateral stimulation of the subthalamic nucleus aggravate apathy in Parkinson's disease?

OBJECTIVE

High frequency stimulation of the subthalamic nucleus (STN) dramatically decreases motor disability in patients with Parkinson"s disease (PD), but has been reported to aggravate apathy. The aim of this study was to analyse the effect of STN stimulation on motivation and reward sensitivity in a consecutive series of PD patients.

METHODS

Apathy and reward sensitivity (Apathy Scale, Stimulus-Reward Learning, Reversal, Extinction, and Gambling tasks) were assessed in 18 PD patients treated by bilateral STN stimulation ("on" and "off" conditions) compared with 23 matched patients undergoing long term treatment with levodopa ("on" and "off" conditions).

RESULTS

Apathy decreased under both STN stimulation and levodopa treatment, whereas explicit and implicit stimulus reward learning was unchanged.

CONCLUSIONS

Bilateral STN stimulation in PD patients does not necessarily have a negative effect on motivation and reward sensitivity and can even improve apathy provided patients have been appropriately selected for neurosurgery.

Specific cerebral networks for maintenance and response organization within working memory as evidenced by the 'double delay/double response' paradigm

Most of the working memory (WM) tasks used in functional imaging studies are based on the principle of the delayed response in which both the storage and the response organization are present during the delay period. It is therefore difficult to isolate activation specific to the storage function from that specific to the organization of the response. To determine the specific neural networks associated with these two WM operations, we performed a functional MRI study in healthy subjects using a new paradigm, 'the double delay/double response' tasks. This paradigm isolates maintenance from response organization by dividing the delay into two separate parts, the first being dedicated to memory, while the second includes response organization. Activation within the dorsolateral prefrontal cortex (DLPFC) followed a relative hemispheric dissociation: activation related to maintenance was predominant in the right DLPFC but was only detected when the load exceeded three items. Activation related to response organization was predominant in the left DLPFC, regardless of whether this response was based on information held in WM ('memory guided') or was independent of WM ('visually-guided'). These results suggest that activation of the DLPFC, should be interpreted in terms of executive processing for both maintenance and response organization.

Syndromes dysexécutifs et maladies dégénératives

A dysexecutive syndrome is observed not only in frontotemporal lobar degeneration, but also in subcortical degenerative diseases, and even in Alzheimer's disease whose lesions predominate in temporoparietal associative areas. The association between a dysexecutive syndrome and various cerebral localisations may be explained by the fact that cognitive and behavioral organisation recruits anatomofunctional frontostriatal and frontoparietal circuits. Both animal experimentation and human clinical observation argue in favour of a functional continuity and complementarity among these loops. The prefrontal cortex would be particularly needed in new situations, to inhibit old programs of action not adapted to the present context and to elaborate new ones; the basal ganglia would be rather required by the repetition of the situation to progressively transform the new program in routine. If we refer to Shallice model, we can hypothesize that optimal executive functions require the preservation not only of the Supervisory Attentional System, mainly dependent on the prefrontal cortex, but also of the Contention Scheduling, recruiting the basal ganglia, and of the Schemas of Action, represented in parietal and premotor areas. Therefore, the neuropsychological assessment of patients with degenerative diseases contributes to the understanding of the anatomofunctional architecture of executive functions.

The prefrontal cortex and conscious monitoring of action: an experimental study

To investigate the role of the prefrontal cortex in conscious monitoring, we used an experimental paradigm generating a conflict between the action planned and the sensory-motor feedback. We analyzed the acquisition of explicit knowledge of the strategy for resolving the conflict and its influence on motor adaptation. Twenty patients with frontal lobe lesions and 18 controls had to trace a sagittal line with a stylus on a graphics tablet. A mirror on which the traced line, processed by a computer, was projected hid the hand. A mask limited visual feedback to the last third of the trajectory. Without informing the subjects, the line traced was modified by introducing a bias of 24 degrees to the right. To succeed in the task, subjects had to modify their motor program and to deviate their trajectory in the opposite direction. Conscious elaboration of the strategy was evaluated by the number of trials needed to explicitly report the required deviation. Three groups of patients were distinguished: (1). with normal explicit strategy; (2). with delayed explicit strategy, and (3). without explicit strategy at the last trial. They significantly differed by the severity of the dysexecutive syndrome, particularly of environmental adherence. Motor adaptation was evaluated by the area between the line traced and the ideal line to compensate for the deviation. In patients with normal elaboration of the strategy, motor control was similar to that of controls, but it was severely disturbed in the other two groups. These results suggest the involvement of the prefrontal cortex in conscious motor monitoring.

Motivation, reward, and Parkinson's disease: influence of dopatherapy

"Orbitofrontal" and "cingulate" striatofrontal loops and the mesolimbic dopaminergic system that modulates their function have been implicated in motivation and sensitivity to reinforcement in animals. Parkinson's disease (PD) provides a model to assess their implications in humans. The aims of the study were to investigate motivation and sensitivity to reinforcement in non-demented and -depressed PD patients and to evaluate the influence of dopaminergic therapy by comparing patients in "on" (with L-Dopa) and "off" (without L-Dopa) states. Twenty-three PD patients were compared, in both the "on" and "off" states, to 28 controls, using: (1) an Apathy Scale; (2) Stimulus-Reward Learning, Reversal, and Extinction tasks; and (3) a Gambling task. PD patients were found: (1) mildly apathetic; (2) impaired on Stimulus-Reward Learning and Reversal, but not on Extinction; and (3) able to progress in the Gambling task during the first, but not the second assessment. There was no significant correlation between these various deficits. L-Dopa treatment clearly improved motivation, but had more limited and contrasting effects on other variables, decreasing the number of omission errors in Reversal, but increasing the number of perseveration errors in Extinction. These results suggest: (1) an implication of striatofrontal loops in human motivation and explicit and implicit sensitivity to reinforcement; (2) a positive influence of L-Dopa treatment on the subjective evaluation of motivation, but contrasting effects on reward sensitivity.

[The concept of frontotemporal lobar degeneration]

Consensus criteria have been recently proposed to improve clinical identification of frontotemporal dementia, non fluent progressive aphasia and semantic dementia (Neary et al., 1998). However, clinical observations show that these syndromes may overlap, underlying the value of the more generic entity of frontotemporal lobar degeneration.

Behavioural disorders, Parkinson's disease and subthalamic stimulation

OBJECTIVE

to analyse 24 parkinsonian patients successfully treated by bilateral STN stimulation for the presence of behavioural disorders.

METHOD

patients were evaluated retrospectively for adjustment disorders (social adjustment scale, SAS), psychiatric disorders (comparison of the results of psychiatric interview and the mini international neuropsychiatric inventory) and personality changes (IOWA scale of personality changes).

RESULTS

parkinsonian motor disability was improved by 69.5% and the levodopa equivalent daily dosage was reduced by 60.5%. Social adjustment (SAS) was considered good or excellent in nine patients, moderately (n=14), or severely (n=1) impaired in 15 patients. Psychiatric disorders consisted of amplification or decompensation of previously existing disorders that had sometimes passed unnoticed, such as depressive episodes (n=4), generalised anxiety (n=18), and behavioural disorders with drug dependence (n=2). Appearance of mild to moderate emotional hyperreactivity was reported in 15 patients. Personality traits (IOWA scale) were improved in eight patients, unchanged in seven, and aggravated in eight

CONCLUSION

Improvement in parkinsonian motor disability induced by STN stimulation is not necessarily accompanied by improvement in psychic function and quality of life. Attention is drawn to the possible appearance of personality disorders and decompensation of previous psychiatric disorders in parkinsonian patients who are suitable candidates for neurosurgery. We suggest that a careful psychological and psychiatric interview be performed before surgery, and emphasise the need for psychological follow up to ensure the best possible outcome.

The neural system that bridges reward and cognition in humans: an fMRI study

We test the hypothesis that motivational and cognitive processes are linked by a specific neural system to reach maximal efficiency. We studied six normal subjects performing a working memory paradigm (n-back tasks) associated with different levels of monetary reward during an fMRI session. The study showed specific brain activation in relation with changes in both the cognitive loading and the reward associated with task performance. First, the working memory tasks activated a network including the dorsolateral prefrontal cortex [Brodmann area (BA) 9/46] and, in addition, in the lateral frontopolar areas (BA 10), but only in the more demanding condition (3-back task). This result suggests that lateral prefrontal areas are organized in a caudo-rostral continuum in relation with the increase in executive requirement. Second, reward induces an increased activation in the areas already activated by working memory processing and in a supplementary region, the medial frontal pole (BA 10), regardless of the level of cognitive processing. It is postulated that the latter region plays a specific role in monitoring the reward value of ongoing cognitive processes. Third, we detected areas where the signal decreases (ventral-BA 11/47 and subgenual prefrontal cortices) in relation with both the increase of cognitive demand and the reward. The deactivation may represent an emotional gating aimed at inhibiting adverse emotional signals to maximize the level of performance. Taken together, these results suggest a balance between increasing activity in cortical cognitive areas and decreasing activity in the limbic and paralimbic structures during ongoing higher cognitive processing.

Clinical predictive factors of subthalamic stimulation in Parkinson's disease

High-frequency stimulation of the subthalamic nucleus (STN) constitutes one of the most effective treatments for advanced forms of Parkinson's disease. The cost and potential risks of this procedure encourage the determination of clinical characteristics of patients that will have the best postoperative outcome. Forty-one Parkinson's disease patients underwent surgery for bilateral STN stimulation. The selection criteria were severe parkinsonian motor disability, clear response of symptoms to levodopa, occurrence of disabling levodopa-related motor complications and the absence of dementia and significant abnormalities on brain MRI. Clinical evaluation was performed 1 month before and 6 months after surgery. The improvement in the activities of daily living subscale of the Unified Parkinson's Disease Rating Scale, Part II (UPDRS II) and parkinsonian motor disability (UPDRS III) was greater when the preoperative scores for activities of daily living and parkinsonian motor disability, in particular axial symptoms, such as gait disorders and postural instability assessed at the time of maximal clinical improvement (on drug), were lower. Age and disease duration were not predictive, but parkinsonian motor disability tended to be more improved in patients with younger age and shorter disease duration. The severity of levodopa-related motor complications was not a predictive factor. The outcome of STN stimulation was excellent in levodopa-responsive forms of Parkinson's disease, i.e. in patients with selective brain dopaminergic lesions, and moderate in patients with axial motor symptoms and cognitive impairment known to be less responsive or unresponsive to levodopa treatment, i.e. when brain non-dopaminergic lesions develop in addition to the degeneration of the nigrostriatal dopaminergic system. The results are consistent with the classical inclusion criteria for STN stimulation, but imply that the decision to operate on the oldest patients and/or patients with gait and postural disorders, who are poorly responsive to levodopa, should be weighed carefully.

Is the HM story only a "remote memory"? Some facts about hippocampus and memory in humans

In this review, we argue that a number of current data support the notion that the hippocampal formations play an important role in episodic memory in humans. We will focus on data gathered from three topics within this field: (1) the neuropsychological study of memory in degenerative diseases, which provides striking dissociations of processes, as a function of the location of cerebral lesions and of their functional consequences; (2) the description of patients' memory difficulties after unilateral medial temporal lobectomy. Given the visuo-verbal dissociation, we may anticipate that the study of the effects of such lesions may help in the understanding of the role of the hippocampus in memory, in terms of: (i) the stage of memory processing where the hippocampus is really involved (encoding, consolidation and/or retrieval); (ii) the specificity of the impairments as a function of the nature (verbal vs. visuo-spatial) of the to-be-remembered material; (3) recent evidence from imaging studies: (i) the morphological approach, which provides interesting information with the study of correlations between the volumes of diverse cerebral regions-particularly the volume of the hippocampus-and episodic memory performance and other cognitive measures; (ii) metabolic studies, using PET scan, which were first designed for correlational analyses between performance in episodic memory tasks and glucose utilization at rest in diverse regions of interest, such as the hippocampal formations; (iii) activation studies with PET and functional MRI, which are actually more straightforward, since they allow correlations between the metabolism in regions of interest and performance on line (e.g. during encoding or retrieval of information). In our view, inasmuch as such different approaches-degenerative diseases, lesions or imagery-provide convergent information, they give renewed weight to the notion according to which the hippocampal formations are critically concerned in episodic memory processes.

[Procedural learning and Parkinson disease: implication of striato-frontal loops]

OBJECTIVE

To investigate procedural learning in non demented patients with idiopathic Parkinson's disease (PD).

BACKGROUND

Experimental evidence implicate the basal ganglia in procedural learning. Selective impairment has more recently been described in patients with frontal lesions.

METHODS

The performance of 20 demented patients and 15 matched normal controls was studied in the serial reaction time task (SRTT). Performance on procedural task was further compared with that of 9 normal controls and with patients' performance on tests assessing explicit memory, executive functions and global efficiency.

RESULTS

The group of patients with PD showed impaired procedural learning. The difference of response time between the repeated and the non-repeated blocks was smaller in PD when compared to controls. Subsequent analyses separated PD patients into two subgroups according to their performance on SRTT, measured by the rebound effect. PD patients whose learning was normal differed from PD patients whose learning was impaired on performance in tests sensitive to frontal lobe dysfunction.

CONCLUSION

These results confirm the implication of the striatum in procedural learning and suggest that performance on cognitive procedural learning depends on the striato-frontal circuits.

Action planning in a virtual context after prefrontal cortex damage

Patients with frontal lobe lesions are known to encounter severe problems in the organisation of their behaviour in everyday life. Script generation tasks assess the subject's conceptual ability to formulate and evaluate a coherent and structured plan of action. In the present study, we investigated to what extent neuropsychological deficits observed at the conceptual level of action knowledge lead to impairments in action execution. We examined seven patients with prefrontal cortex damage and sixteen normal subjects. Subjects were first asked to verbally formulate a plan of action and then to use this knowledge for 'executing' the actions in a virtual 3-dimensional interactive apartment presented on a computer screen. The results indicated that the presence of the realistic context improved patients' performance. However, specific impairments were observed in patients in the execution condition, namely actions slips, omissions, failure in initiating actions and purposeless displacements. Moreover, an analysis of planning time showed that, differently of the patients group, normal subjects spent more time during plan execution as compared to plan generation. These results suggest that after a frontal lobe lesion a defective formulation of a routine plan might affect the execution of the corresponding course of actions.

Preserved Adjustment but Impaired Awareness in a Sensory-Motor Conflict following Prefrontal Lesions

Control of action occurs at different stagesof the executive process, in particular at those of sensory-motor integration and conscious monitoring. The aim of this study was to determine the implication of the prefrontal cortex in the control of action. For that purpose, we compared the performance of 15 patients with frontal lobe lesions and 15 matched controls on an experimental paradigm generating a conflict between the action planned and the sensory-motor feedback. Subjects had to trace a sagittal line witha stylus on a graphic tablet. The hand was hidden by a mirror on which the traced line, processed by a computer, was projected. Without informing the subjects, the line traced was modified by introducing a bias to the right, which increased progressively from 2° to 42°. To succeed the task, subjects had to modify their motor program and deviate their hand in the opposite direction. The sensory-motor adjustment to the bias was evaluated by the surface between the line traced and the ideal line to compensate for the deviation. The awareness of the conflict was measured by the angle of the bias at which subjects expressed the feeling that the line they traced was not the same as the line they saw. The deviation was similarly compensated for by patients and controls until24°. Then 14 controls but only3 patients were aware of a conflict. After that, the variability of performance increased significantly for the unaware patients. These results suggest that the prefrontal cortex is required at the level of conscious monitoring of actions, but not at the level of sensory-motor integration.

The effects of apomorphine on attentional processing in Parkinson's disease

To ascertain whether variations in central dopaminergic transmission can differentially affect motor and cognitive processing, we studied the effects of apomorphine (APO) in 9 patients with Parkinson's disease (PD). The UPDRS motor scores and auditory event-related potentials (ERPs) obtained in the 'odd-ball' (OB) and in the 'covert orientation of attention' (COA) tasks were studied in the 'off' and in the 'on' state after an injection of APO. Although APO injection improved patients' motor status, it induced a significant increase in the latencies of the P2 and P3 ERP components in the OB. In the COA task, right-hand reaction times (RTs) were markedly shortened in the 'on' state while left hand RTs remained unchanged. The contrasting effects of dopaminergic stimulation on the motor performance and on some aspects of cognitive processing suggest the existence of complex interactions within pre- and postsynaptic brain dopamine receptors, and an intervention of segregated basal ganglia-prefrontal cortex loops in motor and cognitive behaviour.

The role of dorsolateral prefrontal cortex in the preparation of forthcoming actions: an fMRI study

The dorsolateral prefrontal cortex (DLPFC) plays a key role in working memory (WM). Yet its precise contribution (the storage, manipulation and/or utilization of information for the forthcoming response) remains to be determined. To test the hypothesis that the DLPFC is more involved in the preparation of actions than in the maintenance of information in short-term memory (STM), we undertook a functional magnetic resonance imaging investigation in normal subjects performing two delayed response tasks (matching and reproduction tasks) in a visuospatial task sequence (presentation, delay, response). In the two tasks, the presentation and delay phases were similar, but the expected response was different: in the matching task, subjects had to indicate whether a visuospatial sequence matched the sequence presented before the delay period; in the reproduction task, subjects had to reproduce the sequence and, therefore, to mentally organize their response during the delay. Using a fMRI paradigm focusing on the delay period, we observed a significant DLPFC activation when subjects were required to mentally prepare a sequential action based on the information stored in STM. When subjects had only to maintain a visuospatial stimulus in STM, no DLPFC activation was found. These results suggest that a parietal-premotor network is sufficient to store visuospatial information in STM whereas the DLPFC is involved when it is necessary to mentally prepare a forthcoming sequential action based on the information stored in STM.

The FAB: a Frontal Assessment Battery at bedside

OBJECTIVE

To devise a short bedside cognitive and behavioral battery to assess frontal lobe functions.

METHODS

The designed battery consists of six subtests exploring the following: conceptualization, mental flexibility, motor programming, sensitivity to interference, inhibitory control, and environmental autonomy. It takes approximately 10 minutes to administer. The authors studied 42 normal subjects and 121 patients with various degrees of frontal lobe dysfunction (PD, n = 24; multiple system atrophy, n = 6; corticobasal degeneration, n = 21; progressive supranuclear palsy, n = 47; frontotemporal dementia, n = 23).

RESULTS

The Frontal Assessment Battery scores correlated with the Mattis Dementia Rating Scale scores (rho = 0.82, p < 0.01) and with the number of criteria (rho = 0.77, p < 0.01) and perseverative errors (rho = 0.68, p < 0.01) of the Wisconsin Card Sorting Test. These variables accounted for 79% of the variance in a stepwise multiple regression, whereas age or Mini-Mental State Examination scores had no significant influence. There was good interrater reliability (kappa = 0.87, p < 0.001), internal consistency (Cronbach's coefficient alpha = 0.78), and discriminant validity (89.1% of cases correctly identified in a discriminant analysis of patients and controls).

CONCLUSION

The Frontal Assessment Battery is easy to administer at bedside and is sensitive to frontal lobe dysfunction.

An ecological approach to planning dysfunction: script execution

Planning, which concerns many activities in everyday life, is a two-stage process. The first one predetermines a course of actions aimed at achieving some specific goals. It is founded on managerial knowledge or overlearned sequences of events and may be tested by script generation. The second stage entails monitoring and guiding the execution of the plan to a successful conclusion. It must take into account environmental contingencies and may be tested by script execution. If the frontal lobes intervene not only in managerial knowledge (Grafman, 1989) but also in binding the plan with contextual environment (Damasio, Tranel and Damasio, 1991; Shallice and Burgess, 1991), script execution would be more sensitive than script generation to planning deficits. To test this hypothesis, script execution and script generation were compared in 11 patients with a dysexecutive syndrome and 10 matched controls, using three scripts of daily life activities: (1) 'shopping for groceries'; (2) 'cooking'; (3) 'answering a letter and finding the way to post the reply'. Two way ANOVAs showed more errors in execution than in generation, more errors in patients than in controls, and a greater difference between execution and generation in patients than in controls. Furthermore, 'context neglect' and 'environmental adherence' were the two types of errors that best differentiated patients from controls. Finally, the total number of errors in execution correlated with the score on behavioral questionnaires answered by occupational therapists. These results confirm our hypothesis and suggest that script execution may be a valid ecological approach to estimate the severity of deficits in daily life activities.

Confabulation in a patient with fronto-temporal dementia and a patient with Alzheimer's disease

This paper describes two patients, O.I. and B.Y., with a confabulatory syndrome. O.I. was diagnosed with probable fronto-temporal dementia, whereas B.Y. met the criteria for probable Alzheimer's disease. O.I., but not B.Y., was impaired on tests of frontal/executive functions, and performed better than B.Y. on clinical tests of memory. Both patients confabulated in episodic/autobiographical memory tasks and in personal future planning tasks. B.Y. confabulated also in a semantic memory task. It is argued that the pattern of confabulation and the cognitive profile shown by the two patients is explained better by the hypothesis proposed by Dalla Barba and co-workers (Dalla Barba et al., 1997b) than by current theories of confabulation.

Neuropsychological changes between "off" and "on" STN or GPi stimulation in Parkinson's disease

BACKGROUND

In a previous study on a consecutive series of 62 patients with PD, the authors showed that bilateral subthalamic or pallidal continuous high-frequency deep brain stimulation (DBS) affects neither memory nor executive functions 3 to 6 months after surgery.

OBJECTIVE

To investigate the specific effects of DBS by comparing the performance of patients with the stimulator turned "on" and "off."

METHODS

The performance of 56 patients on clinical tests of executive function was compared after 3 and 12 months of DBS of the subthalamic nucleus (STN; n = 48) or the internal globus pallidus (GPi; n = 8) with the stimulator "on" or "off." Global intellectual efficiency, verbal learning, and mood were also evaluated with the stimulator "on." The performance of another group of 20 patients was compared after 6 months of DBS of the STN (n = 15) or the GPi (n = 5) with the stimulator "on" or "off" on more experimental tests recently shown to be more sensitive to l-dopa therapy.

RESULTS

When the stimulator was "on," STN patients showed a mild but significant improvement in psychomotor speed and working memory. In comparison with the presurgical state, STN patients had no cognitive deficit at 12 months, except for lexical fluency. There was no differential effect of STN or GPi stimulation.

CONCLUSIONS

1) The specific effect of DBS seems to mimic the action of l-dopa treatment in the cognitive as in the motor domain; 2) the surgery associated with DBS does not appear to affect the cognitive performance of patients with PD 12 months later, except for a mild deficit in lexical fluency.

How patients with Parkinson's disease retrieve and manage cognitive event knowledge

Several studies have pointed out that basal ganglia are involved in adaptive control of action at both motor and cognitive level. This study aimed to investigate how basal ganglia retrieve and manage script event knowledge required in planning behavior. Script event knowledge was investigated in patients with Parkinson's Disease using three kinds of activity that differed in familiarity. Unlike patients with prefrontal lesions, patients with Parkinson's Disease were able to order events in a typical sequence and obeyed the boundaries and hierarchies between events. In contrast, patients with Parkinson's Disease were impaired in evaluating how important each script event was within the context of goal-oriented planning activity. Our findings indicate that the prefrontal cortex and the basal ganglia are differentially involved in planning. The role of the basal ganglia might consist in providing a feedback about the goodness of each action while building up meaningful sequences of events during learning.

Distinct prefrontal activations in processing sequence at the sentence and script level: an fMRI study

Neuropsychological studies have shown that the prefrontal cortex is important in planning and monitoring everyday behaviour. In this study, using functional magnetic resonance imaging (fMRI), we investigated whether specific prefrontal regions are involved in processing a sequence of actions. Subjects were required to perform two different tasks: Script-event order and Sentence-word order. Script sequence and word sequence processing were found to activate partially overlapping areas which are known to be implicated in language processing. In addition, the Script-task activated a large area in the dorsolateral prefrontal cortex (Brodmann area 6 and 8, BA 6 and 8), in both the left and right hemispheres, as well as the left supplementary motor area and left angular gyrus (BA 39). Our results suggest that these prefrontal areas may be more specifically involved in the process of analysing sequential links in the action domain.

Specificity of memory deficits after right or left temporal lobectomy

An impairment of verbal memory has consistently been associated with resection of the left dominant temporal lobe, whereas non-verbal memory deficits have been less reliably observed following resection of the right temporal lobe. Such a dissociation may be due to material-specific differences of processing between verbal and non-verbal information. Alternatively, the influence of the left and right limbic structures may vary according to the stage of memory processing. The aim of the study was to test these hypotheses by comparing verbal and spatial learning in patients with left or right temporal lobe resection for intractable epilepsy, using verbal and visuospatial memory tasks with the same design: control of encoding, multiple trial learning, free and cued recall, short and long delays. The results showed: (1) a similar pattern of learning and recall in the two groups; (2) a higher performance in spatial learning for patients with left temporal lobe resection and in verbal learning for patients with right temporal lobe resection; (3) material-specific effects characterized by a higher sensitivity to cues in the verbal domain and a better retention of information during delays in the spatial domain. These results suggest parallel processing of the two temporal lobes at the various memory stages, rather than an interaction between memory stage and side of the lesion similar to that already proposed for the frontal lobes. They also confirm a double dissociation between verbal/spatial information processing and side of temporal lobe resection.

Bilateral subthalamic or pallidal stimulation for Parkinson's disease affects neither memory nor executive functions: a consecutive series of 62 patients

There is a renewal of interest in surgical approaches including lesions and deep brain stimulation directed at motor subcorticofrontal loops. Bilateral lesioning presents a far greater risk of adverse effects, especially cognitive impairment. Furthermore, the main advantages of the stimulation procedure over lesioning are adaptability and reversibility of effects. The aim of this study was to assess the influence of bilateral stimulation of the subthalamic nucleus or internal globus pallidus on memory and executive functions in Parkinson's disease. Sixty-two patients were assessed before and after 3 to 6 months of chronic bilateral stimulation of the subthalamic nucleus (n = 49) or internal globus pallidus (n = 13). The neuropsychological tests used were the Mattis Dementia Rating Scale, the Grober and Buschke Verbal Learning Test, the Wisconsin Card Sorting Test, category and literal fluency, graphic and motor series, the Stroop Test, and the Trail Making Test. Mood was evaluated by the Beck Depression Inventory. Only 4 of 25 cognitive variables were affected by deep brain stimulation. Under stimulation, performance improved for Parts A and B of the Trail Making Test, but there was a deterioration in literal and total lexical fluency. There was also a mild but significant improvement in mood. It may therefore be concluded that stimulation of the subthalamic nucleus or internal globus pallidus does not change the overall cognitive performance in Parkinson's disease and does not greatly affect the functioning of subcorticofrontal loops involved in cognition in humans. This relative absence of cognitive impairment in bilateral deep brain stimulation is likely because of the accurate positioning of the electrodes, allowing the effects of stimulation to be confined to sensorimotor circuits.

Acute and long-term administration of anticholinergics in Parkinson's disease: specific effects on the subcortico-frontal syndrome

Parkinson's Disease (PD) is often associated with a subcortico-frontal syndrome (SCFS) that is mainly characterized by executive dysfunctions. The complete biochemistry of these dysfunctions remain misunderstood. Most studies have focused on the well-known nigro-striatal dopaminergic degenerations of PD, but a more satisfying understanding of the SCFS has come from the study of the cholinergic systems. We present here two new experiments carried out with long-term and acute anticholinergic treatments in PD. In the first experiment, the effects of a 2-week treatment with trihexyphenidyl were compared to those observed under placebo on a neuropsychological battery. Results showed that anticholinergic-induced deficits in PD were exclusively concerned with executive functions. In the second experiment, the effects of an acute subclinical dose of scopolamine were compared between normal controls and PD patients who were devoid of cognitive deficit on a subset of executive tasks. Results indicates that PD patients but not normal controls developed a transient SCFS for the duration of the drug action. In contrast to other populations with cholinergic depletions-such as Alzheimer's disease-cholinergic blockade in PD exacerbates specifically the SCFS. Such a discrepancy between these two neuropsychological profiles are discussed in terms of the specificity of the underlying cholinergic lesions.

[Fronto-temporal dementia: a clinical approach]

Although the existence of atrophy of the anterior part of the brain has been known for a long time (Pick, 1892), the interest for fronto-temporal dementias (DFT) is relatively recent. Several excellent reviews have been recently published on the topic (Gustafson, 1993; Neary and Snowden, 1996; Pasquier et al., 1998) and, for that reason, we only recall the main aspects of the disease to insist on some lesser known features, illustrated by original observations.

Sensitivity to semantic cuing: an index of episodic memory dysfunction in early Alzheimer disease

Alzheimer disease (AD) is characterized by episodic memory impairment. This study was aimed at assessing various aspects of episodic memory, and particularly sensitivity to semantic cuing, in patients with various degrees of cognitive deterioration, compared with normal elderly subjects. One hundred thirty-one patients, subdivided into four subgroups as a function of their Mini-Mental State Examination score, were included. All subjects, including 20 normal elderly subject, were given an episodic memory test with controlled encoding and selective reminding. The subgroups of patients were homogeneous in terms of free recall and recognition, but differed in terms of responsiveness to cuing by semantic categories corresponding to the to-be-remembered items. The data confirmed that a severe amnesic syndrome occurs very early in AD, even in a subgroup of patients who did not meet the criteria for dementia. The data indicated that free recall performance, characterized in all subgroups by a floor effect, is not likely to be an appropriate index in pharmacological trials. By contrast, sensitivity to semantic cuing seemed relatively preserved in the early stages, and decreased with the progression of the disease. This index would be the most sensitive index of episodic memory in AD.

At which steps of spatial working memory processing do striatofrontal circuits intervene in humans?

Striatofrontal circuits have been implicated in spatial working memory in non-human and human primates. To determine at which steps of information processing (stimulus encoding, storage or response programming) they intervene, we compared 32 levodopa-treated patients with idiopathic Parkinson's disease (PD) and 32 matched control subjects in a visuo-spatial pattern span paradigm. Our testing procedure allowed us to evaluate the influence of: (1) the type of encoding (controlled vs free); (2) the nature of interference during a 10 s delay (spatial vs verbal); and (3) response elaboration (reproduction vs error detection). As expected, the performance of control subjects was significantly better in controlled than in free encoding, in verbal than in spatial interference and in detection than in reproduction, clearly demonstrating the sensitivity of the procedure to these factors. Compared to controls, PD patients were impaired in all conditions and the severity of the deficit was significantly correlated with that observed in tests of executive functions. The global pattern of performance, however, was identical to that of controls. These data confirm the involvement of striatofrontal circuits in spatial working memory in humans and suggest that the executive working memory component intervenes at all steps of working memory processing.

Deficit in evaluating pre-determined sequences of script events in patients with Parkinson's disease

The purpose of the present study was to assess how the striato-frontal system contributes to the manipulation of goal-directed actions. We studied a group of ten patients with Parkinson's disease (PD) in order to investigate which aspects of action knowledge processing are impaired and to define the conditions under which the deficits may occur. PD patients committed errors of sequence and inserted distractors in tasks that required them to order pre-determined events belonging to a given script in a typical sequence. Rather than attributing errors of event sequencing to a deficit of script "syntax" knowledge, we suggest that the difficulties manifested by PD patients were due to an impairment of a switching mechanism that is necessary for processing information in parallel.

Clinicometabolic dissociation of cognitive functions and social behavior in frontal lobe lesions

OBJECTIVE/BACKGROUND

Case studies suggest a dissociation between cognitive functions that have been impaired after damage to the dorsolateral prefrontal cortex and social skills disturbed when the ventromedial prefrontal areas are affected. Because this dissociation had not been confirmed in a clinical setting, clinicometabolic correlations were sought in 13 patients with various lesions of the prefrontal cortex.

DESIGN/METHODS

The clinical assessment included extensive testing of executive functions and evaluation of behavioral abnormalities based on an informant questionnaire. Regional cerebral glucose metabolism (rCMRGlu) was measured with [l8F] fluorodeoxyglucose ([18F] FDG) and 31-slide high-resolution PET.

RESULTS

Executive-function test performance was significantly correlated with rCMRGlu in the dorsolateral prefrontal cortex (Brodmann's areas 8, 9, 45, 46, and 47) and anterior cingulate cortex (Brodmann's areas 24 and 32). Behavioral scores were significantly correlated with rCMRGlu in the frontopolar (Brodmann's area 10) and orbitofrontal cortex (Brodmann's areas 11, 12, 13, and 14).

CONCLUSION

These results show that impaired executive functions and serial skill deficits are associated with distinct metabolic patterns in patients with frontal lobe pathology. In agreement with activation studies in normal subjects, our data suggest the existence of a modular organization of the frontal cortex in humans, as previously reported in nonhuman primates.

Attentional deficits in Parkinson's disease: partial reversibility with naphtoxazine (SDZ NVI-085), a selective noradrenergic alpha 1 agonist

Several authors have suggested that catecholamine depletion may affect attentional processes in human subjects and could be implicated in the frontal lobe syndrome that has been described in Parkinson's disease (PD). The present study reports the effects of a placebo and naphtoxazine (SDZ-NVI-085), a selective noradrenergic alpha 1 agonist. These substances were administered to nine parkinsonian patients who were assessed on measures of attention, including neuropsychological tests and evoked potentials. The results indicate that naphtoxazine may improve performance on some tests of "frontal functions," including the Stroop and the Odd-Man-Out tests, which have been previously found to be affected in PD. However, the results of some other neuropsychological tests of frontal function were not affected by naphtoxazine. Specific evoked potentials such as the Nd1 and Nd2 curves--which are thought to reflect attentional processes and which have been found to be affected in PD--were improved by naphtoxazine. Finally, naphtoxazine reduced the percentage of errors and restored the lateralization of N100 during the Shifting Reaction Time Task, suggesting that this substance may act on the processes underlying the shifting deficit in these patients. The results are discussed in terms of the specific cognitive processes that may be affected by naphtoxazine and in terms of the role of the noradrenaline in attentional deficits found in PD.

Spatio-temporal working memory and frontal lesions in man

The delayed-response paradigm is thought to be a marker of the activity of the dorsolateral convexity of primates' prefrontal cortex, as this procedure requires the activation of working memory processes. Although the role of the dorsolateral prefrontal cortex (DLPC) in working memory seems to be well established, much remains to be understood about the processes this structure actually controls: encoding domain-specific information, its retention in short-term memory, its monitoring in working memory, or its selection and retrieval when a specific response program is required. To clarify the role of the DLPC in delayed-response tasks in humans, a set of sequencing paradigms was designed which incorporates the dissociation of (1) spatial and temporal parameters, (2) recall and recognition processes, and (3) the presence or absence of a delay. Performance of a group of patients with DLPC lesions (n = 8) was compared to that of age-matched normal subjects (n = 8). To verify the specificity of the results obtained for the DLPC lesioned patients, the performance of patients with a temporal lobotomy was also studied (n = 10). A significant effect of the delay was observed only in patients with DLPC lesions, affecting both their spatial and spatio-temporal recall, whereas their spatio-temporal recognition was normal. These findings suggest that the DLPC plays a role in the retrieval of visuospatial information for guiding a response program.

Are cognitive changes the first symptoms of Huntington's disease? A study of gene carriers

BACKGROUND

Huntington's disease is a neurodegenerative disorder due to an excessive number of CAG repeats in the IT15 gene on chromosome 4. The first symptoms are typically choreic movements or psychiatric disorders, whereas global cognitive decline generally becomes obvious later. This study was aimed at detecting early subtle cognitive deficits in asymptomatic gene carriers.

METHODS

As part of the testing procedure for predictive diagnosis of Huntington's disease, 91 asymptomatic at risk candidates had a neuropsychological examination, evaluating global efficiency, attention, memory (Wechsler memory scale and California verbal learning test), and executive functions.

RESULTS

The groups of carriers (n=42) and non-carriers (n=49) differed only on a few memory variables. When we considered the group of gene carriers as a whole, significant correlations emerged between the number of CAG repeats and (a) performance on several tests of executive functions, and (b) performance on the hard pairs associates of the Wechsler memory scale. Further analysis of performance on this memory subtest led to the division of the group of carriers into two subgroups, without any overlap. The performance of subjects without cognitive deficits (n=32) was similar to that of non-carriers on all tests. The subjects with cognitive deficits (n=10) differed from both carriers without cognitive deficits and non-carriers over a wide array of variables measuring executive functions and memory. Moreover, qualitative aspects of the performance of carriers with cognitive deficits in the California verbal learning test closely resembled those of patients diagnosed as having Huntington's disease.

CONCLUSION

This suggests that these subjects already have Huntington's disease, despite a total lack of motor and psychiatric signs. An ongoing follow up study is testing the prediction that they will develop the full range of symptoms of the disease earlier than carriers without cognitive deficits.

Is impaired memory for spatial location in Parkinson's disease domain specific or dependent on 'strategic' processes?

Spatial memory has been found to be impaired in Parkinson's disease (PD). To determine the nature of the deficit, we compared the performance of'standard' levodopa-treated patients with PD to that of matched control subjects in different situations: (i) spatial versus verbal conditional associative learning; (ii) 'global' versus 'local' contextual encoding; (iii) pattern span and related supraspan learning. The relationship between dopaminergic depletion, which characterizes the disease, and the impaired memory processes was investigated by comparing the performance of 'de novo' not yet treated PD patients to that of matched control subjects. Both groups of PD patients were impaired in all situations requiring strategic processes, shared a decreased pattern span and had a normal visuospatial learning once the pattern span was taken into account. All these results suggest that the memory deficit for spatial location observed in PD results mainly from a disturbance of strategic processes and from decreased attentional resources, which may be due, at least in part, to the dopaminergic depletion and related striatofrontal dysfunction.

Memory for spatial location in 'de novo' parkinsonian patients

A deficit in memory for spatial location was recently reported in typical non-demented parkinsonian patients ('standard'). Is this deficit related to dopamine depletion? Such an association would reinforce the suggestion that striato-frontal neuronal circuits are implicated in memory for item-specific spatial coordinates. To answer this question, we compared the performance of 10 recently diagnosed and not yet treated parkinsonian patients ('de novo'), in which the neurobiochemical deficit is considered to involve mainly the nigrostriatal dopaminergic system, to that of 14 controls matched for age, global cognitive efficiency and mood, on a visuospatial learning test. The task required little motor or constructive functions and was designed to allow control of encoding and comparison of free recall, cued recall and recognition. Compared to controls, 'de novo' patients displayed a lower performance in memory for visuospatial location of pictures, contrasting with relative preservation of verbal memory, perceptive visuospatial and executive functions. These results confirm the sensitivity of visuospatial memory even at an early stage of Parkinson's disease and suggest the implication of the nigrostriatal dopaminergic system, and associated striato-frontal neuronal circuits, in executive processes needed for spatial location learning.

Cognitive deficits in Parkinson's disease

Neuropsychological investigations of patients with Parkinson's disease have shown specific impairments even in the early stages of the disease, which include deficit of behavioural regulation in sorting or planning tasks, defective use of memory stores, and impaired manipulation of internal representation of visuospatial stimuli. These deficits, reported in a disease which predominantly involves subcortical structures, have drawn attention to a potential role of the basal ganglia in cognitive processes. Given the modulatory role of the basal ganglia, these disorders might result from more fundamental deficits concerning the allocation of attentional resources, the temporal organization of behaviour, the maintenance of representations in working memory or the self-elaboration of internal strategies, all of which resemble dysfunctions of processes that are commonly considered to be controlled by the frontal lobes. This suggests a functional continuity or complementarity between the basal ganglia and association areas of the prefrontal cortex. The recent description in primates of segregated loops that interconnect discrete regions of the caudate nucleus to the dorsolateral and orbitofrontal regions of the prefrontal cortex via the thalamus may give some support to this hypothesis. Alternatively, degeneration of the ascending cholinergic and catecholaminergic neuronal systems may contribute, at least in part, to the occurrence of this frontal-lobe-like symptomatology associated with Parkinson's disease.

The mental representation of hand movements after parietal cortex damage

Recent neuroimagery findings showed that the patterns of cerebral activation during the mental rehearsal of a motor act are similar to those produced by its actual execution. This concurs with the notion that part of the distributed neural activity taking place during movement involves internal simulations, but it is not yet clear what specific contribution the different brain areas involved bring to this process. Here, patients with lesions restricted to the parietal cortex were found to be impaired selectively at predicting, through mental imagery, the time necessary to perform differentiated finger movements and visually guided pointing gestures, in comparison to normal individuals and to a patient with damage to the primary motor area. These results suggest that the parietal cortex is important for the ability to generate mental movement representations.

Delayed response tasks in basal ganglia lesions in man: further evidence for a striato-frontal cooperation in behavioural adaptation

To determine the respective contribution of the subcortical structures and the prefrontal cortex in behavioural adaptation, we applied the delayed response paradigm, considered as a functional marker of the dorsolateral region of the prefrontal cortex, to patients with striatal dysfunction: Parkinson's disease (n = 27), progressive supranuclear palsy (n = 20); to patients with prefrontal lesions (n = 10) and to normal control subjects (n = 24). The performance of each group was compared in four experiments: a delayed response task in which the correct answer was previously indicated by an explicit cue (externally guided task); delayed alternation and non-alternation tasks coupled with a delayed reversal task in which the patient had to discover the rule by himself in the absence of explicit cues (internally driven tasks). All groups of patients showed a short-term spatial representational memory deficit in the externally guided situation. Patients with striatal dysfunction showed difficulties in re-engaging attention on a new programme and in maintaining it. However, they did not express the spontaneous tendency to alternate nor the severe difficulties in disengaging from a previous pattern of response demonstrated by patients with prefrontal lesions. These results validate the concept of a striato-frontal functional system in humans and suggest the existence of two different levels of behavioural organization: elaboration of new programmes of behaviour in association with inhibition of previously established ones, that might be under frontal lobe control: maintenance of the new programme until the action has been accomplished and automatization for a routine utilization, that might be under control of the striatum.