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A Partiot

Publications and source records attributed to A Partiot.

8 recordsLinked to original sources
PubMed1996

Heterogeneity of information-processing alterations according to dimensions of depression: an event-related potentials study.

To identify alterations in elementary cognitive operations according to dimensions of depression, two stages of information processing, namely the response choice and the motor preparation stages, were explored using an event-related potential paradigm in two subgroups of depressed patients (retarded and blunted affect versus anxious-agitated and impulsive) compared to controls. Two results are common to all depressed patients: a slow encoding of stimuli (P1 wave) and a prolonged processing of stimulus-response compatibility (after P3b). This is compensated by a global velocity increase in stimulus evaluation or decision making (P3b) in anxious-agitated patients or, on the contrary, cumulated with its velocity decrease in retarded-blunted-affect patients. Such results could provide an explanation for the massive retardation observed in blunted-affect patients, contrary to anxious-agitated patients, whose normal reaction times may come from a very high energetical involvement at the P3b level. Results as a whole suggest that impairments in blunted-affect patients concern effort mechanisms, whereas those in anxious-agitated patients concern perceptual processes.

Adult↗
PubMed1996

Brain activation during script event processing.

Regional cerebral blood flow was measured with positron emission tomography in seven normal volunteers while they performed various script event verification tasks. The left frontal lobe, left anterior cingulate and the anterior part of the left superior temporal gyrus were more activated in the script event membership and action categorization conditions, whereas the right frontal lobe, left superior temporal gyrus and the middle temporal gyrus bilaterally were more activated in the script event temporal order verification condition. These results indicate that the temporal ordering of script events and determining whether an event belongs to a particular script or action category are processed by distinctive distributed neuronal networks.

Adult↗
PubMed1996

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.

Adaptation, Psychological↗
PubMed1995

Brain activation during the generation of non-emotional and emotional plans.

We studied 12 normal volunteers who were asked to imagine and plan their behavior in emotional and nonemotional situations while their regional cerebral blood flow was measured with positron emission tomography. The dorsolateral prefrontal and posterior temporal cortex were more activated during the nonemotional situation whereas the medial prefrontal cortex and anterior temporal cortex were more activated during the emotional situation. These results demonstrate that distinctive regions of the prefrontal and temporal cortex used to imagine and plan behavior are activated during the expression of emotional and non-emotional plans.

Adult↗
PubMed1994

Loss of control of pre-motor activation in anxious agitated and impulsive depressives. A clinical and ERP study.

1. Current research uses a variety of traditional validation methods in order to test the clinical expression of biological models in psychiatry. The application of these methods has resulted in a paradoxical situation which requires the definition of new objectives in biological and pharmacoclinical research: the biological specificity of new psychotropic drugs does not assume any congruence between their pharmacological and their therapeutic effects, but raises the question of the relationship between biological systems and clinical symptomatology. The dimensional description of psychopathological disorders may be more appropriate to biological studies in psychiatry. 2. A study was undertaken on a population of twenty-one in-patients fulfilling the DSM III-R criteria for major depressive episode. They were divided into two groups on the basis of contrasting clinical dimensions: anxious-agitation and impulsiveness versus retardation and affective blunting. 3. Significant clinical differences between the two groups on mood profiles were echoed by contrasts in event-related potentials during a go-nogo task: only anxious agitated and impulsive patients developed an abnormal cortical activity, as measured by contingent negative variation (CNV), in the nogo condition. 4. This paper suggests how a paradigm with control of motor action leads to specify premotor activation abnormalities in the agitated impulsive depression subtype.

Adult↗
PubMed1993

Delayed response tasks and prefrontal lesions in man--evidence for self generated patterns of behaviour with poor environmental modulation.

The functions of the frontal lobes in humans are still under debate, mainly because none of the neuropsychological tests used for their assessment is sufficiently specific for frontal dysfunction. In animals, the delayed reaction paradigm is considered to be a specific marker of the function of dorsolateral region of the prefrontal cortex. It seemed of interest, therefore, to attempt to apply this paradigm to patients with recent and limited cortical lesion of vascular origin. The performance of patients with dorsolateral prefrontal lesion (n = 10) was compared to that of patients with post-central lesion (n = 10) and control subjects (n = 24), 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). Patients with prefrontal lesion showed a specific deficit in the Delayed Response task, the emergence of a stereotyped behaviour in the Delayed Alternation task and an inability to deduce and to transfer rules (non-alternation and reversal), mainly because of difficulty in abandoning previous behaviours. Our study demonstrates that the prefrontal cortex plays a role in behavioural adaptation to challenging new situations by inhibiting not only ongoing elaborated programmes but also the emergence of previously established automatic programmes. The respective role of the prefrontal cortex and the basal ganglia in these two levels of behavioural organization is discussed.

Aged↗
PubMedDate not supplied

[Automatic information processing, the frontal system and blunted affect. From clinical dimensions to cognitive processes toward a psychobiological explanation of temperament].

Several theorists have drawn a distinction between automatic and attentional or controlled processing. Hasher and Zacks (1979), were the very first to argue that effortful processes are reduced under conditions of stress including depression. They suggested that, in these conditions, no such deficit occurs in automatic processing. Then, Weingartner and co-workers provided some experiments which seemed to support such an interpretation of the cognitive dysfunction in depressed patients. However, some recent data do not fit with this well admitted theoretical framework. The purpose of our article is to try to clarify this issue both from a theoretical and from a methodological point of view. First, we make a critical review of the most recent results in three fields of experimentation related to the "automatic versus controlled" topic: 1) The classical neuropsychology of memory which manipulates the level of effort required to perform the tasks. Confusion arises when theories at the process level are tested with reference to data collected at the task level. The transparency assumption could be false: Impairment in an effort-demanding task could be due to a defect in automatic processes and it is possible to hypothesize that the more automatic processes are deficient, the more controlled processes are saturated and the effort demanding task impaired. The emergence of controlled processes could depend on the level of automaticity and the regulation of automatic processes could be determinant for the ability of the subject to make associations. 2) The recent studies on implicit memory in depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗