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Biomedical subjects

J L Nandrino

Publications and source records attributed to J L Nandrino.

6 recordsLinked to original sources
PubMed1996

Depression as a dynamical disease.

Mathematical models are helpful in the understanding of diseases through the use of dynamical indicators. A previous study has shown that brain activity can be characterized by a decrease of dynamical complexity in depressive subjects. The present paper confirms and extends these conclusions through the use of recent methodological advances: first episode and recurrent patients strongly differ in their dynamical response to therapeutic interventions. These results emphasize the need for clinical follow-ups to avoid recurrence and the necessity of specific therapeutic intervention in the case of recurrent patients.

Adult↗
PubMed1995

Temporal localization of the response selection processing stage.

Response choice is one of the stages in the information processing model proposed by Sanders. It is influenced by stimulus-response (S-R) compatibility. Segmentation of the processing window in intervals between RT and peak latencies and between peak latencies, was used to test the assumption that the decisional processes would be concomitant with the N200 rather than the P300 component. ERPs were recorded in ten subjects during a spatial S-R compatibility auditory task. The S-R compatibility effect is observed on P300 latencies but is only a trend on the N200 component. An effect also observed on the interval between RT and N200 and especially between N200 and P300 while no effect is observed on the interval between RT and P300. These results support the idea that the selection processes ending with P300 occurrence could start as early as the N200 peak component.

Acoustic Stimulation↗
PubMed1995

[Study of the organization of sensorimotor stages in man using delayed evoked potentials].

The main aim of this study was to test the relative organization of three of the stages of Sanders' 1990 information processing model: "features extraction", "response choice", and "motor adjustment". The variables influencing these stages: stimulus degradation, stimulus-response (SR) compatibility and preparatory period have been manipulated. Event related potentials (N100, N200, P300) and reaction time were recorded from ten healthy subjects, in a dichotic listening task. Reaction times are lengthened for degraded stimuli, in the absence of a preparatory period and for SR non compatible conditions. However, the interaction between preparatory period and stimulus degradation variables, suggests an overlapping of the corresponding stages contrary to Sanders' postulate. The non compatible condition increases the latency of N200 and P300 components. The results suggest that the response choice processing would be contemporary to the N200 component. They are discussed within the framework of models of early communication between sensory and motor systems.

Adult↗
PubMed1994

Decrease of complexity in EEG as a symptom of depression.

Nonlinear dynamic analysis provides new methods for the processing of the electroencephalogram (EEG). We demonstrate here that the EEG dynamics of major depressive subjects is more predictable, that is less complex, than that of control subjects. Moreover, the consequence of treatment upon the EEG dynamics seems to be dependent on the appearance of the illness. Although the specificity of this dynamic signature for different stages of depression is to be confirmed, the assumption of a strong link between a healthy system and a high level of complexity in dynamics is further supported.

Adult↗
PubMed1993

Time for reorienting of attention: a premotor hypothesis of the underlying mechanism.

The paradigm of the covert orienting of attention (COA) has shown that the displacement of visual attention may be assessed even in the absence of eye movement. Stimuli correctly cued before their presentation are usually detected faster than uncued stimuli. However, miscued stimuli induce an increased detection time, which has been attributed to the time required for the reorientation of attention from the incorrect to the correct spatial location. Currently, the mechanism of such a displacement of visual attention remains unknown. Rizzolatti et al. Neuropsychologia 25, 31-40 (1987) have suggested a premotor hypothesis which suggests that an oculomotor disprogramming and reprogramming is necessary to reorient visual attention, even if the eye movement is inhibited. Since shifting of auditory attention from one ear to the other does not require any motor control, we further investigated the model of COA in 20 normal subjects who performed two tasks requiring a reorienting of auditory attention: (1) a choice RT task that requires a response readjustment during the auditory reorienting; (2) a simple RT task that does not require a response readjustment during the auditory reorienting; (2) a simple RT task that does not require a response readjustment during the auditory reorienting. Results indicate that correctly cued stimuli significantly reduce the RT in both tasks and that this reduction is greater in the choice than in the simple RT task. This suggests that a correct cue may produce a pre-programming of the response, in addition to the pre-engagement of the perceptual attention.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗