Biomedical subjects

Jean-Marie Danion

Publications and source records attributed to Jean-Marie Danion.

18 recordsLinked to original sources

PubMed2006

Alteration of protein kinase C conformation in red blood cells: a potential marker for Alzheimer's disease but not for Parkinson's disease.

There is a growing evidence of early changes of blood cells in Alzheimer's disease (AD). We have developed an original novel method for quantifying the alteration of protein kinase C (PKC) by its fluorescence spectrum: by using Fim-1, a specific fluorescent probe made for protein kinase C that detects the conformational changes of this. We show that the PKC conformation is altered in red blood cells (RBC) from AD patients as compared to RBC from healthy controls. This alteration is independent of the patient's age and of the stage of the disease. It is not observed in the RBC of non-demented patients suffering from Parkinson's disease (PD). If PKC alteration is proven to be specific to AD as compared with other dementia, this method could be for a simple, low cost screening test among patients suspected of having AD and may have a strong predictive value.

Age Factors↗

PubMed2005

Assessing a minimal executive operation in schizophrenia.

The minimal cognitive operation of thinking of a just-seen stimulus (refreshing) was studied in 24 patients with schizophrenia and 24 normal controls. Verbal response times were measured when participants read a word, read a word immediately again, or refreshed a word just after it was no longer present. Patients showed equal priming as controls in reading a word for the second time and were slower than controls to say a word only in the refresh condition. On a surprise test, participants were asked to recognize the words they had seen previously and to give Remember, Know, or Guess responses according to whether they recognized words on the basis of conscious recollection, familiarity, or guessing. Although patients showed overall poorer recognition memory, the beneficial effect of refreshing on long-term memory accuracy and Remember responses was preserved, whereas they derived less benefit in familiarity from seeing an item twice than from refreshing it. These results suggest that although patients may have some difficulty engaging the refresh process, they show significant long-term memory benefits when induced to do so.

Adult↗

PubMed2005

The FOCIS international survey on psychiatrists' opinions on cognition in schizophrenia.

BACKGROUND: The goal of this project was to develop an interview to evaluate psychiatrists' views on the nature of cognitive dysfunction in schizophrenia, its importance as a potential treatment target, and its relative importance as a treatment target across different phases of schizophrenia. MATERIALS AND METHODS: A survey (available in paper or on-line) consisting of 27 questions, was developed by the Focus on Cognition in Schizophrenia (FOCIS) group, and distributed in a single wave mailing to 63,295 psychiatrists in 21 countries worldwide. RESULTS: The overall response rate was 4.7% (n=2975). The surveyed psychiatrists perceived cognition as a high treatment priority in stabilized schizophrenia patients, but less so for first episode or acute schizophrenia patients. The potential of atypical antipsychotics to improve cognitive dysfunction in schizophrenia was identified by 81% of the respondent psychiatrists. CONCLUSIONS: Cognitive deficits in people with schizophrenia are seen by clinical psychiatrists as relevant to treatment and rehabilitation plans. They were, however, regarded as a higher treatment priority in stabilized chronic rather than in first episode patients. The results suggest clinical psychiatrists need additional education regarding the nature of cognitive dysfunction in schizophrenia and its importance for psychosocial rehabilitation and community re-entry.

Attitude of Health Personnel↗

PubMed2005

Conscious recollection in autobiographical memory: an investigation in schizophrenia.

Whether or not conscious recollection in autobiographical memory is affected in schizophrenia is unknown. The aim of this study was to address this issue using an experiential approach. An autobiographical memory enquiry was used in combination with the Remember/Know procedure. Twenty-two patients with schizophrenia and 22 normal subjects were asked to recall specific autobiographical memories from four lifetime periods and to indicate the subjective states of awareness associated with the recall of what happened, when and where. They gave Remember, Know or Guess responses according to whether they recalled these aspects of the event on the basis of conscious recollection, simply knowing, or guessing. Results showed that the frequency and consistency of Remember responses was significantly lower in patients than in comparison subjects. In contrast, the frequency of Know responses was not significantly different, whereas the frequency of patients' Guess responses was significantly enhanced. It is concluded that the frequency and consistency of conscious recollection in autobiographical memory is reduced in patients with schizophrenia.

Adolescent↗

PubMed2004

Prenatal exposure of Long-Evans rats to 17alpha-ethinylestradiol modifies neither latent inhibition nor prepulse inhibition of the startle reflex but elicits minor deficits in exploratory behavior.

Prenatal administration of synthetic estrogens in humans as well as lower mammals was reported to alter behavior in adulthood. The alterations remain to be characterized according to specific pathophysiological hypotheses. In this study, three common behavioral models of schizophrenia were tested, i.e., latent inhibition (LI), prepulse inhibition of the startle response (PPI) and hyperlocomotion under amphetamine. Female Long-Evans rats were injected i.p. with a solution of 17alpha-ethinylestradiol (15 microg kg(-1)) everyday from day 9 to 14 of pregnancy, and behavioral characteristics of their offspring, raised by Wistar foster mothers, were compared to those of rats born from dams injected with the vehicle only, over the same gestation period. LI was tested in a conditioned taste aversion and a conditioned passive avoidance paradigm followed by a parametric study of PPI and an evaluation of locomotion in an open field under saline or amphetamine (1.5 mg kg(-1)). Histological brain measurements were also carried out in a subset of the same rats. Neither LI nor PPI was altered using methods that had proven sensitive in previous pharmacological studies. Treated rats' locomotion was impaired, but amphetamine did not elicit a differential enhancement. A thinner Amon's horn layer was observed in their hippocampus. This indicates that standard models of schizophrenia did not fit to the behavioral abnormalities found by others and confirmed in this study. They were not due to the abnormal maternal care to pups elicited by the treatment.

Amphetamine↗

PubMed2004

Impaired performance in a working memory binding task in patients with schizophrenia.

This study investigated feature binding in a working memory task in patients with schizophrenia and in normal controls. Twenty-five patients and 25 controls participated. On each trial, three drawings of familiar objects were presented sequentially, each in a different cell of a 3 x 3 grid. In different blocks of trials, participants remembered either individual features (object and location conditions) or an object and its location (combination condition). The results showed that patients were slower and less accurate than controls under all conditions. Accuracy of both groups was reduced in the combination condition relative to the single-feature conditions, but patients showed disproportionately poorer performance in the combination condition than in the object and location conditions. Thus, patients with schizophrenia exhibit deficits in working memory, particularly when the task requires binding objects to their locations. This finding demonstrates that processes that establish coherent and temporary episodic representations in working memory are impaired in schizophrenia.

Adult↗

PubMed2004

Relations between emotion and conscious recollection of true and false autobiographical memories: an investigation using lorazepam as a pharmacological tool.

RATIONALE: Conscious recollection for autobiographical memory is the subjective experience of reliving a personal event mentally. Its frequency is strongly influenced by the emotion experienced at the time of the event. OBJECTIVE: We addressed the issue of whether conscious recollection for autobiographical memories is also influenced by the emotion experienced at the time of retrieval. We used lorazepam, a benzodiazepine, as a pharmacological tool to modulate this emotional experience. METHODS: Autobiographical memories were recorded in eight healthy volunteers using a diary study methodology. Each day, four entries were made by each subject: two true events, one altered event and one false event. For each event, the subjects were asked to rate emotional variables at encoding and at retrieval. Two months later, there were two sessions of recognition tests during which the subjects received orally an acute administration of either lorazepam (0.038 mg/kg) or placebo using a cross-over design. Subjective states of awareness were assessed using the Remember/Know/Guess procedure. RESULTS: Compared to placebo, lorazepam increased levels of conscious recollection, as assessed by Remember responses, for both true and false memories and induced an overestimation of the personal significance and emotional intensity of past events. Structural equation modelling showed that this overestimation was causal in the increased frequency of conscious recollection. CONCLUSIONS: Our results provide experimental evidence that the frequency of conscious recollection for both true and false autobiographical memories is influenced by the emotion experienced at the time of retrieval.

Adult↗

PubMed2003

Reduced levels of specific autobiographical memories in schizophrenia.

Autobiographical memory is intrinsically related to the self and personal identity. This study investigated whether both personal episodic memory and semantic memory are impaired in schizophrenia, a disease characterized by an abnormal personal identity. Personal episodic memory and personal semantic memory were investigated in 24 patients with schizophrenia and 24 normal subjects using an autobiographical fluency task and an autobiographical memory inquiry. Autobiographical memory scores and the proportion of specific memories were lower in patients with schizophrenia than in normal subjects. The deficit of personal episodic and semantic memory, as assessed by the autobiographical memory inquiry and the autobiographical fluency task, respectively, was most apparent after the onset of clinical symptoms. Schizophrenia is associated with an impairment of both personal episodic and semantic memory and with a reduction of specific autobiographical memories. Those impairments are consistent with the existence of an abnormal personal identity in patients with schizophrenia.

Adult↗

PubMed2003

Impaired strategic regulation of contents of conscious awareness in schizophrenia.

Conscious awareness comprises two distinct states, autonoetic and noetic awareness. Schizophrenia impairs autonoetic, but not noetic, awareness. We investigated the strategic regulation of relevant and irrelevant contents of conscious awareness in schizophrenia using a directed forgetting paradigm. Twenty-one patients with schizophrenia and 21 normal controls were presented with words and told to learn some of them and forget others. In a subsequent test, they were asked to recognize all the words they had seen previously and give remember, know or guess responses according to whether they recognized words on the basis of autonoetic awareness, noetic awareness, or guessing. Overall, patients showed the same degree of a directed forgetting effect as normal subjects. However, whereas the effect was observed both for remember and know responses in normal subjects, it was observed for know, but not for remember, responses in patients. These results indicate that patients with schizophrenia exhibit an impaired strategic regulation of contents of autonetic awareness for relevant and irrelevant information.

Adult↗

PubMed2003

Abnormal sequencing of motor actions in patients with schizophrenia: evidence from grip force adjustments during object manipulation.

OBJECTIVE: During object manipulation, grip force must be adjusted in anticipation of destabilizing load forces to prevent the object from slipping. This study used three gripping tasks to assess whether schizophrenia affects the predictive mechanisms required for the scaling, timing, and/or sequencing of motor actions. METHOD: Sixteen patients with schizophrenia and 16 comparison subjects matched for age, sex, and educational level 1) lifted objects of various mass and texture (lift task) and 2) used a manipulandum to hit (hit task) or resist (resist task) impacts produced by a collision with a pendulum. For an optimized performance, all tasks demanded a predictive increase in grip force and the timing of external events. The fluid sequencing of finger and hand submovements was required for the lift and the hit tasks but not for the resist task. RESULTS: Patients were impaired in the smooth execution of both the lift and the hit tasks but not in the performance of the resist task. In all three tasks, the scaling of grip force was similar for patients and comparison subjects. CONCLUSIONS: Schizophrenia is associated with a specific deficit in the sequencing of motor actions rather than with an overall problem in the predictive control of movement.

Adolescent↗

PubMed2003

Do patients with schizophrenia consciously recollect emotional events better than neutral events?

OBJECTIVE: The influence of the emotional valence of words on conscious awareness was assessed in patients with schizophrenia. METHOD: The remember/know procedure was used to test 24 patients with schizophrenia and 24 normal comparison subjects. RESULTS: Patients' "remember" responses and conscious recollection were more frequent for emotional words than for neutral words. In contrast, the levels of "know" responses and familiarity were independent of emotional words. CONCLUSIONS: Patients with schizophrenia consciously recollected emotional words better than neutral words.

Adult↗

PubMed2003

Subjective qualities of memories associated with the picture superiority effect in schizophrenia.

Patients with schizophrenia (n = 24) matched with 24 normal subjects were presented with both words and pictures. On a recognition memory task, they were asked to give remember, know, or guess responses to items that were recognized on the basis of conscious recollection, familiarity, or guessing, respectively. Compared with normal subjects, patients exhibited a lower picture superiority effect selectively related to remember responses. Unlike normal subjects, they did not exhibit any word superiority effect in relation to guess responses; this explains why the overall picture superiority effect appeared to be intact. These results emphasize the need to take into account the subjective states of awareness when analyzing memory impairments in schizophrenia.

Adult↗

PubMed2002

Effect of benzodiazepines on structural and conceptual/lexical priming.

RATIONALE: Impaired perceptual priming, as assessed by naming reaction times and accuracy, for briefly presented contour-deleted pictures under lorazepam has been documented in several studies but whether the nature of this impairment is visual versus conceptual/lexical is not clear. We used a previously developed paradigm to examine whether lorazepam affects visual processes involved in the coding of contour information or conceptual/lexical representations. METHOD: Three groups were tested (lorazepam, diazepam and placebo). In the study phase, participants named line drawings, presented for 500 ms, in which 50% of the contour was deleted by removing every other line and vertex from each part. In the test phase, participants saw the identical picture, its complement (the other 50% of the contour), or a samename/different-shape picture, each presented for 200 ms. RESULTS: For all three groups, the magnitude of priming, as assessed by naming RTs and error rates, was equivalent in the identical and in the complementary conditions and the amount of facilitation was reduced in the same-name condition. Perceptual priming occurred both in the lorazepam and in the diazepam groups, though reduced, compared to placebo, for RTs. No conceptual priming (i.e. facilitated performance in the same-name condition) was observed in the benzodiazepine groups. CONCLUSION: Equivalent priming for identical and complementary pictures in the three groups suggests that benzodiazepines do not affect the activation of the geon structural description. The lack of priming for same-name pictures suggests that benzodiazepines affect access, retrieval or selection of conceptual/lexical information.

Adolescent↗

PubMed2002

A deficit in the adjustment of grip force responses in schizophrenia.

Delusions of control in schizophrenia may be due to a deficit in the generation of an efference copy, used to distinguish between self generated and externally imposed changes in the environment. This hypothesis was tested using a framework that differentiated automatic and controlled levels of motor behavior. Subjects resisted collisions that were either self or externally imposed. The grip to load force correlation (response accuracy) and the overall grip force level used (response efficiency) were measured. Controls improved both accuracy and efficiency of their grip force responses in self compared to externally imposed collisions. Patients improved accuracy but not efficiency of motor response. There was no difference between patients with and without delusions of control. These results refute the hypothesis of a perturbed efference copy in patients with delusions of control. We rather propose that schizophrenia globally preserves the automatic level but affects the controlled, more voluntary level of motor behavior.

Adult↗

PubMed2002

Effects of the benzodiazepine lorazepam on monitoring and control processes in semantic memory.

Lorazepam has been repeatedly shown to induce memory impairments. The effects of this benzodiazepine on the processes involved in the strategic regulation of memory accuracy have not as yet been explored. An experimental procedure that delineates the role of monitoring and control processes was used. Fifteen lorazepam and 15 placebo subjects were examined using a semantic memory task that combined both a forced- and a free-report option and a no-incentive and an incentive condition. Memory accuracy was lower in the lorazepam than in the placebo group. Lorazepam impaired control sensitivity (the extent to which volunteering of answers is affected by the confidence judgments). While the absolute aspect of monitoring was impaired (calibration scores), both the discriminative aspect (the ability to distinguish between correct and incorrect answers) and the response criterion setting (the confidence threshold set for volunteering a report) were spared. The pharmacological dissociation between monitoring effectiveness and control sensitivity indicates that these two components involve distinct processes.

Adult↗

PubMed2002

Reduced or increased influence of non-pertinent information in patients with schizophrenia?

We tested the ability of 18 patients with schizophrenia and 18 matched controls to filter non-pertinent information in orientation matching tasks. The non-pertinent information consisted of pictures conveying semantic information. The pertinent information consisted of oriented line-segments drawn inside pictures or was represented by the overall orientation of the picture itself. The results showed that non-pertinent information interfered with performance of control subjects in all tasks. In contrast, non-pertinent information interfered with the performance of patients with schizophrenia to the same extent as that of matched controls only when non-pertinent and pertinent information was physically mingled, but not when they were separated. Yet, patients processed non-pertinent information in all experiments, as shown by reversed interference effects when non-pertinent and pertinent information was physically separated. These results suggest a deficit at linking physically distinct visual information in patients with schizophrenia. Additionally, performance was more impaired in patients with schizophrenia than in control subjects when the amount of displayed information increased. The results suggest the coexistence, and a possible relationship between attentional deficits and impairments at linking distinct visual information in patients with schizophrenia.

Adult↗

PubMed2002

Cognitive skill learning and aging: a component process analysis.

The ability to acquire a cognitive and motor skill was investigated in 20 older and 20 younger participants using repeated testing on the Tower of Toronto (TT) puzzle, a variant of the Tower of Hanoi. Explicit memory, perceptual priming, and sustained attention were also assessed. Older subjects exhibited a defective cognitive skill performance despite the fact that cognitive skill learning suffered little or no impairment. Poor problem-solving ability, diminished attention, fatigue, defective explicit memory, and meta-cognitive processes were likely to play a limiting role. Factors interfering with the generation of reliable goal structures are likely to prevent cognitive skill learning, giving important cues for future cognitive remediation.

Journal Article↗

PubMed2002

Impairment of constructive memory in schizophrenia.

Episodic memories are characterized by a specific state of awareness, conscious recollection, which allows subjects to mentally relive past events. They are not a literal reproduction of the past but instead depend on constructive processes. Patients with schizophrenia exhibit a specific impairment of conscious recollection. The aim of this study was to investigate the role of constructive processes into defective conscious recollection of patients with schizophrenia. An experiential approach to false recognition and related states of awareness was used. Thirty patients with schizophrenia, who were matched with 30 normal subjects, studied lists of words semantically related to a non-presented theme word (critical lure). On a recognition memory task with both previously presented words and non presented critical lures, they were asked to give Remember, Know or Guess responses to items that were recognized on the basis of conscious recollection, familiarity or guessing, respectively. Patients with schizophrenia recognized fewer studied words and critical lures than normal subjects. This deficit was restricted to memories associated with conscious recollection as indicated by a decrease in Remember responses, but not Know and Guess responses. Our results indicate that patients with schizophrenia exhibit an impaired conscious recollection, whether memories are true or false. They provide evidence that schizophrenia impairs the mere construction of conscious recollection.

Adult↗