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At least 883 records · Page 49Linked to original sources
PubMed2006

Preserved subliminal processing and impaired conscious access in schizophrenia.

BACKGROUND: Studies of visual backward masking have frequently revealed an elevated masking threshold in schizophrenia. This finding has frequently been interpreted as indicating a low-level visual deficit. However, more recent models suggest that masking may also involve late and higher-level integrative processes, while leaving intact early bottom-up visual processing. OBJECTIVE: To test the hypothesis that the backward-masking deficit in schizophrenia corresponds to a deficit in the late stages of conscious perception, whereas the subliminal processing of masked stimuli is fully preserved. DESIGN: Twenty-eight patients with schizophrenia and 28 normal control subjects performed 2 backward-masking experiments. We used Arabic digits as stimuli and varied quasi-continuously the interval with a subsequent mask, thus allowing us to progressively unmask the stimuli. We finely quantified their degree of visibility using objective and subjective measures to evaluate the threshold duration for access to consciousness. We also studied the priming effect caused by the variably masked numbers in a comparison task performed on a subsequently presented and highly visible target number. RESULTS: The threshold delay between the digit and mask necessary for the conscious perception of the masked stimulus was longer in patients compared with controls. This higher consciousness threshold in patients was confirmed by an objective and a subjective measure, and both measures were highly correlated for the patients and controls. However, subliminal priming of masked numbers was effective and identical in patients and controls. CONCLUSIONS: Access to conscious report of masked stimuli is impaired in schizophrenia, whereas fast bottom-up processing of the same stimuli, as assessed by subliminal priming, is preserved. These findings suggest a high-level origin of the masking deficit in schizophrenia, although they leave open for further research its exact relation to previously identified bottom-up visual processing abnormalities.

Adolescent↗
PubMed1992

Multifocal inflammatory leukoencephalopathy with 5-fluorouracil and levamisole.

A cerebral demyelinating disease developed in 3 patients during adjuvant therapy with 5-fluorouracil and levamisole for adenocarcinoma of the colon. None of the patients had evidence of metastatic disease or prior neurological disease. The duration of chemotherapy before onset of neurological symptoms ranged from 15 to 19 weeks. The total dose of 5-fluorouracil was 9.7 to 15.7 gm. The total dose of levamisole was 2.7 to 3.75 gm. Two patients presented with a subacute (2-3 weeks) progressive decline in mental status and ataxia. The third patient had two unexplained episodes of loss of consciousness. In each, magnetic resonance imaging with gadolinium demonstrated prominent multifocal enhancing white matter lesions. Cerebral biopsy was performed stereotaxically in 2 patients. The morphological features were those of active demyelinating disease. The myelin loss was associated with numerous dispersed as well as vasocentric macrophages, sparing of axons, and perivascular lymphocytic inflammation. Electron microscopy confirmed the light microscopic findings. All 3 patients improved after cessation of chemotherapy and a short course of corticosteroid therapy. Our patients represent the first reported examples of an inflammatory leukoencephalopathy associated with the administration of 5-fluorouracil and levamisole. This syndrome may represent the pathological basis for 5-fluorouracil neurotoxicity, although we cannot completely exclude the role of levamisole.

Adenocarcinoma↗
PubMed2003

Pierre Janet and Félida Artificielle: multiple personality in a nineteenth-century guise.

In the wake of the recent epidemic of multiple personality phenomena, it is important to get a clear idea of what similar phenomena looked like in previous centuries. Pierre Janet's detailed description of his discovery, made during the 1880s, that he could cure hysteria by creating a healthy second personality offers a close look at a form of multiple personalities very different from what has recently been described. His description of the factors that influenced his discovery allow one to see his work in a historical context and to appreciate his confrontation with the paradoxes that this discovery revealed.

Consciousness Disorders↗
PubMed2008

Acute transient encephalopathy following paclitaxel treatment in an adolescent with a recurrent suprasellar germinoma.

Paclitaxel is an antineoplastic agent that is used in the treatment of a variety of solid tumors. Dose-limiting side effects of myelosuppression and peripheral neuropathy are well known. Paclitaxel has minimal penetration of the blood-brain barrier and central nervous system side effects are rare. However, transient encephalopathy following paclitaxel infusion has been described in adults but not in children. We present the case of a 14-year-old female with a recurrent suprasellar germinoma who developed an acute encephalopathy 4-6 hr following paclitaxel infusion.

Adolescent↗
PubMed2006

Cough-induced hemiplegic migraine with impaired consciousness in cystic fibrosis.

The coughing paroxysms of patients with cystic fibrosis may occasion neurological symptoms. Although cough syncope is well-known, and is associated with headache and paralysis, a migrainous mechanism has not been reported. We reviewed the medical records, autonomic testing results, and responses to treatment in two cystic fibrosis patients with similar presentations of cough-induced impairment of consciousness followed by headache and paralysis. A 24-year-old woman and an unrelated 38-year-old man, both with cystic fibrosis, developed post-tussive neurologic deficits. Both patients reported infrequent dramatic spells, always preceded by major hemoptysis, and associated with left-sided paralysis, transient blindness, nausea, and severe pulsating headaches. Autonomic testing demonstrated only postural tachycardia and a near-vasodepressor episode in the woman, and mild, generalized sympathetic dysfunction in the man. Treatment for presumptive migraine with aura with verapamil nearly eradicated symptoms in both patients. Discontinuation of verapamil in the woman was associated with symptom recurrence and a stroke, with significant persistent residual left hemiparesis. In conclusion, cough-induced neurologic deficits were previously reported with cystic fibrosis, without clear understanding of the mechanism of impairment of consciousness. Based on the hemiparesis, nausea, and throbbing headache, which repeatedly followed the events in both patients, and based on the response to verapamil, we hypothesize a migrainous mechanism in both of our patients. The pathophysiology that links the hemoptysis to the spells deserves further investigation.

Adult↗
PubMed2005

Characterization of the spontaneous and gripping-induced immobility episodes on taiep rats.

In 1989, we described a new autosomic-recessive myelin-mutant rat that develops a progressive motor syndrome characterized by tremor, ataxia, immobility episodes (IEs), epilepsy, and paralysis. taiep is the acronym of these symptoms. The rat developed a hypomyelination, followed by demyelination. At an age of 7-8 months, taiep rats developed IEs, characterized electroencephalographically by REM sleep-like cortical activity. In our study, we analyzed the ontogeny of gripping-induced IEs between 5 and 18 months, their dependence to light-dark changes, sexual dimorphism, and susceptibility to mild stress. Our results showed that IEs start at an age of 6.5 months, with a peak frequency between 8.5 and 9.5 months. IEs have two peaks, one in the morning (0800-1000 h) and a second peak in the middle of the night (2300-0100 h). Spontaneous IEs showed an even distribution with a mean of 3 IEs every 2 h. IEs are sexually dimorphic being more common in male rats. The IEs can be induced by gripping the rat by the tail or the thorax, but most of the IEs were produced by gripping the tail. Mild stress produced by i.p. injection of physiological saline significantly decreased IEs. These results suggested that IEs are dependent on several biological variables, which are caused by hypomyelination, followed by demyelization, which causes alterations in the brainstem and hypothalamic mechanisms responsible for the sleep-wake cycle regulation, producing emergence of REM sleep-like behavior during awake periods.

Age Factors↗
PubMedDate not supplied

Korsakoff and amnesia.

Explore the source record for details and available documents.

Alcohol Amnestic Disorder↗
PubMed2005

Phenomenological aspects of consciousness--its disturbance in acute and chronic stages.

The meaning of a disturbance of consciousness is completely different in an acute as opposed to a chronic stage. In the acute stage, the grade of arousal is the most essential component in order to assess the changes of the level of intracranial pressure in neurosurgical emergency room. A new coma scale called Emergency Coma Scale has been proposed, which represents a combination of the Glasgow Coma Scale and the Japan Coma Scale. In the chronic stage, however, contents of consciousness or mental function deserve phenomenological and holistic investigations, keeping the difference between consciousness and mind in consideration, in order not only to treat and care for patients following cerebral injuries, stroke and mild cognitive impairment in aged people. We propose the difference in conception between consciousness and mind; that is, consciousness consists of psycho-sensory afferent system, mind of psycho-motor efferent and afferent system, and memory and language as liaison officers between them. This proposal would play a role to understand mental change in the natural aging processes, when memory and cognition are deteriorating gradually, but is still in evolution in the field of culture.

Acute Disease↗
PubMed1991

Angiotropic lymphoma (malignant angioendotheliomatosis) presenting with rapidly progressive dementia.

An 87-year-old male presented with rapidly progressive dementia, disorder of consciousness and myoclonus, suggesting Creutzfeldt-Jakob disease, but with nonspecific EEG and negative CT findings. Autopsy revealed a malignant angiotropic lymphoma with accumulation of tumor cells within small vessels of the brain and visceral organs. Immunohistochemistry disclosed a large cell lymphoma of B cell type.

Aged↗
PubMed1995

Transient mutism following a posterior fossa approach to cerebellar tumors in children: a critical review of the literature.

Transient mutism has been known as a rare complication following a posterior fossa approach to cerebellar tumors and its cause has not been clearly elucidated. The cerebellar mutism is not accompanied by cranial nerve deficits and disorders of consciousness. Since 1985 only 23 cases of mutism following removal of a cerebellar tumor in children have been reported in the literature. Two additional cases have been operated upon in our department. Extensive injury to the vermian and paravermian cerebellar area, involving the hemispheric cortex, cerebellar peduncles, fibers from the dentato-thalamocortical pathway, and dentate and interpositum nuclei may be the most important anatomical substrate of mutism. The mechanism of such transient mutism seems to be a complex of two or more factors (vascular disturbances due to manipulation or retraction of the cerebellar region around the IV ventricle and emotional factors). On the basis of these 25 cases the major features of the cerebellar mutism are discussed.

Ataxia↗
PubMed1977

Correlation between the clinical picture, the EEG and cerebral blood flow after partial occlusion of the middle cerebral artery in man.

Quantitative measurements of global and regional cerebral blood flow were performed in 18 patients 1 to 3 days after the onset of symptoms of acute cerebral ischemia due to partial occlusion of the middle cerebral artery and were repeated 21 days thereafter. The first rCBF measurement revealed either an extensive ischemic focus or an ischemic focus with simultaneous reduction of the global blood flow within the corresponding hemisphere in all patients. The later measurements indicated no change in blood flow in the ischemic focus in any case, but there was a slight increase of global cerebral blood flow in 1/3 of the cases. The measurements of cerebral blood flow were correlated with the neurological, psychopathological and EEG findings and in spite of an unaltered cerebral blood circulation, all patients showed a distinct clinical imrovement. Various hypotheses for the return of neurological functions in patients with persistent cerebral ischemia are discussed.

Adult↗