Categoría: Papers con abstracts

Disorders of consciousness have captivated neurologists, neuroscientists, and philosophers for decades, but few consistent studies have been conducted on these conditions due to their difficult experimental approach. In recent years, an increasing number of cognitive neuroscience research groups have examined the physiology of consciousness from an experimental perspective, despite the methodological and epistemological complexities of the field. While describing consciousness can be challenging, a close definition must acknowledge a combination of wakefulness and awareness. Form a neurobiological standpoint, it has been argued that the ascending reticular system and its thalamic projections are critical in modulating awareness and wakefulness sleep cycles. Awareness may be a function of the neural networks within the cortex, the thalamus, and the cortico-cortical system. Different models have been employed to tackle this difficult problem, including non-invasive in vivo studies, examination of conscious patients with brain lesions, and studies on both animals and patients with disorders of consciousness. This article reviews the scientific evidence for the neural basis of conscious and unconscious processes in different states of consciousness, focusing on patients in the vegetative and minimally conscious state.

Endophenotypes is one emerging strategy in schizophrenia research that is being used to identify the functional importance of genetically transmitted, brain-based deficits present in this disease. Currently, event-related potentials (ERPs) are timely used in this search. Several ERPs, including N400, present deficits in relation to schizophrenia. In order to assess the genetic liability of N400 as a possible endophenotype, a picture semantic matching task (congruent and incongruent pairs of pictures) was performed by 21 unaffected first-degree relatives of patients with schizophrenia, 21 DSM-IV diagnosed schizophrenia probands, and 21 control subjects, matched by age, gender and educational level. Probands and relatives were selected form Multiplex schizophrenia families. Significantly reduced N400 amplitude for congruent categories in N400 was found in probands and relatives in relation to controls. The latency onset and the maximum peak latency of N400 were delayed in both, relatives and probands groups compared to control. The voltage maps of incongruous-minus-congruous difference indicate a more reduced right restricted negativity in probands and relatives, when compared to a widely extended bilateral negativity in controls. No general differences were found between patients and relatives. These results demonstrate an electrophysiological deficit in semantic match processing in clinically unaffected first-degree relatives of patients with schizophrenia, suggesting a possible use of this marker as endophenotype.

Evaluating brain function in patients with disorders of consciousness may offer important clues to their state of awareness and help to predict prognosis. Disorders of consciousness mainly comprise the comatose state, the vegetative state, and the minimally conscious state. These disorders typically stem from acute brain insults caused by hypoxic-ischemic neural injury or traumatic brain injury, and the type of brain injury frequently determines the neuropathology. Current knowledge, including results from our laboratory, supports a model of extended brain tissue damage from the midbrain to the cortex in anoxia patients and a model of focal or multifocal cortical lesions in trauma patients. These differing models may help to explain differences in prognosis and outcomes in these excruciating life situations. Although the neural basis of consciousness remains puzzling, findings from normal volunteers and pathologies of consciousness show that widely distributed networks such as thalamofrontal and parietofrontal systems may be critical.

In recent years, studies have suggested that gestures influence comprehension of linguistic expressions, for example, eliciting an N400 component in response to a speech/gesture mismatch. In this paper, we investigate the role of gestural information in the understanding of metaphors. Event related potentials (ERPs) were recorded while participants viewed video clips of an actor uttering metaphorical expressions and producing bodily gestures that were congruent or incongruent with the metaphorical meaning of such expressions. This modality of stimuli presentation allows a more ecological approach to meaning integration. When ERPs were calculated using gesture stroke as time-lock event, gesture incongruity with metaphorical expression modulated the amplitude of the N400 and of the late positive complex (LPC). This suggests that gestural and speech information are combined online to make sense of the interlocutor’s linguistic production in an early stage of metaphor comprehension. Our data favor the idea that meaning construction is globally integrative and highly context-sensitive.

Human learning and memory evaluation in real-life situations remains difficult due to uncontrolled variables. Buenos Aires waiters, who memorize all the orders without written support, were evaluated in situ. Waiters received either eight different orders and customers remained seated in their original locations (OL), or changed locations (CL). Match between orders, subjects and location was decreased only in CL. Waiters’ feature/location strategy links client with position at the table and beverage later. The hypothesis we raise is that memory-schemas link working memory to long-term memory networks through rapid encoding, making the information resistant to interference and enabling its fast retrieval if necessary cues are present.

Interpretación de refranes en la Enfermedad de Alzheimer. Autores Báez S, Montañes P.  Año 2009 Journal  Báez S, Montañes P.  Volumen 49(11): 566-72 Abstract   Otra información    

In the last few decades, several works on event related potentials (ERPs hereafter) during sleep have been reported. In spite of numerous studies, clear methodological rules for this kind of study are often missing, making it difficult to valorize the scope of these results. We propose here a description of methodological aspects to be considered when evaluating ERPs during sleep. The use of Rechtschaffen and Kales rules versus automatic methods is assessed, plus the additional use of certain quantitative measures. Additionally, two topics are discussed which must be controlled in ERPs sleep studies: the First Night Effect, and sleep disturbances. Better control of experimental paradigms is relevant for the growth of the neuroscience of sleep.

La demencia es un síndrome que se caracteriza por declinación de la función intelectual, lo bastante severa para interferir en la vida diaria; más de un área cognitiva se ve afectada, hay impacto funcional en las actividades de la vida diaria y, con frecuencia, existen trastornos conductuales. En la actualidad, para poder realizar el diagnóstico de la enfermedad de Alzheimer y otras demencias es necesario combinar los datos de la clínica con la evaluación neuropsicológica, los exámenes de laboratorio y las neuroimágenes. En esta revisión se examinará qué elementos son necesarios para el diagnóstico temprano de las demencias, y se revisará su manejo farmacológico y no farmacológico.

NTRODUCTION: Electroconvulsive therapy (ECT) is an effective, yet controversial treatment. Most patients receiving ECT have depression and it is likely that the majority having this treatment are older adults. However, attitudes towards ECT and knowledge of ECT in this population have never been studied in relation to the patients’ cultural background. OBJECTIVE: To compare the attitudes and knowledge of ECT among older adults depressed patients across three culturally different populations and to explore the relationship between culture, knowledge and attitudes. METHODS: The study was conducted in one centre in each country. A semi-structured survey was used which included three sections: demographics characteristics, attitudes towards and knowledge of ECT. RESULTS: A total of 75 patients were recruited in this study: 30 patients from England; 30 patients from Argentina; and 15 patients from Canada. There was a significant difference in knowledge about ECT across the three countries. No significant difference was found in terms of attitudes. Knowledge was poor in all three countries. The most influential factor shaping subjects’ attitudes and knowledge of ECT differed for the three countries. A weak correlation was found between knowledge of and attitudes towards ECT across all patients from the three different countries. CONCLUSION: Attitudes towards ECT are a very complex phenomenon. We could not find evidence that a particular cultural background affects attitudes towards ECT. Generalising the results of our study is restricted by the fact that this was a pilot study that suffered from limitations including small sample size and number of settings.

NTRODUCTION: In clinical practice it is often difficult to establish whether cognitive impairment is secondary to an affective disorder or a dementing process. AIM: To describe the cognitive performance on the Spanish version of the Addenbrooke’s Cognitive Examination (ACE) of patients with early dementia and depression. SUBJECTS AND METHODS: 77 patients with early dementia (53 Alzheimer disease; 24 frontotemporal dementia), 17 patients with major depression and 54 healthy volunteers were tested with the Spanish version of the ACE. RESULTS: Alzheimer disease and frontotemporal dementia groups were significantly lower than the control group and the major depression group. When the major depression group was compared with the control group no significant differences were found. CONCLUSIONS: The cognitive performance in the ACE is different in patients with early dementia and patient with depression.