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    

BACKGROUND: The Addenbrooke’s Cognitive Examination (ACE) is a brief cognitive test battery designed to detect and differentiate Alzheimer’s disease (AD) and frontotemporal dementia (FTD). Translations of this instrument into French and Malayalam have been recently published OBJECTIVE: To adapt and validate the ACE into Spanish in a rural population of low-educational level. SUBJECTS: A clinical group, composed of 70 patients affected by dementia and 25 patients with memory complaints without dementia, was compared with 72 controls matched for gender, age and educational level METHOD: The clinical group was studied with standard neuropsychological instruments, all patients underwent neuroimaging [Computerized Tomography (CT) or Magnetic Resonance Imaging (MRI), and Single Photon Emission Tomography (SPECT) in all cases of suspected FTD], as well as routine neurological examination. Both groups were studied with the ACE and Clinical Dementia Rating scale (CDR). Sensitivity, specificity, area under curve, reliability and Verbal-Language/ Orientation-Memory (VLOM) ratio were calculated. Subsequently, the sample was stratified regarding educational level in two groups. Receiver Operating Characteristics (ROC) curves were calculated for these conditions. Different cut-off points were calculated addressing educational level. RESULTS: ROC curves demonstrated the superiority of the ACE in the sub sample of patients that finished school at over 14 years old. VLOM ratio confirmed its usefulness for differential diagnosis between AD and FTD CONCLUSIONS: The Spanish version of the ACE is a useful instrument for dementia diagnosis. In our sample VLOM ratio results were useful for differential diagnosis between AD and FTD. Different cut-off points must be used for different educational levels.

A 37-year-old woman with celiac disease, recurrent psychosis, and Parkinsonism. Autores González-Alemán G, Florenzano N, Padilla E, Bourdieu M, Guerrero G, Calvó M, Strejilevich S, de Erausquin GA.  Año 2006 Journal  González-Alemán G, Florenzano N, Padilla E, Bourdieu M, Guerrero G, Calvó M, Strejilevich S, de Erausquin GA.  Volumen 21(5): 729-731 Abstract   Otra información    

Temperament traits associated with risk of schizophrenia in an indigenous population of Argentina. Autores Calvó M, Padilla E, González-Alemán G, Bourdieu M, Guerrero G, Strejilevich S, Escobar J, Svrakic N, Cloninger CR, de Erausquin GA.  Año 2006 Journal  Calvó M, Padilla E, González-Alemán G, Bourdieu M, Guerrero G, Strejilevich S, Escobar J, Svrakic N, Cloninger CR, de Erausquin GA.  Volumen 83(2-3): 299-302 Abstract   Otra información    

Objetivos: La escasez de datos y de camas para internación psiquiátrica en hospitales generales hace prioritaria la producción de información sobre el funcionamiento de este tipo de servicios. El objetivo de este trabajo consiste en describir la población de pacientes internados en una sala de Psiquiatría de un hospital general de la ciudad de Buenos Aires. Método: Entre el 1º de juno del 2004 y el 31 de mayo de 2005 se llevó a cabo un estudio de corte naturalístico, prospectivo y descriptivo, recabando los datos de los pacientes que ingresaron en la sala de Internación del Servicio de Psiquiatría del Hospital «Teodoro Alvarez «. Resultados: La edad promedio fue de 36.7 años; los motivos de ingreso estuvieron relacionados en su mayoría con cuadros de descompensación psicótica y de riesgo para sí. Se produjeron 82 internaciones (correspondientes a 71 pacientes) con 68 egresos en el mismo período. El 48.8% presentaba antecedentes de internaciones previas (de los cuales el 25.6% presentaban cuatro o más internaciones). El 29.3% ingresó por vía judicial. Se retiraron sin alta médica el 19.1%. Los diagnósticos de egreso más frecuentes fueron: Esquizofrenia (29.4%), Trastorno por abuso de sustancia (22.1%), Trastorno límite de la personalidad (10.3%), Trastorno bipolar (8.8%) y Trastorno depresivo (7.4%). El tiempo promedio de internación fue de 45.4 días (pero con un giro cama de 4.1) de las cuales aproximadamente el 90% duraron menos de 90 días. Conclusiones: Estos datos pueden ser comparados con los ya producidos por otros Servicios de Psiquiatría similares y permiten avanzar en mejorar el funcionamiento de servicios que progresivamente tendrán que ser priorizados por sobre los tradicionales manicomios.