ABSTRACT
This study aimed to elucidate cortical mechanisms involved in anticipatory actions when 23 healthy right-handed subjects had to catch a free falling object through quantitative electroencephalogram (qEEG). For this reason, we used coherence that represents a measurement of linear covariation between two signals in the frequency domain. In addition, we investigated gamma-band (30-100 Hz) activity that is related to cognitive and somatosensory processes. We hypothesized that gamma coherence will be increase in both parietal and occipital areas during moment after ball drop, due to their involvement in manipulation of objects, visuospatial processing, visual perception, stimuli identification and attention processes. We confirmed our hypothesis, an increase in gamma coherence on P3-P4 (t= -2.15; p=0.033) and PZ-OZ (t= -2.16; p=0.034) electrode pairs was verified for a paired t-test. We conclude that to execute tasks involving anticipatory movements (feedforward mechanisms), like our own task, probably, there is no need of a strong participation of visual areas in the process of information organization to manipulate objects and to process visuospatial information regarding the contact hand-object.
Este estudo teve como objetivo elucidar os mecanismos corticais envolvidos em ações antecipatórias quando 23 indivíduos saudáveis destros tinham que apreender um objeto em queda livre, através da eletroencefalografia quantitativa (EEGq). Por esta razão, usamos a coerência que representa a covariação linear entre dois sinais no domínio da frequência. Além disso, investigamos a atividade da banda gama (30-100 Hz), que está relacionada à processos cognitivos e somato-sensoriais. Nossa hipótese é que a coerência de gama estará aumentada em ambas as áreas parietais e occipitais durante o momento pós-queda da bola, devido ao seu envolvimento na manipulação de objetos, processamento visuo-espacial, percepção visual, identificação de estímulos e processos de atenção. Confirmamos nossa hipótese. Um aumento de coerência em gama nos pares de eletrodos P3-P4 (t= -2,15; p=0,033) e PZ-OZ (t= -2,16; p=0,034) foi verificado por teste-t pareado. Conclui-se que, para executar tarefas que envolvem movimentos de antecipação (mecanismos de retro-alimentação) como a nossa própria tarefa, provavelmente, não há necessidade de forte participação de áreas visuais no processo de organização da informação como para manipular objetos e processar a informação visuo-espacial no contato mão-objeto.
Subject(s)
Adult , Female , Humans , Male , Electroencephalography/methods , Functional Laterality/physiology , Psychomotor Performance/physiology , Visual Perception/physiology , Brain Mapping , Occipital Lobe/physiology , Parietal Lobe/physiologyABSTRACT
A recent study from our laboratory has provided evidence for the generation of slow potentials occurring in anticipation to task-performance feedback stimuli, in multiple association cortical areas, consistently including two prefrontal areas. In the present study, we intended to determine whether these slow potentials would indicate some abnormality (topographic) in schizophrenic patients, and thus serve as an indication of abnormal association cortex activity. We recorded slow potentials while subjects performed a paired-associates memory task. A 123-channel EEG montage and common average reference were used for 20 unmedicated schizophrenic (mean duration of illness: 11.3 ± 9.2 years; mean number of previous hospitalizations: 1.2 ± 1.9) and 22 healthy control subjects during a visual paired-associates matching task. For the topographic analysis, we used a simple index of individual topographic deviation from normality, corrected for absolute potential intensities. Slow potentials were observed in all subjects. Control subjects showed a simple spatial pattern of voltage extrema (left central positive and right prefrontal negative), whereas schizophrenic patients presented a more complex, fragmented pattern. Topographic deviation was significantly different between groups (P < 0.001). The increased topographic complexity in schizophrenics could be visualized in grand averages computed across subjects. Increased topographic complexity could also be seen when grand averages were computed for subgroups of patients assembled either according to task-performance (high versus low) or by their scores on psychopathological scales. There was no significant correlation between topographic deviation and psychopathology scores. We conclude that the slow potential topographic abnormalities of schizophrenia indicate an abnormality in the configuration of large-scale electrical activity in association cortices.
Subject(s)
Humans , Male , Female , Cerebral Cortex , Evoked Potentials , Schizophrenia , Brain Mapping , Brief Psychiatric Rating Scale , Case-Control Studies , Multivariate Analysis , Photic StimulationABSTRACT
Magnetic Resonance Cholangiopancreatography (MRCP) is an emergent non invasive diagnostic technique for the study of pancreaticobiliary system. Following the contraindications of traditional Magnetic Resonance, the MRCP is safe for the patient. Images can be obtained without administration of any contrast and not using Rx. The objective of this study is to evaluate the sensitivity and the specificity of MRCP respect direct cholangiography ([endoscopic retrograde cholangiography (ERCP) and percutaneous transhepatic cholangiography (PTC)]. Forty one patients older than 60 years old were included, 19 male and 22 female, 73.5 median age. All of them have clinical diagnosis of obstructive jaundice. The patients were tested with MRCP first, and blinded of this results a direct cholangiography (DC) were done (ERCP 34 and PTC 8), less than 48 hs after MRCP. For the present study, the sensitivity was 100 per cent and specificity was 90 per cent of MRCP in the diagnosis of normal biliary tract. For the dilated biliary tract the sensitivity was 93 per cent and the specificity was 92 per cent . In bile duct obstruction the sensitivity was 88 per cent without false positive. MRCP diagnosed the presence of choledocholithiasis with a sensitivity of 74 per cent and specificity of 95 per cent, lower than reported in other studies. 73 per cent of our patients required some kind of therapeutic intervention. MRCP has high sensibility and specificity in the initial evaluation of patients with clinical obstructive jaundice and could replace the DC when is used for diagnostic purpose.
Subject(s)
Humans , Male , Female , Aged , Middle Aged , Biliary Tract Diseases/diagnosis , Cholangiography , Cholangiopancreatography, Endoscopic Retrograde , Magnetic Resonance Imaging , Aged, 80 and over , Biliary Tract/pathology , Prospective Studies , Sensitivity and SpecificityABSTRACT
Estudou-se a influência de fatores sazonais na performance de 21 vacas da raça Holandesa submetidas a 37 superovulaçöes com 3.000 U.I. de PMSG. Os resultados das transferências de embriöes foram analisados segundo o efeito da época do ano: chuvosa (outubro a março) com temperatura máxima média = 30,0 ñ 0,8ºC e precipitaçäo pluviométrica mensal = 153,1 ñ 78,8 mm elevado ao cubo e seca (abril a setembro) com temperatura máxima média = 26,5 ñ 1,6ºC e precipitaçäo pluviométrica mensal = 59,2 ñ 53,8 mm elevado ao cubo. Registrou-se variaçäo climática entre as estaçöes (p<0,05), mas näo houve diferença significativa (p>0,05) entre épocas do ano quando foi comparado o número médio de estruturas por superovulaçäo (5,4 ñ 2,63 e 4,3 ñ 4,00), o percentual de embriöes viáveis (50,0 por cento e 57,6 por cento) e o percentual de prenhezes obtidas: 44,4 por cento e 35,2 por cento, respectivamente. Concluiu-se, portanto, que as diferentes condiçöes climáticas das épocas do ano näo influíram nas transferências de embriöes em vacas holandesas superovuladas com PMSG