Contributions of stimulus valence and arousal to visual activation during emotional perception.

Neuroimaging experiments have revealed that the visual cortex is involved in the processing of affective stimuli: seeing emotional pictures leads to greater activation than seeing neutral ones. It is unclear, however, whether such differential activation is due to stimulus valence or whether the results are confounded by arousal level. In order to investigate the contributions of valence and arousal to visual activation, we created a new category of "interesting" stimuli designed to have high arousal, but neutral valence, and employed standard neutral, unpleasant, and pleasant picture categories. Arousal ratings for pleasant and neutral pictures were equivalent, as were valence ratings for interesting and neutral pictures. Differential activation for conditions matched for arousal (pleasant vs neutral) as well as matched for valence (interesting vs neutral) indicated that both stimulus valence and arousal contributed to visual activation.

Enhanced interictal responsiveness of the migraineous visual cortex to incongruent bar stimulation: a functional MRI visual activation study.

Since visual aura is usually described as expanding zigzag lines, neurones involved with the perception of line orientation may initiate this phenomenon. A visual incongruent line stimulation protocol was developed to obtain functional magnetic resonance images (fMRI) interictally in 5 female migraine patients with typical fortification spectra and in 5 normal matched controls. Activation in the visual cortex was present contralateral to the side of stimulation in 4 of 5 patients, notably in the extrastriate visual cortex. In 4 of 5 controls activation was observed in the medial and anterior orbitofrontal cortex. In one of them additional activation at the right nucleus accumbens/ventral striatum and right ventral pallidum was present. In the remaining control subject activation was present in the left primary visual cortex. The enhanced interictal reactivity of the visual cortex in migraineurs supports the hypothesis of abnormal cortical excitability as an important pathophysiological mechanism in migraine aura, though the role of specific regions of the visual cortex remains to be explored.

Monitoramento e avaliaçäo de uma câmara escura / Monitoring and evaluation of a dark chamber

As condições de operação de uma câmara escura devem ser tais que possibilitem a maior eficiência do Serviço de Radiologia. Os cuidados com as etapas que nela se desenrolam devem ser minuciosos tendo em vista que a menor falha comprometerá todo o processo radiológico. Tal comprometimento, implicará na repetição do procedimento radiográfico expondo desnecessariamente paciente e profissionais envolvidos à radiação ionizante. Além disso, esse fato acarretará, também, em gastos adicionais para a instituição. Para averiguar a integridade e o funcionamento da câmara escura, foram propostos testes básicos que traduziram as reais condições de operação das câmaras escuras avaliadas.

The operating conditions of the Darkroom should be possibility to inérease efficiency of Radiologic Service. The cares with the steps developed on the Darkroom should be circunstantial and the minor mistake will compromisse the radiologic process. This compromisse will implicate on the repetition of all radiographic procedures, exposed unnecessarily patients and professionals involved in ionize radiation. ln addiction, also this fact will cause additional costs to institution. To verify the Darkroom's integrity and performance, had proposed basic tests that express the real conditions of the avaliated darkroom's.