Journal of neuroscience methods
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J. Neurosci. Methods · Feb 2013
Design and evaluation of an innovative MRI-compatible Braille stimulator with high spatial and temporal resolution.
Neural correlates of Braille reading have been widely studied with different neuroimaging techniques. Nevertheless, the exact brain processes underlying this unique activity are still unknown, due to suboptimal accuracy of imaging and/or stimuli delivery methods. To study somatosensory perception effectively, the stimulation must reflect parameters of the natural stimulus and must be applied with precise timing. ⋯ The Braille Character Stimulator was tested with a same-different discrimination task on Braille characters during an event-related fMRI experiment in eleven right-handed sighted adult subjects. The results show significant activations in several cortical areas, including bilateral primary (SI) and secondary somatosensory (SII) cortices, bilateral premotor and supplementary motor areas, inferior frontal gyri, inferior temporal gyri and precuneus, as well as contralateral (to the stimulated hand) thalamus. The results validate the use of the BCS as a method of effective stimuli application in fMRI studies, in both sighted and visually impaired subjects.
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J. Neurosci. Methods · Feb 2013
A chronic combinatory stress model that activates the HPA axis and avoids habituation in BALB/C mice.
A detailed protocol is described to induce chronic stress in BALB/c mice, which affects the hypothalamic-pituitary-adrenal (HPA) axis. The protocol is based on a combination of two mild physical stressors: restraint stress and forced swimming. Physical stressors were applied on an alternative schedule: one day restraint, next day swimming, during a 28-day period. ⋯ In our experimental conditions, catecholamine levels were not useful as an index of stress. The stress model applied here provoked a steady activation of the HPA axis resulting in the constant secretion of corticosterone from the adrenal gland, which may prevent the activation of the ANS axis. The simple and economic stress model presented here affected the HPA axis but not the ANS of BALB/c mice and is useful for the study of metabolic stress-related gastric pathology and stress hormone secretion in mice.