Brain research
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The purpose of this project was to explore the role of the medial thalamus (MT), including the medial dorsal thalamus (MD) and associated midline nuclei in pain processing. Experiment 1 explored the role of electrolytic lesions to the MT in the formalin test. It was hypothesized that animals with electrolytic lesions to the MT would have attenuated paw licking behavior during the second phase of the formalin tests as compared to sham lesion controls. ⋯ No differences in mechanical paw withdrawal thresholds and in escape/avoidance behavior were detected as compared to the sham lesion group. These results indicate a limited role for the medial thalamic nuclei in coding for pain intensity and the affective dimension of pain. Additional research is needed to explore the role of individual medial nuclei in pain processing.
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Migraine with aura occurs in up to 20-30% of all migraineurs. The regional cerebral blood flow (rCBF) changes that occur during cortical spreading depression (CSD) are considered to be an experimental correlate of aura. CSD is synchronous with a failure in brain ion homeostasis and efflux of excitatory amino acids from nerve cells. ⋯ The sodium ion channel blocker was able to inhibit rCBF changes in both the cat and rats. Voltage-dependent calcium channel blockers had little effect on the initiation or propagation of the spread, as did the ATP-activated potassium channel blocker. The data are consistent with what is known of human aura in that sodium ion channels are those predominantly involved in mechanical stimulation-induced rCBF changes and thus may represent therapeutic targets for the aura response in migraine.
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The bed nucleus of the stria terminalis (BNST) in the forebrain shows sexual dimorphism in its neuroanatomical connectivity and neurochemical characteristics. The structure is involved in many behavioral and motivational phenomena particularly related to coping with stress. ⋯ The present study extended the findings to female rats demonstrating that bilateral electrolytic lesions of the BNST increased immobility and decreased climbing compared to sham-operated controls, but failed to affect performance in the water maze. Additionally, lesions did not alter behavior in the open field and the elevated plus-maze tests suggesting not only that the modulation of depression by BNST lesions is specific, but also providing support for the view that the BNST may not necessarily be critically involved in anxiety.