Planarians require an intact brain to behaviorally react to cocaine, but not to react to nicotine.

Planarians possess a rudimentary brain with many features in common with vertebrate brains. They also display a remarkable capacity for tissue regeneration including the complete regeneration of the nervous system. Using the induction of planarian seizure-like movements (pSLMs) as a behavioral endpoint, we demonstrate that an intact nervous system is necessary for this organism to react to cocaine exposure, but not necessary to react to nicotine administration. Decapitated planarians (Girardia tigrina) display pSLMs indistinguishable from intact worms when exposed to nicotine, but cocaine-induced pSLMs are reduced by about 95% upon decapitation. Decapitated worms recover their normal sensitivity to cocaine within 5 days after head amputation. In worms where half of the brain was removed or partially dissected, the expression of cocaine-induced pSLMs was reduced by approximately 75%. Similar amputations at the level of the tail did not show a significant decrease to cocaine exposure. To the best of our knowledge, our work is the first report that explores how regenerating planarians react to the exposure of cocaine.

Acute hemispheric stroke: correlation between three-dimensional transcranial Doppler, MR-angiography, CT and clinical findings.

We examined 50 ischemic stroke patients and 67 controls free of vascular disease, intra- or extracranial. We assessed all subjects clinically by neurological examination (quantified on the Canadian Neurological Scale or CNS), by three-dimensional transcranial Doppler sonography (TCD-3D) and by computed tomography (CT) within 24 h of the acute event, repeating CT 15 days later. 15 patients also underwent magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). We used the following Doppler parameters: interhemispheric asymmetry index (AI), mean flow velocity (mV) and pulsatility index (PI) for the middle cerebral artery (MCA). The difference between patients and controls on analysis of the variance (ANOVA) in respect of AI was significant: F = 50.8, p < 0.0001. The CNS-AI correlation was equally valid: r = -0.56, p < 0.001. The CNS-CT correlation proved to be highly significant: r = -0.72, p < 0.0001. TCD-3D allowed quantitative evaluation of the hemodynamic changes and of the collateral blood supply and proved to be a sound method for the investigation of ischemic stroke, correlating well with the clinical findings, MRA and lesion size on CT.