BACKGROUND AND PURPOSE Cerebral microcirculatory changes during cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) are still controversial and uncertain. The aim of this study was to investigate the changes of cerebral microcirculation during cerebral vasospasm and to clarify the roles of microcirculatory disturbances in cerebral ischemia by measuring cerebral circulation time (C...

BACKGROUND AND PURPOSE Normal values for cerebral blood flow (CBF) and metabolism in adults are well established, but not for children. Our goal, therefore, was to clarify functional developmental changes of the brain in children in relation to CBF and oxygen metabolism. METHODS We measured regional CBF (rCBF), regional cerebral metabolic rate for oxygen (rCMRO2), and regional oxygen extracti...

Sympathoexcitatory reticulospinal neurons of the rostral ventrolateral medulla (RVLM) are oxygen detectors excited by hypoxia to globally elevate regional cerebral blood flow (rCBF). The projection, which accounts for >50% of hypoxic cerebral vasodilation, relays through the medullary vasodilator area (MCVA). However, there are no direct cortical projections from the RVLM/MCVA, suggesting a rel...

Apomorphine, a non-selective dopamine agonist, has been used as a pharmacological probe for investigating central dopaminergic neurotransmission in psychiatric illness. In this study repeated measurements of regional cerebral blood flow (rCBF) were made in normal volunteers before, and after, the administration of apomorphine (5 or 10 micrograms/kg), or placebo. The difference in rCBF, before a...

Positron emission tomography measurements of regional cerebral blood flow (rCBF) were performed in normal volunteers during two auditory--verbal memory tasks: a subspan and supraspan task. The difference in rCBF between tasks was used to identify brain areas/systems involved in auditory--verbal long-term memory. Increases in rCBF were observed in the left and right prefrontal cortex, precuneus ...

The effects of hypercapnia on enhancement of reduced cerebral perfusion were re-evaluated in areas of ischemia produced by occlusion of the canine middle cerebral artery. Perfusion was measured by 85Kr (beta-ray) and 133Xe (gamma-ray) clearances, fluorescein angiography and diameter measurement of arteries. Between 45 and 55 mm Hg of PaCO2 rCBF measured with both isotopes increased significantl...

Different brain regions sense and modulate the counterregulatory responses that can occur in response to declining plasma glucose levels. The aim of this study was to determine if changes in regional cerebral blood flow (rCBF) during hypoglycemia relative to euglycemia are similar for two imaging modalities-pulsed arterial spin labeling magnetic resonance imaging (PASL-MRI) and positron emissio...

Tone recognition is partially subserved by neural activity in the right frontal and primary auditory cortices. First we determined the brain areas associated with tone perception and recognition. This study then examined how regional cerebral blood flow (rCBF) in these and other brain regions correlates with the behavioral characteristics of a difficult tone recognition task. rCBF changes were ...

The presence of hyperglycemia prior to stroke or cardiac arrest can increase neuronal damage caused by brain ischemia. Acute hyperglycemia shows this effect in animal models of stroke. However, chronic hyperglycemia and chronic hyperglycemia with additional acute elevation of blood glucose are more common premorbid states for stroke patients. The effect of chronic hyperglycemia on regional cere...

OBJECTIVES We investigated the effect of shunt surgery in patients with Normal Pressure Hydrocephalus (NPH) using Single Photon Emission Computerised Tomography (SPECT). MATERIALS & METHODS Thirteen patients diagnosed with NPH were assessed clinically and using (99m Tc)-SPECT and MRI both pre- and post-operatively. Regions of interest were placed manually on T2 MRI and transferred to co-regis...