Brian A MacVicar

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Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key(More)
Calcium signalling in astrocytes couples changes in neural activity to alterations in cerebral blood flow by eliciting vasoconstriction or vasodilation of arterioles. However, the mechanism for how these opposite astrocyte influences provide appropriate changes in vessel tone within an environment that has dynamic metabolic requirements remains unclear.(More)
Neuronal excitotoxicity during stroke is caused by activation of unidentified large-conductance channels, leading to swelling and calcium dysregulation. We show that ischemic-like conditions [O(2)/glucose deprivation (OGD)] open hemichannels, or half gap junctions, in neurons. Hemichannel opening was indicated by a large linear current and flux across the(More)
Cerebral blood flow (CBF) is coupled to neuronal activity and is imaged in vivo to map brain activation. CBF is also modified by afferent projection fibres that release vasoactive neurotransmitters in the perivascular region, principally on the astrocyte endfeet that outline cerebral blood vessels. However, the role of astrocytes in the regulation of(More)
Afferent activity can induce fast, feed-forward changes in synaptic efficacy that are synapse specific. Using combined electrophysiology, caged molecule photolysis, and Ca(2+) imaging, we describe a plasticity in which the recruitment of astrocytes in response to afferent activity causes a fast and feed-forward, yet distributed increase in the amplitude of(More)
Cholinergic stimulation of the hippocampal formation results in excitation and/or seizure. We report here, using whole-cell patch-clamp techniques in the hippocampal slice (34-35 degrees C), a cholinergic-dependent slow afterdepolarization (sADP) and long-lasting plateau potential (PP). In the presence of 20 microM carbachol, action potential firing evoked(More)
Pannexin-1 (Px1) is expressed at postsynaptic sites in pyramidal neurons, suggesting that these hemichannels contribute to dendritic signals associated with synaptic function. We found that, in pyramidal neurons, N-methyl-d-aspartate receptor (NMDAR) activation induced a secondary prolonged current and dye flux that were blocked with a specific inhibitory(More)
Cortical spreading depression (SD) is a propagating wave of neuronal and glial depolarization that manifests in several brain disorders. However, the relative contribution of neurons and astrocytes to SD genesis has remained controversial. This is in part due to a lack of utilizing sophisticated experimental methodologies simultaneously to quantify multiple(More)
The chloride/anion channels that have been so far identified in cultured astrocytes and those that have been confirmed in situ by a combination of mRNA identification, immunocytochemistry, and biophysical studies are reviewed. It is emphasized that we are just beginning to describe such channels and analyze their functions in astrocytes. The best-studied(More)
Imaging analysis techniques were used to examine changes in the intrinsic optical properties in hippocampal brain slices that occurred during synaptic activity evoked by Schaffer collateral stimulation in CA1. Repetitive synaptic activity was associated with an increase in light transmission in the synaptic region in stratum radiatum. The effect was seen at(More)