Modeling the response of homogeneous and heterogeneous cerebral capillary networks to local changes in vessel diameters.

While microvascular cerebral capillary networks are known to be highly heterogeneous, previous computational models have predicted that heterogeneous cerebral capillary flow patterns result in lower brain tissue partial oxygen pressures. Moreover, as blood flow increases, the flux among capillaries homogenizes. This homogenization of flow is expected to improve the efficiency of oxygenation extraction from the blood.

Regulation of Rostral Nucleus of the Solitary Tract Responses to Afferent Input by A-type K+ Current.

Responses in the rostral (gustatory) nucleus of the solitary tract (rNST) are modified by synaptic interactions within the nucleus and the constitutive membrane properties of the neurons themselves. The potassium current I is one potential source of modulation. In the caudal NST, projection neurons with I show lower fidelity to afferent stimulation compared to cells without.

Ultrastructural view of astrocyte arborization, astrocyte-astrocyte and astrocyte-synapse contacts, intracellular vesicle-like structures, and mitochondrial network.

The complexity of astrocyte morphology and syncytial coupling through gap junctions are crucial for astrocyte function in the brain. However, the ultrastructural details of astrocyte arborization and interactions between neighboring astrocytes remain unknown. While a prevailing view is that synapses selectively contact peripheral astrocyte processes, the precise spatial-location selectivity of synapses abutting astrocytes is unresolved.

Modeling the effect of cerebral capillary blood flow on neuronal firing.

Adequate cerebral blood flow has long been recognized as essential for the maintenance of the neuronal function while interruption of cerebral blood flow for durations as short as minutes can result in permanent brain damage. A primary goal of this work is to determine how a neuron's ability to respond to synaptic input depends on parameters that control cerebral blood flow. A complex mathematical model is constructed that integrates detailed biophysical models of neuronal action potentials, mitochondrial ATP production and cerebral capillary blood flow.

On the electrical passivity of astrocyte potassium conductance.

Predominant expression of leak-type K channels provides astrocytes a high membrane permeability to K ions and a hyperpolarized membrane potential that are crucial for astrocyte function in brain homeostasis. In functionally mature astrocytes, the expression of leak K channels creates a unique membrane K conductance that lacks voltage-dependent rectification. Accordingly, the conductance is named ohmic or passive K conductance.