Effects of chronic caffeine on patterns of brain blood flow and behavior throughout the sleep-wake cycle in freely behaving mice.

Caffeine has significant effects on neurovascular activity and behavior throughout the sleep-wake cycle. We used a minimally invasive microchip/video system to continuously record effects of caffeine in the drinking water of freely behaving mice. Chronic caffeine shifted both rest and active phases by up to 2 h relative to the light-dark cycle in a dose-dependent fashion.

Different characteristics of cortical spreading depression in the sleep and wake states.

Objective: The objective of this study is to characterize the effects of the sleep-wake cycle on neurovascular and behavioral characteristics of cortical spreading depression (CSD).

Background: There is an important bi-directional relationship between migraine and the sleep-wake cycle, but the basic mechanisms of this relationship are poorly understood.

Methods: We have developed a minimally invasive microchip system to continuously monitor cerebral blood volume (CBV) with optical intrinsic signal (OIS), head movement, and multiple other physiological and behavioral parameters in freely behaving mice over weeks.

Ultrasound stimulation of the motor cortex during tonic muscle contraction.

Transcranial ultrasound stimulation (tUS) shows potential as a noninvasive brain stimulation (NIBS) technique, offering increased spatial precision compared to other NIBS techniques. However, its reported effects on primary motor cortex (M1) are limited. We aimed to better understand tUS effects in human M1 by performing tUS of the hand area of M1 (M1hand) during tonic muscle contraction of the index finger.

Continuous long-term recording and triggering of brain neurovascular activity and behaviour in freely moving rodents.

A minimally invasive, microchip-based approach enables continuous long-term recording of brain neurovascular activity, heart rate, and head movement in freely behaving rodents. This approach can also be used for transcranial optical triggering of cortical activity in mice expressing channelrhodopsin. The system uses optical intrinsic signal recording to measure cerebral blood volume, which under baseline conditions is correlated with spontaneous neuronal activity.

A dark quencher genetically encodable voltage indicator (dqGEVI) exhibits high fidelity and speed.

Voltage sensing with genetically expressed optical probes is highly desirable for large-scale recordings of neuronal activity and detection of localized voltage signals in single neurons. Most genetically encodable voltage indicators (GEVI) have drawbacks including slow response, low fluorescence, or excessive bleaching. Here we present a dark quencher GEVI approach (dqGEVI) using a Förster resonance energy transfer pair between a fluorophore glycosylphosphatidylinositol-enhanced green fluorescent protein (GPI-eGFP) on the outer surface of the neuronal membrane and an azo-benzene dye quencher (D3) that rapidly moves in the membrane driven by voltage.