Design of a novel head-mountable microscope system for laser speckle imaging

Imaging of cortical vasculature in rodents and its dynamic response to experimental conditions, yield valuable information regarding the underlying physiological mechanisms of neuronal activity. Laser Speckle Contrast Imaging (LSCI) facilitates both enhanced micro-vessel visualization and blood flow information. The current state of equipment used: the imaging systems, the external lighting as well as the recording apparatus constrain modern imaging to bench-top experiments with anaesthetized rodents. We describe an imaging system that attempts to shift this paradigm to be capable of imaging awake and behaving rodents in a completely unrestrained manner. To this end, we present a novel integrated optics microscope weighting 7 g and occupying less than 4 cc, coupled with a backpack system weighting 22 g and measuring 2.5×4×2 cm³. The system is capable of providing controlled laser illumination, optimized speckle image formation in 670 nm - 850 nm range with a 1 mm depth of field, image acquisition and data recording as a single system. We present details of system development and provide preliminary results from an anaesthetized rat model.