A miniaturized system for imaging vascular response to deep brain stimulation

We present a miniaturized system for spectroscopic imaging of the cerebrovascular response to deep brain stimulation (DBS). The system consists of an optical module with controllable light emitting diode (LED) illumination and focusing optics, and an electronic module with a high-sensitivity complementary metal oxide semiconductor (CMOS) image sensor, an off-chip controller and a microSD card for image storage. The system is a refinement of our previously described integrated imaging microscope (IIM). Key differences include a further reduced footprint with the head-stage occupying less than 1.5 cm³ and weighing under 1.5 gm, pulse width modulation (PWM) control of illumination intensity and improved signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) performance. Electrical and optical characterization and simulation data, and experimental data from an anesthetized rat are presented. Combined with integrated instrumentation for electrical stimulation and electrophysiology, we expect the tether-free, animal mountable system to facilitate understanding the long-term vascular and electrical effects of deep brain stimulation in freely-moving animals.