The optical laboratory contains all the equipment necessary for conducting optically based brain imaging experiments in rodent and human subjects.

OPTICAL INTRINSIC SIGNAL (OIS) IMAGING and SPECTROSCOPY LABORATORY
Two microscopes are available for rodent imaging – a Leitz Ortholux II compound microscope and a Nikon SMZ 1500 stereomicroscope mounted on a custom z-axis translation stand. Illumination is provided by a DC voltage-stabilized quartz-tungsten-halogen (QTH) light source (Dolan Jenner PL-900) equipped with a heat filter. A high-speed filter wheel (Sutter Lambda 10-2) along with a set of narrow bandpass transmission filters (450 – 850 nm range) allows multiwavelength imaging. Rodent imaging is performed using a high dynamic range Princeton Instruments charge-coupled device (CCD) camera (TE/CCD 576EFT) with a 16-bit analog-digital converter.

 A spectroscopy system is available for OIS spectroscopy. This system includes a Roper Scientific spectroscopy CCD camera (Spec-10:400B) attached to a spectrophotometer (SpectraPro 300i) with three computer-controllable diffraction gratings. The stereomicroscope/camera assembly is housed within a Faraday cage to reduce electromagnetic interference during electrophysiological recording. Electrophysiological data are filtered and recorded with versatile amplifier and digitization components (SCXI, National Instruments). An eight-channel pulse generator (AMPI Master-8) is available for synchronizing imaging, electrophysiology, and stimulation. Data are acquired on a dedicated Pentium III PC connected to the high-speed local network.

 The lab also contains standard physiological monitoring equipment for rodent surgery and experimentation, including surgical instruments and sterilizers, a mechanical ventilator, blood pressure monitor, heating blanket, infusion pump for intravascular anesthesia, and vaporizers/scavengers for inhaled anesthesia.

A second OIS imaging system optimized for and dedicated to intraoperative human cortex imaging is also available. This system is comprised of a custom Hamamatsu electron-bombardment CCD camera (C7190) controlled by a Pentium III PC. The PC contains data acquisition hardware and a BNC cable patch assembly (National Instruments CA-1000) to allow interfacing with operating room monitoring equipment. Image acquisition and stimulation are synchronized with a single-channel pulse generator (Pulsar 6bp). The entire apparatus is rack-mounted within a mobile cart to facilitate transportation between the lab and neurosurgical operating rooms.

NEAR INFRARED SPECTROSCOPY (NIRS) LABORATORY
The spectrophotometer/camera assembly described above for OIS spectroscopy is housed on a mobile cart to conduct NIRS experiments in humans both transcranially and intraoperatively. Additional equipment specific for NIRS includes a stable, 250 Watt DC QTH light source (Oriel Instruments) with a 650 nm high-pass filter and low-pass heat-removing water filter with recirculating cooler, glass fiber optic emitter cables, and spectroscopic bi- and quad-furcated fiber optic detector cables.