Pci 1422

We used intrinsic signal imaging^{68 (link)} of the dorsal cortex to identify the locations of cortical areas V1 and AM. Intrinsic imaging was performed on awake mice while they were head-fixed on top of a freely rotating Styrofoam cylinder. The visual cortex was illuminated with 700 nm light, a macroscope was focused 500 µm below the cortical surface, and the collected light was bandpass-filtered centred at 700 nm (10 nm bandwidth; 67905, Edmund Optics). The images were acquired at a rate of 6.25 Hz with a 12-bit CCD camera (1300QF, VDS Vosskühler), an image acquisition board (PCI-1422, National Instruments) and custom software written in LabVIEW (National Instruments). The visual stimuli, presented on a display 22.5 cm away from the left eye, were generated using Psychophysics Toolbox⁶⁹ running in MATLAB (MathWorks), and consisted of square-wave gratings, covering a 40° visual angle, 0.08 cycles per degree, drifting at 4 Hz in eight random directions, presented on an isoluminant grey background for 2 s, with 18 s inter-stimulus intervals. The gratings were presented alternatively at two positions, at 15° elevation and either 30° or 80° azimuth. Response maps to the grating patches at either position were used to identify the centres of V1 and AM, using a reference map^{70 (link)}.

To determine the location of cortical visual areas AL and PM, mice underwent optical imaging of intrinsic signals (Kalatsky and Stryker, 2003 (link); Schuett et al., 2002 (link)). Two to three days after the implantation of a head holder and thinning of the skull (see Surgical procedures), mice were initially sedated (chlorprothixene, 0.7 mg/kg) and then lightly anesthetized with isoflurane (0.5%–1% in O₂) delivered via a nose cone. Visual cortex was illuminated with 700-nm light split from a LED source into two light guides. Imaging was performed with a tandem lens macroscope focused 500 μm below the cortical surface and a bandpass filter centered at 700 nm with 10 nm bandwidth (67905; Edmund Optics). Images were acquired with a rate of 6.25 Hz with a 12-bit CCD camera (1300QF; VDS Vosskühler), a frame grabber (PCI-1422; National Instruments) and custom software written in Labview (Texas Instruments). The visual stimulus was generated using the open-source Psychophysics Toolbox (Kleiner et al., 2007 ) based on MATLAB (MathWorks) and consisted of a 25° large square-wave grating, (0.08 degrees per cycle) drifting at 4 Hz, presented on a gray background alternatively at two positions, centered at 10° elevation and either 60° or 90° azimuth. Frames in the second following stimulus onset were averaged across 16 to 32 grating presentations to generate intrinsic maps.