Biological Sciences 300/301, Smith College | Neurophysiology Appendix: Capturing data with Sound Studio
	Extracellular recordings of spikes can be captured using the iMac's sound input and Sound Studio 2 software. Captured data can be viewed on the iMac's screen at different magnifications, or it can be played back to the oscilloscope and chart recorder. To capture spike signals from your preamplifier, do the following:
Connect	Connect the stereo jack on the patch panel to the sound input (microphone symbol) on the side of the iMac. We have long cables with stereo miniplugs at each end for this purpose. Channel 1 on the patch panel is wired to the left stereo channel, channel 2 to the right.
Set the sound input	Open the Sound control panel (microphone symbol) using the control strip at the bottom of the screen. (You can also find the control panel under the Apple menu, in the Controls folder.) Select "Sound In" as the source by highlighting it in the scrolling list. Also check the two items under "Settings for input device...." Adjust the signal level until you can hear the spikes through the Mac's speakers. Click image for larger version.
Launch Sound Studio	Double-click the Sound Studio icon on the desktop to launch the application. Activate the "Input Levels" window (Windows menu) if it is not already on the screen. You can further adjust the sound level with the window's sliders.
Open a new recording window Click for larger image.	In the file menu, select "New." A dialog box will appear. Name the recording something descriptive (experiment, date and time, drug and dose). A good choice now will help you organize your files later. In the "Sound Quality" box, select a Rate of 44.100 kHz (This is the number of samples per second that will be taken of the spike signals. It will determine the resolution of the pictures later.) Select 16 bits. If you have only one data channel, select Mono. Click "OK." A new, blank recording window will open. You will not see the spike signals plotted until after you have finished recording.
Start recording	When you have data you wish to capture, click the red "Record" button in the upper left corner of the recording window. It will appear depressed until you click "Stop." The time counter will advance during the recording to show you how much data you have acquired.
View the plot	Click for larger image. After you stop the recording, your total data will be plotted in the upper part of the recording window. A red box will indicate how much of the total stream of data appears in the magnified window in the bottom half. You can move the red box to any region of your total data by dragging it.
Zoom in	You can make the magnification bigger or smaller by using the + and - magnifier symbols on the bottom edge of the recording window, or you can use the drop-down menu and jump to a new magnification. This will let you see individual spikes or whole bursts.
Save the file	If the data appear useful, save the file. You can select portions to delete prior to saving it if you wish. You can also increase the vertical gain (the height of the spikes) by selecting all (Edit menu) and using the "Volume" filter in the Filters menu. Other filter manipulations are probably not wise choices. Once you have saved the file, you can close the window or leave it open. To record new data, open a new recording window.
Printing	Sound Studio is not oriented to printing its plots (most people want to listen to sounds, not view them). You can use the Mac's screen "picture" system to capture portions of the plot window.
Playback to chart	Another way of getting hard copies of files is to play digitized data to the oscilloscope and chart recorder. At the patch panel, disconnect any amplifiers, but leave in place connections to the oscilloscope and the chart recorder. At the computer, unplug the stereo cable from the audio-in connector (microphone symbol) and plug it in to the adjoining audio-out connector (speaker symbol). Open a file to be played back, and click the "Play" button at the top left. The data in the file will be played back as an audio signal that you can display on the oscilloscope and chart recorder. When you have finished playing back files, reconnect the stereo cable to the Mac's audio-in connector. Otherwise, you or a classmate will be very puzzled on another day when spikes from a new experiment fail to appear at your computer.