The Operant Chamber
The operant chamber is constructed of 3/8 inch (9 mm) Plexiglas. The removable front panel contains a glass odor sampling tube, two stainless steel water delivery tubes, a signal light, and a buzzer. Snout insertions into the odor sampling tube are detected by an infrared photocell; lick responses on the water delivery tube are detected by a ‘lickometer’ circuit. Modifications are available for studies using electrophysiological recordings that may require non-electrical contact detectors. Chambers are available for rats and for mice.
The Knosys Digital Interface and Software
The USB connected interface is based on the ACCES USB-IIRO-16 board with 16 isolated outputs (1 amp at 24 vdc drivers) and 16 optically isolated inputs. Our software, written in BBCBASIC, compatible with all Windows operating systems, connects via a powered or un-powered 2.0 USB port. Initialization routines, source code, and sample programs are available for those who wish to write their own programs in Visual Basic, Delphi, C++ Builder, Visual C++ and related languages.
Air compressor and air filter
The modest air volume and pressure requirements of the olfactometer are supplied by a quiet diaphragm type compressor rated at 5 liters/minute at 4 psi whose output is filtered through activated charcoal and a 5 micron particle filter. Charcoal cartridges are long-lasting and easily replaced.
Air flow control
Air streams for dilution air and odorant air are controlled by glass and Teflon needle valves and monitored by calibrated 150 mm Key Instrument flowmeters.
Any regulated and adjustable 24 vdc power supply rated at least 1.5 amps can be used to power the system. The Knosys power supply is a high quality, regulated, and metered unit rated at 3 amps and can power up to 5 olfactometers.
Response and Water Delivery Tubes
Operant chambers contain two water delivery tubes: one (the IN tube) is located within the odor sampling port and a second (the OUT tube) located adjacent to the odor sampling port. IN tube training is highly efficient and most often used. However, OUT tube training allows the operator to measure odor sampling time on each trial. Separate programs are provided for IN and OUT tube training and testing.
Water delivery for correct responding is provided by a gravity-fed water reservoir whose output is controlled by a normally closed solenoid valve. Reliable delivery of volumes of 2 – 4 uL (for mice) or 30 – 50 uL (for rats) is achieved using in-line flow restrictors and appropriatetiming of valve operation.
Odor Saturator Bottles
The PVC odor saturator bottles are disposable and we recommend the purchase of additional odor sampling bottles and several rolls of C-flex tubing (tubing used by the odor control pinch valves). The disposable odor saturator bottles are provided with caps drilled to accommodate input and output tubes.
Software Routines and Computer
Software provided with the olfactometer includes a Utility program, initial training program (BEGIN) and programs for detection and discrimination training allowing the use of 2 or more stimuli. The Utility program contains routines for calibrating reinforcement delivery and checking all interface functions. Training and discrimination programs are based on a typical go, no-go discrete trials training and test procedure in which, on any one trial, either a positive (S+) or negative (S-) stimulus is presented and the subject is rewarded for responding in the presence of the positive stimulus (described in detail in the Slotnick and Restrepo, 2005 paper). These programs are those used in virtually all published accounts employing the Knosys olfactometer. The laptop computer (generally a Thinkpad 4x series) provided with the system contains all required software.
Olfactometers are made to order and each unit is tested and calibrated prior to being mailed. We do not stock all components and it generally takes 2-4 weeks to complete a unit from the time we receive a purchase order.
KNOSYS software programs are NOT multi tasking and we advocate a dedicated computer and interface for each behavior test system.