ActiveRat is an elegant solution for collecting multi-channel EEG, EMG and activity (infrared detector) data from multiple freely-moving small animals. The system architecture incorporates amplification and 24-bit analog-to-digital conversion in a single, compact unit located inside or immediately adjacent to the animal housing. Up to 32 A/D boxes are synchronized but remain galvanically isolated from each other by means of a fiber-optic data daisy chain. Systems with more than 32 A/D boxes connected to a single host PC are also possible on a custom basis, with a proportional reduction in channels per cage and/or sample rate.
The fiber-optic daisy chain permits many meters distance between cages and between the last A/D box and the data acquisition PC (user-supplied), where data from all animals are displayed and stored. Each A/D box has an integrated low-capacitance DC-DC converter. So, all A/D boxes can be powered from a single un-isolated power supply. The galvanic isolation of each separate animal is still ensured by the internal DC-DC converter. The 2 input channels for IR detectors and extra logic input for a timing switch are coupled to the ADC circuitry via integrated low-capacitance optocoupler ensuring the galvanic isolation of each animal.
The RatView data acquisition software provided with the system manages the complex task of storing long-term records from multiple animals. The RatView software is a LabVIEW application, and it is provided as an executable that requires only the free LabVIEW runtime engine (provided) to operate. You do not need to have a LabVIEW programmer to operate the system. However, RatView is open-source software, meaning that the LabVIEW virtual instrument source code is provide with the system, and users are free to modify it to suit their own needs. A typical RatView software configuration will handle a total of 32*16+1=513 channels (last channel is sync channel). The switch data and the CMS in range data are encoded in the LSBs of channel 15 and 16 of each cage, so no channels are wasted for these extra bits.