Fig. 6.

A representation of the entire recording system. a Schematic illustration of the full two rack system. b The EEG cable coming through the swivel is connected to an output relay box placed in the middle of the pivoting rectangular plate, centered over the hinge. The output relay box simplifies the wiring by splitting the signal into two cables only, the red cable carrying the epidural cortical or depth electrode signal (4 per rat), and a black cable carrying signal from the ground and reference electrodes. The red and black cables are then connected respectively to the input relay box and to the common reference/ground relay box. The input relay box splits again the electrical signal of each rat into its 4 epidural cortical or depth electrode wires, and these are connected to 4 ports on the headbox. Given that a single reference port and a single ground port are available on the 32 channel digital headbox (Xltek, Natus Medical, USA), the common reference/ground relay box combines reference and ground electrode signal from 8 rats into one common reference and one common ground respectively, which are placed in their respective headbox ports. The headbox feeds data into an amplifier that is connected to the recording computer. The used cable system and relay boxes minimize the number of wires for easy access and troubleshooting if needed. EEG tracings can be acquired simultaneously on 8 rats using one computer recorder and one headbox. Only two cages are shown for illustrative simplicity