Headfixed Configurations Basic Configuration Main Control Unit (MCU) Environmental Control Unit (ECU) Headstage Combiner Unit (HCU) Horizontal Headstage 128 Channel without Processor (HH128 np) Upright Headstage 32 (UH32) Stimulation Main Control Unit (MCU) Environmental Control Unit (ECU) 32-Channel Electrode Interface Board (EIB) 32 Channel Stimulation Headstage (UH32stim) Stim Capable Headstage Combiner Unit (SHCU)