The presence of synapses in microgrooves raises the possibility of focal synaptic stimulation to investigate synaptic function. To implement this feature, we kept the existing compartmentalized structure but added a perfusion channel perpendicular to the microgrooves. In order to access a high number of dendrites, we placed the perfusion channel 75 μm from the edge of one compartment (we refer to this compartment as the “postsynaptic compartment”), and this compartment is connected to the perfusion channel via the microgrooves (which have the same height and width dimensions as the traditional compartmentalized chamber used above). Since the average length of dendrites extending into the microgrooves is 165 μm at 14 days in culture, the location of the perfusion channel allows for a large percentage of the dendrites to be perfused. The other compartment is 500 μm away from the perfusion channel and connected via an additional set of microgrooves. The long length of this set of microgrooves ensures that only axons from this compartment (we refer to this compartment as the “presynaptic” compartment) are able to extend into the perfusion channel.
