Final answer:
In the cortical subsystem, interneurons are responsible for activation and play a crucial role in controlling and synchronizing the activities of pyramidal neurons, which affects the E/I balance in the brain.
Step-by-step explanation:
Within the cortical subsystem, there are specific neurons responsible for activation. The brain's cerebral cortex consists mainly of two types of neurons: pyramidal cells and interneurons. Pyramidal cells, which use glutamate as their main neurotransmitter, and interneurons, which use GABA, play significant roles in neuronal networks.
Interneurons, making up 20-30% of the cortical neuron population, are important in controlling and synchronizing the activities of pyramidal neurons, thus maintaining the excitatory-inhibitory (E/I) balance. Disruption of this balance has been linked to several neuropathologies. Techniques such as optogenetics help researchers to activate or inhibit specific neurons in such networks, elucidating their roles in cortical function and dysfunction.