Figure 2.

Multiple output modes of dLGN interneurons. A. Axonal output of interneuron. Strong synaptic stimulation near soma/proximal dendrites produce suprathreshold activation of interneuron leading to action potential discharge and subsequent release of neurotransmitter from axonal arbor. B. Local output of F2 terminals. Local synaptic activation of distal dendrites (F2 terminals) leads to focal depolarizations that do not influence the soma/axonal region of the interneuron; however, the focal depolarization allows for GABA release from F2 terminals. Under these conditions, the neuron acts as a multiplexor. C. Global output of F2 terminals. When the interneuron is slightly hyperpolarized, strong synaptic stimulation near soma/proximal dendrites produce suprathreshold activation of interneuron leading to action potential discharge and axonal output. In addition, this can evoke activation of a lasting Ca²⁺ potential that backpropagates into the dendrites producing a lasting activation of F2 terminals throughout the dendritic arbor.