Differential Glutamatergic Inputs to Semilunar Granule Cells and Granule Cells Underscore Dentate Gyrus Projection Neuron Diversity

Semilunar granule cells (SGCs) receive more frequent spontaneous excitatory synaptic inputs than granule cells (GCs), with stronger medial entorhinal and associational drive.

• Why it matters: The dentate gyrus circuit depends on pathway-specific excitation, but how its sparse projection neurons (SGCs) integrate distinct glutamatergic inputs was unclear.
• What they did: Using dual GC–SGC recordings, the study compared spontaneous excitatory input frequency, entorhinal input dynamics, firing probability to medial perforant path, and dendritic spine density on proximal and middle dendrites.
• The result: SGCs showed higher medial entorhinal and associational synaptic drive, greater medial perforant path-evoked firing probability, and higher proximal/middle spine density, while commissural/supramammillary inputs and passive integration did not differ.

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