For the input to the hippocampus proper, the temporoammonic pathway arises in layer III cells of the entorhinal cortex but separates from the perforant pathway to contact the most distal branches of the pyramidal cells in the stratum lacunosum-moleculare of CA1-CA3. The excitatory (glutaminergic) influence of this path has been questioned because influence on the pyramidal cells has been difficult to demonstrate. Recent experiments show that this modulation of pyramidal cells may differentially activate an interneuron subpopulation located in the distal reaches of the apical dendrites.