MOPP cells (Molecular Layer Perforant Path-Associated cells) are a distinct population of GABAergic interneurons found in the molecular layer of the dentate gyrus and hippocampus proper. These cells are characterized by their selective innervation of the perforant path input zone and their critical role in regulating entorhinal cortical inputs to the hippocampal formation. MOPP cells play essential roles in memory encoding, pattern separation, and the filtering of cortical information entering the hippocampal circuit. [@mcbain2009]
Overview
MOPP cells are among the most abundant interneuron types in the hippocampal molecular layer, where they receive synaptic input from the perforant path (the major excitatory pathway from layer II of the entorhinal cortex). They provide feedforward inhibition to granule cells and other interneurons, creating a precisely timed inhibitory gate that controls information flow through the hippocampal formation. [@freund1996]
MOPP cells (Molecular Layer Perforant Path-Associated cells) are a distinct population of GABAergic interneurons found in the molecular layer of the dentate gyrus and hippocampus proper. These cells are characterized by their selective innervation of the perforant path input zone and their critical role in regulating entorhinal cortical inputs to the hippocampal formation. MOPP cells play essential roles in memory encoding, pattern separation, and the filtering of cortical information entering the hippocampal circuit. [@mcbain2009]
Overview
MOPP cells are among the most abundant interneuron types in the hippocampal molecular layer, where they receive synaptic input from the perforant path (the major excitatory pathway from layer II of the entorhinal cortex). They provide feedforward inhibition to granule cells and other interneurons, creating a precisely timed inhibitory gate that controls information flow through the hippocampal formation. [@freund1996]
Key Characteristics: [@houser2007]
Location: Molecular layer of dentate gyrus and CA1
Neurotransmitter: GABA
Primary input: Perforant path from entorhinal cortex
Primary output: Granule cell dendrites and other interneurons
Neuroanatomy
Cellular Morphology
Soma Properties: [@chance2008]
Small to medium-sized cell bodies (10-15 μm diameter)
Dendritic trees confined to the molecular layer
Axonal arborizations in the outer molecular layer
Dendritic Features: [@savanthrapadian2014]
Bipolar or bitufted morphology
Dendrites receive perforant path inputs
Express receptors for entorhinal cortical input
Receive feedback inhibition from other interneurons
Axonal Projections: [@acsdy1998]
Axons terminate on granule cell distal dendrites
Target the same lamina as perforant path synapses
Form inhibitory synapses on excitatory and inhibitory neurons
Connectivity
Afferent Inputs: [@treves1994]
Perforant path: Primary excitatory input from entorhinal cortex layer II
Mossy cells: Associational connections via hilar collaterals