Morphological and electrophysiological properties of lateral entorhinal cortex layers II and III principal neurons

Abstract

The intrinsic electrophysiology and morphology of neurons from layers II and III of the lateral entorhinal cortex (EC) was investigated in a rat brain slice preparation by intracellular recording and biocytin labeling. Morphologically, we distinguished three groups of layer II principal neurons. The most numerous group included cells with multiple radiating dendrites that spread over layers II and I in a fan-like fashion. While morphologically "fan" neurons were similar to the "stellate" cells of the medial EC, electrophysiologically the fan cells lacked the persistent rhythmic subthreshold oscillations and the very pronounced time-dependent inward rectification typical of the stellate cells. The second group consisted of pyramidal cells that manifested regular spike firing and had a more negative resting potential and a longer spike duration than the fan cells. In the third group we included all those neurons that had diverse multipolar appearances distinct from the fan cells. Neurons in this group had electrophysiological profiles intermediate between those of the fan and pyramidal cells. All neurons recorded in layer III were pyramidal in shape with a basal dendritic tree that could extend into layer V and an axon that could also give off collaterals into layer V. Electrophysiologically, layer III pyramidal cells were very similar to those of layer II. On the basis of these and other data we suggest that in different EC regions layer II neurons may be conducting more input-dependent specialized processing, while cells from layer III may perform a more global or generalized function.

Grid cell mechanisms and function: Contributions of entorhinal persistent spiking and phase resetting

“…In contrast to stellate cells, membrane potential oscillations do not usually appear in Layer II and III pyramidal cells (Alonso and Klink, 1993), but are observed in Layer V pyramidal cells, where they may be caused by M-current (Yoshida and Alonso, 2007;Giocomo and Hasselmo, 2008a). Membrane potential oscillations do not appear in neurons of the lateral entorhinal cortex (Tahvildari and Alonso, 2005), and grid cells do not appear in lateral entorhinal cortex (Hargreaves et al, 2005).…”

Firing properties of entorhinal cortex neurons and early alterations in an Alzheimer's disease transgenic model

“…Neuron identification as SCs from layer II of the MEC or FCs of layer II of the LEC was performed by considering their different localization [5,6,7,55], and their morphological similarities [43]. A.).…”

“…Within the layer II of the MEC, the most abundant neurons are represented by the stellate cells (SCs), which form the MPP [1]. Within the layer II of the LEC, the most abundant neurons belong to another type of stellate cells, the so-called "fan cells" (FCs), which form the LPP [43]. Both SCs and FCs are morphologically similar, characterized by multiple radiating dendrites that spread over layers II and I [43].…”

“…Within the layer II of the LEC, the most abundant neurons belong to another type of stellate cells, the so-called "fan cells" (FCs), which form the LPP [43]. Both SCs and FCs are morphologically similar, characterized by multiple radiating dendrites that spread over layers II and I [43]. Functionally, however, these two cell types have been characterized in rat brain and exhibit specific differences.…”

“…SCs are characterized by a pronounced time-dependent inward rectification current, mainly due to the activity of a hyperpolarization-activated inward current (I h ), and by persistent sub-threshold oscillations, activity that corresponds to non-periodic fluctuations, both of which are less pronounced in FCs [1,10,43].…”