The Range of Intrinsic Frequencies Represented by Medial Entorhinal Cortex Stellate Cells Extends with Age

Abstract

In both humans and rodents, the external environment is encoded in the form of cognitive maps. Neurons in the medial entorhinal cortex (mEC) represent spatial locations in a sequence of grid-like patterns scaled along the dorsal-ventral axis. The grid spacing correlates with the intrinsic resonance frequencies of stellate cells in layer II of mEC. We investigated the development of frequency preferences in these cells from weaning to adulthood using patch-clamp and sharp microelectrode recordings. We found that the dorsal-ventral gradient of stellate cell properties and frequency preferences exists before animals are able to actively explore their environment. In the transition to adulthood, cells respond faster and become less excitable, and the range of intrinsic resonance frequencies in the population expands in the dorsal direction. This is likely to reflect both the growth of the brain and the expansion of the internal representation caused by new exploratory experience.

The new KCNQ2 activator 4‐Chlor‐N‐(6‐chlor‐pyridin‐3‐yl)‐benzamid displays anticonvulsant potential

“…Double exponential equations of the form To determine the input resistance of a cell (Rinput), a hyperpolarizing voltage step of 10 mV from a holding potential of -60 mV was applied. The resonance frequency of a cell was determined from the voltage response to a sinusoidal current injection with a linear frequency increase over time (Puil et al, 1986;Hutcheon et al, 2000;Boehlen et al, 2010). The amplitude of the input was adjusted to avoid changes in the membrane potential over 10 mV during sinusoidal current injection.…”

“…The input frequency corresponding to the highest impedance was noted as resonance frequency. The resonance strength (Q-value) was determined as the ratio of the peak impedance to the impedance at by analysis lowest detectable resonance frequency (0.36 Hz; Boehlen et al, 2010;.…”

Neuronal rebound spiking, resonance frequency and theta cycle skipping may contribute to grid cell firing in medial entorhinal cortex

“…In addition, this model avoids the problem of the unreliable nature of subthreshold oscillations by directly focusing on the resonance properties and rebound timing shown to be highly reliable and deterministic in studies of medial entorhinal layer II neurons [29][30][31]33,46,50,58]. The model cannot maintain spatially selective firing without the medial septal input providing a phase signal.…”

Coordinated learning of grid cell and place cell spatial and temporal properties: multiple scales, attention and oscillations

“…If indeed grid cells develop from path integration inputs that are mediated by stripe, or band, cells, then the data of [15] imply that the problem of selecting from multiple scales of stripe cells during development is a real one, [41,42,46,47]. The SOM equations and parameters that were used in the module simulations are provided in appendix A.…”