Electrophysiological characteristics of neurons in neocortical expiant cultures

Abstract

We examined the electrophysiological and morphological properties of neocortical neurons maintained in explant cultures prepared from the parietal cortex of newborn Sprague-Dawley rats. After 3-6 weeks in vitro, cultures showed regional differences in cellular density reminiscent of cortical layering, and an abundance of axonal processes. Pyramidal-shaped neurons with spinous dendrites were the dominant elements revealed by Lucifer yellow injections. Intracellular recordings revealed that many electrophysiological properties of neurons in the explants resembled those of neocortical neurons in vivo and in slice preparations. In response to depolarizing current injection, neurons in the explants showed the same three patterns of repetitive firing described in neocortical slices, as well as a similar array of responses. Spontaneous synaptic potentials were recorded from all neurons and complex PSPs were evoked in response to focal extracellular stimulation. GABAa receptors mediated a significant component of the evoked responses. Fifteen of sixty neurons generated action potentials that arose spontaneously from resting potentials. Neurons in many slices generated large, prolonged depolarizing potentials that reflected coordinated synaptic activity within the explants. These results underscore the usefulness of the neocortical explant as a valuable model for studying aspects of the behavior of circuits of cortical neurons.

Development of NMDA and non‐NMDA receptor‐mediated excitatory synaptic transmission in geniculocortical and corticocortical connections in organotypic coculture preparations

“…These neurons showed spike firing properties similar to those in regular spiking neurons (McCormick et al . 1985; Wolfson et al . 1989).…”

“…In the present study, we analysed neurons with stable (> 1 h) resting membrane potentials deeper than ±50 mV. These neurons showed spike ®ring properties similar to those in regular spiking neurons (McCormick et al, 1985;Wolfson et al, 1989). We found that electrical stimulation of the partner explant rarely evoked postsynaptic potentials (PSPs) in the VC neurons before 7 days in vitro (7 DIV).…”

Activity‐dependent regulation of dendritic spine density on cortical pyramidal neurons in organotypic slice cultures

“…Scale bar = 2 pm. control cultures showed a low level of spontaneous activity, similar to that seen in other organotypic slice culture systems (Wolfson et al, 1989). In order to determine whether the PTX effects observed in this study were attributable to elevated levels of electrophysiological activity and to determine the effect of low spontaneous activity on spine density, a series of cultures were grown in the presence of both PTX and TTX.…”

Computing with the Leaky Integrate-and-Fire Neuron: Logarithmic Computation and Multiplication

“…To solve equation 2.7, four parameters need to be specified: t 0 , τ , V th , and C. Parameter choices are based on physiological values observed in cortical pyramidal cells of the rat and the cat, summarized and derived in Bugmann (1991). The input injection current, I inj , varies over a realistic range of current injection: [1I rh , 13I rh ] amperes, with threshold potential, V th = 15 mV (see Wolfson et al 1989). V th lies between the axon hillock threshold and the soma fast sodium conductance threshold (Schwindt and Crill 1982).…”