M. Avoli et A. Williamson, FUNCTIONAL AND PHARMACOLOGICAL PROPERTIES OF HUMAN NEOCORTICAL NEURONS MAINTAINED IN-VITRO, Progress in neurobiology, 48(6), 1996, pp. 519-554
The availability of neocortical tissue obtained during brain surgery h
as allowed for detailed studies of the membrane and synaptic propertie
s of neurons maintained in vitro in a slice preparation. Many of the f
indings obtained in these studies are summarized here. The majority of
the basic electrophysiological properties appear to be similar when h
uman and rodent neurons are compared. However, some notable exceptions
regarding specific membrane properties have been reported. Since the
majority of the material used in these studies is obtained from epilep
tic patients, several neuroscientists have tried to determine whether
this tissue retains any sign of epileptogenicity when analyzed in vitr
o. Abnormal synaptic activity was only seen in a fraction of neurons n
ear identified anatomical foci, including tumors, or within neocortica
l areas that displayed abnormal electrographic activity in situ. This
cellular activity included both the presence of all-or-none and graded
synaptic bursts. Epileptiform activity comparable to that seen in rod
ent tissue has been obtained in vitro using several pharmacological pr
ocedures including the disinhibition and the Mg2+-free model. In concl
usion, electrophysiological and pharmacological studies of the human n
eocortex obtained during surgery have so far been unsuccessful in isol
ating any definite cellular mechanism that may account for the express
ion of the epileptiform activity in situ. Nevertheless, these studies
have provided valuable information on the cellular and synaptic proper
ties of human neocortex under normal conditions, and following experim
ental procedures capable of increasing neuronal excitability. Copyrigh
t (C) 1996 Elsevier Science Ltd