Expression of intrinsic bursting properties in neurons of maturing sensorimotor cortex.
Intrinsically bursting (IB) neurons, responding with a burst of action potentials to just threshold intracellular depolarizing current pulses, are encountered in layer V of mature rodent sensorimotor cortex. We report the results of intracellular recordings performed on neocortical slices obtained from immature rats between postnatal day (P) 7 and P21, as compared to adult animals (above P60). The bursting properties are here reported to mature abruptly around P14. After this time a subpopulation of IB neurons was recognizable on the basis of both physiological and morphological characteristics (i.e. extensive apical and basal dendrites arborization, axon collaterals limited to layers V-VI). Maturational changes in number and distribution of Ca2+/K+ channels may account for this developmental step. The immaturity of IB neurons may be correlated with the poorly synchronized character of cortical activities in the very young animals.
Franceschetti
S
S
Department of Neurophysiology, Ist. Naz. Neurologico C. Besta, Milan, Italy.
Buzio
S
S
Sancini
G
G
Panzica
F
F
Avanzini
G
G
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D066298:In Vitro Techniques; D007700:Kinetics; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D009044:Motor Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; C013411:biocytin; D008239:Lysine