Single-fibre EPSPs in layer 5 of rat visual cortex in vitro.
Simultaneous intracellular recordings were made from pairs of synaptically connected layer 5 pyramidal neurones less than 150 microns apart, in slices of rat visual cortex. Action potentials were evoked in one cell of a pair by depolarizing current pulses, while spike-triggered averaging was employed to reveal connections in the other cell and vice versa. Only 4 excitatory postsynaptic potentials (EPSPs) (0.7-1.2 mV) were recorded out of 270 cell pairs tested, equivalent to a connection probability of less than 0.02. Therefore, single-fibre EPSPs between pyramidal cells in layer 5 are less frequent, but individually larger in amplitude, than those found previously between pyramidal cells in layer 2/3 of rat visual cortex.
Nicoll
A
A
University Laboratory of Physiology, Oxford, UK.
Blakemore
C
C
D000818:Animals; D005071:Evoked Potentials; D066298:In Vitro Techniques; D009412:Nerve Fibers / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011336:Probability; D011712:Pyramidal Tracts / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*