PT  - JOURNAL ARTICLE
AU  - Marı́a Cecilia Angulo
AU  - Jochen F. Staiger
AU  - Jean Rossier
AU  - Etienne Audinat
TI  - Developmental Synaptic Changes Increase the Range of Integrative Capabilities of an Identified Excitatory Neocortical Connection
AID  - 10.1523/JNEUROSCI.19-05-01566.1999
DP  - 1999 Mar 01
TA  - The Journal of Neuroscience
PG  - 1566--1576
VI  - 19
IP  - 5
4099  - http://www.jneurosci.org/content/19/5/1566.short
4100  - http://www.jneurosci.org/content/19/5/1566.full
SO  - J. Neurosci.1999 Mar 01; 19
AB  - Excitatory synaptic transmission between pyramidal cells and fast-spiking (FS) interneurons of layer V of the motor cortex was investigated in acute slices by using paired recordings at 30°C combined with morphological analysis. The presynaptic and postsynaptic properties at these identified central synapses were compared between 3- and 5-week-old rats. At these two postnatal developmental stages, unitary EPSCs were mediated by the activation of AMPA receptors with fast kinetics at a holding potential of −72 mV. The amplitude distribution analysis of the EPSCs indicates that, at both stages, pyramidal–FS connections consisted of multiple functional release sites. The apparent quantal size obtained by decreasing the external calcium ([Ca2+]e) varied from 11 to 29 pA near resting membrane potential. In young rats, pairs of presynaptic action potentials elicited unitary synaptic responses that displayed paired-pulse depression at all tested frequencies. In older animals, inputs from different pyramidal cells onto the same FS interneuron had different paired-pulse response characteristics and, at most of these connections, a switch from depression to facilitation occurred when decreasing the rate of presynaptic stimulation. The balance between facilitation and depression endows pyramidal–FS connections from 5-week-old animals with wide integrative capabilities and confers unique functional properties to each synapse.