TY - JOUR
T1 - Postsynaptic expression of homeostatic plasticity at neocortical synapses
AU - Wierenga, Corette J.
AU - Ibata, Keiji
AU - Turrigiano, Gina G.
PY - 2005/3/16
Y1 - 2005/3/16
N2 - Synaptic scaling is a form of homeostatic plasticity that scales synaptic strengths up or down to compensate for prolonged changes in activity. It has been controversial whether this plasticity is expressed presynaptically, postsynaptically, or both. Here we describe in detail the homeostatic changes that take place at excitatory synapses in visual cortical cultures after 1 or 2 d of activity blockade. After 7-10 d in vitro, activity blockade significantly increased postsynaptic accumulation of synaptic AMPA receptors via proportional increases in glutamate receptor 1 (GluR1) and GluR2. Time-lapse imaging of enhanced green fluorescent protein-tagged AMPA receptors revealed that receptor accumulation increased progressively over 2 d of activity blockade and affected the entire population of imaged synapses. The strength of synaptic connections between pyramidal neurons was more than doubled after activity blockade without affecting short-term depression or the coefficient of variation of the postsynaptic responses. Furthermore, uptake of the fluorescent styryl dye FM1-43 (N-(3-triethylammoniumpropyl)-4-[4-(dibutylamino)styryl] pyridinium dibromide) by presynaptic terminals was not different at control and activity-blocked synapses. In addition to the increased accumulation of postsynaptic AMPA receptors, boosting of dendritic AMPA currents by sodium channels was increased by activity blockade. These data indicate that, at young neocortical synapses, synaptic scaling has a predominantly postsynaptic locus and functions as a gain control mechanism to regulate neuronal activity without affecting the dynamics of synaptic transmission.
AB - Synaptic scaling is a form of homeostatic plasticity that scales synaptic strengths up or down to compensate for prolonged changes in activity. It has been controversial whether this plasticity is expressed presynaptically, postsynaptically, or both. Here we describe in detail the homeostatic changes that take place at excitatory synapses in visual cortical cultures after 1 or 2 d of activity blockade. After 7-10 d in vitro, activity blockade significantly increased postsynaptic accumulation of synaptic AMPA receptors via proportional increases in glutamate receptor 1 (GluR1) and GluR2. Time-lapse imaging of enhanced green fluorescent protein-tagged AMPA receptors revealed that receptor accumulation increased progressively over 2 d of activity blockade and affected the entire population of imaged synapses. The strength of synaptic connections between pyramidal neurons was more than doubled after activity blockade without affecting short-term depression or the coefficient of variation of the postsynaptic responses. Furthermore, uptake of the fluorescent styryl dye FM1-43 (N-(3-triethylammoniumpropyl)-4-[4-(dibutylamino)styryl] pyridinium dibromide) by presynaptic terminals was not different at control and activity-blocked synapses. In addition to the increased accumulation of postsynaptic AMPA receptors, boosting of dendritic AMPA currents by sodium channels was increased by activity blockade. These data indicate that, at young neocortical synapses, synaptic scaling has a predominantly postsynaptic locus and functions as a gain control mechanism to regulate neuronal activity without affecting the dynamics of synaptic transmission.
KW - AMPA receptors
KW - FM1-43
KW - Homeostasis
KW - Short-term plasticity
KW - Sodium currents
KW - Synaptic plasticity
KW - Time-lapse imaging
UR - http://www.scopus.com/inward/record.url?scp=15244340674&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=15244340674&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.5217-04.2005
DO - 10.1523/JNEUROSCI.5217-04.2005
M3 - Article
C2 - 15772349
AN - SCOPUS:15244340674
VL - 25
SP - 2895
EP - 2905
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 11
ER -