A compound mechanism of deprivation-mediated sensory surround potentiation in the adult somatosensory cortex
Event details
| Date | 01.11.2012 |
| Hour | 13:30 › 14:30 |
| Speaker | Frédéric GAMBINO, Neurosciences Fondamentales, Uni Geneva |
| Location | |
| Category | Miscellaneous |
Functional maps in the cerebral cortex reorganize in response to changes in experience. After a partial sensory deprivation, spared inputs often expand their cortical representations whereas the deprived cortical modalities shrink. The synaptic underpinnings of this map plasticity remain uncertain. We demonstrate that within the lemniscal, ventral posterior medial (VPm) thalamic nucleus-associated pathway, layer (L) 2/3 pyramidal cell synapses in mouse barrel cortex can be potentiated upon pairing of whisker-evoked post-synaptic potentials (PSPs) with action potentials. This spike-timing dependent long-term potentiation (STD-LTP) was only effective for PSPs evoked by deflections of a whisker in the neuron’s receptive field center, and not its surround. Trimming of all except two whiskers, which increases L2/3 spiking and causes the spared whisker representations to merge, rapidly opened the possibility to drive STD-LTP by the spared surround whisker. This facilitated STD-LTP was associated with a strong and specific decrease in the surrounding whisker-evoked inhibitory conductance and partially occluded picrotoxin-mediated LTP facilitation. The deprivation also increased the activity of a non-specific paralemniscal L2/3 synaptic pathway, which is relayed in the posterior medial (POm) thalamic nucleus. Taken together, our data demonstrate that the experience-dependent expansion of receptive fields in the barrel cortex may be promoted by disinhibition-mediated and spike-timing dependent potentiation of a lemniscal surround whisker-specific pathway as well as by the gating of a non-specific paralemniscal pathway.
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Practical information
- General public
- Free
Organizer
- Prof. Wulfram GERSTNER
Contact
- Chantal Mellier