A05: Target-specific synaptic and network mechanisms of memory consolidation

Memory consolidation involves the interaction of a large number of cell types projecting to distributed cortical areas. However, the kind of information that is transmitted between these different brain areas and how the code may change and stabilize over time is poorly understood. One powerful approach to address this problem is to record the activity of distinct neuronal cell types projecting to different cortical regions involved in memory consolidation during and after learning. However, this approach has been limited because few molecular markers exist for cortical excitatory projection neuron subtypes and optical tools have limited recordings to superficial layers. Here we propose to tackle this problem by using improved two-photon in vivo imaging to record the activity of anatomically labelled layer 5 excitatory projection neurons in primary somatosensory forepaw cortex during the consolidation of a thermal perception task. Our task requires the learning of simple movements (licking), the detection of a sensory cue (acoustic) and an association of different sensory stimuli (thermal) with reward. We hypothesize that sensory, motor or reward memories map onto L5 excitatory neurons projecting to different target regions. To monitor activity of excitatory projection neurons at different time scales, and assess both synaptic and network mechanisms, we will use multiple recording methods including: targeted electrophysiological recordings, single cell functional calcium imaging, and expression of genetically encoded activity reporters. Together, we aim to unravel the cell type-specific mechanisms of neuronal ensemble reorganization in cortical layer 5 during memory consolidation.

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