Corticothalamic feedback projections in the mammalian brain exert strong control over single thalamic neurons, thereby shaping how information propagates in thalamocortical circuits implicated in sensation and global brain states. In the rodent whisker system, one such pathway is cortical layer 5B (L5B) to posterior medial (POm) thalamus, which can drive spiking in thalamic target neurons and serves to integrate cortical activity with incoming sensory information. Due to the combination of pronounced synaptic depression and intrinsic POm bursting, spike transfer from L5B to POm is highly nonlinear and dependent on past activity. I propose to model this pathway by fitting a detailed model of POm neurons and L5B depressing synapses. The resulting model will be used to investigate thalamic encoding of low- and high- frequency information present in in vivo L5B spike trains.