Figure 7.

The expression pathway and site of plasticity underlying SLRs. Because proper AIN activity is necessary for SLR expression (E1), the AIN must be part of the expression pathway. The site of plasticity must be upstream of the red nucleus, because inactivating this structure does not prevent the acquisition of SLRs (E2, dotted line), and downstream of the pontine nuclei, because direct stimulation of their mossy fibers supports SLRs (E3, 4, dashed line). The underlying plasticity in the AIN must be input specific and associative, because SLRs are strongly stimulus specific (E4) and induced only by paired training (E5). Thus, SLRs are probably mediated by synaptic plasticity at mossy fiber-to-AIN synapses (green asterisk) or possibly a dendrite-specific increase in the intrinsic excitability of AIN neurons (blue asterisk).