Environmental enrichment potentiates thalamocortical transmission and plasticity in the adult rat visual cortex

It has been demonstrated that the complex sensorimotor and social stimulation achieved by rearing animals in an enriched environment (EE) can reinstate juvenile-like plasticity in the adult cortex. However, it is not known whether EE can affect thalamocortical transmission. Here, we recorded in vivo field potentials from the visual cortex evoked by electrical stimulation of the dorsal lateral geniculate nucleus (dLGN) in anesthetized rats. We found that a period of EE during adulthood shifted the input-output curves and increased paired-pulse depression, suggesting an enhanced synaptic strength at thalamocortical terminals. Accordingly, EE animals showed an increased expression of the vesicular glutamate transporter 2 (vGluT-2) in geniculocortical afferents to layer IV. Rats reared in EE also showed an enhancement of thalamocortical long-term potentiation (LTP) triggered by theta-burst stimulation (TBS) of the dLGN. To monitor the functional consequences of increased LTP in EE rats, we...