PROTEIN AND RNA SYNTHESIS-DEPENDENT AND SYNTHESIS-INDEPENDENT LTPS INDEVELOPING RAT VISUAL-CORTEX

MULTIPLE forms of synaptic potentiation have been described, but their involvement in development versus learning is unknown. To address thi s, we examined whether long-term potentiation (LTP) in visual cortex r equires protein or RNA synthesis using slice preparations. Theta-burst stimulation of white matter induced two distinct types of LTP in laye r 4. A slowly developing LTP, preferentially induced in juveniles, was blocked by protein and RNA synthesis inhibitors and was L-type calciu m channel dependent. A quickly developing LTP, induced in juveniles an d adults, was independent of macromolecular synthesis and required N-m ethyl-D-aspartate receptor activation. Thus, slow LTP might account fo r developmental plasticity in visual cortex including the activity-dep endent refinement of neural circuitry while fast LTP might underlie th e changes in synaptic strength that may participate in visual learning and memory.