Feldman D E, Nicoll R A, Malenka R C, Isaac J T
Department of Psychiatry, University of California, San Francisco 94143, USA.
Neuron. 1998 Aug;21(2):347-57. doi: 10.1016/s0896-6273(00)80544-9.
Sensory experience during an early critical period guides the development of thalamocortical circuits in many cortical areas. This process has been hypothesized to involve long-term potentiation (LTP) and long-term depression (LTD) at thalamocortical synapses. Here, we show that thalamocortical synapses in rat barrel cortex can express LTD, and that LTD is most readily induced during a developmental period that is similar to the critical period for thalamocortical plasticity in vivo. Thalamocortical LTD is homosynaptic and dependent on activation of N-methyl-D-aspartate (NMDA) receptors. The age-related decline of LTD is not due to changes in inhibition nor to changes in NMDA receptor voltage dependence. Minimal stimulation experiments indicate that, unlike thalamocortical LTP, thalamocortical LTD is not associated with a significant change in failure rate. The existence of LTD and its developmental time course suggest that LTD, like LTP, may contribute to the refinement of thalamocortical inputs in vivo.
在早期关键期的感觉体验引导着许多皮质区域丘脑皮质回路的发育。这一过程被推测涉及丘脑皮质突触处的长时程增强（LTP）和长时程抑制（LTD）。在此，我们表明大鼠桶状皮质中的丘脑皮质突触能够表达LTD，并且LTD在一个与体内丘脑皮质可塑性关键期相似的发育阶段最容易被诱导。丘脑皮质LTD是同突触的，并且依赖于N-甲基-D-天冬氨酸（NMDA）受体的激活。LTD随年龄的下降并非由于抑制作用的改变，也不是由于NMDA受体电压依赖性的改变。最小刺激实验表明，与丘脑皮质LTP不同，丘脑皮质LTD与失败率的显著变化无关。LTD的存在及其发育时间进程表明，LTD与LTP一样，可能有助于体内丘脑皮质输入的精细化。
