[PL01]: Spike timing‐dependent plasticity: Hebb's postulate revisited
Mu‐ming Poo · International Journal of Developmental Neuroscience · 2008
Sixty years ago Donald Hebb postulated that perceptual memory of sensory experience may be stored in the neural circuit by strengthening the synapses among a specific group of cells (“cell assembly”), through the action of reverberatory activities created by sensory experience within the cell assembly. In this lecture, I will summarize our work over the past 10 years in addressing the validity of the Hebb's postulate. First, I will describe our discovery of spike timing-dependent plasticity (STDP) in the developing Xenopus retinotectal system, indicating that the timing of pre- and postsynaptic activities plays an important role in the synaptic modification by correlated activities. I will then address the idea of synapse-specificity associated with activity-induced LTP and LTD. I will show that LTP/LTD may undergo extensive spread both in vitro and in vivo from the site of induction to other unstimulated synaptic sites within the neural circuit, in a manner that suggests specific long-range cytoplasmic signaling. Finally, I will present our recent studies of neuronal ensemble activities in the visual system. We found that following the termination of repetitive conditioning visual stimuli, specific cell assembly in the zebrafish optic tectum undergoes regular reverberatory activities at the conditioned time interval (in the absence of sensory stimuli), suggesting circuit reverberatory activities may serve as a mechanism for short-term memory of the time interval of the visual stimuli. Inspired initially by Hebb's postulate, these studies have revealed rather complex rules of activity-dependent synaptic and circuit modifications, the implications of which for perception and memory remain to be elucidated.