Spike-timing-dependent plasticity

Spike-timing-dependent plasticity (STDP) is a biological process that adjusts the strength of synaptic connections between neurons based on the relative timing of their action potentials (or spikes). It is a temporally sensitive form of synaptic plasticity, meaning that the efficiency of synaptic transmission is modified by the timing of neural activity. When a presynaptic neuron consistently fires just before a postsynaptic neuron, the connection is typically strengthened—a process known as long-term potentiation (LTP). If the timing is reversed and the presynaptic neuron fires after the postsynaptic neuron, the connection is weakened through long-term depression (LTD).

STDP is considered a key mechanism in learning and memory formation and helps explain activity-dependent development of neural circuits. It has been observed in multiple brain regions, including the hippocampus, neocortex, and visual system, and has been widely implemented in computational models of biologically inspired learning algorithms and network dynamics.

STDP develops early in life, helping to refine sensory maps and establish functional connectivity during critical periods. The process depends on molecular mechanisms such as NMDA receptor-mediated calcium signaling and is influenced by synapse location and neuromodulators like dopamine and acetylcholine.

Variants of STDP have been found at inhibitory synapses and in response to complex spike patterns. The process also interacts with other forms of plasticity, including rate-based learning, homeostatic regulation, and structural remodeling. Disruptions in STDP have been linked to neurological and psychiatric conditions such as Alzheimer’s disease, Fragile X syndrome, epilepsy, and Parkinson’s disease.