Recent breakthroughs suggest that local, approximate gradient descent
learning is compatible with Spiking Neural Networks (SNNs). Although SNNs can
be scalably implemented using neuromorphic VLSI, an architecture that can learn
in-situ as accurately as conventional processors is still missing. Here, we
propose a subthreshold circuit architecture designed through insights obtained
from machine learning and computational neuroscience that could achieve such
accuracy. Using a surrogate gradient learning framework, we derive local,
error-triggered learning dynamics compatible with crossbar arrays and the
temporal dynamics of SNNs. The derivation reveals that circuits used for
inference and training dynamics can be shared, which simplifies the circuit and
suppresses the effects of fabrication mismatch. We present SPICE simulations on
XFAB 180nm process, as well as large-scale simulations of the spiking neural
networks on event-based benchmarks, including a gesture recognition task. Our
results show that the number of updates can be reduced hundred-fold compared to
the standard rule while achieving performances that are on par with the
state-of-the-art