Positioning and scope ===================== ``brainspike`` is a **differentiable point-neuron modeling substrate**: the same neurons, synapses, plasticity rules, and projections run NEST-validated biological simulation *and* train with gradients or online learning. What sets it apart ------------------ - **Validated like a simulator.** The NEST-compatible family keeps NEST's parameter names and units and is checked against a live NEST install within documented tolerance bands. - **Differentiable like a training library.** Models compile through JAX/XLA and are trainable with surrogate gradients or online learning rules (``braintrace``). - **One graph, written contracts.** Every network is one ``Network`` graph (populations, projections, devices, observers) built from models that *declare* their ports, states, parameters and spike rules. The same compiled graph is what a simulation runs and what a learner differentiates, so NEST parity validates what users train. Who it is for ------------- 1. Computational neuroscientists who want to run NEST models on accelerators, or train them. 2. Brain-inspired-computing researchers who need biologically constrained spiking networks. 3. Libraries in the `BrainX ecosystem `_ that build on it, such as ``braintrace`` for online learning. Model scope ----------- - **Point neurons only.** Multi-compartment and population/mean-field models are out of scope. - **No single-unit rate neurons.** Rate models (``lin_rate``, ``sigmoid_rate``, …) are not carried into the new kernel. Status: kernel redesign in progress ----------------------------------- The package is being moved onto a new kernel, described in the architecture specification (``docs/specs/2026-10-21-architecture-review-and-redesign.md``). The first milestone (K0) has passed its go/no-go gates; hardening (K1a) is next. While this is in progress: - **The current 0.1 API is frozen.** It keeps working, but receives no new features or fixes; it will be removed when the new kernel replaces it. - **The new kernel is private** (not yet exported from ``brainspike``). It becomes public in a later milestone, together with a migration guide. - **One front-end.** ``Network`` will be the only way to build and run a model. The NEST-style ``Simulator`` (``create`` / ``connect`` / ``simulate``) is kept as a thin layer that builds a ``Network``. - **Performance.** CPU performance of the new kernel has been measured against the current simulator on one benchmark (Brunel network); GPU performance has not been measured yet, and no GPU numbers are claimed. Out of scope ------------ - Detailed multi-compartment morphology. - MPI cluster-scale distributed simulation (single-host multi-device execution is in scope). - MUSIC / SONATA co-simulation (importing SONATA network descriptions is in scope). - e-prop and other online-learning algorithms, which are implemented in ``braintrace``.