Figure 5.

Improving BMI performance and longevity by leveraging neural dynamics. A, Graphical model of decoder with dynamical smoothing. B, Illustration of smoothing latent state estimates using neural dynamics. The instantaneous estimate of the latent state (blue) is augmented by a dynamical prior (gray flow-field) to produce a smoother, de-noised estimate (orange). C, Smoothing using neural dynamics results in better closed-loop BMI performance than other approaches. Performance is achieved information bitrate. Adapted from Kao et al., 2015. D, Example of low-dimensional signals that can be used to augment intracortical BMIs. PCA applied to neural activity around the time of target selection identifies a putative “error signal”, allowing real-time detection and correction of user errors in a typing BMI. Adapted from Even-Chen et al., 2017. E, Remembering dynamics from earlier recording conditions can extend performance as neurons are lost. Performance measure is (off-line) mean velocity correlation. F, Comparison of closed-loop performance when 110 channels are “lost” shows a >3× improvement achieved by remembering dynamics. FIT-KF, state-of-the-art kinematic Kalman filter (Fan et al., 2014). Adapted from Kao et al., 2017. G, Dynamic neural stitching with LFADS. A single model was trained on 44 recording sessions. Each session used a 24-channel recording probe. Left, Recording locations in MC. Right, Single-trial reaches from an example session. Arc. Sp., arcuate spur; PCd, precentral dimple; CS, central sulcus. H, Neural state space trajectories inferred by LFADS. Each trace of a given color is from a separate recording session (44 traces per condition). Inferred trajectories are consistent across 5 months. jPC₁ and jPC₂ are the first two components identified by jPCA (Churchland et al., 2012). I, Using LFADS to align 5 months of data (“Stitched”) significantly improves decoding versus other tested methods. Adapted from Pandarinath et al., 2018. ***Significant improvement in median R²; P < 10⁻⁸, Wilcoxon signed-rank test.