BASC : Behavior-Aligned Quantization and Pruning for Low-Bit Spiking Neural Networks
Authors: Linliang Chen, Yan Zhong, Xin Liu, Sai Li, Wang Kang
Organizations: Hangzhou International Innovation Institute, Beihang University, Hangzhou 311115, China · School of Mathematical Sciences, Peking University, Beijing 100871, China · School of Electronic and Information Engineering; Beihang University, Beijing 100191, China · School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
Spiking Neural Networks (SNNs) encode information through binary spikes and compute in an event-driven manner, offering an energy-efficient paradigm for machine intelligence. However, high-performance SNNs incur substantial memory and timestep-wise computation costs that hinder deployment on resource-constrained devices. Quantization and pruning provide complementary routes to reducing these costs, yet both make their decisions with local criteria that overlook temporal task feedback in quantization and inter-channel dependencies in pruning. Consequently, optimizing either criterion can still yield suboptimal compression performance. We refer to this discrepancy as criterion-behavior mismatch and propose Behavior-Aligned SNN Compression (BASC), a unified framework with two lightweight modules. For quantization, the scale is applied to synaptic current at every timestep and therefore shifts spike timing. Temporal-Behavior Scale Correction (TSC) makes the scale learnable under a temporal loss, allowing firing behavior to inform scale optimization. For pruning, channel importance depends on how channels jointly drive the membrane potential across the firing threshold. Boundary-Level Inter-Channel Correction (BIC) uses channelwise importance scores for initial selection and inter-channel information to re-evaluate only channels near the pruning threshold. Extensive experiments on static and neuromorphic benchmarks show that lower-bit BASC models match or outperform higher-bit baselines and retain this accuracy advantage after structured pruning, while further reducing model storage and synaptic operations.
Figures & tables
Figure 1: Overall pipeline of the proposed joint compression framework.
Figure 2: Temporal-behavior scale correction. (a) A scale fixed from the weight distribution settles at a suboptimal point of the task loss, whereas a learnable scale is driven toward the task optimum. (b–c) Top-1 accuracy on CIFAR-10 and CIFAR-100 under three bit-width pairings.
Figure 3: Multiplier sweep around the learned scale ( m=1.00 ). (a) The reconstruction error is minimized at m=0.90 while accuracy peaks at m=1.00 : the two optima do not coincide. (b) The accuracy peak sits at a markedly lower clipping ratio than the error optimum does, showing that the task trades a coarser grid for less clipping.
Figure 4: Boundary-level inter-channel correction. (a) SVS-only scoring can miss redundancy and yield different keep–prune decisions from ICM-aware evaluation. (b) BIC re-evaluates only boundary channels while preserving confident keep and drop decisions. (c) SVS and ICM agree on most channels, while their disagreements concentrate near the decision boundary.
Scoring scheme
ICM evals
Rel. evals
Wall time (s)
SVS only
0
0
0.88
Full-channel CHIP-CI
3,712
1.00
2,995
Boundary-only (ours)
572
0.154
480.35
Table 1: Scoring cost on CIFAR-10/VGG-16 at 4-bit ( T=4 ), measured on one RTX 5090 with 6 calibration batches of 256 samples from the same checkpoint. Restricting ICM to the boundary is 6.24× faster than scoring every channel.
Dataset
Method
Arch.
Bit
T
Acc. (%)
Size (MB)
CIFAR-10
Deng et al. [TNNLS 2023]
7Conv2FC
32/3
8
90.19/87.59
62.16/5.84
Wei et al. [ICLR 2025]
ResNet20
8/4/2
2
95.92/95.74/95.69
17.10/8.59/4.33
BASC (Ours)
4/3/2
96.54/96.40/96.30
8.59/6.46/4.33
Wei et al. [ICLR 2025]
VGG-16
8/4/2
4
93.33/93.28/93.01
14.77/7.42/3.74
BASC (Ours)
4/3/2
93.76/93.77/93.41
7.42/5.58/3.74
CIFAR-100
Deng et al. [TNNLS 2023]
7Conv2FC
3/1
8
57.83/55.95
11.75/5.99
Table 2: Quantization-only top-1 accuracy and model size. Baseline rows are trained under our protocol at each bit width; other prior methods are quoted as published. Bold rows denote BASC.
Configuration
Acc. (%)
Compared to
Δ Acc. (pp)
A. Fixed scale + SVS
74.68
–
–
B. TSC + SVS
75.94
A.
+1.26
C. Fixed scale + BIC
74.93
A.
+0.25
D. TSC + BIC
76.04
A.
+1.36
Table 3: Component and efficiency results. (a) Ablation of the two corrections on CIFAR-100/ResNet20 under the matched 4-bit, T=2 setting. (b) Accuracy–energy comparison against the baseline under matched aggressive 4-bit compression.
Dataset
Method
Arch.
Bit
T
Acc. (%)
Size (MB)
CIFAR-10
Li et al. [ICML 2024]
VGG-16
32
4
91.67/90.26
17.32/5.68
Wei et al. [ICLR 2025]
ResNet20
8/4/2
2
95.21/95.18/95.07
6.27/3.16/1.61
93.92/93.77/93.53
3.92/1.98/1.02
BASC (Ours)
4/3/2
95.61/95.53/95.40
3.16/2.38/1.61
94.82/94.50/94.27
1.98/1.50/1.02
Wei et al. [ICLR 2025]
VGG-16
8/4/2
4
91.61/91.61/91.22
4.28/2.16/1.10
Table 4: Top-1 accuracy and model size after quantization and structured pruning. Grouped rows list the evaluated pruning configurations for each backbone; bold rows denote BASC.
Appendix figures & tables18 assets
Supplementary material from the paper’s appendix.
Appendix
Dataset
Backbone
Downsample
Bit
T
Acc. (%)
Size (MB)
ImageNet
SEW ResNet
ReScaWConv+BN+SN
4
4
62.81
7.71
Conv+BN+SN
4
4
63.40
8.31
Conv+BN
4
4
63.26
8.31
Spiking ResNet
Conv+BN+SN
4
4
61.66
8.31
Conv+BN
4
4
62.02
8.31
Padding
4
4
61.89
7.61
Appendix
Table 5: Architecture comparison on ImageNet. Size uses decimal MB under architecture-specific mixed-precision storage.
Code
Dataset
Backbone
Level
Params
V425
CIFAR-10
VGG-16
standard
4.25M
V142
CIFAR-10
VGG-16
aggressive
1.42M
V231
CIFAR-100
VGG-16
standard
2.31M
V168
CIFAR-100
VGG-16
aggressive
1.68M
V465
TinyImageNet
VGG-16
standard
4.65M
V343
TinyImageNet
VGG-16
aggressive
3.43M
Appendix
Table 6: Compression-level codes used throughout this document. Each code names the target parameter count of the QP-SNN configuration whose channel pruning ratios BASC reuses.
Backbone
Stage (channels)
Standard
Aggressive
VGG-16 (C10)
layers 1–9 (64–256)
0.45
0.49
layers 11–16 (512)
0.51
0.80
VGG-16 (C100)
layers 1–9 (64–256)
0.45
0.45
layers 11–16 (512)
0.70
0.78
VGG-16 (Tiny)
layers 1–9 (64–256)
0.45
0.45
layers 11–16 (512)
0.51
0.62
Appendix
Table 7: Per-stage channel pruning ratios, reproduced from QP-SNN ( Wei et al. 2025 ) . The last convolutional layer of each backbone is left unpruned to preserve the classification head. For VGGSNN, the extreme level (D025) uses 0.82 and 0.93 for the two stages. Within ResNet20’s layer1, the two ratios apply to the first and second convolution of each block.
Bit
Samples
Channels
Agreement (%)
Retained overlap (%)
Jaccard (%)
Spearman ρ
2
1,536
3,712
95.26
95.32
91.06
0.9864
3
1,536
3,712
94.29
94.36
89.33
0.9902
4
1,536
3,712
95.80
95.85
92.03
0.9964
Appendix
Table 8: Global SVS–ICM agreement on CIFAR-10/VGG-16 (V425), aggregated over all 12 pruned layers. The same six fixed calibration batches are used for both scores.
Table 10: Replacement-budget check on CIFAR-10/VGG-16/B4 (V425).
Score
Pairwise Spearman
Top- k overlap (%)
SVS
0.9929
97.74
ICM
0.9932
97.68
Appendix
Table 11: Calibration-batch repeatability on CIFAR-10/VGG-16/B4.
Seed
TSC+SVS
TSC+BIC
Gain
0
75.94
76.04
+0.10
1
75.99
76.16
+0.17
2
76.00
76.24
+0.24
3
76.34
76.49
+0.15
Mean ± std
76.068 ± 0.184
76.233 ± 0.190
+0.165 ± 0.058
Appendix
Table 12: Paired multi-seed best accuracy, TSC+SVS vs. TSC+BIC. Sign consistency 4/4 positive.
Setting
merror
Acc. at merror
mval
Best Acc.
Acc. at m=1
CIFAR-10 / ResNet20 / B2
0.800
90.45
1.025
96.22
96.19
CIFAR-10 / ResNet20 / B3
0.900
95.90
0.975
96.25
96.12
CIFAR-10 / ResNet20 / B4
0.900
96.26
1.000
96.47
96.47
CIFAR-10 / VGG-16 / B2
0.800
58.11
1.000
93.41
93.41
CIFAR-10 / VGG-16 / B3
0.800
86.76
1.000
93.79
93.79
CIFAR-10 / VGG-16 / B4
0.900
93.27
1.000
93.75
93.75
Appendix
Table 13: Global learned-scale multiplier sweep across 19 checkpoints. Weights and learned scales are frozen; no retraining.
Setting
Enative
PrefixCE
Prefix margin
Acc. (%)
Δ Acc. [95% CI]
C100/VGG-16/T4
0.3183 → 0.4133
2.203 → 1.089
0.025 → 2.373
48.78 → 72.53
+23.75 [22.73, 24.76]
C100/ResNet20/T2
0.3001 → 0.3869
2.477 → 0.916
− 0.449 → 5.277
45.06 → 79.51
+34.45 [33.42, 35.48]
DVS-C10/VGGSNN/T10
0.3090 → 0.3729
1.009 → 0.678
2.518 → 3.950
74.90 → 83.90
+9.00 [6.90, 11.10]
Appendix
Table 14: Fixed-weight scale-path endpoints for three B2 checkpoints. Each arrow runs from the per-group reconstruction optimum αE to the learned TSC scale αTSC . Accuracy intervals use 20,000 paired sample-level bootstrap draws. C100 and DVS-C10 denote CIFAR-100 and DVS-CIFAR10.
Setting
tunder/T
Nmiss/Nspur (M)
Lunder/L
ATET
C100/VGG-16/T4
4/4
446.2 / 382.6
9/12 (75.0%)
0.8315
C100/ResNet20/T2
2/2
1748.0 / 1257.9
16/18 (88.9%)
0.6617
DVS-C10/VGGSNN/T10
10/10
172.4 / 126.3
6/7 (85.7%)
0.7843
Appendix
Table 15: Activity and gradient evidence along the fixed-weight correction from αE to αTSC . Here tunder counts under-firing timesteps, Nmiss/Nspur gives missed/spurious crossings in millions, and Lunder counts affected layers with lower activity at αE . Crossing counts compare the same samples and neuron-time elements at the two endpoints. PrefixCE improves and At is positive at every timestep for all three settings.
Bit
Base LR
Scale LR
Best Acc. (%)
4
2×10−3
2.5×10−4
61.96
4
1×10−3
5.0×10−4
62.39
2
2×10−3
2.5×10−4
59.88
2
1×10−3
5.0×10−4
60.78
Appendix
Table 16: ImageNet/ResNet18 optimization-recipe check. Both learning rates vary together.
Seed
Layers
Mean shift
Min–max shift
merror<1
0
12
12.08%
5.00–40.00%
Yes
1
12
8.75%
5.00–15.00%
Yes
2
12
8.33%
5.00–20.00%
Yes
Appendix
Table 17: Layer-wise scale mismatch on CIFAR-100/VGG-16/B4. The shift is measured relative to the learned scale m=1 .
Bit
Learnable scale
Fixed scale
Gain
2
72.87
69.26
+3.61
3
72.96
65.11
+7.85
4
73.23
59.93
+13.30
Appendix
Table 18: Learnable versus fixed quantization scale on CIFAR-100/VGG-16. Top-1 accuracy (%); runs are matched within each bit width.
Bit
Setting
QP Top-1
BASC Top-1
Δ Acc
QP SOP (M)
BASC SOP (M)
Δ Energy
2
D146
79.1
79.1
0.0
279.801
269.886
− 3.43%
2
D090
80.0
78.8
− 1.2
230.228
218.547
− 4.58%
2
D025
73.5
73.6
+0.1
44.678
42.814
− 2.73%
3
D146
79.0
79.7
+0.7
280.579
270.407
− 3.50%
3
D090
79.5
77.0
− 2.5
229.530
222.302
− 3.11%
3
D025
73.4
76.9
+3.5
44.489
46.024
+2.26%
Appendix
Table 19: DVS-CIFAR10/VGGSNN same-bit accuracy–energy matrix. Accuracy values are full-test measurements of the checkpoints instrumented for operation counting, and therefore differ from the best-epoch accuracies reported in the main pruning table; this matrix is used only for checkpoint-level accuracy–energy comparison.
Table 20: Additional efficiency comparisons.
Schedule
Best (%)
Final (%)
One-shot (ours)
73.65
73.24
Progressive A: fixed final plan
72.95
72.33
Progressive B: stage-wise re-scoring
72.78
72.06
Appendix
Table 21: Pruning schedules on CIFAR-100/ResNet20 under matched final compression.
Prune / regrow
Epochs
Best (%)
SCA / instant BN- γ
233
89.40
SCA / EMA BN- γ
233
90.69
SVS / EMA BN- γ
233
90.60
Appendix
Table 22: Exploratory dynamic-regrowth signal comparison on CIFAR-10/VGG-16 under a matched channel budget.
Spiking neural networks process information through discrete, time-dependent neural events, aiming for efficient computation and biologically inspired learning.
Spiking Neural Networks (SNNs) provide energy-efficient computation but their deployment is constrained by dense connectivity and high spiking operation costs. Existing magnitude-based pruning strategies, when naively applied to SNNs, fail to account for temporal accumulation, non-uniform timestep contributions, and membrane stability, often leading to severe performance degradation. This paper proposes Spiking Layer-Adaptive Magnitude-based Pruning (SLAMP), a theory-guided pruning framework that generalizes layer-adaptive magnitude pruning to temporal SNNs by explicitly controlling worst-case output distortion across layers and timesteps. SLAMP formulates sparsity allocation as a temporal distortion-constrained optimization problem, yielding time-aware layer importance scores that reduce to conventional layer-adaptive pruning in single-timestep limit. An efficient two-stage procedure is derived, combining temporal score estimation, global sparsity allocation, and magnitude pruning with retraining for stability recovery. Experiments on CIFAR10, CIFAR100, and the event-based CIFAR10-DVS datasets demonstrate that SLAMP achieves substantial connectivity and spiking operation reductions while preserving accuracy, enabling efficient and deployable SNN inference.
Junqiao Wang, Zhehang Ye, Yuqi Ouyang
Sichuan University-Pittsburgh Institute, Sichuan University, Chengdu, 610207, China · College of Computer Science, Sichuan University, Chengdu, 610065, China
Binary spike coding enables sparse and event-driven computation in spiking neural networks (SNNs), yet its 1-bit-per-timestep representation fundamentally limits information throughput. This bottleneck becomes increasingly restrictive in deep architectures under short simulation horizons. We propose the Quantized Burst-LIF (QB-LIF) neuron, which reformulates burst spiking as a saturated uniform quantization of membrane potentials with a learnable scale. Instead of relying on predefined multi-threshold structures, QB-LIF treats the quantization scale as a trainable parameter, allowing each layer to autonomously adapt its spiking resolution to the underlying membrane-potential statistics. To preserve hardware efficiency, we introduce an absorbable scale strategy that folds the learned quantized scale into synaptic weights during inference, maintaining a strict accumulate-only (AC) execution paradigm. To enable stable optimization in the discrete multi-level space, we further design ReLSG-ET, a rectified-linear surrogate gradient with exponential tails that sustains gradient flow across burst intervals. Extensive experiments on static (CIFAR-10/100, ImageNet) and event-driven (CIFAR10-DVS, DVS128-Gesture) benchmarks demonstrate that QB-LIF consistently outperforms binary and fixed-burst SNNs, achieving higher accuracy under ultra-low latency while preserving neuromorphic compatibility.
On neuromorphic chips, spiking neural networks (SNNs) consume far less energy than artificial neural networks (ANNs), but the limited memory of these chips requires low-bit synaptic weights and membrane potentials. Existing post-training quantization (PTQ) methods provide them without retraining and, like those for ANNs, minimize numerical errors such as the mean squared error (MSE). In an SNN, however, a quantization error reaches later layers only through the spikes it flips. We find that errors of equal MSE can cause very different accuracy losses, whereas errors that flip the same fraction of spikes cause the same loss. We therefore propose SpikeQ, a spike-guided PTQ framework. For weights, we select the level of each weight by simulating the downstream neurons and minimizing their spike errors. For membrane potentials, most existing methods quantize the state after the reset, whereas neuromorphic chips compare the threshold with the membrane potential stored at a fixed bit width. We target this pre-fire quantization and build a reset-aware grid that places the threshold on a rounding boundary, so rounding never flips the spike at the current time step. We evaluate SpikeQ on seven benchmarks of image classification, semantic segmentation, and object detection. With 2-bit pre-fire membrane potentials, every existing grid collapses, whereas SpikeQ retains most of the full-precision accuracy. With both at 4 bits, the models stay within 2.59 points of full precision, shrink their memory footprint 7.8--7.9 times, and use 6.4--6.9 times less energy.
Kai Sun, Peibo Duan, Zhanglu Yan +3
Monash University · National University of Singapore · Northeastern University