BioKERN: Biological Kernel Regularization for Histology-to-Transcriptomics Neighborhood Retrieval
Organizations: Department of Physics and Astronomy Rice University Houston, TX 77005 · Department of Mathematics Rice University Houston, TX 77005
Abstract
Spatially resolved biology requires representations that preserve biological neighborhood structure rather than only exact cross-modal correspondences. Existing histology--transcriptomics objectives can emphasize instance-level matching even when non-paired spots share molecular or spatial context. We introduce BioKERN, a multimodal spatial representation-learning framework that incorporates biological structure as an explicit, learnable inductive bias. BioKERN constructs a training-time biological kernel by combining transcriptomic similarity and spatial proximity, then uses it to provide graded neighborhood supervision and regularize embedding geometry. Evaluation uses a fixed, model-independent biological neighborhood definition shared by all methods. Across Mouse Brain Visium and Human Liver GSE240429, BioKERN consistently improves biological-neighborhood retrieval over BLEEP in both single- and multi-scale settings. Controlled shared-architecture experiments show that most of the improvement arises from biological-kernel regularization rather than increased model capacity. These results support explicit biological geometry as an interpretable inductive bias for multimodal learning in spatial biology.
Figures & tables
| Dataset / Scale | Ridge | PLIP linear | BLEEP | BLEEP ∗ | BioKERN |
|---|---|---|---|---|---|
| Mouse Brain SS | 0.4902 | 0.5407 .0033 | 0.5087 .0033 | 0.5327 .0036 | 0.6190 .0023 |
| Mouse Brain MS | 0.5567 | 0.5831 .0023 | 0.4960 .0056 | 0.5541 .0040 | 0.6716 .0021 |
| Human Liver SS | 0.0383 | 0.0307 .0001 | 0.0302 .0005 | 0.0309 .0004 | 0.0396 .0007 |
| Human Liver MS | 0.0403 | 0.0319 .0005 | 0.0312 .0005 | 0.0321 .0005 | 0.0408 .0005 |
Appendix figures & tables12 assets
Supplementary material from the paper’s appendix.
Appendix
| Method | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| CCA | 0.3910 0.0000 | 0.3677 0.0000 | 0.3558 0.0000 | 0.3100 0.0000 | 0.6409 0.0000 | 0.3709 0.0000 | 18.00 0.00 | 0.7782 0.0000 |
| Ridge | 0.4902 0.0000 | 0.3919 0.0000 | 0.4094 0.0000 | 0.2941 0.0000 | 0.6105 0.0000 | 0.2509 0.0000 | 27.00 0.00 | 0.7670 0.0000 |
| PLIP zero-shot | 0.1653 0.0000 | 0.0647 0.0000 | 0.0794 0.0000 | 0.0599 0.0000 | 0.1469 0.0000 | 0.0327 0.0000 | 202.50 0.00 | 0.6716 0.0000 |
| PLIP linear | 0.5407 0.0033 | 0.4685 0.0025 | 0.4288 0.0028 | 0.4068 0.0016 | 0.7175 0.0042 | 0.4956 0.0162 | 10.80 0.75 | 0.7852 0.0003 |
| BLEEP | 0.5087 0.0033 | 0.4510 0.0024 | 0.4034 0.0043 | 0.3979 0.0033 | 0.6928 0.0045 | 0.4938 0.0096 | 10.80 0.75 | 0.7842 0.0003 |
| BLEEP ∗ | 0.5327 0.0036 | 0.4674 0.0036 | 0.4250 0.0028 | 0.4091 0.0048 | 0.7136 0.0046 | 0.4887 0.0086 | 10.90 0.20 | 0.7851 0.0004 |
| Method | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| CCA | 0.2813 0.0000 | 0.2661 0.0000 | 0.2585 0.0000 | 0.2316 0.0000 | 0.5162 0.0000 | 0.2673 0.0000 | 34.00 0.00 | 0.7662 0.0000 |
| Ridge | 0.5567 0.0000 | 0.4596 0.0000 | 0.4692 0.0000 | 0.3484 0.0000 | 0.6931 0.0000 | 0.3327 0.0000 | 19.00 0.00 | 0.7753 0.0000 |
| PLIP zero-shot | 0.0956 0.0000 | 0.0178 0.0000 | 0.0255 0.0000 | 0.0197 0.0000 | 0.0660 0.0000 | 0.0036 0.0000 | 326.00 0.00 | 0.6399 0.0000 |
| PLIP linear | 0.5831 0.0023 | 0.5109 0.0039 | 0.4494 0.0037 | 0.4588 0.0016 | 0.7471 0.0051 | 0.5418 0.0072 | 9.00 0.00 | 0.7858 0.0003 |
| BLEEP | 0.4960 0.0056 | 0.4647 0.0037 | 0.4074 0.0033 | 0.4263 0.0048 | 0.7183 0.0043 | 0.5298 0.0154 | 9.40 0.49 | 0.7864 0.0004 |
| BLEEP ∗ | 0.5541 0.0040 | 0.4981 0.0032 | 0.4465 0.0035 | 0.4458 0.0023 | 0.7506 0.0030 | 0.5549 0.0071 | 8.60 0.49 | 0.7876 0.0002 |
| Method | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| CCA | 0.0265 0.0000 | 0.0513 0.0000 | 0.0518 0.0000 | 0.0511 0.0000 | 0.1974 0.0000 | 0.0053 0.0000 | 1129.0 0.0 | 0.8574 0.0000 |
| Ridge | 0.0383 0.0000 | 0.0696 0.0000 | 0.0742 0.0000 | 0.0552 0.0000 | 0.1916 0.0000 | 0.0048 0.0000 | 1152.0 0.0 | 0.8366 0.0000 |
| PLIP zero-shot | 0.0312 0.0000 | 0.0553 0.0000 | 0.0754 0.0000 | 0.0498 0.0000 | 0.3088 0.0000 | 0.0057 0.0000 | 951.0 0.0 | 0.8322 0.0000 |
| PLIP linear | 0.0307 0.0001 | 0.0612 0.0003 | 0.0585 0.0012 | 0.0597 0.0006 | 0.1869 0.0007 | 0.0048 0.0010 | 1140.4 5.95 | 0.8527 0.0003 |
| BLEEP | 0.0302 0.0005 | 0.0578 0.0012 | 0.0494 0.0012 | 0.0651 0.0014 | 0.2125 0.0017 | 0.0074 0.0012 | 1043.0 23.1 | 0.8551 0.0004 |
| BLEEP ∗ | 0.0309 0.0004 | 0.0580 0.0011 | 0.0498 0.0012 | 0.0688 0.0009 | 0.2116 0.0043 | 0.0076 0.0014 | 1020.2 4.31 | 0.8525 0.0002 |
| Method | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| CCA | 0.0271 0.0000 | 0.0546 0.0000 | 0.0532 0.0000 | 0.0534 0.0000 | 0.2035 0.0000 | 0.0062 0.0000 | 1084.0 0.0 | 0.8578 0.0000 |
| Ridge | 0.0403 0.0000 | 0.0765 0.0000 | 0.0761 0.0000 | 0.0589 0.0000 | 0.1945 0.0000 | 0.0075 0.0000 | 1097.0 0.0 | 0.8381 0.0000 |
| PLIP zero-shot | 0.0293 0.0000 | 0.0527 0.0000 | 0.0638 0.0000 | 0.0522 0.0000 | 0.2553 0.0000 | 0.0053 0.0000 | 1072.0 0.0 | 0.8317 0.0000 |
| PLIP linear | 0.0319 0.0005 | 0.0645 0.0015 | 0.0571 0.0015 | 0.0607 0.0010 | 0.1822 0.0022 | 0.0062 0.0014 | 1109.6 13.2 | 0.8528 0.0003 |
| BLEEP | 0.0312 0.0005 | 0.0601 0.0010 | 0.0481 0.0029 | 0.0688 0.0012 | 0.2122 0.0021 | 0.0068 0.0017 | 970.4 10.9 | 0.8556 0.0006 |
| BLEEP ∗ | 0.0321 0.0005 | 0.0604 0.0010 | 0.0486 0.0017 | 0.0718 0.0010 | 0.2116 0.0017 | 0.0098 0.0014 | 960.0 12.8 | 0.8532 0.0004 |
| Scale | Method | Bio-mAP | Step | Interpretation |
|---|---|---|---|---|
| SS | BLEEP | 0.5087 | – | baseline |
| BLEEP ∗ | 0.5327 | +0.0240 | architecture | |
| Ret-only | 0.5364 | +0.0037 | objective | |
| BioKERN | 0.6190 | +0.0826 | biological regularization | |
| Shuffled Kernel | 0.4939 | – | sanity check | |
| MS | BLEEP | 0.4960 | – | baseline |
| Scale | Method | Bio-mAP | Step | Interpretation |
|---|---|---|---|---|
| SS | BLEEP | 0.0302 | – | baseline |
| BLEEP ∗ | 0.0309 | +0.0007 | architecture | |
| Ret-only | 0.0313 | +0.0004 | objective | |
| BioKERN | 0.0396 | +0.0083 | biological regularization | |
| Shuffled Kernel | 0.0301 | – | sanity check | |
| MS | BLEEP | 0.0312 | – | baseline |
| Setting | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| Kernel design | ||||||||
| BioKERN | 0.6190 0.0023 | 0.5155 0.0028 | 0.4482 0.0021 | 0.4348 0.0029 | 0.7241 0.0034 | 0.4938 0.0107 | 10.50 0.45 | 0.7862 0.0002 |
| w/o Bio Kernel | 0.5370 0.0042 | 0.4714 0.0043 | 0.4277 0.0049 | 0.4110 0.0017 | 0.7195 0.0060 | 0.4818 0.0040 | 10.40 0.49 | 0.7855 0.0002 |
| only | 0.5834 0.0009 | 0.4953 0.0024 | 0.4496 0.0018 | 0.4081 0.0018 | 0.7228 0.0043 | 0.4775 0.0112 | 11.40 0.49 | 0.7862 0.0003 |
| only | 0.5880 0.0026 | 0.4969 0.0020 | 0.4254 0.0032 | 0.4344 0.0035 | 0.7191 0.0014 | 0.5018 0.0103 | 11.00 0.00 | 0.7853 0.0003 |
| Fixed | 0.6201 0.0035 | 0.5154 0.0034 | 0.4458 0.0037 | 0.4351 0.0010 | 0.7223 0.0015 | 0.4855 0.0141 | 11.20 0.68 | 0.7860 0.0004 |
| Setting | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| BioKERN | 0.6716 0.0021 | 0.5587 0.0034 | 0.4713 0.0024 | 0.4764 0.0018 | 0.7596 0.0033 | 0.5455 0.0125 | 8.90 0.20 | 0.7881 0.0002 |
| w/o Bio Kernel | 0.5628 0.0052 | 0.5044 0.0038 | 0.4499 0.0027 | 0.4508 0.0032 | 0.7597 0.0032 | 0.5542 0.0031 | 9.20 0.40 | 0.7882 0.0004 |
| only | 0.6157 0.0031 | 0.5278 0.0028 | 0.4688 0.0027 | 0.4401 0.0020 | 0.7616 0.0025 | 0.5255 0.0173 | 9.70 0.75 | 0.7880 0.0002 |
| only | 0.6308 0.0036 | 0.5313 0.0047 | 0.4335 0.0027 | 0.4760 0.0028 | 0.7428 0.0043 | 0.5433 0.0072 | 9.00 0.00 | 0.7864 0.0002 |
| Fixed | 0.6711 0.0032 | 0.5577 0.0031 | 0.4668 0.0030 | 0.4812 0.0020 | 0.7580 0.0047 | 0.5425 0.0096 | 9.00 0.55 | 0.7876 0.0004 |
| Shuffled Kernel | 0.5042 0.0056 | 0.4683 0.0045 | 0.4172 0.0034 | 0.4259 0.0053 | 0.7317 0.0027 | 0.5222 0.0161 | 9.80 0.40 | 0.7866 0.0004 |
| Setting | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| BioKERN | 0.0396 0.0007 | 0.0802 0.0017 | 0.0835 0.0023 | 0.0694 0.0005 | 0.2175 0.0021 | 0.0077 0.0016 | 964.2 5.34 | 0.8576 0.0002 |
| w/o Bio Kernel | 0.0314 0.0003 | 0.0584 0.0008 | 0.0502 0.0016 | 0.0686 0.0009 | 0.2099 0.0050 | 0.0079 0.0018 | 1012.0 9.94 | 0.8527 0.0005 |
| only | 0.0445 0.0003 | 0.0895 0.0014 | 0.1197 0.0010 | 0.0617 0.0002 | 0.2171 0.0061 | 0.0063 0.0007 | 1028.2 5.46 | 0.8573 0.0002 |
| only | 0.0298 0.0005 | 0.0548 0.0014 | 0.0404 0.0017 | 0.0722 0.0006 | 0.2055 0.0034 | 0.0094 0.0010 | 968.2 11.7 | 0.8531 0.0004 |
| Fixed | 0.0376 0.0007 | 0.0752 0.0016 | 0.0727 0.0036 | 0.0707 0.0009 | 0.2175 0.0029 | 0.0067 0.0007 | 969.2 9.43 | 0.8567 0.0003 |
| Shuffled Kernel | 0.0294 0.0004 | 0.0559 0.0013 | 0.0473 0.0019 | 0.0663 0.0004 | 0.2081 0.0048 | 0.0070 0.0017 | 1019.6 12.0 | 0.8543 0.0005 |
| Setting | Bio-mAP | BioR@5% | GeneR@5% | SpatR@5% | ClsHit@10 | ExR@10 | MedRank | PCC@10 |
|---|---|---|---|---|---|---|---|---|
| BioKERN | 0.0408 0.0005 | 0.0820 0.0014 | 0.0802 0.0016 | 0.0725 0.0012 | 0.2173 0.0041 | 0.0097 0.0015 | 923.8 16.3 | 0.8581 0.0002 |
| w/o Bio Kernel | 0.0320 0.0004 | 0.0597 0.0009 | 0.0485 0.0013 | 0.0708 0.0008 | 0.2086 0.0017 | 0.0080 0.0004 | 979.6 21.0 | 0.8532 0.0004 |
| only | 0.0403 0.0002 | 0.0824 0.0007 | 0.0793 0.0016 | 0.0634 0.0008 | 0.2124 0.0051 | 0.0074 0.0006 | 1004.2 14.6 | 0.8583 0.0002 |
| only | 0.0318 0.0006 | 0.0603 0.0018 | 0.0446 0.0019 | 0.0726 0.0006 | 0.2116 0.0012 | 0.0080 0.0003 | 917.8 15.0 | 0.8538 0.0005 |
| Fixed | 0.0382 0.0005 | 0.0763 0.0016 | 0.0689 0.0025 | 0.0740 0.0012 | 0.2128 0.0035 | 0.0083 0.0009 | 918.6 14.2 | 0.8570 0.0003 |
| Shuffled Kernel | 0.0291 0.0005 | 0.0558 0.0013 | 0.0441 0.0024 | 0.0676 0.0007 | 0.2066 0.0036 | 0.0091 0.0011 | 984.6 8.19 | 0.8549 0.0004 |
| Bio-mAP | BioR@5% | BioR@10% | ExR@10 | |
|---|---|---|---|---|
| 0.0 | 0.5556 | 0.4776 | 0.5209 | 0.5018 |
| 0.1 | 0.5863 | 0.4962 | 0.5509 | 0.4855 |
| 0.2 | 0.6048 | 0.5086 | 0.5709 | 0.4891 |
| 0.3 | 0.6216 | 0.5165 | 0.5855 | 0.4909 |
| 0.5 | 0.6412 | 0.5288 | 0.6018 | 0.4745 |
| 1.0 | 0.6671 | 0.5415 | 0.6127 | 0.4382 |
| Epoch | (mean std) | Dominant signal |
|---|---|---|
| 5 | 0.6022 0.0003 | gene |
| 10 | 0.6048 0.0005 | gene |
| 20 | 0.6093 0.0008 | gene |
| 30 | 0.6124 0.0009 | gene |
| 40 | 0.6142 0.0009 | gene |
| 50 | 0.6149 0.0009 | gene |
Cross-Modal Representation Learning
Cross-modal representation learning connects information across data types such as images, text, audio, biosignals, and sensor measurements.
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