arXiv Machine Learning

The Platonic brain bridge hypothesis: human brain networks as an architectural prior for multimodal large language models

arXiv Machine Learning
Sep 11

The Platonic brain bridge hypothesis: human brain networks as an architectural prior for omni models

The paper introduces the Platonic brain bridge hypothesis, asserting that omni models—capable of jointly processing video, audio, and text—naturally develop brain‑like representations, and that this relationship is bidirectional. Experiments show that seven omni models exhibit stable brain‑like representations across participants, and their internal states outperform others on the Algonauts 2025 out‑of‑distribution leaderboard. Building on this, the authors propose three brain‑to‑model methods: Brain‑MoE assigns a brain‑pretrained expert to each of seven cortical networks, improving benchmark accuracy; Brain‑AVQA generates video‑based questions using the most responsive brain network, outperforming shuffled mappings; and Brain‑Scope uses sparse autoencoders to pinpoint a small subset of networks whose removal weakens brain prediction, demonstrating that human brain networks can serve as a practical architectural prior for omni models.

By Pengfei Zhang, Biao Tian, Xiangang Li, Li Liu
arXiv AI
Jun 24

Mind the Heads: Topological Representation Alignment for Multimodal LLMs

arXiv:2606. 23885v1 Announce Type: cross Abstract: Representation alignment has emerged as an effective approach to improve Multimodal Large Language Models (MLLMs) by regularizing their internal representations toward those of an external vision encoder.

By Davide Caffagni, Alberto Compagnoni, Federico Melis, Sara Sarto, Pier Luigi Dovesi, Mark Granroth-Wilding, Marcella Cornia, Lorenzo Baraldi
arXiv Computation and Language
Sep 11

OmniHallu: Unified Hallucination Detection for Cross-Modal Comprehension and Generation in Multimodal Large Language Models

OmniHallu is a unified framework for detecting hallucinations in multimodal large language models across both comprehension and generation tasks involving image, video, and audio modalities. It introduces OmniHallu-Bench, a 10,000-sample benchmark with claim-level human annotations for six cross-modal tasks (I2T, V2T, A2T, T2I, T2V, T2A). The system uses a multi‑agent architecture that decomposes outputs into atomic claims, verifies them with modality‑specific experts, and aggregates evidence through structured reasoning, while a preference‑optimized verifier reduces expert calls by 66% with minimal performance loss.

By Jianjiang Yang, Peihang Li, Shanqing Xu, Mengchen Qian, Lu Zhang, Meng Luo
arXiv Machine Learning
Jun 30

BrainJanus: A Unified Model for Understanding and Generation across Brain, Vision, and Language

arXiv:2606. 30319v1 Announce Type: cross Abstract: Modeling the bidirectional correspondence between external sensory stimuli and internal neural activity has emerged as a critical frontier in neuroscience.

By Haitao Wu, Qirui Zhang, Zhouheng Yao, Shangquan Sun, Qihao Zheng, Mianxin Liu, Chi Zhang, Wanli Ouyang, Chunfeng Song, Changqing Zhang, Jiamin Wu
arXiv Computation and Language
Sep 11

Cross-lingual brain-language model alignment is robust but challenges hierarchical and computational accounts

The study examined whether brain-language model alignment reflects shared computational mechanisms or merely stable lexical‑semantic correspondences. Using whole‑brain encoding across Mandarin, English, and French, transformer representations predicted activity in a distributed network that overlapped across languages and remained stable across layers. Contextual embeddings and measures of prediction or compression did not outperform static lexical embeddings, suggesting that alignment is robust but not informative about shared computational processes.

By Ni Yang, Rui He, Philipp Homan, Iris Sommer, Davide Staub, Wolfram Hinzen
arXiv AI
Jun 16

OmniMouse: Scaling properties of multi-modal, multi-task Brain Models on 150B Neural Tokens

arXiv:2604. 18827v2 Announce Type: replace-cross Abstract: Scaling data and artificial neural networks has transformed AI, driving breakthroughs in language and vision.

By Konstantin F. Willeke, Polina Turishcheva, Alex Gilbert, Goirik Chakrabarty, Hasan A. Bedel, Paul G. Fahey, Yongrong Qiu, Marissa A. Weis, Michaela Vystr\v{c}ilov\'a, Taliah Muhammad, Lydia Ntanavara, Rachel E. Froebe, Kayla Ponder, Zheng Huan Tan, Emin Orhan, Erick Cobos, Sophia Sanborn, Katrin Franke, Fabian H. Sinz, Alexander S. Ecker, Andreas S. Tolias
arXiv Computation and Language
Sep 30

Cognitive Expert Language Models Better Align with the Corresponding Brain Systems

The study investigates whether language models tailored to specific cognitive domains better align with corresponding brain systems. By prompting and fine‑tuning large language models into six domain experts—sensory, spatial, numerical, reasoning, social, and abstract—the authors find that each expert’s representations more closely match the brain region associated with its domain than other experts. This domain‑specific alignment holds across multiple base models and fMRI datasets, while overall prediction accuracy remains largely unchanged, indicating that regional alignment can be obscured when summarizing across the brain.

By Zhivar Sourati, Mengxuan Helen Wu, Nona Ghazizadeh, Jonas Kaplan, Morteza Dehghani, Samuel A. Nastase
arXiv Machine Learning
Oct 5

Architecture-Dependent Fusion Pathways in MLLMs

The paper investigates how visual and textual information are fused in Multimodal Large Language Models (MLLMs). By analyzing concatenation and native multimodal architectures through alignment decoupling, attention routing, entropy, intrinsic dimensionality, and causal interventions, the authors uncover two distinct fusion pathways: concatenation models use a text‑first, vision‑later strategy, while native models integrate vision and text earlier and reorganize feature spaces. The study also employs visual CKA to test the Platonic Representation Hypothesis, offering a mechanistic view of multimodal fusion and informing architecture‑aware diagnostics.

By Hebao Zhu, Dongxia Wu
arXiv Computation and Language
Oct 21

Uncovering Audio-Text Alignment in Large Audio-Language Models through Cross-Modal Concept Neurons

The paper investigates how large audio‑language models (LALMs) integrate audio and text representations. By identifying cross‑modal neurons that encode both modalities, the authors demonstrate that audio and text representations align within a shared subspace across three LALMs and four acoustic attribute types. Causal interventions on these neurons confirm their necessity for prediction and show they can be manipulated to steer model outputs.

By Tzu-Quan Lin, Chih-Kai Yang, Yi-Cheng Lin, Hao Tang, Hung-yi Lee