arXiv subjects

Zenas C. Chao

Publications and source records attributed to Zenas C. Chao.

5 recordsLinked to original sources

arXiv2026

Neural noise enables accurate internal simulation of rare events

The brain needs an accurate internal model of the world to generate predictions and guide behavior. However, it must estimate the statistical structure of the environment from limited experience. This is particularly difficult for rare events, whose observed frequencies in a limited sample may substantially under- or overestimate their true frequencies. How the brain constructs an accurate internal model despite this sampling problem remains unclear. We address this problem using a Bayesian Confidence Propagation Neural Network (BCPNN) trained on event sequences from a Markov-chain random walk with controlled event frequencies. Treating the underlying Markov structure as the ground truth, we train the network on limited sample of event sequences and then allow it to generate autonomous replay based on the learned structure. We evaluate replay fidelity at the levels of both marginal event frequencies and conditional transition structure. We find that moderate neural noise, modeled as temporally correlated random fluctuations in unit activity during replay, is critical for faithful internal simulation. Without this variability, deterministic replay systematically under- or overrepresents rare events, whereas moderate noise restores both their marginal and conditional occurrence. Moderate noise also broadens the range of parameter values that produce accurate replay, making the model more robust to parameter variation. Together, these results support noise-assisted internal simulation as a potential mechanism for compensating for sampling errors arising from limited experience. Our model also provides a testable framework for investigating how altered neural variability may impair internal-model fidelity in disorders such as Parkinson's disease.

q-bio.NC↗

arXiv2026

Joint encoding of "what" and "when" predictions through error-modulated plasticity in biologically-plausible spiking networks

The brain anticipates future events using internal models that specify not only what will occur, but also when it will occur and with what probability. We refer to this joint specification of identity, timing, and likelihood as a complete prediction object. Existing computational models typically capture identity and timing separately, omit probability as an explicit representational dimension, or rely on biologically implausible global learning rules. Here we show that a single population of spiking neurons can acquire and flexibly maintain a complete prediction object through biologically grounded learning. We implemented a heterogeneous Izhikevich spiking reservoir with multiplexed readouts trained by an error-modulated, attention-gated three-factor Hebbian rule, and tested it on a task that independently manipulates event identity, latency, and probability. The network develops time-locked anticipatory activity whose amplitude scales with outcome probability and rapidly adapts when timing or probability statistics change. Identity and timing components self-organize into near-orthogonal readout subspaces within a shared neural population, demonstrating that multidimensional predictive structure can emerge without anatomical modularization or global error broadcast. Compared with least-squares-based approaches, local gated plasticity enables stable recalibration under nonstationary conditions. These results suggest that cortical mixed-selective populations, coupled with neuromodulator-gated synaptic plasticity, may be sufficient to jointly encode and update identity, timing, and probability within a single recurrent circuit. Flexible predictive cognition may therefore arise from generic population dynamics shaped by local learning rules rather than from specialized predictive modules.

q-bio.NC↗

arXiv2025

Emergence of Deviance Detection in Cortical Cultures through Maturation, Criticality, and Early Experience

Mismatch negativity (MMN) in humans reflects deviance detection (DD), a core neural mechanism of predictive processing. However, the fundamental principles by which DD emerges and matures during early cortical development-potentially providing a neuronal scaffold for MMN-remain unclear. Here, we tracked the development of DD in dissociated cortical cultures grown on high-density CMOS microelectrode arrays from 10 to 35 days in vitro (DIV). Cultures were stimulated with oddball and many-standards control paradigms while spontaneous and evoked activity were recorded longitudinally. At early stages, stimulus-evoked responses were confined to fast components reflecting direct activation. From DIV15-20 onward, robust late responses appeared, and deviant stimuli progressively evoked stronger responses than frequent and control stimuli, marking the onset of DD. By DIV30, responses became stronger, faster, and more temporally precise. Neuronal avalanche analysis revealed a gradual transition from subcritical to near-critical dynamics, with cultures exhibiting power-law statistics showing the strongest deviant responses. Nonetheless, DD was also present in non-critical networks, indicating that criticality is not required for its emergence but instead stabilizes and amplifies predictive processing as networks mature. Early oddball experience reinforces the deviant pathway, resulting in faster conduction along those circuits. However, as frequent and deviant pathways become less distinct, the deviance detection index is reduced. Together, these findings demonstrate that DD arises intrinsically through local circuit maturation, while self-organization toward criticality and early experience further refine its strength and timing, providing mechanistic insight into predictive coding in simplified cortical networks and informing the design of adaptive, prediction-sensitive artificial systems.

q-bio.NC↗

arXiv2025

Deviance Detection and Regularity Sensitivity in Dissociated Neuronal Cultures

Understanding how neural networks process complex patterns of information is crucial for advancing both neuroscience and artificial intelligence. To investigate fundamental principles of neural computation, we studied dissociated neuronal cultures, one of the most primitive living neural networks, on high-resolution CMOS microelectrode arrays and tested whether the dissociated culture exhibits regularity sensitivity beyond mere stimulus-specific adaptation and deviance detection. In oddball electrical stimulation paradigms, we confirmed that the neuronal culture produced mismatch responses (MMRs) with true deviance detection beyond mere adaptation. These MMRs were dependent on the N-methyl-D-aspartate (NMDA) receptors, similar to mismatch negativity (MMN) in humans, which is known to have true deviance detection properties. Crucially, we also showed sensitivity to the statistical regularity of stimuli, a phenomenon previously observed only in intact brains: the MMRs in a predictable, periodic sequence were smaller than those in a commonly used sequence in which the appearance of the deviant stimulus was random and unpredictable. These results challenge the traditional view that a hierarchically structured neural network is required to process complex temporal patterns, suggesting instead that deviant detection and regularity sensitivity are inherent properties arising from the primitive neural network. They also suggest new directions for the development of neuro-inspired artificial intelligence systems, emphasizing the importance of incorporating adaptive mechanisms and temporal dynamics in the design of neural networks.

q-bio.NC↗

arXiv2012

Higher-Order Partial Least Squares (HOPLS): A Generalized Multi-Linear Regression Method

A new generalized multilinear regression model, termed the Higher-Order Partial Least Squares (HOPLS), is introduced with the aim to predict a tensor (multiway array) $\tensor{Y}$ from a tensor $\tensor{X}$ through projecting the data onto the latent space and performing regression on the corresponding latent variables. HOPLS differs substantially from other regression models in that it explains the data by a sum of orthogonal Tucker tensors, while the number of orthogonal loadings serves as a parameter to control model complexity and prevent overfitting. The low dimensional latent space is optimized sequentially via a deflation operation, yielding the best joint subspace approximation for both $\tensor{X}$ and $\tensor{Y}$. Instead of decomposing $\tensor{X}$ and $\tensor{Y}$ individually, higher order singular value decomposition on a newly defined generalized cross-covariance tensor is employed to optimize the orthogonal loadings. A systematic comparison on both synthetic data and real-world decoding of 3D movement trajectories from electrocorticogram (ECoG) signals demonstrate the advantages of HOPLS over the existing methods in terms of better predictive ability, suitability to handle small sample sizes, and robustness to noise.

cs.AI↗