SearcharxivSearch

arXiv subjects

Ian Jackson

Publications and source records attributed to Ian Jackson.

3 recordsLinked to original sources

Monkey Perceptogram: Reconstructing Visual Representation and Presumptive Neural Preference from Monkey Multi-electrode Arrays

Understanding how the primate brain transforms complex visual scenes into coherent perceptual experiences remains a central challenge in neuroscience. Here, we present a comprehensive framework for interpreting monkey visual processing by integrating encoding and decoding approaches applied to two large-scale spiking datasets recorded from macaque using THINGS images (THINGS macaque IT Dataset (TITD) and THINGS Ventral Stream Spiking Dataset (TVSD)). We leverage multi-electrode array recordings from the ventral visual stream--including V1, V4, and inferotemporal (IT) cortex--to investigate how distributed neural populations encode and represent visual information. Our approach employs linear models to decode spiking activity into multiple latent visual spaces (including CLIP and VDVAE embeddings) and reconstruct images using state-of-the-art generative models. We further utilize encoding models to map visual features back to neural activity, enabling visualization of the "preferred stimuli" that drive specific neural ensembles. Analyses of both datasets reveal that it is possible to reconstruct both low-level (e.g., color, texture) and high-level (e.g., semantic category) features of visual stimuli from population activity, with reconstructions preserving key perceptual attributes as quantified by feature-based similarity metrics. The spatiotemporal spike patterns reflect the ventral stream's hierarchical organization with anterior regions representing complex objects and categories. Functional clustering identifies feature-specific neural ensembles, with temporal dynamics show evolving feature selectivity post-stimulus. Our findings demonstrate feasible, generalizable perceptual reconstruction from large-scale monkey neural recordings, linking neural activity to perception.

q-bio.NC

Perceptogram: Reconstructing Visual Percepts and Presumptive Electrode Preference from EEG

Visual neural decoding from EEG has improved significantly due to diffusion models that can reconstruct high-quality images from decoded latents. While recent works have focused on relatively complex architectures to achieve good reconstruction performance from EEG, less attention has been paid to the source of this information. We present a unified framework that not only enables image reconstruction from EEG using a simple linear decoder, but also isolates interpretable EEG feature maps that support visual perception. Unlike prior approaches that rely on deep, opaque models, our method leverages the inherent structure of CLIP embeddings to keep the mapping linear. We show that training a simple linear decoder from EEG to CLIP latent space, followed by a frozen pre-trained diffusion model, is sufficient to decode images with state-of-the-art reconstruction performance. Beyond reconstruction, Perceptogram enables the visualization of presumptive electrode preference and EEG patterns, revealing interpretable EEG feature maps that correspond to distinct visual attributes, such as semantic class, texture, and hue. We thus use our framework, Perceptogram, to probe EEG signals at various levels of the visual information hierarchy.

q-bio.NC

Low-Frequency Measurements of Seismic Velocity and Attenuation in Antigorite Serpentinite

Laboratory measurements of seismic velocity and attenuation in antigorite serpentinite at a confining pressure of $2$ kbar and temperatures up to $550^\circ$C (i.e., in the antigorite stability field) provide new results relevant to the interpretation of geophysical data in subduction zones. A polycrystalline antigorite specimen was tested via forced-oscillations at small strain amplitudes and seismic frequencies (mHZ--Hz). The shear modulus has a temperature sensitivity, $\partial G/ \partial T$, averaging $-0.017$ GPa K$^{-1}$. Increasing temperature above $500^\circ$C results in more intensive shear attenuation ($Q_G^{-1}$) and associated modulus dispersion, with $Q_G^{-1}$ increasing monotonically with increasing oscillation period and temperature. This "background" relaxation is adequately captured by a Burgers model for viscoelasticity and possibly results from intergranular mechanisms. Attenuation is higher in antigorite ($\log_{10} Q_G^{-1} \approx -1.5$ at $550^\circ$C and $0.01$ Hz than in olivine ($\log_{10} Q_G^{-1} \ll -2.0$ below $800^\circ$C), but such contrast does not appear to be strong enough to allow robust identification of antigorite from seismic models of attenuation only.

physics.geo-ph