Portrait of Nastaran Darjani

Nastaran Darjani

nastaran.darjani@mila.quebec
PhD - Université de Montréal
Supervisor
Shahab Bakhtiari
Research Topics
Brain-inspired AI
Cognitive Science
Computational Neuroscience
Deep Learning
NeuroAI
Neuroscience
Google Scholar
LinkedIn
GitHub

Publications

Divergent specializations for motion-driven representations in higher lateral and dorsal visual areas
Nastaran Darjani
Sophia Robert
Maryam Vaziri-Pashkam
Shahab Bakhtiari
The human visual system integrates both static and dynamic information to support form and shape perception, yet the computational principle… (see more)s underlying the integration of motion for object recognition remain unclear. Artificial neural networks (ANNs) offer a computational framework for developing and testing hypotheses about these principles: if ANNs trained on motion-related tasks develop representations that align with brain activity and support object categorization, this would suggest that the training objectives and architectural constraints of these networks may capture key aspects of motion processing in biological visual systems in general, and motion processing for object recognition, in particular. Here, we investigated this question using “object kinematograms”, stimuli in which object form is conveyed solely through motion cues. We measured neural responses of two higher regions of the lateral and the dorsal visual pathways, respectively, with strong sensitivity to dynamic cues from objects: lateral occipitotemporal cortex (LOT bio ), and left supramarginal gyrus (SMG lh ), as well as primary visual cortex (V1). We compared brain responses to representations extracted from two neural networks: SlowFast, a dual-pathway architecture trained on action recognition that processes slow- and fast-varying visual information with cross-pathway integration, and DorsalNet, a model of the primate dorsal visual pathway trained on embodied self-motion estimation. Representational similarity analysis revealed distinct representational profiles across brain areas, demonstrating functional specialization in motion-based form processing. LOT bio was best characterized by the slow pathway of the SlowFast model, whereas SMG lh showed strong similarity to both models. Critically, we found that representations aligned with brain activity also better supported behavioral function: the full SlowFast model, incorporating both slow and fast pathways, outperformed other models in few-shot categorization of object kinematograms and showed the highest similarity to human perceptual judgments. These findings demonstrate that with appropriate inductive biases, specifically, dual-pathway architectures for multi-scale motion processing and training objectives focused on dynamic visual tasks, ANNs can develop functionally useful representations of motion-defined forms that exhibit better alignment with the visual regions involved in processing dynamic visual signals.
2026-08-11
bioRxiv (preprint)
doi.org