  Decoding visual stimuli from neural responses recorded by functional Magnetic
Resonance Imaging (fMRI) presents an intriguing intersection between cognitive
neuroscience and machine learning, promising advancements in understanding
human visual perception and building non-invasive brain-machine interfaces.
However, the task is challenging due to the noisy nature of fMRI signals and
the intricate pattern of brain visual representations. To mitigate these
challenges, we introduce a two-phase fMRI representation learning framework.
The first phase pre-trains an fMRI feature learner with a proposed
Double-contrastive Mask Auto-encoder to learn denoised representations. The
second phase tunes the feature learner to attend to neural activation patterns
most informative for visual reconstruction with guidance from an image
auto-encoder. The optimized fMRI feature learner then conditions a latent
diffusion model to reconstruct image stimuli from brain activities.
Experimental results demonstrate our model's superiority in generating
high-resolution and semantically accurate images, substantially exceeding
previous state-of-the-art methods by 39.34% in the 50-way-top-1 semantic
classification accuracy. Our research invites further exploration of the
decoding task's potential and contributes to the development of non-invasive
brain-machine interfaces.
