README.md

Effective Biological Representation Learning by Masking Gene Expression

Accepted at the ICLR 2026 Workshop on Foundation Models for Science (FM4Sci).

This repo is under construction - stay tuned for updates as we share relevant code and artifacts.

At a high level, see the following definitions for our loss and activation functions. Note that RectifiedSigmoid is mathematically equivalent to the more elegantly defined RectifiedTanh as presented in the paper.

class PoissonNLLLogSpace(nn.Module):
    def __init__(self, reduction="none"):
        super().__init__()
        self.reduction = reduction

    def forward(self, log1p_input, log1p_target):
        # we must transform target out of log space to have valid poisson loss
        loss = log1p_input.exp() - log1p_target.exp() * log1p_input
        return loss

class RectifiedSigmoid(nn.Module):
    def __init__(self, upper_bound: int = 100000):
        super().__init__()
        self.upper_bound = np.log1p(upper_bound)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        return self.upper_bound * F.relu(2 * torch.sigmoid(x / (2 * np.e)) - 1) 

Benchmarking

See this paper, "Benchmarking Transcriptomics Foundation Models for Perturbation Analysis : one PCA still rules them all", which defines the major perturbational benchmarks we use in this work (repo). Note that we have made some improvements to some of the evaluations originally presented in that paper 2 years ago, as we describe in the appendixc. More updates to come.