Operational Accessibility Isomorphism Between Spectral Damping and Neuromodulatory Gating

This paper formally defines an operational isomorphism between spectral damping in molecular vibronic systems and neuromodulatory control in biological sensory systems. Without asserting causal continuity or physical identity across scales, we show that both domains instantiate the same class of output-selective control structures, characterized by non-monotonic modulation and bounded state accessibility. Within a minimal operational framework, damping is shown to function not as loss or noise, but as a selector of accessible outputs, leading to effective reductions in observable state spaces under parametric control. This perspective clarifies how neuromodulatory phenomena commonly described as gain modulation cannot, in general, be reduced to monotonic gain models, but instead reflect accessibility-based control. The proposed isomorphism is explicitly limited, falsifiable, and non-metaphorical, establishing a principled bridge between molecular spectroscopy and perceptual neuroscience without invoking consciousness, representation, or subjective experience.