Szemere, J. R. | bioRxiv Science

bioRxiv2026

Integration of polarization and intensity contrast information in a highly visual animal

Polarization vision subserves diverse biological functions, such as navigation, communication and target-motion detection. Regarding the detection of biological targets, studies on semi-terrestrial crabs suggest that polarization and intensity contrast are processed in separate visual channels. Information about the polarization contrast of targets would be extracted independently of intensity contrast, and the two signals combined downstream in the visual system. However, understanding how the information about these visual attributes is processed and integrated has been limited, as it is technically challenging to present visual stimuli in which both the polarization and the intensity contrast of a stimulus are controlled. Here we developed a monitor screen that allows us to present stimuli in which both contrasts can be controlled. Thus, to study how polarization and intensity information is processed to increase target detection, we presented moving stimuli with controlled polarization and intensity contrast while recording the cardiac response of the semi-terrestrial crab Neohelice granulata as a sensitive readout of its visual perception. Our results suggest that Neohelice possesses similar sensitivity to vertically and horizontally polarized light; thus, previously reported responses of the animals to polarized stimuli in which figure and background have the same intensity are likely accounted for by the comparison of two polarization channels. In addition, we determined that a moving polarization-only stimulus has a salience equivalent to that of an intensity-only stimulus with a Michelson contrast of 0.51. Finally, we studied how polarization and intensity contrast information is integrated, and found that polarization contrast increases the salience of an intensity-contrast-based target mostly when its intensity contrast is low, i.e. when information about intensity contrast is more ambiguous.

animal behavior and cognition↗

bioRxiv2024

Transient frequency preference responses in cell signaling systems

Ligand-receptor systems, covalent modification cycles, and transcriptional networks are the fundamental components of cell signaling and gene expression systems. While their behavior in reaching a steady state regime under step-like stimulation is well understood, their response under repetitive stimulation, particularly at early time stages is poorly characterized. This is despite the fact that early-stage responses to external inputs are arguably as informative as late-stage ones. In simple systems, a periodic stimulation elicits an initial transient response, followed by periodic behavior. Transient responses are relevant when the stimulation has a limited time span, or when the stimulated components timescale is slow as compared to the timescales of the downstream processes, in which case these fast processes may be capturing only those transients. In this study, we analyze the frequency response of simple motifs at different time stages. We use dose-conserved pulsatile input signals, meaning that the amplitude or the duration of the pulses varies along with frequency to conserve input dose, and consider different metrics versus frequency curves. We show that in ligand-receptor systems, there is a frequency preference response (band-pass filter) in some specific metrics during the transient stages, which is not present in the periodic regime. We suggest this is a general system-level mechanism that cells may use to filter input signals that have consequences for higher order circuits. Additionally, we evaluate how the described behavior in isolated motifs is reflected in similar types of responses in cascades and pathways of which they are a part. Our studies suggest that transient frequency preferences are important dynamic features of cell signaling and gene expression systems, which have been overlooked.

biophysics↗