Biology subjects

Sans-Dublanc, A.

Publications and source records attributed to Sans-Dublanc, A..

4 recordsLinked to original sources

bioRxiv2026

Cooperative processing of visual threat across collicular pathways

Rapid defensive actions require the transformation of sensory cues into appropriate motor responses. The superior colliculus is central to this transformation, containing defined cell-types that form parallel output pathways linking visual inputs to distinct behaviors. However, whether these pathways act independently or cooperate remains unclear. Here we combine cell-type-specific inhibition, large-scale electrophysiology, and functional ultrasound imaging to determine how these pathways contribute to visually evoked defensive behaviors. Inhibiting either narrow-field or wide-field neurons impaired escape to overhead visual threats, demonstrating that both pathways contribute to escape. Recordings from downstream targets revealed a compact representation in the deeper layers of the superior colliculus that selectively distinguished visual stimuli associated with escape, whereas the lateral posterior thalamus contained a broader representation of visual stimuli. The representation of visual threat in the deeper layers of the superior colliculus predicted escape initiation and vigor in freely moving animals. Across the brain, functional ultrasound imaging showed that visual stimuli recruited distinct patterns of activity that could not be explained by response magnitude alone or by the contribution of single cell-types. Together, these results reveal a cooperative circuit architecture in which parallel pathways carry distinct but complementary signals that jointly support visually evoked escape.

neuroscience↗

bioRxiv2026

Visual field position shapes input sampling and output routing in the superior colliculus

Animals use the location of visual stimuli to select appropriate actions1-5, and the upper and lower visual field often carry different ecological and behavioral meaning6-9. In mice, the superior colliculus is a key central hub that transforms visual input into orienting, defensive, and approach behaviors3,10-13. Its superficial layers receive retinotopically organized input from the retina and contain genetically defined cell types with distinct downstream projections, including wide-field neurons that project to the lateral posterior thalamus and narrow-field neurons that target the parabigeminal nucleus and deeper collicular layers14-18. These features raise the question of whether circuits of the superior colliculus are repeated across visual space or exhibit visual-field-dependent specializations. Here, we show that the mouse superficial superior colliculus contains visual-field-dependent circuit modules. Dual-color rabies tracing revealed that wide-field and narrow-field neurons receive input from a largely shared set of brain regions, whereas upper- and lower-field domains differ in how they sample those inputs. Some source regions preferentially innervate one visual-field domain, producing biased regional input strength, while others contain topographically segregated projecting neurons that target upper- or lower-field domains. MAPseq showed that most superficial collicular neurons project to single downstream targets, with upper- and lower-field populations differing in target probability. Two-photon calcium imaging further showed that wide-field neurons in upper- and lower-field domains differ in stimulus selectivity. Together, these findings reveal a visual-field-dependent wiring logic that biases how the superior colliculus samples inputs and routes signals to downstream pathways. HighlightsO_LIWide- and narrow-field neurons receive broadly overlapping inputs C_LIO_LIUpper- and lower-field domains differ in input strength and topographic organization C_LIO_LIMost superficial collicular neurons project to a single target C_LIO_LIVisual field position biases downstream target probability C_LI

neuroscience↗

bioRxiv2020

Brain-wide mapping of neural activity mediating collicular-dependent behaviors

Neuronal cell-types are arranged in brain-wide circuits to guide behavior. In mice, the superior colliculus is comprised of a set of cell-types that each innervate distinct downstream targets. Here we reveal the brain-wide networks downstream of four collicular cell-types by combining functional ultrasound imaging (fUSi) with optogenetics to monitor neural activity at a resolution of ~100 m. Each neuronal group triggered different behaviors, and activated distinct, partially overlapping sets of brain nuclei. This included regions not previously thought to mediate defensive behaviors, e.g. the posterior paralaminar nuclei of the thalamus (PPnT), that we show to play a role in suppressing habituation. Electrophysiological recordings support the fUSi findings and show that neurons in the downstream nuclei preferentially respond to innately threatening visual stimuli. This work provides insight into the functional organization of the networks governing defensive behaviors and demonstrates an experimental approach to explore the whole-brain neuronal activity downstream of targeted cell-types.

neuroscience↗

bioRxiv2019

Septal GABAergic Inputs to CA1 Govern Contextual Memory Retrieval

Whether projections from the medial septum regulate the function of the CA1 hippocampus in episodic memory retrieval is not known. Here we show that septal GABAergic inputs to CA1 promote contextual fear memory, blocking the activation of parvalbumin-rich interneurons to facilitate Erk/MAP-kinase signaling in pyramidal cells during retrieval. Thus, suppression of feed-forward inhibition onto CA1 by septal GABAergic neurons gates contextual fear behavior.

neuroscience↗