Sensory maps in the telencephalic pallium of goldfish

The functional organization of the teleost telencephalic pallium remains poorly understood, particularly regarding the presence of modality-specific sensory domains and their topographic arrangement. Here, we used in vivo wide-field voltage-sensitive dye imaging to map sensory-evoked neural activity across the dorsal surface of the telencephalic pallium of adult goldfish. Somatosensory, auditory, gustatory, and visual stimulation revealed distinct, modality-specific domains located within the dorsomedial (Dm) and dorsolateral (Dl) pallium, that closely matched cytoarchitectural boundaries. Within Dm, somatosensory and auditory stimuli activated partially overlapping territories in the caudal subregion (Dm4), exhibiting clear somatotopic and tonotopic organization along the mediolateral axis. Gustatory stimulation selectively engaged Dm3, where different tastants activated spatially distinct but partially overlapping domains. A more rostral subregion (Dm2) responded only to high-intensity somatosensory stimulation, suggesting involvement in processing negatively valenced inputs, whereas the adjacent Dm1 remained unresponsive to all sensory modalities tested. Visual stimulation activated a circumscribed area within the dorsolateral pallium (Dld2). Pharmacological blockade of ionotropic glutamate receptors markedly reduced sensory-evoked responses, indicating that these maps depend on glutamatergic synaptic transmission. Together, these findings reveal a more elaborate and functionally differentiated pallial organization than previously recognized and provide the first direct evidence for modality-specific topographic sensory maps in the teleost pallium. More broadly, they offer a new framework for understanding how sensory, affective, and mnemonic functions are organized within the teleost pallium and for comparing this organization with distributed pallial systems in other vertebrates.