--- res: bibo_abstract: - The parabigeminal nucleus (PBG) is the mammalian homologue to the isthmic complex of other vertebrates. Optogenetic stimulation of the PBG induces freezing and escape in mice, a result thought to be caused by a PBG projection to the central nucleus of the amygdala. However, the isthmic complex, including the PBG, has been classically considered satellite nuclei of the Superior Colliculus (SC), which upon stimulation of its medial part also triggers fear and avoidance reactions. As the PBG-SC connectivity is not well characterized, we investigated whether the topology of the PBG projection to the SC could be related to the behavioral consequences of PBG stimulation. To that end, we performed immunohistochemistry, in situ hybridization and neural tracer injections in the SC and PBG in a diurnal rodent, the Octodon degus. We found that all PBG neurons expressed both glutamatergic and cholinergic markers and were distributed in clearly defined anterior (aPBG) and posterior (pPBG) subdivisions. The pPBG is connected reciprocally and topographically to the ipsilateral SC, whereas the aPBG receives afferent axons from the ipsilateral SC and projected exclusively to the contralateral SC. This contralateral projection forms a dense field of terminals that is restricted to the medial SC, in correspondence with the SC representation of the aerial binocular field which, we also found, in O. degus prompted escape reactions upon looming stimulation. Therefore, this specialized topography allows binocular interactions in the SC region controlling responses to aerial predators, suggesting a link between the mechanisms by which the SC and PBG produce defensive behaviors.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Alfonso foaf_name: Deichler, Alfonso foaf_surname: Deichler - foaf_Person: foaf_givenName: Denisse foaf_name: Carrasco, Denisse foaf_surname: Carrasco - foaf_Person: foaf_givenName: Luciana foaf_name: Lopez-Jury, Luciana foaf_surname: Lopez-Jury - foaf_Person: foaf_givenName: Tomas A foaf_name: Vega Zuniga, Tomas A foaf_surname: Vega Zuniga foaf_workInfoHomepage: http://www.librecat.org/personId=2E7C4E78-F248-11E8-B48F-1D18A9856A87 - foaf_Person: foaf_givenName: Natalia foaf_name: Marquez, Natalia foaf_surname: Marquez - foaf_Person: foaf_givenName: Jorge foaf_name: Mpodozis, Jorge foaf_surname: Mpodozis - foaf_Person: foaf_givenName: Gonzalo foaf_name: Marin, Gonzalo foaf_surname: Marin bibo_doi: 10.1038/s41598-020-72848-0 bibo_volume: 10 dct_date: 2020^xs_gYear dct_identifier: - UT:000577142600032 dct_isPartOf: - http://id.crossref.org/issn/20452322 dct_language: eng dct_publisher: Springer Nature@ dct_title: A specialized reciprocal connectivity suggests a link between the mechanisms by which the superior colliculus and parabigeminal nucleus produce defensive behaviors in rodents@ ...