title: Attentional capture? Synchronized feedback signals from the isthmi boost retinal signals to higher visual areas.
abstract: When a salient object in the visual field captures attention, the neural representation of that object is enhanced at the expense of competing stimuli. How neural activity evoked by a salient stimulus evolves to take precedence over the neural activity evoked by other stimuli is a matter of intensive investigation. Here, we describe in pigeons (Columba livia) how retinal inputs to the optic tectum (TeO, superior colliculus in mammals), triggered by moving stimuli, are selectively relayed on to the rotundus (Rt, caudal pulvinar) in the thalamus, and to its pallial target, the entopallium (E, extrastriate cortex). We show that two satellite nuclei of the TeO, the nucleus isthmi parvocelullaris (Ipc) and isthmi semilunaris (SLu), send synchronized feedback signals across tectal layers. Preventing the feedback from Ipc but not from SLu to a tectal location suppresses visual responses to moving stimuli from the corresponding region of visual space in all Rt subdivisions. In addition, the bursting feedback from the Ipc imprints a bursting rhythm on the visual signals, such that the visual responses of the Rt and the E acquire a bursting modulation significantly synchronized to the feedback from Ipc. As the Ipc feedback signals are selected by competitive interactions, the visual responses within the receptive fields in the Rt tend to synchronize with the tectal location receiving the "winning" feedback from Ipc. We propose that this selective transmission of afferent activity combined with the cross-regional synchronization of the areas involved represents a bottom-up mechanism by which salient stimuli capture attention.
authors.affiliation: Departamento de Biología, Universidad de Chile, 7800024 Santiago, Chile. gmarin@uchile.cl
authors.forename: Gonzalo J
authors.initials: GJ
authors.lastname: Marín
authors.forename: Ernesto
authors.initials: E
authors.lastname: Durán
authors.forename: Cristian
authors.initials: C
authors.lastname: Morales
authors.forename: Cristian
authors.initials: C
authors.lastname: González-Cabrera
authors.forename: Elisa
authors.initials: E
authors.lastname: Sentis
authors.forename: Jorge
authors.initials: J
authors.lastname: Mpodozis
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Letelier
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001288:Attention / Q000502:physiology*; D001522:Behavior, Animal; D001931:Brain Mapping; D010856:Columbidae; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D025461:Feedback, Physiological / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009433:Neural Inhibition; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D015398:Signal Transduction / Q000502:physiology*; D018709:Statistics, Nonparametric; D013477:Superior Colliculi / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014794:Visual Fields / Q000187:drug effects / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione