title: Locomotion and Task Demands Differentially Modulate Thalamic Audiovisual Processing during Active Search.
abstract: Active search is a ubiquitous goal-driven behavior wherein organisms purposefully investigate the sensory environment to locate a target object. During active search, brain circuits analyze a stream of sensory information from the external environment, adjusting for internal signals related to self-generated movement or "top-down" weighting of anticipated target and distractor properties. Sensory responses in the cortex can be modulated by internal state, though the extent and form of modulation arising in the cortex de novo versus an inheritance from subcortical stations is not clear. We addressed this question by simultaneously recording from auditory and visual regions of the thalamus (MG and LG, respectively) while mice used dynamic auditory or visual feedback to search for a hidden target within an annular track. Locomotion was associated with strongly suppressed responses and reduced decoding accuracy in MG but a subtle increase in LG spiking. Because stimuli in one modality provided critical information about target location while the other served as a distractor, we could also estimate the importance of task relevance in both thalamic subdivisions. In contrast to the effects of locomotion, we found that LG responses were reduced overall yet decoded stimuli more accurately when vision was behaviorally relevant, whereas task relevance had little effect on MG responses. This double dissociation between the influences of task relevance and movement in MG and LG highlights a role for extrasensory modulation in the thalamus but also suggests key differences in the organization of modulatory circuitry between the auditory and visual pathways.
authors.affiliation: Massachusetts Eye and Ear Infirmary, Eaton-Peabody Laboratories, 243 Charles Street, Boston, MA 02114, USA; Center for Computational Neuroscience and Neural Technology, Boston University, 677 Beacon Street, Boston, MA 02215, USA. Electronic address: ross_williamson@meei.harvard.edu.
authors.forename: Ross S
authors.initials: RS
authors.lastname: Williamson
authors.affiliation: Massachusetts Eye and Ear Infirmary, Eaton-Peabody Laboratories, 243 Charles Street, Boston, MA 02114, USA; Department of Otology and Laryngology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Hancock
authors.affiliation: Center for Computational Neuroscience and Neural Technology, Boston University, 677 Beacon Street, Boston, MA 02215, USA.
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Shinn-Cunningham
authors.affiliation: Massachusetts Eye and Ear Infirmary, Eaton-Peabody Laboratories, 243 Charles Street, Boston, MA 02114, USA; Center for Computational Neuroscience and Neural Technology, Boston University, 677 Beacon Street, Boston, MA 02215, USA; Department of Otology and Laryngology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Polley
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000502:physiology*; D001307:Auditory Perception; D008124:Locomotion; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013788:Thalamus / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception