title: Bursting thalamic responses in awake monkey contribute to visual detection and are modulated by corticofugal feedback.
abstract: The lateral geniculate nucleus is the gateway for visual information en route to the visual cortex. Neural activity is characterized by the existence of two firing modes: burst and tonic. Originally associated with sleep, bursts have now been postulated to be a part of the normal visual response, structured to increase the probability of cortical activation, able to act as a "wake-up" call to the cortex. We investigated a potential role for burst in the detection of novel stimuli by recording neuronal activity in the lateral geniculate nucleus (LGN) of behaving monkeys during a visual detection task. Our results show that bursts are often the neuron's first response, and are more numerous in the response to attended target stimuli than to unattended distractor stimuli. Bursts are indicators of the task novelty, as repetition decreased bursting. Because the primary visual cortex is the major modulatory input to the LGN, we compared the results obtained in control conditions with those observed when cortical activity was reduced by TMS. This cortical deactivation reduced visual response related bursting by 90%. These results highlight a novel role for the thalamus, able to code higher order image attributes as important as novelty early in the thalamo-cortical conversation.
authors.affiliation: Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A Coruña Coruña, Spain ; Biomedical Research Institute of A Coruna (INIBIC) Coruña, Spain.
authors.forename: Tania
authors.initials: T
authors.lastname: Ortuño
authors.affiliation: Faculty of Life Science, University of Manchester Manchester, UK.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Grieve
authors.affiliation: MODES Group, Department of Mathematics, Faculty of Computer Science, University of A Coruña Coruña, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cao
authors.affiliation: Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A Coruña Coruña, Spain ; Biomedical Research Institute of A Coruna (INIBIC) Coruña, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Cudeiro
authors.affiliation: Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A Coruña Coruña, Spain ; Biomedical Research Institute of A Coruna (INIBIC) Coruña, Spain.
authors.forename: Casto
authors.initials: C
authors.lastname: Rivadulla
keywords: LGN; attention; burst; thalamo-cortical; visual