title: Nucleus accumbens activity dissociates different forms of salience: evidence from human intracranial recordings.
abstract: Theoretical models and empirical work indicate a critical role of the NAcc in salience processing. For instance, the NAcc not only responds to appetitive and aversive information, but it also signals novelty, contextual deviance, and action monitoring. However, because most studies have investigated only one specific type of salience independently, it remains unclear how the NAcc concurrently differentiates between different forms of salience. To investigate this issue, we used intracranial electroencephalography in human epilepsy patients together with a previously established visual oddball paradigm. Here, three different oddball categories (novel, neutral, and target images) were infrequently presented among a standard scene image, and subjects responded to the target via button press. This task allowed us to differentiate "item novelty" (new vs neutral oddballs) from "contextual deviance" (neutral oddballs vs standard images) and "targetness" (target vs neutral oddballs). Time-frequency analysis revealed a dissociation between item novelty and contextual deviance on the basis of decreases in either θ (4-8 Hz) or β power (20-30 Hz). Targetness, on the other hand, was signaled by positive deflections in the stimulus-locked local field potentials, which, importantly, correlated with subjects' reaction times. These findings indicate that, in an ongoing stream of information, the NAcc differentiates between types of salience by distinct neural mechanisms to guide goal-directed behavior.
authors.affiliation: Department of Neurology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
authors.forename: Tino
authors.initials: T
authors.lastname: Zaehle
authors.forename: Eva M
authors.initials: EM
authors.lastname: Bauch
authors.forename: Hermann
authors.initials: H
authors.lastname: Hinrichs
authors.forename: Friedhelm C
authors.initials: FC
authors.lastname: Schmitt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Voges
authors.forename: Hans-Jochen
authors.initials: HJ
authors.lastname: Heinze
authors.forename: Nico
authors.initials: N
authors.lastname: Bunzeck
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009714:Nucleus Accumbens / Q000503:physiopathology*; D010775:Photic Stimulation; D011930:Reaction Time; D021641:Recognition, Psychology / Q000502:physiology*; D013057:Spectrum Analysis; D013997:Time Factors; D014796:Visual Perception