title: Neuronal coding of implicit emotion categories in the subcallosal cortex in patients with depression.
abstract: BACKGROUND
  The subcallosal cingulate and adjacent ventromedial prefrontal cortex (collectively referred to here as the subcallosal cortex or SCC) have been identified as key brain areas in emotional processing. The SCC's role in affective valuation as well as severe mood and motivational disturbances, such as major depression, has been largely inferred from measures of neuronal population activity using functional neuroimaging. On the basis of imaging studies, it is unclear whether the SCC predominantly processes 1) negatively valenced affective content, 2) affective arousal, or 3) category-specific affective information.
  
  
  METHODS
  To clarify these putative functional roles of the SCC, we measured single neuron activity in the SCC of 15 human subjects undergoing deep brain stimulation for depression while they viewed emotionally evocative images grouped into categories that varied in emotional valence (pleasantness) and arousal.
  
  
  RESULTS
  We found that the majority of responsive neurons were modulated by specific emotion categories, rather than by valence or arousal alone. Moreover, although these emotion-category-specific neurons responded to both positive and negative emotion categories, a significant majority were selective for negatively valenced emotional content.
  
  
  CONCLUSIONS
  These findings reveal that single SCC neuron activity reflects the automatic valuational processing and implicit emotion categorization of visual stimuli. Furthermore, because of the predominance of neuronal signals in SCC conveying negative affective valuations and the increased activity in this region among depressed people, the effectiveness of depression therapies that alter SCC neuronal activity may relate to the down-regulation of a previously negative emotional processing bias.
authors.affiliation: Department of Neurosurgery, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina; Department of Surgery, Toronto Western Hospital, Institute of Medical Science, University of Toronto, Toronto, Canada. Electronic address: alaxton@wakehealth.edu.
authors.forename: Adrian W
authors.initials: AW
authors.lastname: Laxton
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Neimat
authors.forename: Karen D
authors.initials: KD
authors.lastname: Davis
authors.forename: Thilo
authors.initials: T
authors.lastname: Womelsdorf
authors.forename: William D
authors.initials: WD
authors.lastname: Hutchison
authors.forename: Jonathan O
authors.initials: JO
authors.lastname: Dostrovsky
authors.forename: Clement
authors.initials: C
authors.lastname: Hamani
authors.forename: Helen S
authors.initials: HS
authors.lastname: Mayberg
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D046690:Deep Brain Stimulation; D003865:Major Depressive Disorder / Q000503:physiopathology*; D004644:Emotions / Q000502:physiology*; D005260:Female; D006179:Gyrus Cinguli / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000502:physiology*; D017397:Prefrontal Cortex / Q000503:physiopathology*
keywords: Cingulate cortex; deep brain stimulation; depression; emotion; humans; neuronal activity