title: Determination of hemispheric emotional valence in individual subjects: a new approach with research and therapeutic implications.
abstract: BACKGROUND
  Much has been theorized about the emotional properties of the hemispheres. Our review of the dominant hypotheses put forth by Schore, Joseph, Davidson, and Harmon-Jones on hemispheric emotional valences (HEV) shows that none are supported by robust data. Instead, we propose that individual's hemispheres are organized to have differing HEVs that can be lateralized in either direction.
  
  
  METHODS
  Probe auditory evoked potentials (AEP) recorded during a neutral and an upsetting memory were used to assess HEV in 28 (20 F) right-handed subjects who were either victims of childhood maltreatment (N = 12) or healthy controls. In a sub-population, we determined HEV by emotional response to lateral visual field stimulation (LVFS), in which vision is limited to one, then the other hemifield. We compare a number of morphometric and functional brain measures between individuals who have right-negative versus left-negative HEV.
  
  
  RESULTS
  Using AEPs to determine HEV, we found 62% of controls and 67% of maltreated subjects had right negative HEV. There was a strong interaction between HEV-laterality and gender, which together accounted for 60% of individual variability in total grey matter volume (GMV). HEV-laterality was associated with differences in hippocampal volume, amygdala/hippocampal ratios, and measures of verbal, visual and global memory. HEV-laterality was associated also with different constellations of symptoms comparing maltreated subjects to controls. Emotional response to LVFS provided a convenient and complementary measure of HEV-laterality that correlated significantly with the HEVs determined by AEPs.
  
  
  CONCLUSIONS
  Our findings suggest that HEV-laterality, like handedness or gender, is an important individual difference with significant implications for brain and behavioral research, and for guiding lateralized treatments such as rTMS.
authors.affiliation: Department of Psychiatry, Harvard Medical School, and the Developmental Biopsychiatry Research Program, McLean Hospital, 115 Mill Street Belmont, MA 02478, USA. fschiffer@mclean.harvard.edu
authors.forename: Fredric
authors.initials: F
authors.lastname: Schiffer
authors.forename: Martin H
authors.initials: MH
authors.lastname: Teicher
authors.forename: Carl
authors.initials: C
authors.lastname: Anderson
authors.forename: Akemi
authors.initials: A
authors.lastname: Tomoda
authors.forename: Ann
authors.initials: A
authors.lastname: Polcari
authors.forename: Carryl P
authors.initials: CP
authors.lastname: Navalta
authors.forename: Susan L
authors.initials: SL
authors.lastname: Andersen