Brain function and personality in normal males: a SPECT study using statistical parametric mapping R.M. Turner, a, * I.L. Hudson, a P.H. Butler, b and P.R. Joyce c a Department of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand b Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand c Department of Psychological Medicine, Christchurch School of Medicine, Christchurch, New Zealand Received 3 December 2002; revised 25 February 2003; accepted 17 March 2003 Abstract Understanding the differences between individuals’ personality types at a functional brain level is now possible due to recent developments in both functional brain imaging and personality models. The psychobiological model for temperament and character offers one approach to exploring personality. This study uses SPECT imaging to investigate brain function in relationship to the personality traits in the Temperament and Character Index. A general linear model approach was implemented at a voxel-by-voxel level, using quartile groupings for the personality predictors. t contrasts were used to investigate significant clusters of activation or deactivation. The results show a number of significant relationships between personality traits and regional cerebral blood flow, which show distinct nonlinear trends. All seven of the Cloninger personality traits were significantly related to regional cerebral blood flow. The results suggest that differences in brain function in some regions may reflect differences in personality traits. © 2003 Elsevier Science (USA). All rights reserved. 1. Introduction Recently developed noninvasive methods for investigat- ing brain function have allowed functional brain informa- tion, rather than structural information, to be related to psychological measures. These methods have largely been applied to individuals with disorders such as schizophrenia (Curtis et al., 2001; Ebmeier et al., 1993) and mood disor- ders, including depression (Meyer et al., 2001; Videbech et al., 2001; Mayberg et al., 1999; Bench et al., 1995). Less attention has been paid to investigating correlations between brain function and personality traits within normal subjects, using these noninvasive methods. The noninvasive methods developed, in the past 30 years, to investigate brain function, as distinct from brain structure, include single photon emission computed tomog- raphy (SPECT), positron emission tomography, and func- tional magnetic resonance imaging. This study uses SPECT to measure brain function. SPECT images contain counts of received radiation in each pixel (or voxel). The count is in proportion to the blood flow at the time of tracer injection, giving an indicator of oxygen uptake, and thus brain func- tion. While it has been accepted that mental disorders such as schizophrenia, bipolar disorder, and depression arise from abnormalities of neurotransmitter function in specific brain regions, it is becoming accepted that “normal emotional experiences,” (Mayberg et al., 1999) and “normal person- ality traits” will also be related to changes in neurotrans- mitter function in specific regions. For instance, the person- ality trait of “detachment,” which represents an individual’s description of themselves as cold and socially aloof, is related to dopamine D2 receptor density (Breier et al., 1998; Farde et al., 1997). One specific model of personality, de- veloped by Cloninger, was explicitly based upon an asso- ciation of specific personality traits to an underlying neuro- biology (Cloninger, 1986). One of the temperament dimensions in the model, reward dependence, is strongly * Corresponding author. Department of Mathematics and Statistics, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Fax: +64-3-364-2587. E-mail address: r.turner@math.canterbury.ac.nz (R.M. Turner). NeuroImage 19 (2003) 1145–1162 www.elsevier.com/locate/ynimg 1053-8119/03/$ – see front matter © 2003 Elsevier Science (USA). All rights reserved. doi:10.1016/S1053-8119(03)00171-X