Page 27 - PIECES OF THE PUZZLE Eline Vissia

et al. 2001) and by the use of sMRI, potential neuroanatomical abnormalities in DID and PTSD patients can be studied.
Functional magnetic resonance imaging (fMRI) is a procedure that measures brain activity by detecting associated changes in blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled (that is, when an area of the brain is in use, blood flow to that region also increases). Blood oxygenation level dependent (BOLD) fMRI is a powerful approach to define activity in the human brain (Matthews, Jezzard 2004).
Despite the fact that imaging neuroscience has been around for more than 20 years and is by now the predominant technique in behavior and cognitive neuroscience (Friston 2009), few neuroimaging studies have been conducted in patients with DID (Dorahy et al. 2014, Dalenberg et al. 2012, Reinders 2008). In contrast, numerous functional neuroimaging studies have studied the neural mechanism underlying PTSD. Although imaging studies have elucidated neurophysiological markers of the dissociative response in patients with a range of DD and PTSD, studies performed specifically in DID patients are more limited (Dorahy et al. 2014), even though prevalence estimates are similar to for example schizophrenia, a disorder that many neuroimaging studies were devoted to. Dorahy et al. (2014) reviewed psychobiological findings and suggested a unique neurophysiological profile in DID.
Switching processes in DID are characterized by activation and inhibition of various brain areas and the exact patterning of these may be related to the psychobiological characteristics of the dissociative personality states involved (Dorahy et al. 2014). During a personality state switch, Tsai et al. (1999) observed brain activity in hippocampal areas, as well as the parahippocampus, medial temporal structures, substantia nigra, and global pallidus, as well as right hippocampal activation when the participant was returning to her original identity (Dorahy et al. 2014). Savoy et al. (2012) demonstrated involvement of the dorsolateral prefrontal cortex, the anterior prefrontal cortex, and orbitofrontal cortex, as well as bilateral activation in the nucleus accumbens during switching in a DID patient.
Reinders et al. (2003) conducted a PET study in DID and found two distinct states of self-awareness, each with its own access to autobiographical trauma-related memory with involvement of the medial prefrontal cortex
GENERAL INTRODUCTION
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