The research in the Understanding Hallucinations (UH) Lab is driven by the question how and why the human brain produces hallucinations. The phenomenon of hallucinations is studied using several neuroimaging techniques such as structural (T1-weighted and diffusion-weighted MR imaging) and functional (fMRI and EEG) imaging. This is done in a wide spectrum of psychiatric and neurological diagnoses as well as the general population, in order to understand the transdiagnostic neurobiology of hallucinations. By developing novel assessment tools such as the Questionnaire for Psychotic Experiences we aim to better grasp the phenomenology of hallucinations across disorders and health. Lastly, we study treatment of hallucinations through brain stimulation protocols (TMS, tDCS) and medication trials.


  • Professor Kenneth Hugdahl (PhD), Head of Bergen fMRI Group, University of Bergen, Norway
  • Professor Mark van der Gaag (PhD), Clinical and Developmental Psychopathology, VU University, Amsterdam, The Netherlands & Parnassia GGZ, The Hague, The Netherlands


Key Publications:

  • Sommer IEC, Slotema CW, Daskalakis ZJ, Derks EM, Blom JD, Van Der Gaag M (2012): The treatment of hallucinations in schizophrenia spectrum disorders. Schizophr Bull 38:704–714.
  • Sommer IEC, Diederen KMJ, Blom JD, Willems A, Kushan L, Slotema K, Boks MPM, Daalman K, Hoek HW, Neggers SFW, Kahn RS (2008): Auditory verbal hallucinations predominantly activate the right inferior frontal area. Brain 131:3169–3177.
  • De Weijer AD, Neggers SFW, Diederen KMS, Mandl RCW, Kahn RS, Hulshoff Pol HE, Sommer IE (2013): Aberrations in the arcuate fasciculus are associated with auditory verbal hallucinations in psychotic and in non-psychotic individuals. Hum Brain Mapp 34:626–634.
  • Diederen KM., Neggers SFW, Daalman K, Blom JD, Goekoop R, Kahn, René S.Sommer IEC (2010): Deactivation of the Parahippocampal Gyrus Preceding Auditory Hallucinations in Schizophrenia. Am J Psychiatry 167:427–435.
  • van Lutterveld R, van den Heuvel MP, Diederen KMJ, de Weijer AD, Begemann MJH, Brouwer RM, Daalman K, Blom JD, Kahn RS, Sommer IE (2014): Cortical thickness in individuals with non-clinical and clinical psychotic symptoms. Brain 137:2664–2669.
  • van Dellen E, Bohlken MM, Draaisma L, Tewarie PK, van Lutterveld R, Mandl R, Stam CJ, Sommer IE (2015): Structural Brain Network Disturbances in the Psychosis Spectrum. Schizophr Bull:sbv178–.
  • Diederen KMJ, Daalman K, De Weijer AD, Neggers SFW, Van Gastel W, Blom JD, Kahn RS, Sommer IEC (2012): Auditory hallucinations elicit similar brain activation in psychotic and nonpsychotic individuals. Schizophr Bull 38:1074–1082.
  • Koops S, Dellen E van, Schutte MJL, Nieuwdorp W, Neggers SFW, Sommer IEC (2015): Theta Burst Transcranial Magnetic Stimulation for Auditory Verbal Hallucinations: Negative Findings From a Double-Blind-Randomized Trial. Schizophr Bull 42:sbv100.


Current Lab Members:


  • Iris Sommer (PI, Professor of Psychiatry)
  • Marc Bohlken (Postdoctoral Fellow, psychologist)
  • Sophie Heringa (Postdoctoral Fellow, psychologist)
  • Edwin van Dellen (Postdoctoral Fellow, psychiatry resident)
  • Sanne Schuite-Koops (PhD candidate, neuroscientist)
  • Maya Schutte (PhD candidate, neuroscientist)
  • Marieke Begemann (PhD candidate, psychologist)
  • Meenakshi Dauwan (PhD candidate, MD)
  • Mascha Linszen (PhD candidate, MD)
  • Kim Maijer (PhD candidate, psychiatrist)
  • Bas Oude Ophuis (PhD candidate, psychiatry resident)
  • Janna de Boer (PhD candidate, MD)
  • Charissa van Kesteren (PhD candidate, MD)
  • Wendy Nieuwdorp (PhD candidate, MD)
  • Margot Slot (Research Assistant, psychologist)
  • Lyliana Nasib (Research Assistant, psychologist)
  • Hannemieke Haisma-Pieterse (Personal Assistent)



  • Remko van Lutterveld (PhD)
  • Kelly Diederen (PhD)
  • Antoin de Weijer (PhD)
  • Karin Slotema (MD, PhD)
  • Kirstin Daalman (PhD)