ISSN : 2146-3123
E-ISSN : 2146-3131

Auditory Hallucinations as Translational Psychiatry: Evidence from Magnetic Resonance Imaging
Kenneth Hugdahl
1Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
2Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
DOI : 10.4274/balkanmedj.2017.1226
In this invited review article I present a translational perspective and overview of our research on auditory hallucinations in schizophrenia at the University of Bergen, Norway with a focus on the neuronal mechanisms underlying the phenomenology of experiencing "hearing voices". An auditory verbal hallucination, i.e. "hearing a voice", is defined as a sensory experience in the absence of a corresponding external sensory source that could explain the phenomenological experience. I suggest a general frame or scheme for the study of auditory verbal hallucinations which is called Levels of Explanation (LoE). With a LoE approach is meant that mental phenomena can be described and explained at different levels, from a cultural to a molecular level, with clinical, cognitive, brain imaging and cellular levels in between. Another way of saying this is that in order to advance knowledge in a research field it is not only necessary to replicate findings, but also to show how evidence obtained with one method, and at one level of explanation, converges with evidence obtained with another method at another level. In order to achieve breakthroughs in our understanding of auditory verbal hallucinations we have to advance vertically through the various levels, rather than the more common approach of staying at our favorite level ad advancing horizontally by adding more and more advanced techniques and data acquisition analyses. Horizontal expansion will however not advance a deeper understanding of how an auditory verbal hallucination spontaneously starts and stops. Finally, I successively present data from the clinical, cognitive, bran imaging, and cellular level where data from one level validates and support data at another level. Using a translational approach, the current status when it comes to auditory verbal hallucinations is that they implicate speech perception areas in the left temporal lobe, impair perception of and attention to external sounds. Preliminary results also show that amygdala is implicated in the emotional «coloring» of the voices, and likewise that excitatory neurotransmitters may be involved. What we do not know is why hallucinatory episodes occur spontaneously, and why they fluctuate over time, and what makes them spontaneously stop. Moreover, is voice hearing a category or dimension in its own right, independent of diagnosis, and why is the auditory modality predominantly implicated in psychotic disorders, while the visual modality dominates in e.g. neurological diseases?
Keywords : Auditory hallucinations, schizophrenia, fMRI, DTI, neuroimaging, glutamate, dichotic listening
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