When a patient cafflicted with schizophrenia hears inner voices something is taking place inside the brain that prevents the individual from perceiving real voices. A simple electronic application may help the patient learn to shift focus.
"The patient experiences the inner voices as 100 per cent real, just as if someone was standing next to him and speaking" explains Professor Kenneth Hugdahl of the University of Bergen. "At the same time, he can't hear voices of others actually present in the same room."
Auditory hallucinations are one of the most common symptoms associated with schizophrenia.
Neural activity ceases
Dr Hugdahl's research group has made use of a variety of neuroimaging techniques, including functional magnetic resonance imaging technology (fMRI) to enable them quite literally to see what happens inside the brain when the inner voices make their presence known. The project received funding under the NevroNor national initiative on neuroscientific research administered under the auspices of the Research Council of Norway
Images of patients' brains reveal a spontaneous activation of neurons in a particular area of the brain - specifically the rear, upper region of the left temporal lobe. This is the area responsible for speech perception, and when healthy people hear speech it becomes activated. So what happens when patients with schizophrenia hear a real voice and a hallucinatory one at the same time?
"It would be natural to assume that neural activity would increase somewhat - even twofold. But quite the opposite takes place; we actually observed that the activity ceased altogether," states Professor Hugdahl.
Losing contact with the outside world
In order to learn more about what was happening, Hugdahl and his colleagues Kristiina Kompus and René Westerhausen carried out a meta-analysis of 23 studies. These studies focused either on spontaneous inner-voice triggered neural activation in subjects with schizophrenia or the stimulatory reaction prompted by actual sounds in both healthy and schizophrenic subjects.
It emerged that many researchers had observed either that a spontaneous activation of neurons occurs in patients hearing inner voices or that the patients' perception of actual voices becomes suppressed when these are heard simultaneously with inner voices. No one had seen the connection between these findings.
"Previously, we thought these were two separate phenomena. But our analyses revealed that the one causes the other: when neurons become activated by inner voices it inhibits perception of outside speech. The neurons become 'preoccupied' and can't 'process' voices from the outside," explains Professor Hugdahl.
"This may explain why schizophrenic patients close themselves off so completely and lose touch with the outside world when experiencing hallucinations," he purports.
Electronic app designed to improve impulse control