Akademik

(VAH)

   Also known as auditory verbal hallucination, voice hallucination, phoneme, hallucinated speech, and 'voices'. All five terms are used to denote a subclass of the group of *auditory hallucinations, the content of which is verbal in nature. The expressions verbal auditory hallucination (VAH) and auditory verbal hallucination (AVH) refer to the same phenomenon, and in most cases they may be used interchangeably. And yet the two terms have a slightly different connotation, due to the different conceptual backgrounds from which they stem. By definition, VAHs are primarily auditory in nature. They are distinguished from other auditory hallucinations (i.e. *musical hallucinations, *nonverbal auditory hallucinations) by means ofthe adjective verbal. The notion of the AVH, on the other hand, refers to a type of hallucination that is primarily verbal in nature and is distinguished from other verbal hallucinations (such as * psychomotor verbal hallucinations and * visual verbal hallucinations) by means of the adjective auditory. Phe-nomenologically, VAHs consist of one or more voices which are experienced as coming from within the head (i.e. *internal auditory hallucinations) or from outside the head (i.e. * external auditory hallucinations). In some cases the difference may be unclear, and in other cases voices may swap their perceived location. VAHs may be benign or malignant in nature, in the sense thattheymaygivevaluableadviceormakepleas-ant comments, or they may insult or threaten the affected individual. When they consist of spoken orders or incentives, they are referred to as command hallucinations or *imperative hallucinations. They may also give a running commentary on the individual's thoughts or behaviour. They may speak in a regular tone of voice, whisper or shout, and they may be intelligible or unintelligible. When voices are unintelligible, this may be because they are muffled, faint or far-off, because they speak in a foreign language, or because they are masked by other voices or nonverbal sounds. In clinical practice the assertion that voices are unintelligible is not seldom a euphemism for their impudent content, which is often of a sexual or aggressive nature. Regarding their pathophysiol-ogy, VAHs are associated with aberrant neuro-physiological activity in the left temporal lobe, more specifically, the gyrus temporalis superior, Heschl's gyrus, the planum temporale, and the speech areas (i.e. Broca's area and Wernicke's area). However, findings from functional imaging studies suggest that the right homologue of Broca's area may also be involved in the mediation of VAHs. Parallel to the work of such scientists as the American psychologist Julian Jaynes (1920-1997) and the British psychiatrist Timothy Crow, it has been hypothesized that this may be a sign of incomplete lateralization of language functions in the brain. Moreover, it has been hypothesized that cortical hallucinatory activity may be preceded by subcortical activity, notably in the limbic system and amygdala. Theoretically, this would make sense if the hallucinations are interpreted as * reperceptions of priorly memorized speech. When voices are attributable to the top of the brainstem and/or its surrounding midbrain structures, the term * brainstem auditory hallucinosis is used. For further details on VAHs see the entries Auditory hallucination, Auditory illusion, Auditory pareidolia, Auditory verbal hallucination, Gedankenlautwerden, Subvocaliza-tion, and Verbal hallucination.

   References

   Blom, J.D., Sommer, I.E.C. (2009). Auditory hallucinations. Cognitive and Behavioral Neurology (in press).

   Sommer, I.E.C., Aleman, A., Kahn, R.S. (2003). Left with the voices or hearing right? Later-alization of auditory verbal hallucinations in schizophrenia. Journal of Psychiatry and Neuroscience, 28, 17-18.

   Sommer, I.E.C., Diederen, K.M.J., Blom, J.D., Willems, A., Kushan, L., Slotema, K., Boks, M.P.M., Daalman, K., Hoek, H.W., Neggers, S.F.W., Kahn, R.S. (2008). Auditory verbal hallucinations predominantly activate the right inferior frontal area. Brain, 131, 31693177.

   Sommer, I.E.C., Kahn, R.S., eds. (2009). Language lateralization and psychosis. Cambridge: Cambridge University Press.