8, 9 This review briefly summarizes evidence supporting the existence of parallel auditory pathways and draws links between this functional organization, the phenomenology of hallucinations, and current cognitive accounts of AHs. These developments provide a clear framework for understanding and integrating current neural and cognitive models of AHs in schizophrenia and in the normal population. 7Įmerging evidence points to the existence of, at least 2, partially distinct, processing streams in human auditory cortex specialized for the identification (what) and localization (where) of auditory objects. A similar formulation, ie, abnormal object perception, has recently been put forward to account for recurrent complex visual hallucinations, 6 raising the possibility that impaired object perception provides a more general framework underpinning all forms of complex hallucinations. 4, 5 Consequently impairment in high-level (complex) auditory object processing would seem to be a reasonable candidate mechanism. Alternatively, it is possible that a common abnormality underpins these auditory events because, descriptively, both types of experience involve the perception of complex auditory objects. Given this phenomenological diversity, it seems likely that the pathophysiology underlying such phenomena is heterogeneous, involving multiple cognitive and neural mechanisms that are needed to explain both verbal and nonverbal AHs. Phenomenological surveys indicate that almost 60% of patients also report hallucinations involving environmental noises 2 (such as a door banging, a barking dog) and occasionally music, 3 which cannot readily be explained within purely language or speech-based cognitive models. The human voice may, then, be thought of as an “auditory face” 1 involving high-level (complex) perception processes in much the same way as faces are processed in the visual system. Somewhat intriguingly, patients with schizophrenia tend to perceive hallucinated voices more often as male, while the tone of voice is most frequently described as being negative or critical. However, the perception of voice normally entails more than just words it involves the perception of information about speaker identity and vocal affect. Not surprisingly many cognitive explanations of AH have assumed abnormal mechanisms of speech. Obviously, voices carry speech, and in schizophrenia, these may range from single words or short phrases to linguistically complex perceptions of multiple voices conversing or commenting on the voice hearer. Finally, current cognitive explanations of hallucinations, based on intrusive cognitions and impaired source memory, are briefly outlined and set within this framework to provide an integrated cognitive neuropsychological model of auditory hallucinations.Īuditory hallucinations (AHs) in schizophrenia typically involve voices. Then, using recent functional neuroimaging data from healthy subjects and patients with schizophrenia, key phenomenological features of hallucinations are linked to abnormal processing both within and between these pathways. First, the structural and functional organization of auditory what and where pathways is briefly described. The current review offers a reexamination of the nature of auditory hallucinations in schizophrenia using this object-based framework. Recent developments in auditory neuroscience have rapidly increased our understanding of normal auditory perception revealing (partially) separate pathways for the identification (“what”) and localization (“where”) of auditory objects. Auditory hallucinations are generally defined as false perceptions.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |