Crow further considered that, arising from this evolutionary event, schizophrenia could be seen as an epiphenomenon of a failure to establish hemispheric specialization for language 8, 13, 14. From an evolutionary perspective, Crow proposed that a “saltational genetic change” which occurred between 100 and 250 thousand years ago allowed the two cerebral hemispheres to develop somewhat independently, laying the foundation for language to evolve 13. Bleuler argued that “looseness of associations” in thought, speech and other psychological functions is a core feature of schizophrenia 12. Kraepelin described one form of dementia praecox as “an unusually striking disorder of expression in speech, with relatively little impairment of the remaining psychic activities” 11. By examining the relative weight of patients’ two cerebral hemispheres, Crichton-Browne suggested that, in the course of schizophrenia development, the left hemisphere may suffer first 1, implying that cortical language-related brain regions might be affected. The study of the language system in schizophrenia has a long tradition. While these phenomena appear ostensibly varied, they can be conceptually traced to a shared pathophysiological and neurocognitive substrate: the language system 7, 8, 9, 10. Besides, several pragmatic, semantic and syntactic processing deficits are seen across all stages of schizophrenia (for reviews, see 6, 7). Delusions are also viewed as a disturbance in the referential use of language 5. Disrupted speech productions (e.g., derailment, tangentiality, and thought block), reduced verbal output (the negative symptom of alogia), and aberrant speech perceptions (e.g., hearing “voices” in the absence of acoustic-linguistic stimuli) are hallmark symptoms and diagnostic criteria for schizophrenia 3, 4. ![]() Schizophrenia is a neuropsychiatric disorder involving several language disturbances 2. Investigations of language pathology in schizophrenia could facilitate the development of diagnostic tools and treatments, so we call for multilevel confirmatory analyses focused on modulations of the language network as a therapeutic goal in schizophrenia. We argue that these observations converge into the possibility that a glutamatergic dysfunction in language-processing brain regions might be a shared neural basis of both FTD and AVHs. Third, genetic findings further show how genes that overlap between schizophrenia and language disorders influence neurodevelopment and neurotransmission. ![]() Second, neurochemical studies point to a glutamate-related dysfunction in these language-processing brain regions, contributing to verbal production deficits. First, neuroanatomical evidence indicates substantial shared abnormalities in language-processing regions between FTD and AVHs, even in the early phases of schizophrenia. In this review, we synthesize observations from three key domains. Epidemiological and experimental evidence points to an overlap between FTD and AVHs, yet a thorough investigation examining their shared neural mechanism in schizophrenia is lacking. ![]() From an evolutionary perspective, Crow (1997) proposed that “schizophrenia is the price that Homo sapiens pays for the faculty of language”. In schizophrenia, formal thought disorder (FTD) and auditory verbal hallucinations (AVHs) are manifestations respectively relating to concrete disruptions of those abilities. ![]() Both the ability to speak and to infer complex linguistic messages from sounds have been claimed as uniquely human phenomena.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |