Auditory hallucinations, top-down processing and language perception: a general population study.

BACKGROUND: Studies investigating the underlying mechanisms of hallucinations in patients with schizophrenia suggest that an imbalance in top-down expectations v. bottom-up processing underlies these errors in perception. This study evaluates this hypothesis by testing if individuals drawn from the general population who have had auditory hallucinations (AH) have more misperceptions in auditory language perception than those who have never hallucinated. METHODS: We used an online survey to determine the presence of hallucinations. Participants filled out the Questionnaire for Psychotic Experiences and participated in an auditory verbal recognition task to assess both correct perceptions (hits) and misperceptions (false alarms). A hearing test was performed to screen for hearing problems. RESULTS: A total of 5115 individuals from the general Dutch population participated in this study. Participants who reported AH in the week preceding the test had a higher false alarm rate in their auditory perception compared with those without such (recent) experiences. The more recent the AH were experienced, the more mistakes participants made. While the presence of verbal AH (AVH) was predictive for false alarm rate in auditory language perception, the presence of non-verbal or visual hallucinations were not. CONCLUSIONS: The presence of AVH predicted false alarm rate in auditory language perception, whereas the presence of non-verbal auditory or visual hallucinations was not, suggesting that enhanced top-down processing does not transfer across modalities. More false alarms were observed in participants who reported more recent AVHs. This is in line with models of enhanced influence of top-down expectations in persons who hallucinate.

Joint innervation in joint injury.

When considering joint innervation, it is important to appreciate that the joint receptors and the muscle tendon units about the joint interact in a complimentary manner forming a single afferent system. This system remains complex, and its overall function is still relatively unclear. Although the role of joint afferents can not be explicitly described, it is important to appreciate that alterations in joint innervation caused by athletic trauma can occur and can markedly affect joint function.

Neural anatomy of the human anterior cruciate ligament.

The histology of the anterior cruciate ligament was studied by a modified technique of the Gairns gold chloride stain for neural elements. Three morphological types of mechanoreceptors and free nerve-endings were identified: two of the slow-adapting Ruffini type and the third, a rapidly adapting Pacinian corpuscle. Rapidly adapting receptors signal motion and slow-adapting receptors subserve speed and acceleration. Free nerve-endings, which are responsible for pain, were also identified within the ligament. These neural elements comprise 1 per cent of the area of the anterior cruciate ligament.