Decomposing neural responses to melodic surprise in musicians and non-musicians: Evidence for a hierarchy of predictions in the auditory system.

Neural responses to auditory surprise are typically studied with highly unexpected, disruptive sounds. Consequently, little is known about auditory prediction in everyday contexts that are characterized by fine-grained, non-disruptive fluctuations of auditory surprise. To address this issue, we used IDyOM, a computational model of auditory expectation, to obtain continuous surprise estimates for a set of newly composed melodies. Our main goal was to assess whether the neural correlates of non-disruptive surprising sounds in a musical context are affected by musical expertise. Using magnetoencephalography (MEG), auditory responses were recorded from musicians and non-musicians while they listened to the melodies. Consistent with a previous study, the amplitude of the N1m component increased with higher levels of computationally estimated surprise. This effect, however, was not different between the two groups. Further analyses offered an explanation for this finding: Pitch interval size itself, rather than probabilistic prediction, was responsible for the modulation of the N1m, thus pointing to low-level sensory adaptation as the underlying mechanism. In turn, the formation of auditory regularities and proper probabilistic prediction were reflected in later components: The mismatch negativity (MMNm) and the P3am, respectively. Overall, our findings reveal a hierarchy of expectations in the auditory system and highlight the need to properly account for sensory adaptation in research addressing statistical learning.

Pain, referred sensations, and involuntary muscle movements in brachial plexus injury.

OBJECTIVES: Examination of the relationship between pain, sensory hypersensitivity, referred sensations and involuntary muscle jerks in patients with brachial plexus injury. MATERIALS AND METHODS: Fourteen patients with brachial plexus lesions were included. Spontaneous background and paroxysmal pain and mechanically and thermally evoked pain were recorded. Areas with sensory hypersensitivity and referred pain were mapped on a body chart. This was supplemented by electrophysiological analysis in three patients. RESULTS: Sensory hypersensitivity and areas with pinprick-induced referred phantom sensations were present in adjacent dermatomes. There was no clear relationship between chronic neuropathic pain and referred sensations, but there was a correlation between pain paroxysms and sensory hypersensitivity in dermatomes adjacent to deafferented areas. In three patients, simultaneous referred sensations and short latency motor action potentials ipsilateral to the denervated side suggested origin at subcortical sites. CONCLUSION: The study suggests a possible role of a spinal generator for sensory hypersensitivity and referred sensations following denervation.

[Patient consultation via broad-band network--pilot project in hand surgery]. / Patientundersøgelse via bredbånd--et håndkirurgiprojekt.

A pilot project launched at Esbjerg was designed to ascertain whether broad-band audiovisual transmission of clinical examination can replace direct contact between patient and physician, and if so to what extent. Provided the technique can be improved and simplified, video consultation is an obvious and economically advantageous alternative to referral to a specialised tertiary clinic. Not only will the technique need to be further tested and improved, however, but doctors will require training in the assessment of moving two-dimensional images and diagnosis via a visual display unit (VDU).

Median artery in carpal tunnel syndrome.

Among the large group of carpal tunnel syndromes, it is possible to distinguish two distinct entities, which are related to a persistent median artery. The first is associated with thrombosis, which causes a sudden onset of pain and paresthesia, often severe, while the second is associated with a normal median artery. In the latter case, symptoms predominate during work, and the physical signs are inconsistent. For both entities, the patients are fairly young, with a mean age of 33.6 years. Resection of the artery is recommended after ensuring an adequate arterial supply to the fingers.