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Biomedical subjects

R Salmelin

Publications and source records attributed to R Salmelin.

60 records · Page 4Linked to original sources
PubMed1991

Psychosomatic symptoms in preadolescent children.

As part of a Finnish national epidemiological study on child psychiatric disorders, psychosomatic symptoms were studied in a sample (n = 1,100) of 8-year-old children on the basis of self-report questionnaires by the children, their parents and teachers. Psychosomatic symptoms were common, although constant symptoms were rare. There were no sex differences in the occurrence of symptoms, but interesting differences were observed in associations between symptoms and other factors. Psychosomatic symptoms were strongly associated with depression scores and school performance.

Achievement↗
PubMedDate not supplied

Activation of the human occipital and parietal cortex by pattern and luminance stimuli: neuromagnetic measurements.

We compared cortical reactivity to pattern and luminance stimuli by recording evoked responses and spontaneous brain rhythms from 10 subjects with a whole-scalp neuromagnetometer. Hemifield patterns (black-and-white checkerboards) elicited strong contralateral transient activation of the occipital V1/V2 cortex, maximum at 65-75 ms, followed by sustained activation during the 2 s stimulus. Responses to hemifield luminance stimuli also had an occipital component, but they were dominated by activation of the medial parieto-occipital sulcus (POS) 60-70 ms later. The POS region was equally well activated by foveal and extrafoveal stimuli. The occipital responses to hemifield luminance stimuli differed from those to pattern stimuli in two main aspects: the sustained activation was significantly weaker, and the responses were almost symmetrical, indicating a surprisingly bilateral occipital activation. These effects were similar with foveal and extrafoveal stimuli. The spontaneous 10 Hz alpha rhythm, originating predominantly in the POS region, was suppressed after both stimulus onsets and offsets, more strongly for luminance than pattern stimuli. Activation of the occipital cortex dominated after pattern stimuli, whereas the effect of luminance stimulation was stronger in the parieto-occipital region. The distinct signal distributions in the occipital and POS regions suggest that the two types of stimuli activate the magno- and parvocellular pathways to a varying degree. These findings are also in line with a stronger attention-catching value of the luminance than pattern stimuli.

Alpha Rhythm↗
PubMedDate not supplied

Dissociation of normal feature analysis and deficient processing of letter-strings in dyslexic adults.

Neuroimaging studies have revealed that the functional organization of reading differs between developmentally dyslexic and non-impaired individuals. However, it is not clear how early in the reading process the differences between fluent and dyslexic readers start to emerge. We studied cortical activity of ten dyslexic adults using magnetoencephalography (MEG), as they silently read words or viewed symbol-strings which were clearly visible or degraded with Gaussian noise. This method has previously been used to dissociate between analysis of local features and pre-lexical word processing in fluent adult readers. Signals peaking around 100 ms after stimulus onset and originating in the postero-medial extrastriate cortex were associated with increasing local luminance contrast in the noise patches. These early visual responses were similar in dyslexic and non-impaired readers. In contrast, the letter-string-specific responses peaking around 150 ms predominantly in the left inferior occipito-temporal cortex in fluent readers were undetectable in dyslexic readers. Thus, while the early visual processing seems intact in dyslexic adults, the pattern of cortical activation starts to differ from that of fluent readers at the point where letter-string-specific signals first emerge during reading.

Adult↗
PubMedDate not supplied

The pure-tone hearing thresholds of otologically healthy 14-year-old children.

The mean pure-tone air conduction (AC) and bone conduction (BC) hearing thresholds (HT) of 534 randomly selected, caucasian, white, urban children with normal otoscopy, otomicroscopy and impedance audiometry, i.e. normal middle ear function, are presented here. Children with pathological middle ear findings or abnormal impedance audiometry were excluded. The average age was 13.8 years, SD 0.5, at the date of examination. The mean air conduction thresholds varied between 0.6 dB at 1 kHz and 9.9 dB at 6 kHz, and the bone conduction thresholds varied between -1.1 dB at 0.5 kHz and 1.1 dB at 4 kHz. The pure-tone average (PTA) (the average of AC hearing thresholds of 0.5, 1 and 2 kHz) of all ears was 1.5 dB. Ninety to ninety-eight per cent of pure-tone AC hearing thresholds at frequencies of 0.5-4 kHz were between -5 dB and 10 dB. The distributions are presented and compared.

Adolescent↗