| 1. |
- Kujala, A, et al.
(författare)
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Speech-sound discrimination in neonates as measured with MEG
- 2004
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Ingår i: NeuroReport. - 1473-558X. ; 15:13, s. 2089-2092
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic brain responses to speech sounds were measured in 10 healthy neonates. The stimulation consisted of a frequent vowel sound [a] with a steady pitch contour, which was occasionally replaced by the vowel [i:] with a steady pitch, or the vowel [a] with a rising pitch, manifesting a change of intonation. The magnetic mismatch-negativity response (MMNm) was obtained and successfully modelled to the speech sound quality change in all infants and to the intonation change in 6 infants. The present results indicate that auditory-cortex speech-sound discrimination may well be studied with magnetic recordings as early as in newborn infants.
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| 2. |
- Nissila, I, et al.
(författare)
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Auditory hemodynamic studies of newborn infants using near-infrared spectroscopic imaging
- 2004
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Ingår i: IEEE Engineering in Medicine and Biology Society. Conference Proceedings. - 1557-170X. ; 2, s. 1244-1274
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Tidskriftsartikel (refereegranskat)abstract
- The noninvasive study of tissue blood volume and oxygenation using near-infrared light is a new and actively developing technology. We have used near-infrared spectroscopic imaging (NIRSI) to study hemodynamic responses on the auditory cortices evoked by auditory stimulation. Ten healthy newborn infants were studied. The otoacoustic emission hearing test was performed for each infant. Pulse oximetry was used to monitor the heart rate during the measurement, video recording was used to monitor motion artifacts, and the eye movements were noted in order to determine sleep stage. A 16-channel frequency-domain optical imaging system developed in our laboratory was used for NIRSI measurements. The stimuli were presented in trains of seven 1 kHz beeps with 700-ms inter-stimulus intervals. The stimulus trains were separated by 25-s silent periods in order to allow for the hemodynamic delay. In 3/8 cases, we obtained a clear bilateral increase in [HbO/sub 2/], and in two additional cases, a clear response on one hemisphere. The mean change in [HbO/sub 2/] was +0.9+/-0.9muM and the mean change in [Hb] was -0.3+/-0.4muM for those channels producing the largest response for each subject. No statistically significant response was found in 3/8 cases.
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| 3. |
- Ruusuvirta, T, et al.
(författare)
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Newborn human brain identifies repeated auditory feature conjunctions of low sequential probability
- 2004
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 20:10, s. 2819-2821
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Tidskriftsartikel (refereegranskat)abstract
- Natural environments are usually composed of multiple sources for sounds. The sounds might physically differ from one another only as feature conjunctions, and several of them might occur repeatedly in the short term. Nevertheless, the detection of rare sounds requires the identification of the repeated ones. Adults have some limited ability to effortlessly identify repeated sounds in such acoustically complex environments, but the developmental onset of this finite ability is unknown. Sleeping newborn infants were presented with a repeated tone carrying six frequent (P = 0.15 each) and six rare (P similar to0.017 each) conjunctions of its frequency, intensity and duration. Event-related potentials recorded from the infants' scalp were found to shift in amplitude towards positive polarity selectively in response to rare conjunctions. This finding suggests that humans are relatively hard-wired to preattentively identify repeated auditory feature conjunctions even when such conjunctions occur rarely among other similar ones.
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| 4. |
- Ruusuvirta, T, et al.
(författare)
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The newborn human brain binds sound features together
- 2003
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Ingår i: NeuroReport. - 1473-558X. ; 14:16, s. 2117-2119
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Tidskriftsartikel (refereegranskat)abstract
- To process a stimulus as a holistic entity, the human brain must be able to conjoin its different features. Previous evidence suggests that this ability emerges during the first months of life, implying its considerable dependence on postnatal development. We recorded human newborn (1-3 days of age) electrical brain responses to frequently occurring (standard) sounds and to rarely occurring (deviant) sounds in a series. Responses to deviants differed from those to standards despite the fact that only the combination of sound frequency and intensity could be used as a cue for discriminating between these sound types. Our finding suggests that the human brain is ready for auditory feature binding very soon after birth.
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