Hemispheric lateralization in preattentive processing of speech sounds.

Event-related magnetoencephalographic (MEG) responses to infrequently presented spoken deviant syllables [di] and [ba] among repetitive standard [da)]syllables were recorded in subjects who either attended to these stimuli in order to discriminate the [ba] syllables or ignored them while attending a silent movie. In both conditions, the deviant syllables elicited a mismatch response (MMNm, the magnetic counterpart of mismatch negativity), which was stronger in the left than in the right auditory cortex, indicating left-hemispheric dominance in speech processing already at a preattentive processing level.

Phonetic invariance in the human auditory cortex.

Neuromagnetic signals evoked by synthesized syllables (/bae/ and /gae/) were recorded over the left auditory cortex of healthy humans. The fundamental frequencies of the syllables varied as if the same speaker had pronounced them at 16 different pitches. Specific mismatch responses to infrequent syllables among frequent syllables of the other type indicated that phonetically invariant information had been extracted at the level of the auditory cortex from the extensive irrelevant pitch variation.

Seeing speech: visual information from lip movements modifies activity in the human auditory cortex.

Neuromagnetic responses were recorded over the left hemisphere to find out in which cortical area the heard and seen speech are integrated. Auditory stimuli were Finnish/pa/syllables presented together with a videotaped face articulating either the concordant syllable/pa/(84% of stimuli, V = A) or the discordant syllable/ka/(16%, V not equal to A). In some subjects the probabilities were reversed.

Event-related potentials to infrequent changes in synthesized phonetic stimuli.

Event-related potentials (ERPs) to synthetic consonant-vowel syllables were recorded. Infrequent changes in such a syllable elicited a "mismatch negativity" as well as an enhanced N100 component of the ERP even when subjects did not pay attention to the stimuli. Both components are probably generated in the supratemporal auditory cortex suggesting that in these areas there are neural networks that are automatically activated by speech-specific auditory stimulus features such as formant transitions.

Sound spectrographic cry analysis of infants with hydrocephalus.

Altogether 248 cries from 62 infants with hydrocephalus were analysed by sound spectrography: 92 cries from infants with congenital hydrocephalus and 52 cries from each of the groups with cerebral malformations, hydrocephalus as sequelae of meningitis, and after closure of a meningomyelocele. The cries were compared with 104 cries of normal healthy infants of corresponding age. The cry analysis showed that the most abnormal cries were seen in infants with congenital hydrocephalus and cerebral malformations.