Abstract
Which aspects of language and cognitive processing take place irrespective
of whether subjects focus their attention on incoming stimuli and
are, in this sense, automatic? The Mismatch Negativity (MMN), a neurophysiological
brain response recorded in the EEG and MEG, is elicited by attended
and unattended stimuli alike. Recent studies investigating the cognitive
processes underlying spoken language processing found that even under
attentional withdrawal, MMN size and topography reflect the activation
of memory traces for language elements in the human brain. Familiar
sounds of one's native language elicit a larger MMN than unfamiliar
sounds, and at the level of meaningful language units, words elicit
a larger MMN than meaningless pseudowords. This suggests that the
MMN reflects the activation of memory networks for language sounds
and spoken words. Unattended word stimuli elicit an activation sequence
starting in superior-temporal cortex and rapidly progressing to left-inferior-frontal
lobe. The spatio-temporal patterns of cortical activation depend
on lexical and semantic properties of word stems and affixes, thus
indicating that the MMN can give clues about lexico-semantic information
processing stored in long term memory. At the syntactic level, MMN
size was found to reflect whether a word string conforms to abstract
grammatical rules. This growing body of results suggests that lexical,
semantic and syntactic information can be processed by the central
nervous system outside the focus of attention in a largely automatic
manner. Analysis of spatio-temporal patterns of generator activations
underlying the MMN to speech may be an important tool for investigating
the brain dynamics of spoken language processing and the activated
distributed cortical circuits acting at long-term memory traces.
- acoustic
- methods,animals,attention,attention:
- methods,humans,language,magnetoencephalography,magnetoencephalography:
- methods,speech,speech:
- physiology
- physiology,cognition,cognition:
- physiology,electroencephalography,electroencephalography:
- stimulation,acoustic
- stimulation:
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