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Simone Lang

Publications and source records attributed to Simone Lang.

7 recordsLinked to original sources
PubMed2006

Precursors of insight in event-related brain potentials.

Event-related potentials (ERPs) were investigated to find precursors of insightful behavior. Participants had to process successive pairs in strings of digits to obtain a final response in each trial. Within the sequence of five responses required in each trial, the last two responses mirrored the two preceding ones. This hidden regularity, allowing for shortcutting each trial from five to two responses, was discovered by 6 out of 26 participants. Both groups, solvers and nonsolvers, implicitly learned the regularity, reflected by faster responses to the repeated, predictable responses, but this differential effect was larger in solvers, whereas nonsolvers became unspecifically faster with all responses. Several ERP components were larger in solvers than in nonsolvers from the outset: slow positive wave, frontocentral P3a, anterior N1 to those digits that triggered the critical repeating responses, and P3b to the digit that evoked the immediately repeating response. Being already present in the first block, these effects were early precursors of insightful behavior. This early occurrence suggests that participants who will gain insight may be distinguished beforehand by their individual characteristics.

Adult↗
PubMed2005

Pectin-chitosan multilayer formation.

The deposition of alternating layers of pectin and chitosan at a solid surface was studied using surface plasmon resonance. The binding of biopolymer to the surface was irreversible over the time scales examined. The deposition was dependent on the flow rate through the measurement cell with mass transport limitation at lower flow rates. The thickness of the deposited layer was dependent on the biopolymer concentration and was particularly marked for pectin. This was consistent with a process of initial attachment, followed by a slower structural rearrangement, which was inhibited at high initial surface concentrations of adsorbed biopolymer. Sequential deposition resulted in the formation of multilayers with an essentially linear growth rate.

Adsorption↗
PubMed2003

Parallel processing of physical and lexical auditory information in humans.

We usually process auditory information at the physical level (e.g., pitch or side of presentation) and the formal level (e.g., semantic or syntax) simultaneously. However, most physiological studies investigate either the former or the latter level of processing. In this experiment, words belonging to three lexical categories (nouns, verbs, and adverbs) were randomly presented to the right or left ear. Participants were required to count all nouns presented on the relevant side. All side-relevant stimuli elicited two negativities between 100-250 and 450-650 ms post-stimulus. Nouns yielded more positive potential amplitudes between 200 and 700 ms than verbs and adverbs. This effect was observed for words presented in both relevant and irrelevant ear, i.e., it was independent of whether nouns were targets or not. After 600 ms post-stimulus, a P300-like wave was recorded to target nouns only. This component was maximal at left temporal sites. The data contradict the hierarchic processing hypothesis (first side selection, then target selection) and indicate parallel processing of physical and lexical information. Implications for the issue of language specificity of brain potentials are discussed.

Adult↗
PubMed2003

Event-related brain potentials in a patient with akinetic mutism.

The clinical pattern of complete akinetic mutism (AM) was observed in a patient with a bilateral infarction of the anterior cerebral arteries extending to the rostral cingulate cortex and the supplementary motor areas. Since the patient was unable to produce any overt response, event-related brain potentials (ERPs) were used to obtain information about cortical processing of stimuli. Oddball tasks with simple acoustical stimuli and semantic categories were used. Verbal processing was further assessed by comparing event-related potentials to words compatible versus incompatible to the semantic context. Although the pattern of cortical responses was abnormal, differential responses were clearly obtained to semantically different word classes. Thus, the hypothesis about cortical non-responsivity of AM patients, drawn from several previous reports, was not supported. An ERP examination in AM patients can deliver information about their mental state, provided that the stimuli and tasks possess a wide range of informational complexity and motivational value.

Akinetic Mutism↗
PubMed2002

Brain responses to number sequences with and without active task requirement.

OBJECTIVE: To examine the effect of the active task involvement versus the passive knowledge of the structure of the stimulation on event-related potentials (ERPs) to violation in number sequences. This should contribute to future development of an ERP test for neurological patients. METHODS: ERPs were recorded in subjects who listened to 4-item sequences of numbers incrementing by one. Half of the sequences had an appropriate end item, whereas the other half ended inappropriately. The role of active versus passive condition was investigated in a between-subject design. RESULTS: Incorrectly ending sequences yielded a large P300 wave in all groups. Subjects who were explicitly informed about the nature of the stimulation but did not have a motor task displayed a slow negativity which followed P300 and slightly suppressed it. In addition, incorrect sequence endings elicited an early (70-200 ms) negativity at frontal sites. This effect was inverted on mastoids. CONCLUSIONS: Auditory perception of 3 consecutive numbers constituting a simple incrementing row leads to building a strong expectancy concerning the subsequent number, and unexpected events are detected already after the initial phoneme.

Acoustic Stimulation↗
PubMed2002

Is there a mind? Electrophysiology of unconscious patients.

Event related brain potentials (ERPs) provide information about cortical processing in severe neurological patients whose cognitive abilities cannot be expressed in their behavior. In coma, ERPs contribute to the prediction of the outcome. In a vegetative state, ERPs uncover the functional state of cortical processes. The significance of ERPs in the neurophysiological study of consciousness is discussed.

Cerebral Cortex↗