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Biomedical subjects

B Van Sweden

Publications and source records attributed to B Van Sweden.

At least 19 recordsLinked to original sources
PubMed1998

Impaired early visual processing in disorganised schizophrenia.

Topographic differences in flash/pattern shift VEP data are evaluated in paranoid (n: 38), disorganized (n: 23) and residual (n: 23) schizophrenic subtypes and compared to normal controls. Increased early P1 and a restricted diffusion of the late P2 responses suggest dopaminergic over- and cholinergic underactivity in paranoid and residual schizophrenia. A distinctive pattern N145 reflects well-preserved attentional resources in the paranoid subtype. Latency increase and amplitude decrease of the pattern N145 concur with abnormal antisaccades documented in disorganized behaviour. VEP-data might help differentiate between schizophrenic subtypes.

Adult↗
PubMed1997

Auditory vertex potential in children: a cognitive hypothesis.

In children the early N1P2 response generated by an auditory oddball paradigm is a compound negative potential with distinctive 165-ms temporal and 240-ms frontocentral components. As this configuration differs considerably from the adult response, it may be assumed that neural systems engaged in auditory attentional processes differ with age. It is argued that the auditory vertex potential might index frontal lobe development and matching mechanisms. In combination with EEG spectral data this cognitive parameter could initiate an alternative approach to the evaluation and research of learning and attention deficit disorders.

Adult↗
PubMed1997

Auditory information processing in schizophrenia.

Early N1P2 and late N2P3 responses generated in an auditory oddball paradigm are topographically compared in three psychiatric patient groups. In schizophrenia N1 and N2 amplitude is comparable with dementia and significantly decreased with respect to affective disorder. In contrast, P3 amplitude does not allow discriminating schizophrenia from affective disorder but is significantly diminished in dementia. The late N2P3 response shows a topographic effect along the fronto-occipital axis. Schizophrenia is characterized by an iCNV and N2 maximum over the frontal planes and a compound P3 lacking distinct frontal and parietal components. The findings are discussed in reference to literature data and current hypotheses/theories concerning information processing. Our findings favour an important dysfunction of automatic processing including early selection in schizophrenia.

Adult↗
PubMed1997

Facilitation of early and masking of late cortical responses in dementia.

Topographic differences in longlatency SSEP and flash VEP data are compared in 3 different psychiatric patient groups. Differences between schizophrenia and affective disorder are restricted to somatosensory P100 amplitude gradients along the antero-posterior axis. In contrast EP-differences between psychiatric patients and dementia are prominent, encompassing both late and early (< 100 ms) responses. Our flash P 2 and somatosensory P 3 data are in accordance with previous findings. Multi-modal positive responses with a latency of 40-80 ms are significantly increased in dementia. This facilitation suggests cortical dysfunction and/or subcortical gating impairment.

Adult↗
PubMed1996

Sleep and the temporal lobe.

The main interest in the association between sleep and temporal lobe dysfunction is based on the activation of ictal and interictal epileptic phenomena. The clinical semiology of NREM and REM parasomnias may resemble complex partial seizures. The differentiation between epilepsy and dissociated states of wakefulness and sleep is of high diagnostic and therapeutic importance. Systems within temporal lobe structures are also responsible for disturbed sleep or dyssomnia. The limbic brain is connected with different nodal points in the network underlying sleep organisation and participates in both sleepinducing and arousal mechanisms. Experimental amygdala kindling, an animal epilepsy model involving temporal structures, induces disturbed sleep patterns favouring waking and light sleep. In epilepsy unstable disrupted and superficial sleep patterns prevail without overt seizures. Sleep-fragmentation and deprivation may impair daytime functioning and cognitive performance by lowering the seizure-threshold. The recognition of dyssomnia and of excessive sleepfragmentation and sleepiness has obvious implications for behavioural and drug treatment.

Adult↗
PubMed1994

Auditory information processing in sleep: late cortical potentials in an oddball paradigm.

Information processing of auditory stimuli in sleeping healthy volunteers is studied by means of an oddball paradigm. Latencies of the early (N1P2) complex are affected by NREM sleep depth and show a progressive slowing. The amplitude of the early N1 component depends on stimulus type and probability and is increased following deviant stimuli. In strict comparison with waking, late responses (N2-P3) complex only follows deviant stimuli. Both latencies and amplitude increase more in NREM than in REM sleep. Thus the early response is mainly affected by vigilance, the late response mainly depends on stimulus type. Results are discussed in terms of comparison processing, context updating and orienting response patterning hypotheses put forward in cognitive psychophysiology.

Adult↗
PubMed1991

Variability of normal sleep patterns in 40 consecutive ambulatory sleep-wakefulness records.

Sleep-wakefulness (S-W) patterns were recorded continuously for 40 consecutive 24 h using subcutaneous chronic electrodes and an ambulatory cassette recorder in a healthy 57-year-old volunteer. Variability of sleep patterns was assessed in steady-state conditions and in the course of a scientific journey encompassing flights in both west/east and south/north directions. Data were compared with findings from age-matched laboratory control records. Polysomnographic evaluation of our sleep data shows: (1) Stability of the first 3 sleep cycles and variability of the remaining sleep period with respect to both duration and structure. Vulnerability of REM sleep to environmental interference. (2) Stability of the WASO/drowsiness cluster as an intraindividual biological trait independent of social interactions. The clinical relevance of ambulatory serial recording is stressed. (3) The role of the first sleep cycle structure in the chronobiological adaptation process is documented. Apparently travelling in south/north directions may have similar or even more polygraphic implications than west/east transfer.

Chronobiology Phenomena↗
PubMed1991

Long-term EEG monitoring in the early premature: developmental and chronobiological aspects.

Long-term cassette EEG monitoring in the neonatal intensive care unit has established prognostic criteria regarding the developmental outcome by quantifying seizure activity. The clinical significance of the organization of continuous and discontinuous EEG patterns in the early premature is still an open question. This report presents quantified EEG data from repeated 24 h records during the first week of life in premature infants (conceptional age less than 32 weeks) with and without ultrasound evidence of intracerebral hemorrhage. The repartition and evolution of EEG background activity is not a reliable parameter regarding pathology. The continuity index is rather a maturational variable and its ultradian fluctuation is an early expression of the "basic rest activity cycle" (BRAC) rhythm.

Aging↗
PubMed1990

Habituation of K-complexes or event-related potentials during sleep.

We examined habituation and dishabituation of evoked K-complexes (equivalent to auditory event-related potentials) during sleep. Habituation is investigated by presenting trains of stimuli with a 5 sec inter-stimulus interval and a 4 min inter-train interval. Habituation is complete by the third identical stimulus in a train and dishabituation occurs after deviant stimuli and after the inter-train interval. Although there are morphological differences between K-complexes in sleep and auditory event-related potentials in wakefulness, they share the phenomenon of habituation to repetitive events.

Acoustic Stimulation↗