ABSTRACT
We report an infant with severe hypotonia, feeding problems and failure to thrive in the neonatal period, followed by developmental delay. In addition, pale skin, eyelid and pedal edema, cryptorchidism and micrognathia were present. The tentative diagnosis of Prader-Labhart-Willi syndrome was made and confirmed by specific molecular testing at the age of 5 months. The Prader-Labhart-Willi syndrome is usually diagnosed in older infants when the main clinical features such as obesity, short stature, hypogonadism and developmental delay become obvious, in most of the patients typical clinical features are present already in the neonatal period. In conclusion, in neonates and young infants presenting with hypotonia and feeding problems, the Prader-Labhart-Willi syndrome should be considered.
Subject(s)
Prader-Willi Syndrome/diagnosis , Ribonucleoproteins, Small Nuclear , Autoantigens/genetics , Chromosomes, Human, Pair 15 , Diagnosis, Differential , Humans , Infant , Infant, Newborn , Male , Neurologic Examination , Polymerase Chain Reaction , Prader-Willi Syndrome/genetics , snRNP Core ProteinsABSTRACT
Motor inhibition and its correlates in the event-related potential (ERP) are often studied in go/nogo tasks. However, go and nogo trials differ in their motor and their attentional requirements, rendering an interpretation of corresponding changes in ERP components difficult. As an alternative strategy to study motor inhibition, a hybrid choice-reaction go/nogo procedure involving selective response priming was used. Eighteen subjects performed the task. Response time (RT) and error measures as well as the lateralized readiness potential (LRP) indicated that responses were primed by flanker stimuli that were associated with one of the two possible responses. In nogo trials, selective response priming influenced the N2 amplitude whereas the P3 amplitude was unaffected. Because the N2 appeared irrespective of whether an erroneous response was correctable (in go trials) or not (in nogo trials), we conclude that the N2 reflects either the detection or the inhibition of an inappropriate tendency to respond.
Subject(s)
Brain/physiology , Contingent Negative Variation/physiology , Functional Laterality/physiology , Adult , Analysis of Variance , Electroencephalography , Evoked Potentials/physiology , Female , Humans , Male , Task Performance and AnalysisABSTRACT
Event-related potentials were recorded in a flanker task using arrowheads pointing to the left or to the right as targets and as congruent or incongruent flanker stimuli using squares as neutral flanker stimuli. The onset of the flanker stimuli preceded that of the target stimuli by 100 ms. Lateralized readiness potentials showed response activation below execution threshold in correspondence to the information conveyed by the flanker stimuli. Exclusively, the incongruent flanker condition provoked a N2c, which evolved closely synchronized to the erroneous response. Graded response analyses separating incongruent trials with weak, medium, and strong incorrect response activation revealed that the N2c amplitude covaried with the magnitude of the erroneous response. The N2c in the incongruent compatibility condition of the flanker task thus corresponds to the avoidance of inappropriate responses, possibly reflecting the inhibition of automatically but erroneously primed responses. The results are compatible with studies of error correction, suggesting that efference monitoring is a constituent of executive control.
Subject(s)
Evoked Potentials/physiology , Psychomotor Performance/physiology , Adult , Electroencephalography , Female , Functional Laterality/physiology , Humans , MaleABSTRACT
Visual distractibility was studied in schizophrenic patients. Subjects had to respond to target stimuli while they ignored the visual context, which was either congruent, neutral, or incongruent with respect to the target stimulus. Eighteen schizophrenic patients and 18 healthy subjects performed this flanker task. Schizophrenic patients did not show increased distractibility compared with healthy subjects, and both groups showed the same attenuation of visual context effects when the spatial distance between target and flanker stimuli was increased. The two groups showed the same amount of interference by incongruent visual context. Thus, schizophrenic patients did not show enhanced distractibility, spatial extension of attention, or response competition. When flanker and target stimuli were redundant, the responses of schizophrenic patients were less accelerated than those of healthy subjects.
