In this fMRI study we investigated a simulation of this learning process.We used three sets of noise-vocoded (i.e., cochlear implant simulated) speechstimuli with a different number of spectral bands (4-bands, 8-bands, and 16-bands) and unprocessed speech. Noise-vocoded stimuli were constructed byextracting the temporal envelope of the original stimuli, and using it tomodulate filtered white noise. We recruited 20 normal subjects assigning halfof them to the experimental group and half to the control group. Theexperimental group alone was exposed for a period of time to noise-vocodedspeech in the three conditions of interest.

We investigated the brain network supporting the recognition of CIsimulated speech with fMRI acquisitions before and after the training phase.For both groups, the level of intelligibility pre- and post-training wascompared. The experimental group profited from the learning process andshowed an increased level of intelligibility for the higher impoverished noise-vocoded speech (4-bands condition). For this group we found increasedactivation in the orbitofrontal and cerebellar cortices that correlated to theenhanced intelligibility. On the contrary, no increase in intelligibility, and nodifferentially activated brain sites were observed for the control group afterthe same period of time.

These results shed light on the perceptual learning process that cochlearimplantees undergo adapting to the new artificially reconstructed speechstimuli. The present study uncovers training-induced plasticity of the corticalnetworks that allow speech decoding.

doi:10.1016/j.ijpsycho.2008.05.072

Greater N400 repetition effect indicates development of recognitionmemory in primary-school children

E.A. De Bruina, V.E.G. Martensa, J.C. Glimmerveenb, J.W. Van Strienb

a Consumer Perception & Behaviour, Unilever Food and Health ResearchInstitute, Vlaardingen, The Netherlandsb Institute of Psychology, Faculty of Social Sciences, Erasmus UniversityRotterdam, Rotterdam, The Netherlands

In adults, aspects of recognition memory such as implicit and consciousrecollection are reflected by particular ERP components, respectively theN400and the late positive complex (LPC). Development of these memory aspects inchildren have been evidenced by changes in N400 repetition effects (old/neweffects) in older versus younger primary-school children. In the current study,an extended continuous recognitionparadigmwas used inwhich a series of 30target words was presented six times in random order interspersed with fillerwords. The taskwas to indicatewhether a particular word had been presentedbefore or not. Development of recognitionmemory inprimary-school childrenwas investigated by comparing repetition effects in 8–9-year-olds with thosein 11–12-year-olds. In both age groups, there were repetition effects for theN400 and LPC component; however, the N400 repetition effect wassignificantly larger for older compared to younger children. Consistent withearlier research, the extended repetition effect was only present for the LPCand not for the N400; this effect did not differ between groups. In conclusion,this study confirms that the N400 repetition effect is indicative of develop-ment of word recognition memory in children. The larger N400 repetitioneffect in older children suggests a greater contribution of implicit memory inolder compared to younger primary-school children.

doi:10.1016/j.ijpsycho.2008.05.073

Diurnal cortisol patterns of young schizophrenic patients: Increasedmorning cortisol levels

R.J. Hempela, J.H.M. Tulena, N.J.M. Van Beverena, C.H. Roedera,F.H. De Jongb, M.W. Hengevelda

a Erasmus University Medical Center, Department of Psychiatry, Rotterdam,The Netherlandsb Erasmus University Medical Center, Department of Internal Medicine,Rotterdam, The Netherlands

It has been suggested that schizophrenic patients are more vulnerable tostress, and that stressors can trigger a psychotic episode or worsen symptoms.The biological system often studied in relation to stress is the hypothalamic–

pituitary–adrenal (HPA) axis, which controls the release of several hormones,including cortisol. The aim of our study was to investigate whether youngmale schizophrenic patients suffered from an increased basal activity of theHPA-axis, assessed by means of cortisol concentrations in saliva throughoutthe day. Twenty-seven male patients (mean age 22±5) and 38 healthy malecontrol subjects (mean age 22±3) were included in the present study. Salivawas sampled at five different time points during the day: directly afterawakening, 30 min thereafter, and at 12:00, 16:00 and 22:00 hrs. When wecompared the cortisol day curves of the schizophrenic patients with those ofthe healthy controls, we found a significant interaction effect of Group byTime (F[4,248]=3.09, pb0.05), indicating that the shape of the cortisol daycurves differed between groups. The cortisol concentration directly afterawakening was significantly higher in the patient group (18.37 nmol/L±8.22)than in the control group (13.60 nmol/L±8.95), F[1,62]=4.21, pb0.05. Also,patients showed a significantly decreased AUCi (area under the curve withrespect to the increase; F[1,60]=4.84, pb0.05), indicating that the cortisolconcentrations decreased more during the day in schizophrenic patients thanin healthy controls. Both the morning peak and the AUCi showed significantnegative correlations with the scores on the subscale of the Positive andNegative Symptoms Scale for negative symptoms (r=−0.42 and r=−0.45respectively, both pb0.05). At present, it is still unclear how the morningcortisol response is associated with affect and general health. In our study, wefound that an increase in the negative symptom severity was related to asmaller morning cortisol response, possibly the result of the social impair-ments these patients suffer from. On the other hand, this finding may be dueto the increased basal cortisol levels directly after awakening. Future studiesshould further investigate the nature of the association between morningcortisol levels, psychosocial variables and general health in schizophrenia.

doi:10.1016/j.ijpsycho.2008.05.074

Increased FRN response in patients with depressive disorder

G.W. Miesa, F.M. Van Der Veena, J.H.M. Tulena,M.W. Hengevelda, M.W. Van Der Molenb

a Erasmus MC, Department of Psychiatry, Rotterdam, The Netherlandsb University of Amsterdam, Department of Psychology, Amsterdam,The Netherlands

Flexibility of behaviour is important in a constantly changing environment.Monitoring your own performance and adjusting behaviour accordingly is,therefore, essential in everyday life. This performance monitoring is assumedto be disturbed in patients with depressive disorder. The present study aimedat investigating performance and the feedback-related negativity (FRN) inseverely depressed inpatients. 13 depressed inpatients (6 female, mean age54 years, mean Hamilton score 25) and 17 healthy controls (13 female, meanage 52 years) were included. Participants performed a time estimation task inwhich they received positive (e.g. a happy face) or negative feedback (e.g. afearful face). The gender of the negative feedback stimuli indicated whetherthe estimation was too short or too long. Horizontal and vertical backgroundgrating indicated whether the feedback was informative or misleading (notrelated to the time estimation). The depressed patients made as many correctadjustments following negative feedback as healthy control participants. Inaddition, depressed patients and controls were equally able to ignore themisleading feedback. Importantly, depressed patients showed an increasedFRN following negative feedback comparedwith healthy controls, irrespectiveof the information communicated by the feedback (i.e. valid vs. misleading).The latter finding is interpreted to suggest that the monitoring system indepressed patients needs to emit a stronger signal to ensure remedial action.

doi:10.1016/j.ijpsycho.2008.05.075

Response activation and inhibition in global and selective stop-signaltasks: A Laplacian analysis

M.C. Van De Laara, W.P.M. Van Den Wildenberga, G.J.M. Van Boxtelb,B. Burlec, M.W. Van Der Molena

a Department of Psychology, University of Amsterdam, Amsterdam,The Netherlands

226 Poster presentations sessions 1,2,3 / International Journal of Psychophysiology 69 (2008) 207–241