Evaluation of sound and ear advantage relationship via Turkish consonant–vowel dichotic syllables paradigm

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Posters session 3 / International Journal of Psychophysiology 69 (2008) 276–316

to controls (p b 0.05). The dichotic analysis revealed a Right Ear Advantage both in patient and control groups. However, the error rates were higher for patients than controls (p b 0.05). Furthermore, for the late time window, the dichotic conditions revealed significant differences between conditions (p b 0.05). Consequently, the combined application of a battery incorporating MMN and DL can effectively be applied for the assessment of schizophrenia patients and multiple sensory and cognitive components. The results also validate the comparative easiness and cost effectiveness of such an application. doi:10.1016/j.ijpsycho.2008.05.277

Evaluation of sound and ear advantage relationship via Turkish consonant–vowel dichotic syllables paradigm O. Bayazit, U. Erdogan, A. Oniz, M. Ozgoren Dokuz Eylul University, Faculty of Medicine, Department of Biophysics, Izmir, Turkey There are anatomical and physiological asymmetries in human brain (1). A number of researchers have emphasized the brain asymmetry with behavioral data (1,2). Recently, one of the most frequently used methods to study functional laterality (language asymmetry) has been the dichotic listening (DL) (1, 2, 3). In dichotic listening paradigm, semantically meaningless syllables are presented to the subjects (‘GA’, ‘BA’, ‘KA’, ‘DA’, ‘TA’, ‘PA’). Some of these syllables are matched as homonyms (i.e. BAL–BAR) but most of them are matched as heteronyms (i.e. BAL GAR). In dichotic listening paradigm, the subjects mostly hear the syllables that are presented from the right ear. The possible ear advantage may also be related to the effects from syllables which have short or long voice onset time (VOT). The present study was held with total of 60 healthy subjects in the age range of 23.38 years (30 females) whose native language was Turkish. The participants sat in a sound-proof and dimly illuminated echofree room and listened to the dichotic syllables. 144 dichotic syllable pairs were presented at 80 dB, randomly via Sony CDR50 headphones. The participants were asked to listen to the syllables and choose the syllables which they heard the first or the best by pressing the button first with their right hand then their left hand. The results revealed 56.82% right ear advantage (REA), 33.32% left ear advantage (LEA). The dichotic syllable pairs such as LGA–RPA, LDA– RKA, LPA–RTA, LKA–RPA, LGA–RDA, LKA–RTA, LDA–RPA, LBA–RPA resulted in left ear advantage. The percentage of the wrong answers given for LGA–RTA and LBA–RTA dichotic syllable pairs were higher. Accordingly, the evaluation of DL ear advantage and sound analysis (incorporating VOT) provide a basis for understanding the sensorial and cognitive processes in the assessment of brain asymmetry. References Bayazıt, O., Öniz, A., Güntürkün, O., Özgören, M., in press. Electrophysiological assessment of brain asymmetry using a dichotic listening paradigm, New Symposium. Eichele, T., Nordby, H., Rimol, L.M., Hugdahl, K., 2005. Asymmetry of evoked potential latency to speech sounds predicts the ear advantage in dichotic listening. Cognitive Brain Research 24, 405–412. Hugdahl, K., 2005b. Dichotic Listening. In: Hugdahl, K., Davidson, R.J. (Eds.). The Study of Auditory Laterality, The asymmetrical brain. MIT Press, Massachusetts. 441–476. Kimura, D., 1961. Cerebral dominance and the perception of verbal stimuli. Canadian Journal of Psychology 15, 166–171.

doi:10.1016/j.ijpsycho.2008.05.278

Expressions of mRNA for GDNF in schizophrenia K. Alptekin a, S. Aykan b, B.B.K. Akdede a, H. Ulas a, A. Aktener a, C. Can a, N. Cengizcetin a, S. Mertol a, M. Oguz a, S. Taslica c, A. Oniz c, M. Ozgoren c a Dokuz Eylul University, Faculty of Medicine, Department of Psychiatry, Izmir, Turkey b Dokuz Eylul University, Department of Neuroscience, Izmir, Turkey c Dokuz Eylul University, Biophysics Department, Izmir, Turkey Introduction: Glial cell line-derived neurotrophic factor (GDNF) may play an important role in the development and maintenance of dopamine neurons and support neurodevelopmental hypothesis of schizophrenia. This study aimed to determine the relationship between GDNF mRNA expression levels and negative, positive subtypes of schizophrenia. Methods: Thirty-five DSM-IV schizophrenia patients, rated with PANSS and 33 healthy volunteers were included. Negative subtype was defined as having dominant negative symptoms without positive symptoms since one-year. Lymphocytes were isolated from peripheral blood. Total RNA extracted from lymphocytes of individuals was amplified by RT-PCR. Quantitative real time PCR using SYBR Green I was used to quantify the expression of GDNF gene. Relative expression of GDNF was normalized with beta-actin as housekeeping gene. The DeltaDeltaCt method was used for the analysis of relative expression. Results: No significant differences in expressions of mRNA for GDNF between schizophrenia patients and healthy subjects were observed. GDNF mRNA levels negatively correlated to the duration of schizophrenia, and positively correlated with PANSS Negative subitems such as, emotional withdrawal, poor report, and passive/ apathetic social withdrawal. We did not find any relation between GDNF mRNA levels and positive symptoms of schizophrenia. Discussion: This study has enhanced a relation between expressions of mRNA for GDNF and negative symptoms of schizophrenia. There are few studies indicating a possible involvement of GDNF in schizophrenia. However this is the first study to show the association between GDNF and negative symptoms of schizophrenia that may support a neurodevelopmental etiology for schizophrenia, especially related to the negative subtype. References Williams, H.J., Norton, N., Peirce, T., Dwyer, S., Williams, N.M., Moskvina, V., Owen, M.J., O'Donovan, M.C., 2007. Association analysis of the glial cell line-derived neurotrophic factor (GDNF) gene in schizophrenia. Schizophrenia Research 97, 271–276.

doi:10.1016/j.ijpsycho.2008.05.279

The BIS and EEG relationship during non-REM sleep S. Kocaaslan, A. Oniz, A. Yildirim, M. Ozgoren Dokuz Eylul University, Biophysics Department, Izmir, Turkey Bispectral index (BIS) is used as a measure of depth of anesthesia and sedation. The aims of the present study were 1) to show the relationship between the non-REM stages of early sleep and BIS; 2) to investigate the influence of auditory stimuli on BIS as well as on sleep stages. No such studies have been undertaken how BIS and sleep stages are affected under ongoing auditory stimulation. Eight healthy subjects (mean age 24.8 ± 3.9; 2 female) were recruited for the study without history of any neurological, psychiatric or sleep related disorders. Computerized EEG signals were analyzed manually according to the R&K standard criteria, classifying each 30-s epoch as a specific sleep stage. BIS scores were acquired on-line. During the entire sleep, auditory stimuli (261–362/1500–1600 Hz, 75 dB) were applied with