Variations of Simple Somatosensory Evoked Potentials in the First and Second Halves of Sleep

Introduction: The study aims to investigate variations in brain responses to non-painful tactile stimulation on right hand in the first and second halves of NREM sleep. Materials and Methods: Sixteen healthy volunteers (9 female, mean age: 22.44±1.75) participated in the study. 40-channel NuAmps recording system [electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG)], Embedded Microcontroller Stimulation Unit (EMISU), pneumatic stimulation unit (Somatosensory Stimulus Generator 4-D Neuroimaging), video recording system, and analysis PC were used during recordings. Single-type non-painful somatosensory stimulus was applied to the index and middle fingers of right hands of participant. All night long records of EEG, EOG, and EMG were classified into sleep stages according to American Academy of Sleep Medicine (AASM). As the variations in first and second halves of the NREM sleep were localized in central region, Cz electrode was investigated. Results: When the brain responses to non-painful tactile stimuli in NREM sleep were investigated, P50, N100, p200, N300, P450, N550, P900, and N_late responses were observed. When the responses in the first and the second halves of sleep were compared, latency of P900 response in the first half was significantly shorter than that in the second half; and amplitudes of N300 and P900 responses in the first half were significantly larger than that in the second half. Discussion: There are different stages in their sleep in the process and studies in the literature often seen where some sleep stages. However our results showed that the the time of night, during sleep, influences the brain responsiveness to non-painful tactile stimuli

Auditory evoked potentials in sleep

AMAÇ: Bu çalısmanın amacı uykunun farklı evrelerinde uygulanan işitsel uyaranlara karşı verilen yanıtların değişimini irdelemektir. GEREÇ ve YÖNTEM: Çalısmaya 12 gönüllü birey alınmıştır (18-32 yas, ort: 24.5±4.1; 2 kadın). Kayıtlar, NuAmps 40 kanallı [Elektroensefalografi (EEG), Elektrookülografi (EOG), çene Elektromyografisi (EMG)] kayıt sistemi, ses uyarı modülü, video ve Bispektral indeks (BIS) monitorizasyonu kullanılarak gerçekleştirilmiştir. Uyku kayıtları sırasında (1500 Hz, 80 dB, 500 ms) işitsel uyaranlar kulak içine (etimotik) uygulanmıştır. Sürekli EEG, EOG ve EMG verileri, Rechtschaffen ve Kales (R&K) skorlama sistemine göre uyku evrelerine ayrılmıştır. Her bir evrede [Non-REM (N1, N2, N3 ve N4) ve REM] isitsel uyarılma potansiyelleri (IUP) incelenmiştir. Cz elektrotundan kayıtlı N100, P200, N300, P450, N550 ve P900 yanıtlarının uyku evrelerine göre değişimi araştırılmıştır. Istatistiksel analizlerde uyku evreleri ile IUP bileşenlerinin genlik ve latans ilişkileri tek yönlü varyans analizi (ANOVA) ile incelenmiştir. Ikili karşılaştırmalarda Bonferroni post hoc testi uygulanmıştır. BULGULAR: Uykunun derinleşmesi ile N100 bileseninin küçüldüğü, N300 ve P900 bileşeninin ise büyüdüğü gösterilmiştir. Dalga formlarında bulunan değişiklikler uykunun farklı evrelerinde (ve mikro evrelerde) dinamik bilgi işlemleme süreçleri olduğunu göstermektedir. SONUÇ: Isitsel uyarılma potansiyelleri, erken duyusal potansiyellerden geç işlemleme süreçlerine kadar beyin fonksiyonlarının çalışılmasında yararlı bir yöntemdir. Bu elektrofizyolojik ipuçları gelecekte uyku araştırmalarına ve klinik uygulamalara yararlı olabilirler.OBJECTIVE: The aim of the present study is to investigate the responses to auditory stimulations during different sleep stages. MATERIALS and METHODS: Twelve subjects (mean age: 24.5±4.1; 2 female) participated in the study. Data collection was performed with 40 channel NuAmps [Electroencephalography (EEG), electrooculography (EOG), chin electromyography (EMG)] recording system, auditory stimulation unit, video and Bispectral Index (BIS) monitorization. The records were scored according to Rechtschaffen and Kales (R&K) scoring system. Auditory evoked potentials (AEP) were analyzed in each sleep stage [Non-REM (N1, N2, N3 and N4) and REM]. N100, P200, N300, P450, N550 and P900 (P750) components were examined in Cz electrode. One-wayANOVA was applied to compare amplitudes and latencies of AEP components in different sleep stages. Post-hoc comparisons were conducted with Bonferroni method. RESULTS: The results showed that by deepening of sleep N100 decreased, N300 and P900 increased. The changes and interactions in the waveforms pointed at a dynamic information processing in the brain throughout different stages (and also microstates) of sleep. CONCLUSION: The auditory stimulations serve as a plausible study method providing a scope for brain functioning from early sensory potentials to very late processes (as late as 900 ms post-stimulus). These electrophysiological hints may be utilized for future sleep research studies as well as clinical applications

Non-Painful Tactile Stimuli and Sleep

Introduction The aim of this study is to examine electrophysiological responses in the brain to painless somatosensory stimulation during sleep. Materials and Methods Fifteen healthy volunteers (8 female, with mean age: 22.13±1.41) participated in the study. Recordings were carried out using NuAmps 40 channeled recording system, pneumatic stimulation unit (Somatosensory Stimulus Generator 4-D Neuroimaging), Embedded Microcontroller Stimulation Unit (EMISU), and additional equipment such as video recording system and analysis computer. Painless air pressure stimulation was applied at constant pressure rate to the fore and middle fingers of the right hand. Infrequent oddball stimulation was applied to one of the fingers (%25 of the time). Continuous electroencephalography (EEG), electrooculography (EOG) and electromyography (EMG) recordings were sorted into sleep phases according to the guidelines set by the American Academy of Sleep Medicine (AASM). Responses recorded from the C3 and C4 electrodes were examined as somatosensory regions of priority. Paired samples T-tests were used for statistical analysis. Results N100, P200, N300, P450, N550, P900 Nlate wave forms were clearly observed for both frequent and infrequent stimuli in light and deep sleep. Responses to both target and non-target stimuli on the right hand were found to be similar to each other. Discussion Brain responsiveness continues in sleep; however electrophysiological response pattern can vary. Furthermore as processes such as directed attention, stimulus discrimination and working memory cannot be voluntarily employed during sleep; responses to both kinds of stimuli are similar to one another

THE EFFECT OF THE ATTENTION TO EAR ADVANTAGE DURING DICHOTIC LISTENING TEST

Dikotik dinleme testi; işitsel sistemdeki fonetik işlemlemenin asimetrisi çalışmalarında kullanılan girişimsel olmayan, uygulaması kolay ve düşük maliyetli bir yöntemdir. Sessiz-sesli harflerden oluşan hecelerin (consonant-vowel/CV) aynı anda, iki farklı kulaktan dinletilmesiyle yapılan testte, katılımcılar duydukları hece için yanıtlarını verirler. Klasik dikotik dinleme testi sonucunda sağlıklı kişilerin %65-90'nında sağ kulak tercih edilir. Kulak tercihi mekanizmasını açıklamak için anatomik bağlantılara dayanan duyusal (aşağıdan yukarıya işlemleme/bottom up processing) ve kortikal kontrolün (yukarıdan aşağıya kontrol/top down control) rol aldığı dikkate bağlı iki ana model ileri sürülmüştür. Bazı patolojik durumlarda yapılan çeşitli dikotik dinleme testi araştırmalarında, bu testin sol hemisferdeki merkezlerin normal çalışıp çalışmadığının belirlenmesi, dikkat eksikliğinin tespiti, kallozal transfer fonksiyonunun tayininde kullanılabileceği önerilmektedir. Amaç: Konuşma heceleri uygulanan sağlıklı gönüllülerde işitsel sistemde baskın hemisferin tayin edilmesi ve dikkat yönergesinin bu asimetrik yapıya etkisinin araştırılmasıdır. Ayrıca dikotik dinleme testinin Türk toplumu için geçerliliğinin değerlendirilmesidir. Gereç ve yöntem: 20 sağlıklı gönüllüye (20 sağlak, 12 erkek) 36 adet CV dikotik hece, dikkat hiçbir kulağa yönlendirilmeden (non-forced/NF), dikkat sağ kulağa (forced right ear attention/FR) ve sol kulağa (forced left ear attention/FL) yönlendirilerek uygulandı. Kişilerin verdiği yanıtlar yeni geliştirilen elektronik bir sistemle değerlendirildi. İstatistiksel analizde yineleyen ölçümlerde ANOVA testi kullanıldı. Bulgular: NF durumda ortalama %53,95 sağ kulak tercihi (REA), FR durumda %61,23 REA ve FL durumda %37,72 REA bulundu. FL durumda ise sol kulak tercihi %47,19 olup, NF ve FR durumundan yüksekti. Sonuç: Sağlıklı bireylerde sol hemisfer üstünlüğü bulunmaktadır. Yukarıdan aşağıya kontrol mekanizmasıyla kulak tercihi değiştirilebilmektedir. Burada uygulanan dikotik dinleme testleri Kulak Burun Boğaz, Odyoloji, Nöroloji, Psikiyatri ve ilgili diğer bilim dallarının işbirliğiyle geliştirilerek işitme merkezi hasarı ve dikkat bozukluğu hastalıklarının tayininde ve ayrıca bu hastalıkların tedavilerinin izleminde kullanılabilir. The dichotic listening test is a non-invasive, low cost and easy to apply technique used in studying asymmetry of phonetic processing. In this test, participants are presented with two syllables, one in each ear, simultaneously and are asked to declare the syllab le they hear. Syllables are constructed as consonant-vowel (CV) pairs. In the classical dichotic listening test, 65-90% of healthy individuals declare the syllable presented in the right ear. In order to explain this right ear advantage (REA), anatomical and attention- related models are proposed. According to these models, REA can be associated with left hemisphere dominance; besides, attention drive top down control can modify REA. It is suggested that this test can be used to investigate attention deficits, functioning of different areas in left hemisphere and callosal transfer function in studies of pathological conditions. Objective: Establishing dominant hemisphere of healthy subjects in auditory system and investigation of effect of instructional attention on this asymmetry. Also, correlation of this new Turkish version of the dichotic test results with other nation's dichotic test results. Material and method: 36 CV syllable pairs were presented to 20 healthy subjects (all right-handed, 12 male) in three different conditions: no direction of the attention (nonforced, NF), directing attention to right ear (forced-right, FR), directing attention to left ear (forced-left, FL). Declarations of the heard syllable were recorded by a recently developed electronic system. In statistical analysis, repeated measures of ANOVA's was used. Results: REA was 53.95% (±17.20) in NF condition, 61.23% in FR condition, 37.72% in FL condition. In FL condition, the rate of left ear advantage was found to be %47.19, which was greater than in NF and FR conditions. Conclusion: In healthy subjects, left hemisphere dominance was found. REA can be modified by top down control mechanisms. Dichotic listening test can be used in determination of conditions related to auditory cortex malfunctions and attention deficit disorders as well as in follow-up of medical treatments of these types of disorders

The assessment of learning through the scope of somatosensory event related potentials

AMAÇ: Bu çalışmada basit dokunsal uyaranlar kullanılarak elektrofizyolojik yaklaşımla öğrenme ve bilişsel süreçlerin irdelenmesi hedeflenmiştir. GEREÇ ve YÖNTEMLER: 23 sağlıklı bireye (21.44±2.73 yas; 8 kadın) ait 64 kanal EEG kayıtları değerlendirilmiştir. Basit dokunsal uyaran olarak 4-D Pnömatik Stimulatör cihazı içeren düzenekle farklı iki el işaret (hedef) ve üçüncü parmaklarına (hedef olmayan) dokunsal basınç uygulanmıştır. Hedef uyaranların sayılması istenmiş, hata oranları%10 altında olan koşullardaki süpürümler elde edilmiştir. Post analizde bireysel ve grup ortalaması yanıtları 14 elektrotta (F , F , F ,C ,C ,C ,T ,T , P , P , P , P ,O ve O ) gösterilmiştir. BULGULAR: Tüm kafada yaygın olarak gözlenen, en yüksek genlikle Cz'de saptanan olaya ilişkin potansiyeller (SERP) ve basit dokunsal uyarılma potansiyelleri (SEP) saptanmıştır. Bu yanıtlarda çok erken, erken ve geç zaman pencerelerinde dalga bileşenleri analiz edilmiştir. Analize göre, çok erken yanıtlar (50-120 msn) ilk ve ikinci uygulamada değismezken, erken yanıtlar (150-250 msn) belirgin olarak küçülmüştür (her bir ölçüm için, <0.05). Geç yanıt bileşenleri (300-450 msn) ise deney sonuna kadar korunmuştur. Geç yanıt bileşenleri hedef uyaran yanıtlarında hedef olmayanlara göre anlamlı olarak yüksek bulunmuştur (herbir ölçüm için, <0.001). SONUÇ: Çok erken yanıtların değişmemesi, duyusal yanıtların korunması olarak değerlendirilmiştir. Erken yanıtların belirgin azalması, bilissel süreç olarak deneye katılımın ölçütü olarak ele alınmış ve bu koşul bireylerin deney desenini öğrenmesi olarak yorumlanmıştır. Geç yanıtların korunması ise bireylerin sayma ödevlerini tüm deney boyunca koruması ve bununla ilgili dikkat bileşenlerinin öne çıkması olarak değerlendirilmiştir.OBJECTIVE: The current study aims to investigate the cognitive processes through the scope of electrophysiological approach on the application of simple somatosensory stimuli. MATERIALand METHODS: Total of 23 subjects participated to the study (21.44±2.73 years; 8 females) for the analysis of 64 channel EEG data. Simple tactile stimuli were delivered using 4-D pneumatic stimulator, delivering a soft touch stimulus to the index (target) and middle fingers (non-target) of the subjects in two consecutive sessions. The subjects were requested to mentally count the target stimuli. The sweeps resulting from less than 10 percent error rate were accepted into the study. The individual and group event related responses were analyzed over 14 electrode (F , F , F ,C ,C ,C ,T ,T , P , P , P , P ,O andO ) sites in a post-analysis session. RESULTS: The responses (SEP and SERP) to the tactile stimuli were widely observed across the electrode sites with the the biggest amplitudes at Cz (central) electrode. Within the responses, very early, early and late time windows and their respective wave forms were analysed. The analysis revealed that very early waveforms (50- 120 msn) remained the same in two sessions, whereas, the early responses (150-250 msn) decreased significantly from the first session to the second (for each comparison, p<0.05). The late time components (300-450 msn) maintained their level throughout the experiment. The target and standard late responses were also found to differ significantly in two consecutive sessions (for each comparison, <0.001). CONCLUSION: No changes very early responses suggests the preservation of sensory responses. The significant decrease of early responses may be explained by the attendance of the subjects to the experiment, pointing their learning of the template of the experimental set-up. On the other hand, the maintaining of the late responses might be related to the task performance of the subjects, where they are demanded to keep their attention throughout the experiment

The Effect of Appetitive Daytime Napping on Cognitive Functions

Objective:The need for sleep is universal and its function is not completely clarified. Daytime alertness decreases after midday and one of the ways of preventing this decrease is daytime napping. The aim of this study is to investigate the effects 60-minutes appetitive daytime napping on cognitive performance.Materials and Methods:This study was carried out at Dokuz Eylül University Faculty of Medicine, Department of Biophysics Sleep Dynamics Research Laboratory. Participants who came to the sleep laboratory in two different days slept one day and the other day were included in the control group. A total of 14 healthy individuals between age of 19-24 (5 male; mean age: 21.86±1.23 years) without any neurological, psychological, chronic diseases, or sleep disorders were included in the study. Participants slept on their regular sleep pattern before both conditions. Various cognitive tests were administered to participants before sleep recordings. Electroencephalography was used on the purpose of following the sleep/wakefulness situation while sleeping. At the end of 60-minutes, the participants were woken up and after then same tests were performed again. On the control day, without sleep recording, determined questionnaires were applied to the participants. The resting period was set 60-minutes as it was during the sleeping period.Results:Cognitive performances of 14 participants on napping and control conditions were measured. The average duration of sleep was 57.3 (±3.57) minutes. Participants’ scores of N-Back, Psychomotor Vijilans test, and Timewall tests on both conditions were examined. Although there were differences in the scores they were not significant.Conclusion:Daytime napping has different effects on cognitive functions. In future studies, it is aimed that the evaluation of the replacement and appetitive daytime napping in terms of the behavioral and sleep stages as electrophysiologically

Dikotik dinlemede dikkatin kulak tercihine etkisi

The dichotic listening test is a non-invasive, low cost and easy to apply technique used in studying asymmetry of phonetic processing. In this test, participants are presented with two syllables, one in each ear, simultaneously and are asked to declare the syllab le they hear. Syllables are constructed as consonant-vowel (CV) pairs. In the classical dichotic listening test, 65-90% of healthy individuals declare the syllable presented in the right ear. In order to explain this right ear advantage (REA), anatomical and attention- related models are proposed. According to these models, REA can be associated with left hemisphere dominance; besides, attention drive top down control can modify REA. It is suggested that this test can be used to investigate attention deficits, functioning of different areas in left hemisphere and callosal transfer function in studies of pathological conditions. Objective: Establishing dominant hemisphere of healthy subjects in auditory system and investigation of effect of instructional attention on this asymmetry. Also, correlation of this new Turkish version of the dichotic test results with other nation;amp;#8217;s dichotic test results. Material and method: 36 CV syllable pairs were presented to 20 healthy subjects (all right-handed, 12 male) in three different conditions: no direction of the attention (nonforced, NF), directing attention to right ear (forced-right, FR), directing attention to left ear (forced-left, FL). Declarations of the heard syllable were recorded by a recently developed electronic system. In statistical analysis, repeated measures of ANOVA;amp;#8217;s was used. Results: REA was 53.95% (;plusmn;17.20) in NF condition, 61.23% in FR condition, 37.72% in FL condition. In FL condition, the rate of left ear advantage was found to be %47.19, which was greater than in NF and FR conditions. Conclusion: In healthy subjects, left hemisphere dominance was found. REA can be modified by top down control mechanisms. Dichotic listening test can be used in determination of conditions related to auditory cortex malfunctions and attention deficit disorders as well as in follow-up of medical treatments of these types of disorders.Dikotik dinleme testi; işitsel sistemdeki fonetik işlemlemenin asimetrisi çalışmalarında kullanılan girişimsel olmayan, uygulaması kolay ve düşük maliyetli bir yöntemdir. Sessiz-sesli harflerden oluşan hecelerin (consonant-vowel/CV) aynı anda, iki farklı kulaktan dinletilmesiyle yapılan testte, katılımcılar duydukları hece için yanıtlarını verirler. Klasik dikotik dinleme testi sonucunda sağlıklı kişilerin %65-90’nında sağ kulak tercih edilir. Kulak tercihi mekanizmasını açıklamak için anatomik bağlantılara dayanan duyusal (aşağıdan yukarıya işlemleme/bottom up processing) ve kortikal kontrolün (yukarıdan aşağıya kontrol/top down control) rol aldığı dikkate bağlı iki ana model ileri sürülmüştür. Bazı patolojik durumlarda yapılan çeşitli dikotik dinleme testi araştırmalarında, bu testin sol hemisferdeki merkezlerin normal çalışıp çalışmadığının belirlenmesi, dikkat eksikliğinin tespiti, kallozal transfer fonksiyonunun tayininde kullanılabileceği önerilmektedir. Amaç: Konuşma heceleri uygulanan sağlıklı gönüllülerde işitsel sistemde baskın hemisferin tayin edilmesi ve dikkat yönergesinin bu asimetrik yapıya etkisinin araştırılmasıdır. Ayrıca dikotik dinleme testinin Türk toplumu için geçerliliğinin değerlendirilmesidir. Gereç ve yöntem: 20 sağlıklı gönüllüye (20 sağlak, 12 erkek) 36 adet CV dikotik hece, dikkat hiçbir kulağa yönlendirilmeden (non-forced/NF), dikkat sağ kulağa (forced right ear attention/FR) ve sol kulağa (forced left ear attention/FL) yönlendirilerek uygulandı. Kişilerin verdiği yanıtlar yeni geliştirilen elektronik bir sistemle değerlendirildi. İstatistiksel analizde yineleyen ölçümlerde ANOVA testi kullanıldı. Bulgular: NF durumda ortalama %53,95 sağ kulak tercihi (REA), FR durumda %61,23 REA ve FL durumda %37,72 REA bulundu. FL durumda ise sol kulak tercihi %47,19 olup, NF ve FR durumundan yüksekti. Sonuç: Sağlıklı bireylerde sol hemisfer üstünlüğü bulunmaktadır. Yukarıdan aşağıya kontrol mekanizmasıyla kulak tercihi değiştirilebilmektedir. Burada uygulanan dikotik dinleme testleri Kulak Burun Boğaz, Odyoloji, Nöroloji, Psikiyatri ve ilgili diğer bilim dallarının işbirliğiyle geliştirilerek işitme merkezi hasarı ve dikkat bozukluğu hastalıklarının tayininde ve ayrıca bu hastalıkların tedavilerinin izleminde kullanılabilir