RESUMEN
Stress during pregnancy may impact subsequent generations, which is demonstrated by an increased susceptibility to childhood and adulthood health problems in the children and grandchildren. Although the importance of the prenatal environment is well reported with regards to future physical and emotional outcomes, little is known about the molecular mechanisms that mediate the long-term consequences of early stress across generations. Recent studies have identified DNA methylation as a possible mediator of the impact of prenatal stress in the offspring. Whether psychosocial stress during pregnancy also affects DNA methylation of the grandchildren is still not known. In the present study we examined the multigenerational hypothesis, that is, grandmaternal exposure to psychosocial stress during pregnancy affecting DNA methylation of the grandchildren. We determined the genome-wide DNA methylation profile in 121 children (65 females and 56 males) and tested for associations with exposure to grandmaternal interpersonal violence during pregnancy. We observed methylation variations of five CpG sites significantly (FDR<0.05) associated with the grandmother's report of exposure to violence while pregnant with the mothers of the children. The results revealed differential methylation of genes previously shown to be involved in circulatory system processes (FDR<0.05). This study provides support for DNA methylation as a biological mechanism involved in the transmission of stress across generations and motivates further investigations to examine prenatal-dependent DNA methylation as a potential biomarker for health problems.
Asunto(s)
Metilación de ADN , Epigénesis Genética , Exposición Materna , Efectos Tardíos de la Exposición Prenatal/genética , Estrés Psicológico/genética , Adolescente , Niño , Islas de CpG , Estudios Transversales , Exposición a la Violencia/psicología , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Madres , EmbarazoRESUMEN
BACKGROUND: Individuals with trauma-related disorders are complex and heterogeneous; part of this complexity derives from additional psychopathology like dissociation as well as environmental adversities such as traumatic stress, experienced throughout the lifespan. Understanding the neurophysiological abnormalities in Post-traumatic stress disorder (PTSD) requires a simultaneous consideration of these factors. METHODS: Resting state magnetoencephalography (MEG) recordings were obtained from 41 women with PTSD and comorbid depressive symptoms, and 16 healthy women. Oscillatory brain activity was extracted for five frequency bands and 11 source locations, and analyzed in relation to shutdown dissociation and adversity-related measures. RESULTS: Dissociative symptoms were related to increased delta and lowered beta power. Adversity-related measures modulated theta and alpha oscillatory power (in particular childhood sexual abuse) and differed between patients and controls. LIMITATIONS: Findings are based on women with comorbid depressive symptoms and therefore may not be applicable for men or groups with other clinical profiles. In respect to childhood adversities, we had no reliable source for the early infancy. CONCLUSION: Trauma-related abnormalities in neural organization vary with both exposure to adversities as well as their potential to evoke ongoing shutdown responses.
Asunto(s)
Adultos Sobrevivientes de Eventos Adversos Infantiles/psicología , Trastornos Disociativos/psicología , Magnetoencefalografía/métodos , Traumatismo Múltiple/psicología , Trastornos por Estrés Postraumático/psicología , Adulto , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Comorbilidad , Depresión/diagnóstico por imagen , Depresión/fisiopatología , Depresión/psicología , Trastornos Disociativos/diagnóstico por imagen , Trastornos Disociativos/fisiopatología , Femenino , Humanos , Persona de Mediana Edad , Traumatismo Múltiple/fisiopatología , Psicopatología , Trastornos por Estrés Postraumático/diagnóstico por imagen , Trastornos por Estrés Postraumático/fisiopatologíaRESUMEN
With each additional accumulative exposure to severe and traumatic stressors, the likelihood of developing mental health problems and physical diseases increases. Displaced individuals have usually experienced a number of serious threats to health due to organized violence in their home country or attacks during the flight. Frequently, domestic violence adds additional strain to the stressors experienced. The resulting impairments in psychosocial functioning reduce the resources needed for social adjustment and integration. Social exclusion then in turn often further aggravates the existing mental health complications. For the treatment of trauma spectrum disorders, different evidence-based psychotherapies are available. In high-income countries, trained and licensed psychotherapists are typically in positions to apply such interventions; however, even an advanced system with a high capacity, such as the psychotherapeutic care offered in Germany, severely struggles to manage the demands associated with the rapid addition of hundreds of thousands of displaced people. Germany's mental healthcare system at present lacks the resources, both human and technological, to effectively manage the present demands. Systematic scientific studies in resource-poor regions of war and conflict have demonstrated that the dissemination of effective treatment to local personnel, even with limited training, results in substantial improvements in the mental health challenges within the community: Organized as a cascade model, members of the refugee community learn to identify weakened fellow citizens requiring in-depth diagnostic interviews. Educated, bilingual individuals acquainted with their country's healthcare system (e. g. nurses, teachers and social workers) receive training to conduct structured interviews and evidence-based interventions under the supervision of centrally organized licensed psychotherapists. More complex cases are referred to local psychotherapists, psychiatrists or specialized treatment centers. These humanitarian efforts are based on the convention for the protection of human rights and secure the safety, freedom and dignity of these persons.
Asunto(s)
Tamizaje Masivo/métodos , Educación del Paciente como Asunto/métodos , Psicoterapia/educación , Refugiados/psicología , Apoyo Social , Trastornos de Estrés Traumático/terapia , Barreras de Comunicación , Humanos , Difusión de la Información/métodos , Psicoterapia/métodos , Trastornos de Estrés Traumático/diagnóstico , Trastornos de Estrés Traumático/psicología , Resultado del Tratamiento , GuerraRESUMEN
Stress, particularly when experienced early in life, can have profound implications for mental health. Previous research covering various tissues such as the brain, suggests that the detrimental impact of early-life stress (ELS) on mental health is mediated via epigenetic modifications including DNA methylation. Genes of the hypothalamic-pituitary-adrenal axis--in particular, the glucocorticoid receptor (hGR) gene--stand out as key targets for ELS. Even though the link between hGR methylation and either ELS or psychopathology is fairly well established, the mutually dependent relationships between ELS, DNA methylation and psychopathology remain to be uncovered. The specific psychopathology an individual might develop in the aftermath of stressful events can be highly variable, however, most studies investigating hGR methylation and psychopathology suffer from being limited to a single symptom cluster of mental disorders. Here, we screened volunteers for childhood maltreatment and analyzed whether it associates with hGR methylation in lymphocytes and a range of measures of psychological ill-health. hGR methylation in lymphocytes most likely reflects methylation patterns found in the brain and thus provides valuable insights into the etiology of psychopathology. We find the interaction between childhood maltreatment and hGR methylation to be strongly correlated with an increased vulnerability to psychopathology providing evidence of epigenome × environment interactions. Furthermore, our results indicate an additive effect of childhood maltreatment and hGR methylation in predicting borderline personality disorder (BPD)-associated symptoms, suggesting that the combination of both ELS and DNA methylation that possibly represents unfavorable events experienced even earlier in life poses the risk for BPD.
Asunto(s)
Adultos Sobrevivientes del Maltrato a los Niños/psicología , Maltrato a los Niños/psicología , Metilación de ADN , Interacción Gen-Ambiente , Trastornos Mentales/genética , Receptores de Glucocorticoides/genética , Adolescente , Ansiedad/genética , Ansiedad/psicología , Déficit de la Atención y Trastornos de Conducta Disruptiva/genética , Déficit de la Atención y Trastornos de Conducta Disruptiva/psicología , Trastorno de Personalidad Limítrofe/genética , Trastorno de Personalidad Limítrofe/psicología , Niño , Estudios de Cohortes , Depresión/genética , Depresión/psicología , Epigénesis Genética , Femenino , Predisposición Genética a la Enfermedad , Humanos , Masculino , Trastornos Mentales/psicología , Adulto JovenRESUMEN
Exposure-based therapies are considered the state-of-the-art treatment for Posttraumatic Stress Disorder (PTSD). Yet, a substantial number of PTSD patients do not recover after therapy. In the light of the well-known gene × environment interactions on the risk for PTSD, research on individual genetic factors that influence treatment success is warranted. The gene encoding FK506-binding protein 51 (FKBP5), a co-chaperone of the glucocorticoid receptor (GR), has been associated with stress reactivity and PTSD risk. As FKBP5 single-nucleotide polymorphism rs1360780 has a putative functional role in the regulation of FKBP5 expression and GR sensitivity, we hypothesized that this polymorphism influences PTSD treatment success. We investigated the effects of FKBP5 rs1360780 genotype on Narrative Exposure Therapy (NET) outcome, an exposure-based short-term therapy, in a sample of 43 survivors of the rebel war in Northern Uganda. PTSD symptom severity was assessed before and 4 and 10 months after treatment completion. At the 4-month follow-up, there were no genotype-dependent differences in therapy outcome. However, the FKBP5 genotype significantly moderated the long-term effectiveness of exposure-based psychotherapy. At the 10-month follow-up, carriers of the rs1360780 risk (T) allele were at increased risk of symptom relapse, whereas non-carriers showed continuous symptom reduction. This effect was reflected in a weaker treatment effect size (Cohen's D=1.23) in risk allele carriers compared with non-carriers (Cohen's D=3.72). Genetic factors involved in stress response regulation seem to not only influence PTSD risk but also responsiveness to psychotherapy and could hence represent valuable targets for accompanying medication.
Asunto(s)
Terapia Implosiva/métodos , Trastornos por Estrés Postraumático/genética , Trastornos por Estrés Postraumático/terapia , Proteínas de Unión a Tacrolimus/genética , Resultado del Tratamiento , Adulto , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Recurrencia , Trastornos por Estrés Postraumático/etiología , Sobrevivientes/psicología , GuerraRESUMEN
Stressful war experiences can cause posttraumatic stress disorder (PTSD) in survivors. To what extent were the soldiers and young women of World War II affected by PTSD symptoms over the course of their lives? Do these men and women differ in the traumatic experiences and PTSD symptom severity? To investigate these questions 52 male and 20 female Germans aged 81-95 years were recruited through newspaper advertisements and notices and interviewed regarding war experiences and PTSD symptoms. Of the men 2% and 7% met the criteria for current and lifetime PTSD diagnoses, respectively, as compared to 10% and 30% of the women, respectively. Using multiple linear regression a dose-response relationship between the number of trauma types experienced and PTSD symptom severity could be demonstrated. The slope of the regression curve was steeper for women than for men. When controlling for the number of different traumatic experiences women reported a significantly higher severity of PTSD symptoms than men. It is presumed that this difference in severity of symptoms can be attributed to qualitative differences in the type of traumatic stress factors during the war. The present study provides evidence that even today people continue to be affected by PTSD symptoms due to events which occurred during World War II; therefore, during patient contact with this age group the war experiences specific to each individual need to be considered as potential moderators of symptoms.
Asunto(s)
Personal Militar/estadística & datos numéricos , Trastornos por Estrés Postraumático/epidemiología , Trastornos por Estrés Postraumático/psicología , Sobrevivientes/estadística & datos numéricos , Segunda Guerra Mundial , Heridas y Lesiones/epidemiología , Heridas y Lesiones/psicología , Anciano de 80 o más Años , Comorbilidad , Femenino , Alemania/epidemiología , Humanos , Masculino , Personal Militar/psicología , Prevalencia , Factores de Riesgo , Distribución por Sexo , Sobrevivientes/psicologíaRESUMEN
The prevalence of age-related diseases is increased in individuals with post-traumatic stress disorder (PTSD). However, the underlying biological mechanisms are still unclear. N-glycosylation is an age-dependent process, identified as a biomarker for physiological aging (GlycoAge Test). To investigate whether traumatic stress accelerates the aging process, we analyzed the N-glycosylation profile in n=13 individuals with PTSD, n=9 trauma-exposed individuals and in n=10 low-stress control subjects. Individuals with PTSD and trauma-exposed individuals presented an upward shift in the GlycoAge Test, equivalent to an advancement of the aging process by 15 additional years. Trauma-exposed individuals presented an intermediate N-glycosylation profile positioned between severely traumatized individuals with PTSD and low-stress control subjects. In conclusion, our data suggest that cumulative exposure to traumatic stressors accelerates the process of physiological aging.
Asunto(s)
Envejecimiento Prematuro/metabolismo , Polisacáridos/metabolismo , Trastornos por Estrés Postraumático/metabolismo , Estrés Psicológico/metabolismo , Adulto , Envejecimiento Prematuro/sangre , Estudios de Casos y Controles , Femenino , Glicosilación , Humanos , Masculino , Persona de Mediana Edad , Polisacáridos/sangre , Trastornos por Estrés Postraumático/sangre , Estrés Psicológico/sangre , Adulto JovenRESUMEN
A presumed hook effect in the semiquantitative DRI Oxycodone immunoassay, OXY3S (Cobas Integra, Roche Diagnostics), was investigated in 14 urine samples with gas chromatography/mass spectrometry (GC-MS) >10,000 ng/mL but OXY3S <1,000 ng/mL. These samples included the index case, a false-negative OXY3S result with >75,000 ng/mL oxycodone + oxymorphone by GC-MS confirmation. Patient samples needed 2- to 16-fold dilution to obtain the correct OXY3S response. The OXY3S test did not hook at high-spiked concentrations of oxycodone, oxymorphone or oxymorphone-3ß-d-glucuronide in drug-free urine. The OXY3S test parameters were replicated in a development channel on the Cobas using DRI Reagents (Microgenics, CA, USA) and were subsequently modified. Delayed sample addition or doubling of Reagent 1 (R1: antibody/substrate/co-factor) yielded maximal immunoassay response (>10,000 ng/mL) in 12 of 14 and 14 of 14 undiluted patient samples, respectively. Supplementation of R1 with substrate alone did not correctly recover oxycodone from any of the samples, while co-factor supplementation resulted a maximal OXY3S response in 13 of 14 samples. The remaining (index) sample could only be corrected by supplemental R1. The semiquantitative utility of the DRI Oxycodone assay is questionable. Although the precise cause of the under-recovery could not be determined, the modification presented permits reliable oxycodone determination at the high concentrations frequently seen in clinical urine samples.
Asunto(s)
Inmunoensayo/métodos , Oxicodona/orina , Adulto , Anciano , Femenino , Cromatografía de Gases y Espectrometría de Masas/métodos , Humanos , Masculino , Persona de Mediana Edad , Oximorfona/orina , Manejo de Especímenes , Detección de Abuso de Sustancias/métodosRESUMEN
Posttraumatic stress disorder (PTSD) arises as a long-term result of exposure to trauma and brings with it an altered autonomic response to potentially threatening stimuli. The present study investigates the dynamic sequence of cardiac defense in women with and without PTSD. An acoustic noise of 0.5-s duration and 105 dB was used to elicit the cardiac defense reaction. The stimulus was repeated three times. Within the PTSD sample, respondents who suffered from more severe PTSD showed a higher heart rate at rest, a higher baseline, and a greater response. Compared to the healthy subjects, the PTSD group showed an elevated heart rate from 6 s to 25 s following the presentation of the first stimulus. There was evidence of habituation in the PTSD group and hints of differential effects on the cardiac defense of traumatic experiences with a high proximity of danger.
Asunto(s)
Frecuencia Cardíaca/fisiología , Reflejo Anormal/fisiología , Trastornos por Estrés Postraumático/fisiopatología , Adulto , Femenino , Humanos , Persona de Mediana Edad , Índice de Severidad de la Enfermedad , Trastornos por Estrés Postraumático/etiologíaRESUMEN
BACKGROUND: The aim of the present randomized controlled trial was to compare the outcome of 2 active treatments for posttraumatic stress disorder (PTSD) as a consequence of war and torture: narrative exposure therapy (NET) and stress inoculation training (SIT). METHODS: Twenty-eight PTSD patients who had experienced war and torture, most of them asylum seekers, received 10 treatment sessions of either NET or SIT at the Outpatient Clinic for Refugees, University of Konstanz, Germany. Posttests were carried out 4 weeks after treatment, and follow-up tests were performed 6 months and 1 year after treatment. The main outcome measure was the PTSD severity score according to the Clinician-Administered PTSD Scale (CAPS) at each time point. RESULTS: A significant reduction in PTSD severity was found for NET, but not for SIT. A symptom reduction in the NET group occurred between pretest and the 6-month follow-up examination, the effect size being d = 1.42 (for SIT: d = 0.12), and between pretest and the 1-year follow-up, the effect size being d = 1.59 (for SIT: d = 0.19). The rates and scores of major depression and other comorbid disorders did not decrease significantly over time in either of the 2 treatment groups. CONCLUSIONS: The results indicate that exposure treatments like NET lead to a significant PTSD symptom reduction even in severely traumatized refugees and asylum seekers.
Asunto(s)
Terapia Implosiva/métodos , Refugiados/psicología , Trastornos por Estrés Postraumático/terapia , Tortura , Guerra , Comorbilidad , Estudios de Seguimiento , Alemania , Humanos , Trastornos del Humor/diagnóstico , Trastornos del Humor/epidemiología , Narración , Escalas de Valoración Psiquiátrica , Índice de Severidad de la Enfermedad , Trastornos por Estrés Postraumático/diagnóstico , Trastornos por Estrés Postraumático/epidemiología , Tortura/psicología , Resultado del TratamientoRESUMEN
Prenatal exposure to maternal stress can have lifelong implications for psychological function, such as behavioral problems and even the development of mental illness. Previous research suggests that this is due to transgenerational epigenetic programming of genes operating in the hypothalamic-pituitary-adrenal axis, such as the glucocorticoid receptor (GR). However, it is not known whether intrauterine exposure to maternal stress affects the epigenetic state of these genes beyond infancy. Here, we analyze the methylation status of the GR gene in mothers and their children, at 10-19 years after birth. We combine these data with a retrospective evaluation of maternal exposure to intimate partner violence (IPV). Methylation of the mother's GR gene was not affected by IPV. For the first time, we show that methylation status of the GR gene of adolescent children is influenced by their mother's experience of IPV during pregnancy. As these sustained epigenetic modifications are established in utero, we consider this to be a plausible mechanism by which prenatal stress may program adult psychosocial function.
Asunto(s)
Metilación de ADN/genética , Regiones Promotoras Genéticas/genética , Receptores de Glucocorticoides/genética , Parejas Sexuales/psicología , Violencia , Adolescente , Adulto , Niño , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Proteína 1 de la Respuesta de Crecimiento Precoz/metabolismo , Femenino , Humanos , Relaciones Intergeneracionales , Masculino , Intercambio Materno-Fetal/genética , Embarazo , Efectos Tardíos de la Exposición Prenatal/genética , Receptores de Glucocorticoides/metabolismo , Receptores de Glucocorticoides/fisiología , Estudios Retrospectivos , Adulto JovenRESUMEN
Multispeckle diffusing-wave spectroscopy (DWS) is used to measure blood flow transients in the human visual cortex following stimulation by 7.5 Hz full-field and checkerboard flickering. The average decay time tau(d) characterizing the decay of the DWS autocorrelation function shows a biphasic behavior; within about 2 s after stimulation onset, tau(d) increases rapidly to about 6% above the baseline value. At later times, tau(d) slowly decreases and reaches a steady-state value about 5% below the baseline value after about 15 s. The initial increase of the DWS signal suggests a transient reduction of the cortical blood flow velocity shortly after stimulation onset. Measurements of this transient response at different positions over the primary visual cortex show a spatial pattern different from the one measured by electroencephalography.
Asunto(s)
Velocidad del Flujo Sanguíneo/fisiología , Mapeo Encefálico/métodos , Circulación Cerebrovascular/fisiología , Potenciales Evocados Visuales/fisiología , Espectrofotometría Infrarroja/métodos , Corteza Visual/fisiología , Adulto , Femenino , Humanos , Corteza Visual/irrigación sanguíneaRESUMEN
There is widespread recognition that consistency between research centres in the ways that patients with tinnitus are assessed and outcomes following interventions are measured would facilitate more effective co-operation and more meaningful evaluations and comparisons of outcomes. At the first Tinnitus Research Initiative meeting held in Regensburg in July 2006 an attempt was made through workshops to gain a consensus both for patient assessments and for outcome measurements. It is hoped that this will contribute towards better cooperation between research centres in finding and evaluating treatments for tinnitus by allowing better comparability between studies.
Asunto(s)
Encuestas y Cuestionarios/normas , Acúfeno/diagnóstico , Acúfeno/terapia , Consenso , Humanos , Resultado del TratamientoRESUMEN
Careful analysis of a rhytidectomy patient is an important aspect of facial plastic surgery. Surgeons and physicians are successful when they diagnose patients correctly and apply the correct treatment plan. The skilled facial plastic surgeon appropriately evaluates the patient physically and emotionally then performs the correct surgical maneuvers to achieve the desired results. The focus of this article is the senior author's 20 years of experience in analyzing faces, and the goal of this article is to assist surgeons in achieving postoperative patients who are happy and "natural looking."
Asunto(s)
Ritidoplastia/métodos , Envejecimiento de la Piel , Humanos , Cuello , Selección de PacienteRESUMEN
OBJECTIVE: The possibility of simultaneously observing activation of primary and secondary auditory cortices has been demonstrated by Engelien et al. [Hear Res 2000;148:153-60]. METHODS: Such a dual monitoring by means of neuromagnetic recordings can be achieved when a subject is stimulated by brief pulses of 40Hz-modulated tones. Depending on the frequency filter applied, either the steady-state field (SSF) or the N1m can be extracted from the evoked magnetic field complex. RESULTS: Using this "combined" (two-maps) paradigm with 4 carrier frequencies, we show that it is possible to synchronously screen two tonotopic maps--one map each reflected either by the SSF or the N1m. Indicators are the systematic variation in the location (higher frequencies are more posterior) and orientation (higher frequencies oriented differently in the sagittal plane) of the equivalent current dipole (ECD). These parameters were compared with those obtained from "classic" (one map) paradigms in which either a pure tone elicits an N1m or a 40 Hz continuous (3 s) stimulation produces an SSF. Overall the results were similar, however, systematic differences between the paradigms were found for ECD localization, dipole strength, amplitude, and phase. CONCLUSIONS AND SIGNIFICANCE: One possible interpretation of these results is that different tonotopically arranged cortical fields were involved in the generation of the components.
Asunto(s)
Corteza Auditiva/fisiología , Mapeo Encefálico , Potenciales Evocados Auditivos/fisiología , Magnetoencefalografía , Percepción de la Altura Tonal/fisiología , Estimulación Acústica/métodos , Adulto , Corteza Auditiva/anatomía & histología , Femenino , Humanos , MasculinoRESUMEN
OBJECTIVE: The purpose of this study was to determine the effect of combined CO2 and Er:YAG laser irradiation on normal (NF) and keloid (KF) facial dermal fibroblast production of TGF-beta1 and bFGF. BACKGROUND DATA: Keloids produce excess collagen. TGF-beta1 is integral to the growth and stimulation of fibroblasts and collagen; bFGF inhibits collagen synthesis. TGF-beta1 and bFGF production influence wound healing and may be manipulated by laser irradiation. MATERIALS AND METHODS: Human normal fibroblasts (NF) and keloid fibroblasts (KF) (2 x 10(4) cells/mL in serum-free media) were exposed to 1.7 J/pulse Er:YAG laser energy and CO2 delivered at either 3 or 5 W and at a duty cycle of 25%, 50%, or 100%. TGF-beta1 and bFGF were assayed using a quantitative ELISA. RESULTS: KF demonstrated a statistically significant mean population doubling time (PDT) when compared with NF (p=0.01). Irradiated KF and NF had longer PDTs than controls. All NF, excluding one irradiated group, and the three KF treated with 3 W secreted more bFGF than controls. Irradiated KF secreted less TGF-beta1 than controls. Significance was reached with the two groups exposed to 3 W at a duty cycle of 25% and 50% (p=0.04 and 0.05, respectively). All irradiated NF secreted less TGF-beta1 than controls. CONCLUSION: The combined CO2 and Er:YAG laser increased the release of bFGF, which has been shown to promote tightly organized collagen bundles, and decreased the concentration of TGF-beta1, which has also been shown to promote fibrosis formation. This laser may have a future role in keloid treatment, as well as normal facial scar prevention.
Asunto(s)
Fibroblastos/efectos de la radiación , Queloide/terapia , Terapia por Láser , Células Cultivadas , Medio de Cultivo Libre de Suero , HumanosAsunto(s)
Ritidoplastia/métodos , Envejecimiento de la Piel , Algoritmos , Femenino , Humanos , Masculino , Examen Físico/métodos , Derivación y ConsultaRESUMEN
We describe a methodology to apply current source density (CSD) and minimum norm (MN) estimation as pre-processing tools for time-series analysis of single trial EEG data. The performance of these methods is compared for the case of wavelet time-frequency analysis of simulated gamma-band activity. A reasonable comparison of CSD and MN on the single trial level requires regularization such that the corresponding transformed data sets have similar signal-to-noise ratios (SNRs). For region-of-interest approaches, it should be possible to optimize the SNR for single estimates rather than for the whole distributed solution. An effective implementation of the MN method is described. Simulated data sets were created by modulating the strengths of a radial and a tangential test dipole with wavelets in the frequency range of the gamma band, superimposed with simulated spatially uncorrelated noise. The MN and CSD transformed data sets as well as the average reference (AR) representation were subjected to wavelet frequency-domain analysis, and power spectra were mapped for relevant frequency bands. For both CSD and MN, the influence of noise can be sufficiently suppressed by regularization to yield meaningful information, but only MN represents both radial and tangential dipole sources appropriately as single peaks. Therefore, when relating wavelet power spectrum topographies to their neuronal generators, MN should be preferred.
Asunto(s)
Encéfalo/fisiología , Electroencefalografía/métodos , Artefactos , Simulación por Computador , Humanos , Modelos LinealesRESUMEN
A number of findings indicate gender differences in language-related functional hemispheric brain asymmetry. To test if such gender-specific laterality is already present at the level of vowel-processing, the auditory evoked magnetic field was recorded in healthy right-handed male and female participants in response to the German synthetic vowels [a], [e] and [i]. Female participants exhibited stronger N100m responses than male participants over the left hemisphere. This observation was highly reliable across repeated experimental sessions. The present lateralization shows that previous findings suggesting a stronger left-hemispheric dominance for verbal material in males than in females can not be generalized to basic speech elements. Furthermore, the present results support the importance of controlling for gender ratio in studies of phonetic processing.
Asunto(s)
Corteza Auditiva/fisiología , Potenciales Evocados Auditivos/fisiología , Lateralidad Funcional/fisiología , Lenguaje , Caracteres Sexuales , Percepción del Habla/fisiología , Conducta Verbal/fisiología , Estimulación Acústica , Adulto , Corteza Auditiva/anatomía & histología , Femenino , Humanos , Magnetoencefalografía , Masculino , Reproducibilidad de los ResultadosRESUMEN
The present study aimed at examining the oscillatory brain-electric correlates of human operant learning using high-density electroencephalography (EEG). Induced gamma-band activity (GBA) was studied using a fixed-interval reinforcement schedule with a variable limited hold period, which was decreased depending on response accuracy. Thus, participants' behavior was shaped during the course of the learning session. After each response, numbers indicating the money value of that response served as reinforcing stimuli. Random reinforcement and self-paced button pressing without reinforcement were added as control conditions. GBA around 40 Hz was enhanced at posterior electrodes in response to visual feedback stimuli during shaping and random reward compared to the self-paced pressing condition where no visual feedback was provided. Furthermore, shaping was associated with a pronounced left frontal lower gamma (20-30 Hz) increase in response to feedback stimuli, whereas this pattern was not observed in the random reinforcement and self-paced pressing conditions. The present findings are in line with the notion that macroscopic high-frequency dynamics of neuronal cell assemblies may be regarded as a mechanism involved in learning and memory formation.