Search

Depression is a heterogeneous syndrome that impacts an individual's emotional, social, cognitive and bodily functioning. Depression is associated with biases in emotional processing, but alterations in basic sensory processing have received less attention in depression research. Here, we measured event‐related potentials (ERPs) in response to changes in the intensity of auditory stimuli and the location of somatosensory stimuli in participants with depression and in non‐depressed control participants. We tested whether auditory mismatch negativity, P3a or N1 intensity dependence response or somatosensory mismatch response, P3a, P50 or N80 can dissociate depressed participants and non‐depressed controls, and we also analysed the effects of depression medication and age in this sample. N1 intensity dependence response was increased in unmedicated depressed participants relative to non‐depressed controls. When age was controlled for in the analysis, the effect of depression was only at a trend level. N1 intensity dependence response correlated with depression severity at the whole sample level. We did not observe any depression‐related alterations in auditory mismatch negativity or P3a or somatosensory ERPs. Our results may reflect an association between the N1 intensity dependence response and altered neurotransmitter activity in depression, but this should be confirmed in future studies. [ABSTRACT FROM AUTHOR]

Objective: To investigate the after-effects of 25-Hz repetitive transcranial magnetic stimulation (rTMS) at 60, 100, and 120% resting motor threshold (rMT) on long-term potentiation (LTP) in the rat hippocampus, to clarify the intensity dependence of rTMS, and to determine whether it simultaneously affects learning and memory ability. Methods: Five rats were randomly selected from 70 male Wistar rats, and evoked rMT potentials were recorded in response to magnetic stimulation. The remaining 65 rats were randomly assigned to five groups (n  =  13), including sham rTMS, 1  Hz 100% rMT, and 25  Hz rTMS groups with 3 subgroups of 60% rMT, 100% rMT, and 120% rMT. Five rats in each group were anesthetized and induced by a priming TMS-test design for population spike (PS) response of the perforant path-dentate gyrus in the hippocampus; the remaining eight rats in each group were evaluated for object recognition memory in the novel object recognition (NOR) task after the different rTMS protocols. Results: Forty-five percent (approximately 1.03  T) of the magnetic stimulator output was confirmed as rMT in the biceps femoris muscle. The PS ratio was ranked as follows: 25  Hz 100% rMT (267.78  ±  25.71%)  >  sham rTMS (182  ±  9.4%) >1  Hz 100% rMT (102.69  ±  6.64%)  >  25  Hz 120% rMT (98  ±  11.3%)  >  25  Hz 60% rMT (36  ±  8.5%). Significant differences were observed between the groups, except for the difference between the 25  Hz 120% rMT and the 1  Hz 100% rMT groups (p  =  0.446). LTP was successfully induced over the 60-min recording period only in the sham rTMS and 25  Hz 100% rMT groups. Moreover, these two groups spent more time exploring a novel object than a familiar object during the NOR task (p  <  0.001), suggesting long-term recognition memory retention. In the betweengroup analysis of the discrimination index, the following ranking was observed: 25  Hz 100% rMT (0.812  ±  0.158)  >  sham rTMS (0.653  ±  0.111)  >  25  Hz 120% rMT (0.583  ±  0.216) >1  Hz 100% rMT (0.581  ±  0.145)  >  25  Hz 60% rMT (0.532  ±  0.220). Conclusion: The after-effect of 25-Hz rTMS was dependent on stimulus intensity and provided an inverted (V-shaped) bidirectional modulation on hippocampal plasticity that involved two forms of metaplasticity. Furthermore, the effects on the recognition memory ability were positively correlated with those on LTP induction in the hippocampus in vivo. [ABSTRACT FROM AUTHOR]

Using polarized femtosecond laser transmission measurements toward (100), (110), (111) ZnSe, and (100) GaP, we show that in a wide laser irradiation intensity range over two orders of magnitude before the laser damage threshold, a periodic amplitude modulation always appears clearly in the angle-dependent two-photon absorption (TPA) curves for (100), (110) ZnSe, and (100) GaP. It also exhibits a close connection between the orientation-dependent TPA and the ionic bonding symmetrical characteristics of specific crystal plane, thus revealing the origin of the orientation dependence of nonlinear absorption in the strong field laser-solid interaction. Interestingly, the modulation amplitudes of orientation-dependent TPA exhibit significant intensity dependence, with the maxima occurring around 1011 W cm−2. For the orientation-dependent nonlinear absorption in solids, such a nonmonotonic relationship between the irradiation intensity and the modulation amplitude has not been revealed previously in the near-damage-threshold regime by direct transmission measurements. In particular, with the intensity approaching the laser damage threshold, the significant descending trend of modulation amplitude confirms the consistent characteristics of saturation or even attenuation for the orientation dependence of TPA in the two crystals, which might be considered as a product of absorption saturation phenomenon of TPA at high irradiation intensity and would provide new understanding about the orientation-dependent TPA in the near-damage-threshold regime. [ABSTRACT FROM AUTHOR]

Various odorants trigger complex animal behaviors across species in both quality- and quantity-dependent manners. However, how the intensity of olfactory input is encoded remains largely unknown. Here we report that isoamyl alcohol (IAA) induces bi-directional currents through a Gα- guanylate cyclase (GC)- cGMP signaling pathway in Caenorhabditis elegans olfactory neuron amphid wing “C” cell (AWC), while two opposite cGMP signaling pathways are responsible for odor-sensing in olfactory neuron amphid wing “B” cell (AWB): (1) a depolarizing Gα (GPA-3)- phosphodiesterase (PDE) – cGMP pathway which can be activated by low concentrations of isoamyl alcohol (IAA), and (2) a hyperpolarizing Gα (ODR-3)- GC- cGMP pathway sensing high concentrations of IAA. Besides, IAA induces Gα (ODR-3)-TRPV(OSM-9)-dependent currents in amphid wing “A” cell (AWA) and amphid neuron “H” cell with single ciliated sensory ending (ASH) neurons with different thresholds. Our results demonstrate that an elaborate combination of multiple signaling machineries encode the intensity of olfactory input, shedding light on understanding the molecular strategies on sensory transduction.

Various odorants trigger complex animal behaviors across species in both quality- and quantity-dependent manners. However, how the intensity of olfactory input is encoded remains largely unknown. Here we report that isoamyl alcohol (IAA) induces bi-directional currents through a Gα- guanylate cyclase (GC)- cGMP signaling pathway in Caenorhabditis elegans olfactory neuron amphid wing "C" cell (AWC), while two opposite cGMP signaling pathways are responsible for odor-sensing in olfactory neuron amphid wing "B" cell (AWB): (1) a depolarizing Gα (GPA-3)- phosphodiesterase (PDE) – cGMP pathway which can be activated by low concentrations of isoamyl alcohol (IAA), and (2) a hyperpolarizing Gα (ODR-3)- GC- cGMP pathway sensing high concentrations of IAA. Besides, IAA induces Gα (ODR-3)-TRPV(OSM-9)-dependent currents in amphid wing "A" cell (AWA) and amphid neuron "H" cell with single ciliated sensory ending (ASH) neurons with different thresholds. Our results demonstrate that an elaborate combination of multiple signaling machineries encode the intensity of olfactory input, shedding light on understanding the molecular strategies on sensory transduction. [ABSTRACT FROM AUTHOR]

The current solar cells and modules are marketed according to the behaviour at standard test conditions (STC), however, these devices are more often operated at lower irradiance levels. The dependence on illumination stems mainly from the voltage at the open circuit and at the maximum power point. The latter might also be strongly influenced by serial resistance, but that is more an engineering problem not addressed here. More fundamentally, the voltage is determined by quasi-Fermi levels at the contacts. In the case of unconstrained conductivity between the absorber and electrode, the quasi-Fermi levels are flat, and determined by their splitting in the absorber. Our analysis shows that the modulation doping mechanism working in Si heterojunction solar cell between the doped amorphous Si layer with a higher bandgap and crystalline absorber with a lower bandgap can, for certain parameter settings, lead to strongly depleted contact layer that limits conduction. This is a prerequisite for decoupling the quasi-Fermi level between contact and absorber and offers the possibility for additional voltage increase. Based on this understanding, we simulate a heterojunction solar cell with a varying thickness and doping of amorphous silicon p-type contact. We demonstrate that for a certain combination of thinner or lower-doped contact, higher efficiency at low illumination can be achieved compared to the technological baseline. This is fully in line with the experimental findings. This analysis is crucial not only for using solar cells for indoor applications but also for designing photovoltaic modules optimized for low irradiance, potentially increasing the level of self-sufficiency of buildings. • Experimental observation of higher efficiency at low light illumination for thinner and lower doped hole selective contacts. • Verification of experimental data with TCAD device simulation. • Optimized Silicon Heterojunction Solar cells to improve low-light illumination efficiency. • Understand device physics through band alignment, Fermi level and modulation doping. • This analysis is crucial not only for using solar cells for indoor applications but also for designing photovoltaic modules optimized for low irradiance. [ABSTRACT FROM AUTHOR]

Measures of the brain’s automatic electrophysiological responses to sounds represent a potential tool for identifying age- and depression-related neural markers. However, these markers have rarely been studied related to aging and depression within one study. Here, we investigated auditory event-related potentials (ERPs) in the brain that may show different alterations related to aging and depression. We used an oddball condition employing changes in sound intensity to investigate: (i) sound intensity dependence; (ii) sensory gating; and (iii) change detection, all within a single paradigm. The ERPs of younger (18–40 years) and older (62–80 years) depressed female participants and age-matched non-depressed participants were measured. Intensity dependence was examined as the difference between N1 responses to repeated high- and low-intensity sounds, sensory gating as N1 responses to rare and repeated sounds, and change detection as indexed by the mismatch negativity (MMN). We found that intensity dependence was greater in older participants than younger ones, indicating effects related to aging but not to depression. For sensory gating, we found depression- and age-related alterations as increased N1 responses. No group differences were found for MMN. Although a sensory gating deficit was expected in older adults, this study is the first to demonstrate age-related overexcitability in sound intensity dependency. The results indicate that automatic brain responses to sound intensity changes are suitable for studying age- and depression-related neural markers but may not be sensitive enough to differentiate the effects of aging and depression.

Measures of the brain's automatic electrophysiological responses to sounds represent a potential tool for identifying age- and depression-related neural markers. However, these markers have rarely been studied related to aging and depression within one study. Here, we investigated auditory event-related potentials (ERPs) in the brain that may show different alterations related to aging and depression. We used an oddball condition employing changes in sound intensity to investigate: (i) sound intensity dependence; (ii) sensory gating; and (iii) change detection, all within a single paradigm. The ERPs of younger (18–40 years) and older (62–80 years) depressed female participants and age-matched non-depressed participants were measured. Intensity dependence was examined as the difference between N1 responses to repeated high- and low-intensity sounds, sensory gating as N1 responses to rare and repeated sounds, and change detection as indexed by the mismatch negativity (MMN). We found that intensity dependence was greater in older participants than younger ones, indicating effects related to aging but not to depression. For sensory gating, we found depression- and age-related alterations as increased N1 responses. No group differences were found for MMN. Although a sensory gating deficit was expected in older adults, this study is the first to demonstrate age-related overexcitability in sound intensity dependency. The results indicate that automatic brain responses to sound intensity changes are suitable for studying age- and depression-related neural markers but may not be sensitive enough to differentiate the effects of aging and depression. [ABSTRACT FROM AUTHOR]

Upconversion (UC) materials enable the emission of a higher energy photon following the absorption of two or more lower-energy photons. The efficiency of UC is non-linear as it depends on the power density of the optical excitation. Hence, the measurement of the UC intensity as a function of excitation power density is a standard material characterization. Such a measurement reveals at which excitation power densities the UC material can be effectively used and hints at the underlying physical mechanisms of UC. One issue in the interpretation of these measurements is the decrease in the UC intensity due to the excitation-laser-induced heating of the sample. Here, we study the excitation-laser-induced heating of β-NaYF 4 :Yb 3+ /Er 3+ (18/2%) micro-powders, ascertaining the temperature as a function of time (and the steady-state temperature reached) for a series of excitation power densities by monitoring the thermally coupled peaks in the emission of the Er 3+ ion. Based on this, we demonstrate a technique to correct the excitation power density dependence of the UC in order to remove the effect of sample heating from the measured data. Correcting the reduction in UC intensity at higher power densities (>50 W/cm 2 ), we recover the UC excitation power density dependencies that agree with theoretical predictions (that disregard thermal effects) in the high excitation power density regime. The reduction in UC intensity due to sample heating can be significant; for example, a 60 K temperature rise lead to a 24% decrease in UC intensity at an excitation power density of 250 W/cm 2 . However, the heating does depend on the nature of the sample. In contrast to the powder samples, β-NaYF 4 :Yb 3+ /Er 3+ (18/2%) nanoparticles in toluene solution showed no heating at excitation power densities up to 250 W/cm 2 . Therefore, we conclude that the proposed correction can remove the effects of sample heating to allow accurate comparison to physical models, and is of especial relevance to powder samples due to their higher absorption of the excitation and poorer thermal transport. [ABSTRACT FROM AUTHOR]

Perception of a facial expression can be altered or biased by a prolonged viewing of other facial expressions, known as the facial expression adaptation aftereffect (FEAA). Recent studies using antiexpressions have demonstrated a monotonic relation between the magnitude of the FEAA and adaptor extremity, suggesting that facial expressions are opponent coded and represented continuously from one expression to its antiexpression. However, it is unclear whether the opponent-coding scheme can account for the FEAA between two facial expressions. In the current study, we demonstrated that the magnitude of the FEAA between two facial expressions increased monotonically as a function of the intensity of adapting facial expressions, consistent with the predictions based on the opponent-coding model. Further, the monotonic increase in the FEAA occurred even when the intensity of an adapting face was too weak for its expression to be recognized. These results together suggest that multiple facial expressions are encoded and represented by balanced activity of neural populations tuned to different facial expressions. [ABSTRACT FROM AUTHOR]

Hosts face mortality from parasitic and environmental stressors, but interactions of parasitism with other stressors are not well understood, particularly for long-lived hosts. We monitored survival of flour beetles (Tribolium confusum) in a longitudinal design incorporating cestode (Hymenolepis diminuta) infection, starvation and exposure to the pesticide diatomaceous earth (DE). We found that cestode cysticercoids exhibit increasing morphological damage and decreasing ability to excyst over time, but were never eliminated from the host. In the presence of even mild environmental stressors, host lifespan was reduced sufficiently that extensive degradation of cysticercoids was never realized. Median host lifespan was 200 days in the absence of stressors, and 3–197 days with parasitism, starvation and/or DE. Early survival of parasitized hosts was higher relative to controls in the presence of intermediate concentrations of DE, but reduced under all other conditions tested. Parasitism increased host mortality in the presence of other stressors at times when parasitism alone did not cause mortality, consistent with an interpretation of synergy. Environmental stressors modified the parasite numbers needed to reveal intensity-dependent host mortality, but only rarely masked intensity dependence. The longitudinal approach produced observations that would have been overlooked or misinterpreted if survival had only been monitored at a single time point. [ABSTRACT FROM AUTHOR]

Some studies suggest that women with primary dysmenorrhea have distinct emotional or personality features. For example, they might exaggerate their responses to external stimuli, such as to intensity-increasing auditory stimuli. Fifteen women with primary dysmenorrhea and 15 healthy women were invited to undergo tests of the intensity dependence of auditory evoked potentials (IDAEP), the Functional and Emotional Measure of Dysmenorrhea, and the Plutchik-van Praag Depression Inventory. Study participants with dysmenorrhea showed higher Functional and Emotional scale scores and stronger IDAEP. Regarding the IDAEP generation, the source inversion of N1 and P2 disclosed the activated bilateral superior temporal gyri, medial and superior prefrontal gyri in all participants, and additionally, the middle frontal gyri in dysmenorrhea patients. We report a pronounced IDAEP in primary dysmenorrhea, which indicates the decreased cerebral serotonergic innervations and points to increased activations in the prefrontal and frontal areas in the disorder.Perspective: Using an IDAEP technique, the authors found decreased serotonergic innervation and altered cerebral activation in women with primary dysmenorrhea, which might offer some pharmacotherapeutic clues for the disorder. [ABSTRACT FROM AUTHOR]

Background Many studies report a habituation deficit of visual evoked potentials (VEP) and/or increased intensity dependence of auditory evoked cortical potentials (IDAP) in episodic migraine patients between attacks. These findings have a pathophysiological interest, but their diagnostic utility is not known. Aims To perform an audit on a large database of interictal VEP and IDAP recordings in episodic migraine patients and evaluate their diagnostic accuracy. Methods We pooled data for VEP habituation and IDAP measured in 624 episodic migraineurs (EM) and 360 healthy volunteers (HV) from three centers. Thresholds were calculated by Receiver Operating Curve analysis and used to calculate sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-) and the accuracy of each test, using ICHD diagnostic criteria as the gold standard. Results In EM, VEP habituation was significantly lower than in HV, and IDAP slopes were significantly steeper. VEP (five blocks of 50 responses), VEP (six blocks of 100 responses) and IDAP had respectively 61.0%, 61.4% and 45.7% sensitivity, and 77.9%, 77.9% and 87.2% specificity. Their positive (LR+) and negative (LR-) likelihood ratios were respectively 2.760, 2.778, 3.570 and 0.500, 0.495, 0.623, with diagnostic accuracies of 65.3%, 69.0% and 54.3%. In combined VEP + IDAP recordings, an abnormality of at least one test had 83.4% sensitivity, 66.7% specificity, 2.504 LR+, 0.249 LR- and 81.1% accuracy. Conclusions In this large database, VEP habituation is significantly reduced and IDAP increased in episodic migraine patients between attacks. Taken alone, neither VEP nor IDAP has sufficient diagnostic accuracy. However, when both tests are performed in the same patient, an abnormality of at least one of them is highly predictive of interictal episodic migraine. [ABSTRACT FROM AUTHOR]

It is widely assumed that damage to the peripheral hearing system is an essential prerequisite for the occurrence of tinnitus. However, previous studies have failed to target tinnitus patients with normal hearing. This study aims to investigate if tinnitus patients with normal audiological presentation demonstrate increased intensity dependence at the selected frequencies. Methods: This study applied auditory cortical evoked potential test to investigate nine tinnitus patients with normal audiological presentation and nine age-and sex-matched healthy subjects without tinnitus. Auditory cortical evoked potentials (N1-P2) were elicited from stimuli at four frequencies (4000, 2000, 1000 and 500 Hz) with five intensities (50, 56, 62, 68 and 74 dB nHL). Intensity dependences by latency of N1 and amplitude of N1-P2 were surveyed at midline electrodes. Results: The results showed that the intensity dependence by latency of N1 to the pooled frequencies at three midline electrodes, e.g. Fz, Cz and Pz, revealed non-significant difference. However, significant differences existed in the intensity dependence of amplitude N1-P2 to the pooled frequencies at the Fz and Cz positions. These differences suggested that tinnitus patients tended to respond less to increased sound intensity and were inclined to weaker intensity dependence. Conclusion: Increased intensity dependence of N1-P2 component at the selected frequencies cannot be demonstrated in tinnitus patients with normal hearing. Restated, the edge frequency phenomenon fails to present in tinnitus patients with normal hearing, a different characteristic from tinnitus patients with hearing loss.

Rationale: Tobacco use is linked to cerebral atrophy and reduced cognitive performance in later life. However, smoking-related long-term effects on brain function remain largely uncertain. Previous studies suggest that nicotine affects serotonergic signaling, and the intensity dependence (alias loudness dependence) of the auditory evoked N1-P2 potential has been proposed as a marker of serotonergic neurotransmission. Objective: In the present study, we assesed the effects of chronic smoking on amplitude and intensity dependence of the auditory evoked N1-P2 potential. Methods: Subjects underwent a 15-min intensity dependence of auditory evoked potentials (IAEP) paradigm. From N = 1739 eligible subjects (40-79 years), we systematically matched current smokers, ex-smokers, and never-smokers by sex, age, alcohol and caffeine consumption, and socioeconomic status. Between-group differences and potential dose-dependencies were evaluated. Results: Analyses revealed higher N1-P2 amplitudes and intensity dependencies in never-smokers relative to ex- and current smokers, with ex-smokers exhibiting intermediate intensity dependencies. Moreover, we observed pack years and number of cigarettes consumed per day to be inversely correlated with amplitudes in current smokers. Conclusions: According to the IAEP serotonin hypothesis, our results suggest serotonin activity to be highest in current smokers, intermediate in ex-smokers, and lowest in never-smokers. To our knowledge, the present study is the first providing evidence for a dose-dependent reduction in N1-P2 amplitudes. Further, we extend prior research by showing reduced amplitudes and intensity dependencies in ex-smokers even 25 years, on average, after cessation. While we can rule out several smoking-related confounders to bias observed associations, causal inferences remain to be established by future longitudinal studies. [ABSTRACT FROM AUTHOR]

Abstract: We have used photoinduced absorption (PA) spectroscopy and measured the intensity dependence on thin films of 1:1 blends of regioregular-poly(3-hexylthiophene):PCBM before and after annealing as well as on 1:1 blends of regiorandom-poly(3-hexylthiophene):PCBM. We have calculated the bimolecular recombination coefficients from the out-of-phase component of the photoinduced absorption. Annealing shows no change in the bimolecular recombination coefficients of rr-P3HT:PCBM, but the increased PA amplitude suggests that the geminate (monomolecular) recombination is reduced. In rra-P3HT:PCBM, the bimolecular recombination coefficient estimated by the same method (disregarding dispersion) is significantly smaller, indicating together with a low PA amplitude that the recombination is primarily geminate. [Copyright &y& Elsevier]

Loudness dependence of auditory evoked potentials (LDAEP) is a validated in vivo marker of central serotonergic function. We aimed at measuring serotonergic activity in a follow-up study of suicidal patients. It should be investigated whether suicide attempts or suicidal states cause changes in the LDAEP. Thirteen patients (mean age, 40.9 ± 11.3 years; age range, 20-61, 6 male) with a major depressive episode who had attempted suicide or had suicidal plans (Hamilton Depression Rating Scale item 3 [suicidality] ≥3) were included in the study. LDAEP and psychometric measurements took place about 2, 5, 9 and 16 days after attempted suicide or suicidal action. On day 9, LDAEP was significantly higher compared to day 2 and day 16; there was a similar tendency compared to day 5. Instability of central serotonergic function is suggested resulting in reduced serotonergic activity about 1 week after suicide attempt. Further studies are necessary that include larger samples in order to distinguish between different psychiatric diseases and to consider confounding factors like gender, smoking, medication, impulsivity or lethality of suicidal action. [ABSTRACT FROM AUTHOR]

Abstract: Temporal summation of C-fiber evoked responses generates an increase in action potential discharge in second-order neurons and in perceived pain intensity (wind-up). This may be related to the central serotonergic system which modulates and partly inhibits sensory input. Aim of the study was to investigate the relationship between wind-up and serotonergic activity using loudness dependence of auditory evoked potentials (LDAEP). 18 healthy subjects were compared to 18 patients with major depression, a disease with a putative serotonin deficit. They were examined with quantitative sensory testing (QST) using the protocol of the German Research Network on Neuropathic Pain (DFNS), including the wind-up ratio (WUR), LDAEP, and psychometric measurements. We found a slight positive correlation between WUR and LDAEP both in healthy controls and depressed patients combined (r =0.340, p =0.043), indicating that WUR may be modulated by serotonergic activity. It can be concluded that inhibitory control to noxious stimuli is partly associated with the central serotonergic function as indicated by LDAEP. [Copyright &y& Elsevier]

Abstract: Intensity dependence is an electrophysiological measure of intra-individual stability of the augmenting/reducing characteristic of N1/ P2 event-related potential amplitudes in response to stimuli of varying intensities. Abstinent ecstasy users typically show enhanced intensity dependence and higher levels of impulsivity and aggression. Enhanced intensity dependence and high impulsivity and aggression levels may be due to damage in the brain''s serotonergic neurons as a result of ecstasy use. The present study investigated whether intensity dependence, impulsivity and aggression history can be used as indictors of previous chronic ecstasy usage. Forty-four abstinent polydrug users (8 women; age 19 to 61years old) were recruited. All participants were currently residents at a local substance abuse facility receiving treatment and had been free of all drugs for a minimum of 21days. The study found significantly enhanced intensity dependence of tangential dipole source activity and a history of more aggressive behavior in those who had previously been involved in chronic ecstasy use. Intensity dependence of the tangential dipole source and aggressive behavior history correctly identified 73.3% of those who had been regular ecstasy users and 78.3% of those who had not. Overall, 76.3% of the participants were correctly classified. [Copyright &y& Elsevier]

Background/purpose: It is widely assumed that damage to the peripheral hearing system is an essential prerequisite for the occurrence of tinnitus. However, previous studies have failed to target tinnitus patients with normal hearing. This study aims to investigate if tinnitus patients with normal audiological presentation demonstrate increased intensity dependence at the selected frequencies.Methods: This study applied auditory cortical evoked potential test to investigate nine tinnitus patients with normal audiological presentation and nine age- and sex-matched healthy subjects without tinnitus. Auditory cortical evoked potentials (N1-P2) were elicited from stimuli at four frequencies (4000, 2000, 1000 and 500 Hz) with five intensities (50, 56, 62, 68 and 74 dB nHL). Intensity dependences by latency of N1 and amplitude of N1-P2 were surveyed at midline electrodes.Results: The results showed that the intensity dependence by latency of N1 to the pooled frequencies at three midline electrodes, e.g. Fz, Cz and Pz, revealed non-significant difference. However, significant differences existed in the intensity dependence of amplitude N1-P2 to the pooled frequencies at the Fz and Cz positions. These differences suggested that tinnitus patients tended to respond less to increased sound intensity and were inclined to weaker intensity dependence.Conclusion: Increased intensity dependence of N1-P2 component at the selected frequencies cannot be demonstrated in tinnitus patients with normal hearing. Restated, the edge frequency phenomenon fails to present in tinnitus patients with normal hearing, a different characteristic from tinnitus patients with hearing loss. [ABSTRACT FROM AUTHOR]

We report a laser spectroscopic investigation of saturation effects in the spectra and dynamics of Eu2O3. The saturation effects occur at high laser intensity and appear as dips in the center of the fluorescence excitation lines and as a shortening of the 5D0 excited-state decay curve. The saturation effects are observed in nanoparticles, micrometer-sized particles, and a fused crystal of monoclinic-phase Eu2O3 and in micrometer-sized particles of cubic-phase Eu2O3. We attribute the mechanism of the nonlinear luminescence quenching to upconversion by energy transfer. [ABSTRACT FROM AUTHOR]

Intensity dependence of auditory-evoked potentials (IAEP) has been suggested as an indicator of central serotonergic neurotransmission. Two recent studies investigated a possible association of IAEP with a functional polymorphism in the transcriptional control region of the serotonin transporter gene (5-HTTLPR) that has a short (s) and a long (l) variant. Although both studies found an association between 5-HTTLPR and IAEP, Gallinat et al found l/l individuals to exhibit lower IAEP, whereas Strobel et al observed stronger IAEP in l/l individuals. These conflicting results require further evaluation and more attention needs to be paid to variables that are known to be confounded with the effects of IAEP and 5-HTTLPR. Using a paradigm comparable to Strobel et al, the present study analyzes the effect of 5-HTTLPR on IAEP in a healthy male student sample (N=91; age=23 years, SD=1.9) that was homogenous for most significant confounding variables. A stronger IAEP was shown in l/l individuals, irrespective of the method of IAEP parametrization. This also held at retest after 3 weeks in a subsample (N=18). Given the successful replication of Strobel et al, several possible reasons for conflicting results with regard to Gallinat et al are discussed. It is argued that the most significant difference between Gallinat et al on the one hand, and Strobel et al and this study on the other, is that different intensity ranges are used which impact IAEP. Therefore, this study encourages further analysis of dose dependence of results.Neuropsychopharmacology (2006) 31, 2047–2054. doi:10.1038/sj.npp.1301020; published online 18 January 2006 [ABSTRACT FROM AUTHOR]

Abstract: Patients with personality disorders such as the histrionic type exaggerate their responses when receiving external social or environmental stimuli. We speculated that they might also show an augmenting pattern of the auditory evoked potential N1–P2 component in response to stimuli with increasing levels of intensity, a response pattern that is thought to be inversely correlated with cerebral serotonin (5-HT) activity. To test this hypothesis, we collected auditory evoked potentials in 191 patients with personality disorders (19 patients with the paranoid type, 12 schizoid, 14 schizotypal, 18 antisocial, 15 borderline, 13 histrionic, 17 narcissistic, 25 avoidant, 30 dependent and 28 obsessive-compulsive) and 26 healthy volunteers. Their personality traits were measured using the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ). Compared with healthy subjects and other patient groups, the histrionic group scored higher on the basic traits Affective Instability, Stimulus Seeking, Rejection and Narcissism, and on the higher traits Emotional Dysregulation and Dissocial, than the other groups, and the schizoid group scored lower on most of the DAPP-BQ basic and higher traits. In addition, the histrionic group showed steeper amplitude/stimulus intensity function (ASF) slopes at three midline scalp electrodes than the healthy controls or the other patient groups. The ASF slopes were not correlated with any DAPP-BQ traits in the total sample of 217 subjects. However, the DAPP-BQ basic trait Rejection was positively correlated with the ASF slopes at all three electrode sites in the histrionic group. The increased intensity dependence of the auditory N1–P2 component might indicate that cerebral 5-HT neuronal activity is, on average, weak in the histrionic patients. [Copyright &y& Elsevier]

An all-optical signal processor based on the self-wavelength conversion of Raman solitons is described. The processor consists of an erbium-doped fiber amplifier (EDFA), a highly nonlinear fiber, and an optical bandpass filter. The timing-jitter-free demultiplexing of the processor was demonstrated by an 80-km transmission experiment. Error-free bit error rate (BER) performance was achieved. Transmitted fourfold optical time-division multiplexing (OTDM) signals with a large timing jitter of about 16 ps for an OTDM signal interval of 25 ps were demultiplexed to 9.95-Gb/s signals without signal degradation. [ABSTRACT FROM PUBLISHER]

The intensity dependence of the auditory evoked N1 ERP component (IDAP) has been suggested as an indicator of central serotonergic neurotransmission with relevance to pharmacological treatment. We report the results of a study evaluating the IDAP in 16 in-patients fulfilling DSM-IV criteria for major depressive episode in the course of treatment with the SSRI Citalopram. Our data revealed a significant correlation between the intensity slopes of the N1 amplitude prior to Citalopram treatment and treatment response: patients with higher intensity slopes of N1 amplitude showed a significantly stronger decrease of HDRS-Score after Citalopram treatment than patients within the lower intensity slope ranges. Our results indicate an association of N1 amplitude intensity dependence with response to antidepressant treatment with Citalopram. [Copyright &y& Elsevier]

Dysfunction of central serotonergic activity has been assumed in patients with borderline personality disorder (BPD) characterized by a prominent impulsive behavioral style. Following the high serotonergic innervation of the primary auditory cortex, there is increasing evidence of the intensity dependence of auditory evoked potentials (AEP), especially the N1/P2 component, indicating serotonergic neurotransmission in animals and humans. 15 females who met the IPDE-criteria for BPD and a group of comparative healthy females (controls) completed extensive personality questionnaires which gave special regard to impulsiveness. We obtained event-related AEP through the application of various loudness stimuli. We examined the relevant N1/P2 amplitude of the tangential dipole of the auditory evoked response using dipole source analysis. The augmentation of the N1/P2 amplitude of tangential dipole source activity with rising stimulus intensity was significantly pronounced in BPD as opposed to controls, accompanied by a reduction in N1 and P2 latencies. The strong loudness dependency of AEP correlated with aspects of impulsiveness. These data imply reduced inhibiting control over cortical sensory processing in BPD. Our findings contribute a further argument to the hypothesis of low serotonergic neurotransmission in BDP and may point to a trait character of impulsiveness in this personality disorder. [Copyright &y& Elsevier]

Migraine patients show abnormalities of cerebral electrophysiology that manifest themselves mainly during the attack interval. Cortical-evoked potentials of migraineurs fail to habituate to repetitive presentations of visual stimuli, and the amplitude of components of their auditory cortical-evoked potentials have a higher dependence on the stimulus intensities than in healthy subjects. A computer model of a neural hetwork has been developed that is able to reproduce both these neurophysiological dysfunctions. It predicts a positive correlation between the magnitudes of both these dysfunctions. The model also offers an explanation of why mutations in the same ion channel gene with opposite consequences on channel function, e.g. P/Q Ca2+ channels in migraine, may lead to similar electrophysiological abnormalities. [ABSTRACT FROM AUTHOR]