Rhythm perception: Speeding up or slowing down affects different subcomponents of the ERP P3 complex

The aim of this study was to investigate, by measuring the event related potential (ERP) P3 complex, whether the perception of small accelerations differs from that of small decelerations. Participants had to decide whether the last beat of a short sequence was presented 'too early' or 'too late'. Target beats were accelerated or decelerated with 0%, 2%, 5%, or 10%. Individuals differed in their capability to detect small tempo changes. We found that good responders were able to identify all tempo changes whereas poor responders were only able to identify large (10%) tempo changes. In addition, we found that tempo changes affected two subcomponents of the ERP P3 in good performers. Accelerations increased a late-P3 amplitude whereas decelerations increased an early-P3 amplitude. These results imply the principle possibility to measure differential P3 effects within one task. This is important for acquiring more refined knowledge concerning different subcomponents of the ERP P3 complex and the cognitive processes by which they are elicited.     

Fos-like immunoreactivity in auditory and nonauditory brain structures of hamsters previously exposed to intense sound

Fos-like immunoreactivity (FLI) was evaluated in auditory and nonauditory brain structures in hamsters that had been exposed previously to intense sound and tested behaviorally for tinnitus. The immunocytochemical results demonstrated a significant increase in exposed animals of FLI in auditory brain structures such as the lateral lemniscus, central nucleus of inferior colliculus, and auditory cortex, as well as in some nonauditory brain structures such as the locus coeruleus, lateral parabrachial nucleus, certain subregions of the hypothalamus, and amygdala. The behavioral scores suggest that animals that had been exposed to intense sound developed tinnitus. This is consistent with the hypothesis that FLI induced by intense sound exposure might represent a neural correlate of tinnitus or of plasticity associated with tinnitus. The possibility and the mechanisms underlying the increased FLI are discussed.     

Can an auditory illusion trick the brain into turning down tinnitus?

Tinnitus, the phantom perception of sound with no external source, affects an estimated 10–15% of the adult population. Current treatments for this oftentimes distressing condition are of limited effectiveness. The “central gain” model proposes that tinnitus arises from an increase in the responsiveness, or gain, of neurons in central auditory pathways, triggered by damage to the auditory periphery. It has been suggested that tinnitus might be treated by compensating for the peripheral damage, thereby restoring normal levels of input to the central pathways, and hence reducing central gain. Unfortunately, when tinnitus originates with permanent damage to the auditory periphery, it may be impossible to compensate for this damage directly. However, we hypothesize that tinnitus may be treated by tricking the brain into believing that it temporarily receives normal levels of input at frequencies where peripheral damage has occurred. We identify an auditory illusion that seems capable, in principle, of achieving this objective. If effective, this approach would offer a safe, accessible, and non-invasive treatment for tinnitus.     

Auditory brainstem response in premenopausal women taking oral contraceptives

BACKGROUND: The aim of this prospective study was to evaluate the effects of the new monophasic oral contraceptives on the audiological system in premenopausal women. METHODS: The auditory brainstem response (ABR) was measured in 94 women during the follicular, periovular and luteal phases of one menstrual cycle in which ovulation was confirmed using sonography and serum progesterone concentration. The latencies for waves I, III and V were determined, and the inter-peak intervals were calculated for waves I-III, I-V and III-V. All 94 women began taking oral contraceptives: 23 women used 20 microg ethinyl estradiol (EE) plus 150 microg desogestrel, 24 women used 30 microg EE plus 75 microg gestodene, and 47 women used 15 microg EE plus 60 microg gestodene. During the third month of contraceptive intake, each subject was again tested for ABR, as above. RESULTS: The wave latencies and inter-peak intervals showed shorter values during the periovular phase with respect to the luteal phase (P < 0.05), the follicular phase for wave I and for inter-peak interval I-V (P < 0.05) of the menstrual cycle. All of the ABR results in pill users were statistically different from those of the periovular phase (P < 0.05), though similar to those of both the luteal and follicular phases (P = NS). CONCLUSIONS: ABR seems to depend on the variations of ovarian steroids during the menstrual cycle and during oral contraceptive intake.     

Effects of intensity of repetitive acoustic stimuli on neural adaptation in the ventral cochlear nucleus of the rat

To study neural adaptation as a function of stimulus intensity, auditory near-field evoked potentials were recorded from the ventral cochlear nucleus in awake Long Evans rats. Responses to 250-ms trains of repetitive clicks (pulse rates ranging from 100 to 1000 pulses per second) were collected at stimulus intensities of 5, 10, 30, 50 and 70 dB SPL. The amplitude of the first negative (N₁) component of the average evoked potentials to individual pulses in the train was measured by using a subtraction method. The N₁ responses were normalized with respect to the highest cochlear nucleus potential observed in the train, and then plotted as a function of click position in the train. As expected, the general trend of the curves was an exponential decay reaching a plateau more or less rapidly as a function of both intensity and rate of stimulation. Fitting these curves with exponential decay equations revealed that the rapid time constant decreased for increasing stimulus intensities whereas the short-term time constant is relatively independent of intensity. The amount of adaptation (expressed as the ratio of the plateau to the first peak amplitude) was substantially less prominent at low intensities (5–10 dB SPL) and low rates (100–200 pulses per second) than at higher intensities and high rates. These results indicate that adaptation patterns obtained in the ventral cochlear nucleus by using near-field evoked potentials exhibit properties comparable to those already present at the level of the auditory nerve.     

The ATP-mediated fast current of rat dorsal root ganglion neurons is a novel effector for GABA(B) receptor activation

To elucidate serotonin modulation of selective attention, 13 volunteers (21–30 years) were studied in two sessions, 5 h after either acute tryptophan depletion (ATD) that decreases brain serotonin synthesis, or control-mixture ingestion (randomized, double-blind, cross-over design). Simultaneous electroencephalogram and magnetoencephalogram were measured during dichotic listening of two concurrent trains of standard and deviant tones. Subjects counted the deviants presented to one ear and ignored those presented to the other ear. ATD lowered plasma total tryptophan by 75% and free tryptophan by 39%. ATD suppressed the amplitude enhancement of P50 and N1 to selectively attended tones, but did not affect the later aspects of processing negativity. The P50 latencies were increased after ATD, irrespective of attention. In conclusion, serotonin may regulate attentional modulation of early cortical stimulus processing.     

癫癎患者听觉事件相关电位的检测报告

目的:探讨听觉事件相关电位(ERP)在癫癎患者中的应用价值。方法:对40例癫癎患者和30名正常人进行ERP检测比较,并将癫癎患者ERP的结果与其发作类型、用药情况等进行比较分析。结果:40例癫癎患者的ERP P300潜伏期较对照组延长(P<0．05),但其P300波幅差异无统计学意义(P>0．05)。全身强直阵挛性发作的28例癫癎患者,P300潜伏期延长尤著。多药治疗组较单药治疗组P300潜伏期延长。结论:癫癎患者存在认识功能障碍,ERP可作为癫癎患者认知功能障碍诊断的参考指标,对指导临床,及早给予干预和治疗有一定意义。     

忽视症多感觉通道缺陷研究的新进展

忽视症可表现为多感觉通道缺陷。该文着重综述了与视觉忽视并存的听觉忽视。视觉忽视的病人常表现出对病损对侧声音的定位缺陷，尤其是当病损同侧存在竞争性声音刺激时，视觉和听觉缺陷的严蘑程度有硅著的相关性。神经影像学研究结果表明，忽视症病人受损的脑区可能与多感觉通道的空间表征有关。     

Tikhonov regularized solutions for improvement of signal-to-noise ratio in case of auditory-evoked potentials

In the present study, standard Tikhonov regularization (STR) Technique and the subspace regularization (SR) method have been applied to remove the additive EEG noise on average auditory-evoked potential (EP) signals. In methodological manner, the difference between these methods is the formation of regularization matrices which are used to solve the weighted problem of EP estimation. Those methods are compared to ensemble averaging (EA) with respect to signal-to-noise-ratio (SNR) improvement in experimental studies, simulations and pseudo-simulations. The results of tests no superiority of the SR in comparison to STR has been observed. In addition, the STR is found to be less computational complex. Moreover, results support the theoretical fact that the STR was introduced to be optimum for smooth solutions whereas the SR allows sharp variations in solutions. Thus, the STR is found to be more useful in removing the noise with the average signal remaining.     

Neurophysiology of hearing in patients with mucopolysaccharidosis type IV

Background

Hearing impairment is a common problem in patients with mucopolysaccharidosis IV (MPS IV) throughout their life. Many of the adult patients with MPS IV exhibit permanent or severe hearing loss. However, there has been no systematic review of detailed audiological test results in MPS IV.