Hearing Range of White-Tailed Deer as Determined by Auditory Brainstem Response

Abstract: Basic knowledge of white-tailed deer (Odocoileus virginianus) hearing can improve understanding of deer behavior and may assist in the development of effective deterrent strategies. Using auditory brainstem response testing, we determined that white-tailed deer hear within the range of frequencies we tested, between 0.25–30 kilohertz (kHz), with best sensitivity between 4–8 kHz. The upper limit of human hearing lies at about 20 kHz, whereas we demonstrated that white-tailed deer detected frequencies to at least 30 kHz. This difference suggests that research on the use of ultrasonic (frequencies >20 kHz) auditory deterrents is justified as a possible means of reducing deer—human conflicts.     

Uptake and Release of d-Aspartate, GABA, and Glycine in Guinea Pig Brainstem Auditory Nuclei

Abstract: This study attempts to determine if the medial (MSO) and lateral superior olive (LSO), medial nucleus of the trapezoid body (MNTB), ventral nucleus of the lateral lemniscus (VNLL), and central nucleus of the inferior colliculus (ICc) contain glutamatergic synaptic endings. Micropunch and microdissection procedures provided fresh samples of these auditory nuclei for the measurement of the high-affinity uptake and electrically evoked release of exogenous d -[³H]ASP. The study also determined if the LSO and MSO contain glycinergic synaptic endings by measuring uptake and release of [¹⁴C]-Gly in these nuclei, and whether the MNTB, VNLL, and ICc contain GABAergic endings by assessing the uptake and release of [¹⁴C]GABA in these structures. Several strategies optimized the evoked Ca²⁺-dependent release of the labeled amino acids. These included the enhancement of high-affinity uptake during loading of the markers into the tissues, inhibition of uptake during the subsequent measurement of release, and use of an electrical stimulus current that evoked maximal Ca²⁺-dependent release. Each of these nuclei manifested the high-affinity uptake and the evoked Ca²⁺-dependent release of d -[³H]Asp, suggesting the presence of synaptic endings that may use Glu or Asp as a transmitter. Similar findings suggest the presence of glycinergic synaptic endings in the LSO and MSO, and of GABAergic synaptic endings in the MNTB, VNLL, and ICc.     

Individual Differences in the Frequency-Following Response: Relation to Pitch Perception

The scalp-recorded frequency-following response (FFR) is a measure of the auditory nervous system’s representation of periodic sound, and may serve as a marker of training-related enhancements, behavioural deficits, and clinical conditions. However, FFRs of healthy normal subjects show considerable variability that remains unexplained. We investigated whether the FFR representation of the frequency content of a complex tone is related to the perception of the pitch of the fundamental frequency. The strength of the fundamental frequency in the FFR of 39 people with normal hearing was assessed when they listened to complex tones that either included or lacked energy at the fundamental frequency. We found that the strength of the fundamental representation of the missing fundamental tone complex correlated significantly with people''s general tendency to perceive the pitch of the tone as either matching the frequency of the spectral components that were present, or that of the missing fundamental. Although at a group level the fundamental representation in the FFR did not appear to be affected by the presence or absence of energy at the same frequency in the stimulus, the two conditions were statistically distinguishable for some subjects individually, indicating that the neural representation is not linearly dependent on the stimulus content. In a second experiment using a within-subjects paradigm, we showed that subjects can learn to reversibly select between either fundamental or spectral perception, and that this is accompanied both by changes to the fundamental representation in the FFR and to cortical-based gamma activity. These results suggest that both fundamental and spectral representations coexist, and are available for later auditory processing stages, the requirements of which may also influence their relative strength and thus modulate FFR variability. The data also highlight voluntary mode perception as a new paradigm with which to study top-down vs bottom-up mechanisms that support the emerging view of the FFR as the outcome of integrated processing in the entire auditory system.     

Alterations in Peripheral and Central Components of the Auditory Brainstem Response: A Neural Assay of Tinnitus

Chronic tinnitus, or “ringing of the ears”, affects upwards of 15% of the adult population. Identifying a cost-effective and objective measure of tinnitus is needed due to legal concerns and disability issues, as well as for facilitating the effort to assess neural biomarkers. We developed a modified gap-in-noise (GIN) paradigm to assess tinnitus in mice using the auditory brainstem response (ABR). We then compared the commonly used acoustic startle reflex gap-prepulse inhibition (gap-PPI) and the ABR GIN paradigm in young adult CBA/CaJ mice before and after administrating sodium salicylate (SS), which is known to reliably induce a 16 kHz tinnitus percept in rodents. Post-SS, gap-PPI was significantly reduced at 12 and 16 kHz, consistent with previous studies demonstrating a tinnitus-induced gap-PPI reduction in this frequency range. ABR audiograms indicated thresholds were significantly elevated post-SS, also consistent with previous studies. There was a significant increase in the peak 2 (P2) to peak 1 (P1) and peak 4 (P4) to P1 amplitude ratios in the mid-frequency range, along with decreased latency of P4 at higher intensities. For the ABR GIN, peak amplitudes of the response to the second noise burst were calculated as a percentage of the first noise burst response amplitudes to quantify neural gap processing. A significant decrease in this ratio (i.e. recovery) was seen only at 16 kHz for P1, indicating the presence of tinnitus near this frequency. Thus, this study demonstrates that GIN ABRs can be used as an efficient, non-invasive, and objective method of identifying the approximate pitch and presence of tinnitus in a mouse model. This technique has the potential for application in human subjects and also indicates significant, albeit different, deficits in temporal processing in peripheral and brainstem circuits following drug induced tinnitus.     

Identifying the Threshold of Iron Deficiency in the Central Nervous System of the Rat by the Auditory Brainstem Response

The deleterious effects of anemia on auditory nerve (AN) development have been well investigated; however, we have previously reported that significant functional consequences in the auditory brainstem response (ABR) can also occur as a consequence of marginal iron deficiency (ID). As the ABR has widespread clinical use, we evaluated the ability of this electrophysiological method to characterize the threshold of tissue ID in rats by examining the relationship between markers of tissue ID and severity of ABR latency defects. To generate various levels of ID, female Long-Evans rats were exposed to diets containing sufficient, borderline, or deficient iron (Fe) concentrations throughout gestation and offspring lifetime. We measured hematological indices of whole body iron stores in dams and offspring to assess the degree of ID. Progression of AN ID in the offspring was measured as ferritin protein levels at different times during postnatal development to complement ABR functional measurements. The severity of ABR deficits correlated with the level of Fe restriction in each diet. The sufficient Fe diet did not induce AN ID and consequently did not show an impaired ABR latency response. The borderline Fe diet, which depleted AN Fe stores but did not cause systemic anemia resulted in significantly increased ABR latency isolated to Peak I.The low Fe diet, which induced anemia and growth retardation, significantly increased ABR latencies of Peaks I to IV. Our findings indicate that changes in the ABR could be related to various degrees of ID experienced throughout development.     

孤独症谱系障碍儿童听觉脑干反应特征分析

摘要 目的：探讨孤独症谱系障碍(autism spectrum disorder,ASD)儿童听觉脑干反应(auditory brainstem response,ABR)各波潜伏期和波间期特征与ASD行为表型间的关联。方法：对2019年7月-2020年12月来我科就诊的26例明确诊断的2~6岁ASD儿童的患儿进行声导抗,听性脑干反应,畸变产物耳声发射及多频稳态听觉诱发电位测试,以38例正常儿童为对照组,进行同样的测试,并对其测试结果进行统计分析。分析ASD儿童左右耳各波潜伏期,波间期特征及与ASD临床表型的关联。结果：ASD儿童左右耳Ⅰ,Ⅲ,Ⅴ波潜伏期分别为(1.42±0.09)ms,(3.67±0.09)ms,(5.65±0.13)ms;(1.45±0.11)ms,(3.69±0.08)ms,(5.62±0.15)ms。ASD组的右耳I,III波的潜伏期均值大于正常组 (P 值均＜0.05);ASD儿童两组间左耳III-V,右耳III-V,右耳I-V的波间期分别是(1.97±0.07)ms,(1.93±0.10)ms,(4.15±0.14)ms;ASD组的左耳III-V,右耳III-V,右耳I-V波间期均小于正常组(P 值均＜0.05);ASD组中小于等于3岁组与大于3岁组间ABR波间期差异不具有统计学意义。关联性分析发现,ASD儿童语言能力与右耳III波潜伏期,右耳最小阈值V波潜伏期负相关;社会行为能力与右耳I-III波间期负相关;社会生活能力与左耳最小阈值V波潜伏期负相关;而ABC评分与ASD儿童右耳III波潜伏期,左耳I-III波间期,右耳I-III波间期正相关。结论：ASD儿童存在异常的听觉脑干反应特征,且异常程度与 ASD 儿童语言,社会行为能力,社会生活能力的严重程度存在明显关联。     

Ontogenesis of Spermatozoa Autoantigens in Guinea Pigs

The ontogenetic appearance of three independant spermatozoa autoantigens (S, P and T) has been studied in guinea pig germinal cells by immunofluorescence and comparison with cytology and histological structures during early maturation of seminiferous tubule cells. The maturation of 120 testes from 60 guinea pigs studied from day 1 to day 50 after birth has shown an evolution in 3 periods. During the first, or negative, period (day 1 to day 25), only spermatogonia (from day 1) and spermatocytes I (from day 16) are present. No significant PAS-positive formations are seen and no autoantigen is detected. During the second, or transitional, period (day 26 to 29), spermatocytes II and spermatids appear as well as paranuclear PAS-positive golgian proacrosomal and acrosomal granules. At the same time, the three autoantigens S, P and T are detected on the same PAS-positive formations with a frequency that increases from day to day. During the third, or positive, period (from day 30) all testes present cells with PAS-positive formation, progressive maturation of acrosomes in spermatids and appearance of spermatozoa (present on day 39) leading to the adult structure of seminiferous tubules. The three autoantigens are constantly present during that period. The simultaneous appearance of the 3 antigens in haploid germinal cells (spermatids and possibly spermatocytes II) as an early expression of cytodifferentiation and their total absence from diploid germinal cells (spermatogonia and spermatocytes I) seem to be of biological significance.     

Dimensions of Animal Personalities in Guinea Pigs

Behavioural phenotypes can be studied from a variety of perspectives. Recent developments have focused on the individual, seeking patterns of behaviour that are stable over time and/or across different contexts (animal personalities). This study applied this method of understanding individual behavioural variability to domestic guinea pigs. Two behavioural domains were investigated: emotionality and social behaviour. Additionally, individual cortisol–stress reactivity and dominance status were examined. Adult male domestic guinea pigs living in large mixed‐sex colonies were subjected to a series of behavioural and physiological tests twice with an intertest interval of 8 wk. Individual consistency over time was found regarding social behaviour, cortisol reactivity and dominance status, whereas no stability regarding emotional behaviour was detected. Furthermore, no stability over contexts was found. Our results suggest that the concept of animal personality is applicable to domestic guinea pigs. The ecological relevance of these data is underscored by the fact that they were obtained in animals from a very rich, socially complex scenario. Moreover, our study highlights that behaviour alone is not sufficient to describe individual phenotypic consistency. Physiological parameters such as stress reactivity should be included in animal personality research. Furthermore dominance – a relative measure which is not an absolute attribute of individuals – proved to be stable over time and thus also shed light on individuality.     

Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region

Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO₂) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO₂ stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs.     

Antibody Response of Guinea Pigs to Trivalent Parainfluenza Virus Vaccine Prepared from Embryonated Eggs

A trivalent parainfluenza virus vaccine has been tested in guinea pigs. The parainfluenza 2 virus vaccine component was superior in the magnitude of antibody titers, and in the ability to convert animals serologically after two doses of an undiluted or a 10-fold diluted vaccine. The parainfluenza 1 virus vaccine gave a higher percentage of conversion than parainfluenza 3 virus vaccine after administration of two doses of either undiluted or 10-fold diluted vaccine.     

Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber)

Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.     

Broadband Onset Inhibition Can Suppress Spectral Splatter in the Auditory Brainstem

In vivo intracellular responses to auditory stimuli revealed that, in a particular population of cells of the ventral nucleus of the lateral lemniscus (VNLL) of rats, fast inhibition occurred before the first action potential. These experimental data were used to constrain a leaky integrate-and-fire (LIF) model of the neurons in this circuit. The post-synaptic potentials of the VNLL cell population were characterized using a method of triggered averaging. Analysis suggested that these inhibited VNLL cells produce action potentials in response to a particular magnitude of the rate of change of their membrane potential. The LIF model was modified to incorporate the VNLL cells’ distinctive action potential production mechanism. The model was used to explore the response of the population of VNLL cells to simple speech-like sounds. These sounds consisted of a simple tone modulated by a saw tooth with exponential decays, similar to glottal pulses that are the repeated impulses seen in vocalizations. It was found that the harmonic component of the sound was enhanced in the VNLL cell population when compared to a population of auditory nerve fibers. This was because the broadband onset noise, also termed spectral splatter, was suppressed by the fast onset inhibition. This mechanism has the potential to greatly improve the clarity of the representation of the harmonic content of certain kinds of natural sounds.     

Social Status and Plasma-Testosterone-Titers in Male Guinea Pigs (Cavia aperes f. porcellus)

The relationship between social status and testosterone (T) titers was studied in male guinea pigs living in a) either one group of 12 males and 12 females for 14–20 months in a 7.86 m² enclosure or in b) five groups of 3 males and 2 females for four months in 3.00 m² enclosures. As described in the literature the social structure of the large group was mainly characterized by long-term male-female associations and spatial preferences whereas in the small groups the linear rank-order between the males was the most obvious element. In all groups the rank-position was positively correlated with the amount of courtship bouts displayed. Fighting occurred only in the large group and in one small group where a challenge to the alpha-position took place. Here the highest ranking males showed highest T-titers in their groups. In those four groups where no fighting occurred rank-position and amount of courtship behaviour displayed was uncorrelated to plasma-T-titers. Our findings suggest that endogenous levels of T only reflect the highest ranking males' social status when their social position is challenged. When dominance relations are resolved and stabilized a male's rank-position and its amount of courtship behaviour displayed appear independent of plasma-T-levels in guinea pigs.     

Role of BMP Signaling for the Formation of Auditory Brainstem Nuclei and Large Auditory Relay Synapses

Large excitatory synapses are found at specific points in the neuronal circuits of the auditory brainstem, to enable fast information transfer and the preservation of acoustic timing information. The extracellular cues and signaling mechanisms that lead to the development of these specialized synaptic connections, exemplified by the calyx of Held in the medial nucleus of the trapezoid body (MNTB), are still largely unknown. Here, we investigate the role of BMP signaling for the early development of the ventral cochlear nucleus (VCN) and MNTB, and for the initial formation of the calyx of Held synaptic connection. We used conditional alleles of two BMP type‐1 receptors in the background of a constitutive BMPR1b knock‐out (KO), or else a conditional allele of SMAD4. The conditional alleles were recombined by the Krox20^Cre mouse line that is active around mid‐gestation in rhombomeres (r) 3 and 5 from which the VCN and MNTB are derived; alternatively, virus‐mediated Cre‐expression was performed early postnatally in the VCN. The data show that embryonic SMAD‐dependent BMP‐signaling in r3 and r5 contributes to the histogenesis of auditory brainstem nuclei. On the other hand, BMP‐receptor signaling early postnatally in presynaptic neurons of the calyx of Held projection is necessary for correct axon branch retraction, which suggests a cell‐autonomous role of presynaptic BMP‐receptors in synapse elimination at the developing calyx of Held. Thus, our work dissects developmentally early and late roles of BMP‐signaling for the formation of auditory brainstem nuclei, and the highly specialized synaptic connectivity in these structures.     

Nonbacteremic Pseudomonas Pneumonia in Immunosuppressed Guinea Pigs

An experimental model of nonbacteremic pneumonia with a virulent strain of Pseudomonas aeruginosa was successfully established in guinea pigs immunosuppressed with cortisone acetate although the organisms were eliminated rapidly from the lungs without cortisone treatment. Using a pocket nebulizer, almost all the animals which received 10⁶ organisms/g-lung developed bronchopneumonia without any septic findings as long as 10 days after challenge. The lesions produced in such animals were characterized by dissemination of multiple purulogranulomatous changes. In the early stage of infection, infiltration of polymorphonuclear cells (PMNs) in the bronchiolar and alveolar spaces was diffuse, later showing multifocal accumulation with the formation of central spherical grains enclosing bacterial colonies. In the later stage, granulation tissue consisting of large mononuclear cells, fibroblasts and collagen fibers developed around the PMN accumulation. The animals which received 10⁷ organisms/g-lung, on the other hand, developed severe pulmonary hemorrhages and necrosis followed by septic death.     

脑干听觉诱发电位与后循环TIA及脑干梗死的相关性研究

目的:研究脑干听觉诱发电位(BAEP)与后循环短暂性脑缺血发作(TIA)及脑干梗死的相关性。方法:选取我院收治的后循环TIA患者46例作为TIA组,选取同期收治的脑干梗死患者44例作为脑干梗死组,选取同期健康体检者49例作为健康组,TIA组和脑干梗死组均在发病后1周内进行BAEP检查,健康体检者在体检时进行BAEP检查,比较3组的Ⅰ、Ⅲ、Ⅴ波的潜伏期(PL)及Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ波峰间的潜伏期(IPL)。结果:TIA组BAEP异常率71.74%,脑干梗死组BAEP异常率56.82%,健康组BAEP异常率24.49%,TIA组患者BAEP异常率高于健康组,差异有统计学意义(P0.05)。脑干梗死组BAEP异常率高于健康组,差异有统计学意义(P0.05)。TIA组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。TIA组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL与PL均明显高于TIA组(P0.05)。结论:BAEP与后循环TIA及脑干梗死存在相关性,并且较为敏感,是优秀的诊断方法之一。