Active head rolls enhance sonar-based auditory localization performance.

Animals utilize a variety of active sensing mechanisms to perceive the world around them. Echolocating bats are an excellent model for the study of active auditory localization. The big brown bat (Eptesicus fuscus), for instance, employs active head roll movements during sonar prey tracking. The function of head rolls in sound source localization is not well understood. Here, we propose an echolocation model with multi-axis head rotation to investigate the effect of active head roll movements on sound localization performance. The model autonomously learns to align the bat's head direction towards the target. We show that a model with active head roll movements better localizes targets than a model without head rolls. Furthermore, we demonstrate that active head rolls also reduce the time required for localization in elevation. Finally, our model offers key insights to sound localization cues used by echolocating bats employing active head movements during echolocation.

Network Canvas: Key decisions in the design of an interviewer assisted network data collection software suite.

Self-reported social network analysis studies are often complex and burdensome, both during the interview process itself, and when conducting data management following the interview. Through funding obtained from the National Institute on Drug Abuse (NIDA/NIH), our team developed the Network Canvas suite of software - a set of complementary tools that are designed to simplify the collection and storage of complex social network data, with an emphasis on usability and accessibility across platforms and devices, and guided by the practical needs of researchers. The suite consists of three applications: Architect: an application for researchers to design and export interview protocols; Interviewer: a touch-optimized application for loading and administering interview protocols to study participants; and Server: an application for researchers to manage the interview deployment process and export their data for analysis. Together, they enable researchers with minimal technological expertise to access a complete research workflow, by building their own network interview protocols, deploying these protocols widely within a variety of contexts, and immediately attaining the resulting data from a secure central location. In this paper, we outline the critical decisions taken in developing this suite of tools for the network research community. We also describe the work which guides our decision-making, including prior experiences and key discovery events. We focus on key design choices, taken for theoretical, philosophical, and pragmatic reasons, and outline their strengths and limitations.

Composite gelfoam/fascia graft: a novel technique in tympanoplasty surgery.

BACKGROUND: Traditional tympanoplasty techniques require graft placement and then supporting material (GelFoam) as a two-step process. Both steps potentially disrupt accurate graft placement leading to failure and persistence of the perforation. METHODS: We demonstrate a novel technique for graft preparation and placement using composite gelfoam/fascia in which the gelfoam and fascia are compressed into a common layer and applied to the perforation and drum remnant in a single step. Placement is ergonomically efficient and effective. CONCLUSION: This novel modification of traditional graft preparation and placement is simple and ergonomically efficient.

Functional Organization and Dynamic Activity in the Superior Colliculus of the Echolocating Bat, Eptesicus fuscus.

Sensory-guided behaviors require the transformation of sensory information into task-specific motor commands. Prior research on sensorimotor integration has emphasized visuomotor processes in the context of simplified orienting movements in controlled laboratory tasks rather than an animal's more complete, natural behavioral repertoire. Here, we conducted a series of neural recording experiments in the midbrain superior colliculus (SC) of echolocating bats engaged in a sonar target-tracking task that invoked dynamic active sensing behaviors. We hypothesized that SC activity in freely behaving animals would reveal dynamic shifts in neural firing patterns within and across sensory, sensorimotor, and premotor layers. We recorded neural activity in the SC of freely echolocating bats (three females and one male) and replicated the general trends reported in other species with sensory responses in the dorsal divisions and premotor activity in ventral divisions of the SC. However, within this coarse functional organization, we discovered that sensory and motor neurons are comingled within layers throughout the volume of the bat SC. In addition, as the bat increased pulse rate adaptively to increase resolution of the target location with closing distance, the activity of sensory and vocal premotor neurons changed such that auditory response times decreased, and vocal premotor lead times shortened. This finding demonstrates that SC activity can be modified dynamically in concert with adaptive behaviors and suggests that an integrated functional organization within SC laminae supports rapid and local integration of sensory and motor signals for natural, adaptive behaviors.SIGNIFICANCE STATEMENT Natural sensory-guided behaviors involve the rapid integration of information from the environment to direct flexible motor actions. The vast majority of research on sensorimotor integration has used artificial stimuli and simplified behaviors, leaving open questions about nervous system function in the context of natural tasks. Our work investigated mechanisms of dynamic sensorimotor feedback control by analyzing patterns of neural activity in the midbrain superior colliculus (SC) of an echolocating bat tracking and intercepting moving prey. Recordings revealed that sensory and motor neurons comingle within laminae of the SC to support rapid sensorimotor integration. Further, we discovered that neural activity in the bat SC changes with dynamic adaptations in the animal's echolocation behavior.

Action Enhances Acoustic Cues for 3-D Target Localization by Echolocating Bats.

Under natural conditions, animals encounter a barrage of sensory information from which they must select and interpret biologically relevant signals. Active sensing can facilitate this process by engaging motor systems in the sampling of sensory information. The echolocating bat serves as an excellent model to investigate the coupling between action and sensing because it adaptively controls both the acoustic signals used to probe the environment and movements to receive echoes at the auditory periphery. We report here that the echolocating bat controls the features of its sonar vocalizations in tandem with the positioning of the outer ears to maximize acoustic cues for target detection and localization. The bat's adaptive control of sonar vocalizations and ear positioning occurs on a millisecond timescale to capture spatial information from arriving echoes, as well as on a longer timescale to track target movement. Our results demonstrate that purposeful control over sonar sound production and reception can serve to improve acoustic cues for localization tasks. This finding also highlights the general importance of movement to sensory processing across animal species. Finally, our discoveries point to important parallels between spatial perception by echolocation and vision.

Midbrain auditory selectivity to natural sounds.

This study investigated auditory stimulus selectivity in the midbrain superior colliculus (SC) of the echolocating bat, an animal that relies on hearing to guide its orienting behaviors. Multichannel, single-unit recordings were taken across laminae of the midbrain SC of the awake, passively listening big brown bat, Eptesicus fuscus. Species-specific frequency-modulated (FM) echolocation sound sequences with dynamic spectrotemporal features served as acoustic stimuli along with artificial sound sequences matched in bandwidth, amplitude, and duration but differing in spectrotemporal structure. Neurons in dorsal sensory regions of the bat SC responded selectively to elements within the FM sound sequences, whereas neurons in ventral sensorimotor regions showed broad response profiles to natural and artificial stimuli. Moreover, a generalized linear model (GLM) constructed on responses in the dorsal SC to artificial linear FM stimuli failed to predict responses to natural sounds and vice versa, but the GLM produced accurate response predictions in ventral SC neurons. This result suggests that auditory selectivity in the dorsal extent of the bat SC arises through nonlinear mechanisms, which extract species-specific sensory information. Importantly, auditory selectivity appeared only in responses to stimuli containing the natural statistics of acoustic signals used by the bat for spatial orientation-sonar vocalizations-offering support for the hypothesis that sensory selectivity enables rapid species-specific orienting behaviors. The results of this study are the first, to our knowledge, to show auditory spectrotemporal selectivity to natural stimuli in SC neurons and serve to inform a more general understanding of mechanisms guiding sensory selectivity for natural, goal-directed orienting behaviors.

Active acoustic interference elicits echolocation changes in heterospecific bats.

Echolocating bats often forage in the presence of both conspecific and heterospecific individuals, which have the potential to produce acoustic interference. Recent studies have shown that at least one bat species, the Brazilian free-tailed bat (Tadarida brasiliensis), produces specialized social signals that disrupt the sonar of conspecific competitors. We herein discuss the differences between passive and active jamming signals and test whether heterospecific jamming occurs in species overlapping spatiotemporally, as well as whether such interference elicits a jamming avoidance response. We compare the capture rates of tethered moths and the echolocation parameters of big brown bats (Eptesicus fuscus) challenged with the playback of the jamming signal normally produced by Brazilian free-tailed bats and playback of deconstructed versions of this signal. There were no differences in the capture rates of targets with and without the jamming signal, although significant changes in both spectral and temporal features of the bats' echolocation were observed. These changes are consistent with improvements of the signal-to-noise ratio in the presence of acoustic interference. Accordingly, we propose to expand the traditional definition of the jamming avoidance response, stating that echolocation changes in response to interference should decrease similarity between the two signals, to include any change that increases the ability to separate returning echoes from active jamming stimuli originating from conspecific and heterospecific organisms. Flexibility in echolocation is an important characteristic for overcoming various forms of acoustic interference and may serve a purpose in interspecific interactions as well as intraspecific ones.

Adaptive sonar call timing supports target tracking in echolocating bats.

Echolocating bats dynamically adapt the features of their sonar calls as they approach obstacles and track targets. As insectivorous bats forage, they increase sonar call rate with decreasing prey distance, and often embedded in bat insect approach sequences are clusters of sonar sounds, termed sonar sound groups (SSGs). The bat's production of SSGs has been observed in both field and laboratory conditions, and is hypothesized to sharpen spatiotemporal sonar resolution. When insectivorous bats hunt, they may encounter erratically moving prey, which increases the demands on the bat's sonar imaging system. Here, we studied the bat's adaptive vocal behavior in an experimentally controlled insect-tracking task, allowing us to manipulate the predictability of target trajectories and measure the prevalence of SSGs. With this system, we trained bats to remain stationary on a platform and track a moving prey item, whose trajectory was programmed either to approach the bat, or to move back and forth, before arriving at the bat. We manipulated target motion predictability by varying the order in which different target trajectories were presented to the bats. During all trials, we recorded the bat's sonar calls and later analysed the incidence of SSG production during the different target tracking conditions. Our results demonstrate that bats increase the production of SSGs when target unpredictability increases, and decrease the production of SSGs when target motion predictability increases. Furthermore, bats produce the same number of sonar vocalizations irrespective of the target motion predictability, indicating that the animal's temporal clustering of sonar call sequences to produce SSGs is purposeful, and therefore involves sensorimotor planning.

Geographic variation in hybridization and ecological differentiation between three syntopic, morphologically similar species of montane lizards.

To understand factors shaping species boundaries in closely related taxa, a powerful approach is to compare levels of genetic admixture at multiple points of contact and determine how this relates to intrinsic and extrinsic factors, such as genetic, morphological and ecological differentiation. In the Australian Alps, the threatened alpine bog skink Pseudemoia cryodroma co-occurs with two morphologically and ecologically similar congeners, P. entrecasteauxii and P. pagenstecheri, and all three species are suspected to hybridize. We predicted that the frequency of hybridization should be negatively correlated with genetic divergence, morphological differentiation and microhabitat separation. We tested this hypothesis using a mitochondrial locus, 13 microsatellite loci, morphological and microhabitat data and compared results across three geographically isolated sites. Despite strong genetic structure between species, we detected hybridization between all species pairs, including evidence of backcrossed individuals at the two sites where all three species are syntopic. Hybridization frequencies were not consistently associated with genetic, morphological or ecological differentiation. Furthermore, P. entrecasteauxii and P. pagenstecheri only hybridized at the two sites where they are syntopic with P. cryodroma, but not at the largest site where P. cryodroma was not recorded, suggesting that P. cryodroma may serve as a bridging species. This study reveals the complex dynamics within a three species hybrid zone and provides a baseline for assessing the impact of climate change and anthropogenic habitat modification on future hybridization frequencies.

Social cognition dysfunction in adolescents with 22q11.2 deletion syndrome (velo-cardio-facial syndrome): relationship with executive functioning and social competence/functioning.

BACKGROUND: Social difficulties are often noted among people with intellectual disabilities. Children and adults with 22q.11.2 deletion syndrome (22q11DS) often have poorer social competence as well as poorer performance on measures of executive and social-cognitive skills compared with typically developing young people. However, the relationship between social functioning and more basic processes of social cognition and executive functioning are not well understood in 22q11DS. The present study examined the relationship between social-cognitive measures of emotion attribution and theory of mind with executive functioning and their contribution to social competence in 22q11DS. METHOD: The present cross-sectional study measured social cognition and executive performance of 24 adolescents with 22q11DS compared with 27 age-matched typically developing controls. Social cognition was tested using the emotion attribution task (EAT) and a picture sequencing task (PST), which tested mentalising (false-belief), sequencing, cause and effect, and inhibition. Executive functioning was assessed using computerised versions of the Tower of London task and working memory measures of spatial and non-spatial ability. Social competence was also assessed using the parent-reported Strengths and Difficulties Questionnaire. RESULTS: Adolescents with 22q11DS showed impaired false-belief, emotion attribution and executive functioning compared with typically developing control participants. Poorer performance was reported on all story types in the PST, although, patterns of errors and response times across story types were similar in both groups. General sequencing ability was the strongest predictor of false-belief, and performance on the false-belief task predicted emotion attribution accuracy. Intellectual functioning, rather than theory of mind or executive functioning, predicted social competence in 22q11DS. CONCLUSIONS: Performance on social-cognitive tasks of theory of mind indicate evidence of a general underlying dysfunction in 22q11DS that includes executive ability to understand cause and effect, to logically reason about social scenarios and also to inhibit responses to salient, but misleading cues. However, general intellectual ability is closely related to actual social competence suggesting that a generalised intellectual deficit coupled with more specific executive impairments may best explain poor social cognition in 22q11DS.

Neural coding of 3D spatial location, orientation, and action selection in echolocating bats.

Echolocating bats are among the only mammals capable of powered flight, and they rely on active sensing to find food and steer around obstacles in 3D environments. These natural behaviors depend on neural circuits that support 3D auditory localization, audio-motor integration, navigation, and flight control, which are modulated by spatial attention and action selection.

Spatially clustered neurons encode vocalization categories in the bat midbrain.

Rapid categorization of vocalizations enables adaptive behavior across species. While categorical perception is thought to arise in the neocortex, humans and other animals could benefit from functional organization of ethologically-relevant sounds at earlier stages in the auditory hierarchy. Here, we developed two-photon calcium imaging in the awake echolocating bat (Eptesicus fuscus) to study encoding of sound meaning in the Inferior Colliculus, which is as few as two synapses from the inner ear. Echolocating bats produce and interpret frequency sweep-based vocalizations for social communication and navigation. Auditory playback experiments demonstrated that individual neurons responded selectively to social or navigation calls, enabling robust population-level decoding across categories. Strikingly, category-selective neurons formed spatial clusters, independent of tonotopy within the IC. These findings support a revised view of categorical processing in which specified channels for ethologically-relevant sounds are spatially segregated early in the auditory hierarchy, enabling rapid subcortical organization of call meaning.

FGL2/fibroleukin mediates hepatic reperfusion injury by induction of sinusoidal endothelial cell and hepatocyte apoptosis in mice.

BACKGROUND & AIMS: Sinusoidal endothelial cell (SEC) and hepatocyte death are early, TNF-α mediated events in ischemia and reperfusion of the liver (I/Rp). We previously reported that TNF-α induced liver injury is dependent on Fibrinogen like protein 2 (FGL2/Fibroleukin) and showed that FGL2 binding to its receptor, FcγRIIB, results in lymphocyte apoptosis. In this study we examine whether I/Rp is induced by specific binding of FGL2 to FcγRIIB expressed on SEC. METHODS: Hepatic ischemia and reperfusion was induced in wild type (WT) mice and in mice with deletion or inhibition of FGL2 and FcRIIB. Liver injury was determined by AST release, necrosis and animal death. Apoptosis was evaluated with caspase 3 and TUNEL staining. RESULTS: FGL2 deletion or inhibition resulted in decreased liver injury as determined by a marked reduction in both levels of AST and ALT and hepatocyte necrosis. Caspase 3 staining of SEC (12% vs. 75%) and hepatocytes (12% vs. 45%) as well as TUNEL staining of SEC (13% vs. 60%, p=0.02) and hepatocytes (18% vs. 70%, p=0.03), markers of apoptosis, were lower in Fgl2(-/-) compared to WT mice. In vitro incubation of SEC with FGL2 induced apoptosis of SEC from WT mice, but not FcγRIIB(-/-) mice. Deletion of FcγRIIB fully protected mice against SEC and hepatocyte death in vivo. Survival of mice deficient in either Fgl2(-/-) (80%) or FcγRIIB(-/-) (100%) was markedly increased compared to WT mice (10%) which were subjected to 75min of total hepatic ischemia (p=0.001). CONCLUSIONS: FGL2 binding to the FcγRIIB receptor expressed on SEC is a critical event in the initiation of the hepatic reperfusion injury cascade through induction of SEC and hepatocyte death.

Tension pneumocephalus: case report and review.

Tension pneumocephalus is a rare complication of frontal sinus fracture or neurosurgical intervention resulting from compression of the brain by entrapped air, leading to seizure, altered mental status, brain herniation, and death. This report presents a case of traumatic tension pneumocephalus associated with an anterior and posterior table frontal sinus fracture in a patient with pneumosinus dilatans and osteogenesis imperfecta.

Linked control of syllable sequence and phonology in birdsong.

The control of sequenced behaviors, including human speech, requires that the brain coordinate the production of discrete motor elements with their concatenation into complex patterns. In birdsong, another sequential vocal behavior, the acoustic structure (phonology) of individual song elements, or "syllables," must be coordinated with the sequencing of syllables into a song. However, it is unknown whether syllable phonology is independent of the sequence in which a syllable is produced. We quantified interactions between phonology and sequence in Bengalese finch song by examining both convergent syllables, which can be preceded by at least two different syllables and divergent syllables, which can be followed by at least two different syllables. Phonology differed significantly based on the identity of the preceding syllable for 97% of convergent syllables and differed significantly with the identity of the upcoming syllable for 92% of divergent syllables. Furthermore, sequence-dependent phonological differences extended at least two syllables away from the convergent or divergent syllable. To determine whether these phenomena reflect differences in central control, we analyzed premotor neural activity in the robust nucleus of the arcopallium (RA). Activity associated with a syllable varied significantly depending on the sequence in which the syllable was produced, suggesting that sequence-dependent variations in premotor activity contribute to sequence-dependent differences in phonology. Moreover, these data indicate that RA activity could contribute to the sequencing of syllables. Together, these results suggest that, rather than being controlled independently, the sequence and phonology of birdsong are intimately related, as is the case for human speech.

Genetic determinants of mouse hepatitis virus strain 1 pneumovirulence.

We report here investigation into the genetic basis of mouse hepatitis virus strain 1 (MHV-1) pneumovirulence. Sequencing of the 3' one-third of the MHV-1 genome demonstrated that the genetic organization of MHV-1 was similar to that of other strains of MHV. The hemagglutinin esterase (HE) protein was truncated, and reverse transcription-PCR (RT-PCR) studies confirmed previous work that suggested that the MHV-1 HE is a pseudogene. Targeted recombination was used to select chimeric viruses containing either the MHV-1 S gene or genes encoding all of the MHV-1 structural proteins, on an MHV-A59 background. Challenge studies in mice demonstrated that expression of the MHV-1 S gene within the MHV-A59 background (rA59/S(MHV-1)) increased the pneumovirulence of MHV-A59, and mice infected with this recombinant virus developed pulmonary lesions that were similar to those observed with MHV-1, although rA59/S(MHV-1) was significantly less virulent. Chimeras containing all of the MHV-1 structural genes on an MHV-A59 background were able to reproduce the severe acute respiratory syndrome (SARS)-like pathology observed with MHV-1 and reproducibly increased pneumovirulence relative to rA59/S(MHV-1), but were still much less virulent than MHV-1. These data suggest that important determinants of pneumopathogenicity are contained within the 3' one-third of the MHV-1 genome, but additional important virulence factors must be encoded in the genome upstream of the S gene. The severity of the pulmonary lesions observed correlates better with elevated levels of inflammatory cytokines than with viral replication in the lungs, suggesting that pulmonary disease has an important immunological component.

Evolutionary origins and diversification of dragon lizards in Australia's tropical savannas.

Australia's monsoonal tropics are dominated by the largest and least modified savanna woodlands in the world, and they are globally significant for their high biodiversity and regional endemism. Despite this, there have been very few molecular studies of the evolutionary origins and diversification of vertebrates in this region. The semi-arboreal dragon lizards of Lophognathus and Amphibolurus are widely distributed in the savanna and dry sclerophyll woodlands of Australasia, including the monsoon tropics. We sequenced a ~1400 bp region of mitochondrial DNA and a ~1400 bp nuclear gene (RAG1) to investigate the phylogenetic relationships and phylogeographic structuring of all seven species of Lophognathus and Amphibolurus. Our analyses show that there is a higher level of species and generic diversity in the monsoon tropics than previously thought, and a full morphological review and taxonomic revision of these genera is required. Relaxed molecular clock analyses indicate that species across both genera originated in the late Miocene and early Pliocene, with significant phylogeographic structure within species. We did not find any evidence that the monsoon tropics species were a monophyletic group that had diversified within the region; instead Amphibolurus and Lophognathus represent at least three independent evolutionary colonizations of the monsoon tropics. It is probable that the origins and phylogeographic patterns of the northern Lophognathus species have evolved under the climatic influence of the Australian monsoon, rather than being either an ancient Gondwanan lineage that pre-dates the monsoon or the result of a more recent dispersal event across Wallace's Line.

Risk Factors for Facial Nerve and Other Nonauditory Side Effects Following Cochlear Implantation.

OBJECTIVE: The purpose of this study was to characterize a cohort of patients with nonauditory side-effects (NASx) following cochlear implant (CI) surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: One hundred twenty three multichannel CI recipients with intraoperative facial nerve stimulation (FNS). INTERVENTIONS: Intraoperative electrical auditory brainstem responses (eABR) during CI surgery. MAIN OUTCOME MEASURES: Nonauditory side effects post-CI activation. RESULTS: Intraoperative FNS was identified in 2.26% of patients (123/5441), of whom, 34% (42/123) experienced VII stimulation on CI activation. Pain was experienced by 22% (27/123) and vestibular dysfunction was experienced by 4% (5/123) of cases. All case who experienced pain and/or vestibular NASx also experienced VII stimulation. The majority of cases were managed by CI remapping or observation and habituation.Significant relationships were found between etiology of hearing loss and presence of FNS upon initial activation (p < 0.05). No significance was found between FNS intraoperatively and at initial activation for all assumed mechanisms of hearing loss (p > 0.05) with the exceptions of acquired hearing loss of undetermined etiology and toxic etiology group (p < 0.05).There was no significant impact of implant array design (p > 0.05). CONCLUSIONS: This study has characterized patients with NASx in a large cohort of CI patients. One third of cases identified with FNS intraoperatively, developed NASx post-CI activation. Risk factors for NASx postactivation include high-risk etiologies and intraoperative objective measures (i.e., eABR). This may assist surgeons and audiologists to identify at-risk patients who may need modifications in CI program planning.

Validation of a 3D-printed human temporal bone model for otology surgical skill training.

HYPOTHESIS: Three-dimensional (3D) printed temporal bones are comparable to cadaveric temporal bones as a training tool for otologic surgery. BACKGROUND: Cadaveric temporal bone dissection is an integral part of otology surgical training. Unfortunately, availability of cadaveric temporal bones is becoming much more limited and concern regarding chemical and biological risks persist. In this study, we examine the validity of 3D-printed temporal bone model as an alternative training tool for otologic surgery. METHODS: Seventeen otolaryngology trainees participated in the study. They were asked to complete a series of otologic procedures using 3D-printed temporal bones. A semi-structured questionnaire was used to evaluate their dissection experience on the 3D-printed temporal bones. RESULTS: Participants found that the 3D-printed temporal bones were anatomically realistic compared to cadaveric temporal bones. They found that the 3D-printed temporal bones were useful as a surgical training tool in general and also for specific otologic procedures. Overall, participants were enthusiastic about incorporation of 3D-printed temporal bones in temporal bone dissection training courses and would recommend them to other trainees. CONCLUSION: 3D-printed temporal bone model is a viable alternative to human cadaveric temporal bones as a teaching tool for otologic surgery.