On cortical coding of vocal communication sounds in primates

Understanding how the brain processes vocal communication sounds is one of the most challenging problems in neuroscience. Our understanding of how the cortex accomplishes this unique task should greatly facilitate our understanding of cortical mechanisms in general. Perception of species-specific communication sounds is an important aspect of the auditory behavior of many animal species and is crucial for their social interactions, reproductive success, and survival. The principles of neural representations of these behaviorally important sounds in the cerebral cortex have direct implications for the neural mechanisms underlying human speech perception. Our progress in this area has been relatively slow, compared with our understanding of other auditory functions such as echolocation and sound localization. This article discusses previous and current studies in this field, with emphasis on nonhuman primates, and proposes a conceptual platform to further our exploration of this frontier. It is argued that the prerequisite condition for understanding cortical mechanisms underlying communication sound perception and production is an appropriate animal model. Three issues are central to this work: (i) neural encoding of statistical structure of communication sounds, (ii) the role of behavioral relevance in shaping cortical representations, and (iii) sensory–motor interactions between vocal production and perception systems.

Inhibitory network interactions shape the auditory processing of natural communication signals in the songbird auditory forebrain

The role of GABA in the central processing of complex auditory signals is not fully understood. We have studied the involvement of GABA(A)-mediated inhibition in the processing of birdsong, a learned vocal communication signal requiring intact hearing for its development and maintenance. We focused on caudomedial nidopallium (NCM), an area analogous to parts of the mammalian auditory cortex with selective responses to birdsong. We present evidence that GABA(A)-mediated inhibition plays a pronounced role in NCM`s auditory processing of birdsong. Using immunocytochemistry, we show that approximately half of NCM`s neurons are GABAergic. Whole cell patch-clamp recordings in a slice preparation demonstrate that, at rest, spontaneously active GABAergic synapses inhibit excitatory inputs onto NCM neurons via GABA(A) receptors. Multi-electrode electrophysiological recordings in awake birds show that local blockade of GABA(A)-mediated inhibition in NCM markedly affects the temporal pattern of song-evoked responses in NCM without modifications in frequency tuning. Surprisingly, this blockade increases the phasic and largely suppresses the tonic response component, reflecting dynamic relationships of inhibitory networks that could include disinhibition. Thus processing of learned natural communication sounds in songbirds, and possibly other vocal learners, may depend on complex interactions of inhibitory networks.

How siblings adjust sib-sib communication and begging signals to each other

Parents allocate food resources to their offspring in proportion to the intensity of begging behaviour. Begging encompasses several activities including vocalizations that should honestly signal need and jostling for the position in the nest where parents predictably deliver food items. Although siblings are known to adjust begging level to each other, the underlying mechanism remains unknown. We examined this issue in experimental two-chick broods of the barn owl, Tyto alba, a species in which siblings communicate vocally with each other in the prolonged absence of parents. The function of sib-sib vocal communication, so-called sibling negotiation, is to resolve conflicts over which individual will have priority of access to the next delivered indivisible food item. We found that when a nestling produced longer negotiation calls and stood closer to the nestbox entrance in the absence of parents, its sibling vocally negotiated at a lower rate. Additionally, when an individual produced more negotiation calls in the absence of parents, its sibling begged less intensely at the parent's return, with begging being the key factor that determined which nestling obtained a food item. We conclude that position in the nest and the duration of negotiation calls produced in the absence of parents influence the rate of producing negotiation calls, which in turn influences the rate at which siblings beg for food from their parents. Adjusting begging behaviour could therefore depend on complex sib-sib interactions taking place in the prolonged absence of parents.

Nestling barn owls assess short-term variation in the amount of vocally competing siblings.

Assessing the amount of rivals is crucial to optimally adjust investment into a contest. If laboratory animals show numerical abilities, little is known about the ecological implications particularly in young animals. The two to nine barn owl (Tyto alba) siblings vocally compete for priority of access to food resources before parents actually deliver them. In dyads, the individual that vocalizes at the highest rate in the absence of parents deters its siblings from competing for next delivered prey. We tested the novel hypothesis that to optimally adjust vocal investment, barn owl nestlings assess how many of their siblings are currently competing. To singleton owlets, we broadcasted a fixed global number of calls emitted by one, two or four pre-recorded unfamiliar nestlings. We could thus distinguish the independent effect on singletons' vocal behavior of the global number of calls produced by a brood from the number of competitors that produced these calls. Overall, nestlings retreated more from vocal contest when facing more competitors. However, in front of one highly motivated competitor, nestlings refrained from vocalizing to a larger extent than when competing against more but less motivated individuals. Therefore, young animals assess variation in the number of currently competing siblings based on individual-specific vocal cues.

The Role of Orexin-A in Anxiety and the Emission of Ultrasonic Vocalizations in Rats

Central administration of orexin-A has been shown to activate autonomic arousal in rats, reliably inducing anxiety-like behaviours in the open field. To date, there has yet to be a study investigating the role of orexin-A in the communication of such negative affective state. In the current study, forty-six adult male rats were chronically cannulated and administered orexin-A into the medial preoptic area/anterior hypothalamic area to determine the effect of this neuropeptide on anxiety-like behaviour and the production of 22 kHz aversive ultrasonic vocalizations. It was found that intracerebral administration of orexin-A increased autonomic arousal as measured by a significant increase in fecal boli output, however orexin-A did not significantly affect locomotor activity or induce 22 kHz calling. These data suggest that orexin-A is involved in the regulation of the autonomic aspect of anxiety-like behaviour but not in the vocal communication of such negative affect

Did they talk their way out of Africa?

Corballis suggests that fully vocal communication was invented by modern humans between 170,000 and 50,000 years ago. Because this new form of communication did not require hand gestures, he wondered whether this may have facilitated the development of lithic manufacture. I cast doubt on this interesting notion but offer an enhanced version that may have more potential.

Bioacoustic analysis of advertisement call in Hyla nana and Hyla sanborni (Anura, Hylidae) in Botucatu, São Paulo, Brazil

As características relacionadas à comunicação sonora em duas espécies aparentadas, Hyla nana e H. sanborni, pertencentes ao grupo nana de espécies, foram estudadas, entre agosto de 1997 e junho de 1999, em duas poças permanentes de grande porte em área aberta na região de Botucatu, Estado de São Paulo. Foram obtidas gravações de 131 exemplares, 71 indivíduos de H. nana e 58 de H. sanborni, durante início de atividade de vocalização e atividade de vocalização em coro. Houve diferença nos ritmos de emissão de notas dos cantos entre o início das atividades e durante os coros. O canto de anúncio das espécies consiste na emissão de séries consecutivas de notas simples, pulsadas, com taxa de repetição rápida. Hyla nana e H. sanborni apresentam dois tipos de notas em seu canto de anúncio, denominados aqui como tipos A e B. Notas do tipo A, introdutórias, apresentam maior duração e número de pulsos, e suas emissões foram mais freqüentes durante o início das atividades de vocalização. As notas introdutórias são as primeiras da série emitida em atividade de coro. As notas do tipo B, secundárias, são curtas e com menor número de pulsos, sendo emitidas durante as vocalizações em coro. Os dois tipos de notas encontrados diferem significativamente em sua estrutura temporal. As duas espécies apresentaram segregação acústica tanto na estrutura espectral como na temporal de seus cantos de anúncio.

Zmiany w systemach komunikacji akustycznej ptaków jako bioindykatory zmian w środowisku

Wydział Biologii

Vocal Symptoms in Telemarketers: A Random and Controlled Field Trial

The present study was carried out to evaluate the effectiveness of a specific program regarding the occurrence of vocal attrition symptoms in telemarketers. A total of 71 subjects participated in this study: 28 completed the Vocal Symptoms questionnaire to test its reliability, and 43 were randomly assigned to two groups: an 8-week vocal training group (n = 14) and a no-training control group (n = 29), to evaluate the effectiveness of the training program with this tool. The voice training group also filled in the posttraining questionnaire `Benefits Obtained with Voice Training` (BVT). The vocal training program was not considered effective with regard to the occurrence of vocal symptoms. However, due to a probable increase in symptoms in untrained telemarketers, it can work as a protective factor. According to BVT answers, the vocal training contributed to an improvement in vocal use as a communication tool for telemarketers. Copyright (C) 2009 S. Karger AG, Basel

Differential modes of alaryngeal communication and long-term voice outcomes following pharyngolaryngectomy and laryngectomy

Patterns of vocal rehabilitation for 37 pharyngolaryngectomy patients and 55 total laryngectomy patients over a 5-year period were compared. An electrolarynx (EL) was introduced as the initial communication mode immediately after surgery for 98% of patients, with 30% of pharyngolaryngectomy and 74% of laryngectomy patients subsequently developing tracheoesophageal speech (TES) as their primary mode of communication. Follow-up with 14 of 37 pharyngolaryngectomy patients and 36 of 55 laryngectomy patients was conducted 1-6 years following surgery and revealed that 90% of the pharyngolaryngectomy patients maintained the use of TES in the long term compared to 69% of the laryngectomy group. Long-term outcomes relating to communication disability and handicap did not differ significantly between the two surgical groups, however the laryngectomy patients had significantly higher levels of wellbeing. Across the whole group of patients, statistical comparison revealed that patients using TES had significantly lower levels of disability, handicap and distress than EL users. Considering that lower levels of disability, handicap and distress are associated with TES, and the data supports that suitably selected patients can maintain functional TES in the long term, increased application of this form of communication rehabilitation should be encouraged where viable for the pharyngolaryngectomy population. Copyright (C) 2003 S. Karger AG, Basel.

Magnetic resonance imaging of the vocal tract: techniques and applications

Magnetic resonance (MR) imaging has been used to analyse and evaluate the vocal tract shape through different techniques and with promising results in several fields. Our purpose is to demonstrate the relevance of MR and image processing for the vocal tract study. The extraction of contours of the air cavities allowed the set - up of a number of 3D reconstruction image stacks by means of the combination of orthogonally oriented sets of slices for e ach articulatory gesture, as a new approach to solve the expected spatial under sampling of the imaging process. In result these models give improved information for the visualization of morphologic and anatomical aspects and are useful for partial measure ments of the vocal tract shape in different situations. Potential use can be found in Medical and therapeutic applications as well as in acoustic articulatory speech modelling.

Social rules govern vocal competition in the barn owl

To resolve the share of limited resources, animals often compete through exchange of signals about their relative motivation to compete. When two competitors are similarly motivated, the resolution of conflicts may be achieved in the course of an interactive process. In barn owls, Tyto alba, in which siblings vocally compete during the prolonged absence of parents over access to the next delivered food item, we investigated what governs the decision to leave or enter a contest, and at which level. Siblings alternated periods during which one of the two individuals vocalized more than the other. Individuals followed turn-taking rules to interrupt each other and momentarily dominate the vocal competition. These social rules were weakly sensitive to hunger level and age hierarchy. Hence, the investment in a conflict is determined not only by need and resource-holding potential, but also by social interactions. The use of turn-taking rules governing individual vocal investment has rarely been shown in a competitive context. We hypothesized that these rules would allow individuals to remain alert to one another's motivation while maintaining the cost of vocalizing at the lowest level.