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Budgerigars were trained with operant conditioning procedures to discriminate among sets of calls from several species in a Same-Different task. Response latencies from this task were analyzed in several ways including multidimensional scaling (MDS) and cluster analysis. The pattern of response latencies from budgerigars reared in a large group of conspecifics was compared to that of budgerigars reared in acoustic and social isolation. Results show that budgerigars with previous experience with species-specific vocalizations and isolate-reared birds who had never heard such sounds can both discriminate among the categories of species-specific vocal signals. But, results from MDS and cluster analysis also show that rearing budgerigars in isolation has subtle effects on the perception of these categories of vocal signals.

In stroke, the sudden deprivation of oxygen to neurons triggers a profuse release of glutamate that induces anoxic depolarization (AD) and leads to rapid cell death. Importantly, the latency of the glutamate‐driven AD event largely dictates subsequent tissue damage. Although the contribution of synaptic glutamate during ischaemia is well‐studied, the role of tonic (ambient) glutamate has received far less scrutiny. The majority of tonic, non‐synaptic glutamate in the brain is governed by the cystine/glutamate antiporter, system xc−. Employing hippocampal slice electrophysiology, we showed that transgenic mice lacking a functional system xc− display longer latencies to AD and altered depolarizing waves compared to wild‐type mice after total oxygen deprivation. Experiments which pharmacologically inhibited system xc−, as well as those manipulating tonic glutamate levels and those antagonizing glutamate receptors, revealed that the antiporter's putative effect on ambient glutamate precipitates the ischaemic cascade. As such, the current study yields novel insight into the pathogenesis of acute stroke and may direct future therapeutic interventions. Key points: Ischaemic stroke remains the leading cause of adult disability in the world, but efforts to reduce stroke severity have been plagued by failed translational attempts to mitigate glutamate excitotoxicity.Elucidating the ischaemic cascade, which within minutes leads to irreversible tissue damage induced by anoxic depolarization, must be a principal focus.Data presented here show that tonic, extrasynaptic glutamate supplied by system xc− synergizes with ischaemia‐induced synaptic glutamate release to propagate AD and exacerbate depolarizing waves.Exploiting the role of system xc− and its obligate release of ambient glutamate could, therefore, be a novel therapeutic direction to attenuate the deleterious effects of acute stroke. [ABSTRACT FROM AUTHOR]

The naked mole rat (Heterocephalusglaber) is a strictly subterranean, extraordinarily long-lived eusocial mammal (1). Although it is the size of a mouse, its maximum lifespan exceeds 30 years, making this animal the longest-living rodent. Naked mole rats show negligible senescence, no age-related increase in mortality, and high fecundity until death (2). In addition to delayed ageing, they are resistant to both spontaneous cancer and experimentally induced tumorigenesis (3,4). Naked mole rats pose a challenge to the theories that link ageing, cancer and redox homeostasis. Although characterized by significant oxidative stress (5), the naked mole rat proteome does not show age-related susceptibility to oxidative damage or increased ubiquitination (6). Naked mole rats naturally reside in large colonies with a single breeding female, the 'queen', who suppresses the sexual maturity of her subordinates (7). They also live in full darkness, at low oxygen and high carbon dioxide concentrations (8), and are unable to sustain thermogenesis (9) nor feel certain types of pain (10,11). Here we report the sequencing and analysis of the naked mole rat genome, which reveals unique genome features and molecular adaptations consistent with cancer resistance, poikilothermy, hairlessness and insensitivity to low oxygen, and altered visual function, circadian rythms and taste sensing. This information provides insights into the naked mole rat's exceptional longevity and ability to live in hostile conditions, in the dark and at low oxygen. The extreme traits of the naked mole rat, together with the reported genome and transcriptome information, offer opportunities for understanding ageing and advancing other areas of biological and biomedical research., We applied a whole-genome shotgun strategy to sequence the genome of an individual male naked mole rat (NMR) (Table 1 and Supplementary Tables 1-3). The sequencing depth of 98.6% of [...]

Nine small birds of 3 species (Melopsittacus undulatus, Serinus canarius, and Poephila guttata) were trained in an operant procedure to fly to sound sources for food reward. The angle between the 2 sound sources was varied on a session-by-session basis, and threshold (i.e., minimum resolvable angle) was taken as the angle that corresponded to a performance level of 75% correct. In all, thresholds were calculated for pure tones of 5 different frequencies, noise bands of 3 different spectral compositions, and species-specific contact or distance calls recorded from each of the 3 species. Thresholds for both simple and complex stimuli were larger than 25 [degrees]. There were statistically significant species differences for each stimulus set, but these differences were not correlated with species differences in head size. Birds with 1 ear plugged performed as well as binaural birds in this task. Birds deafened in 1 ear, however, performed at chance.

Abstract Recent research has proposed a pathway in which sensory neurons expressing the capsaicin activated ion channel TRPV1 are required for histamine-induced itch and subsequent scratching behavior. We examined histamine-induced itch in the African naked mole-rat (Heterocephalus glaber) and found that although naked mole-rats display innate scratching behavior, histamine was unable to evoke increased scratching as is observed in most mouse strains. Using calcium imaging, we examined the histamine sensitivity of naked mole-rat dorsal root ganglia (DRG) neurons and identified a population of small diameter neurons activated by histamine, the majority of which are also capsaicin-sensitive. This suggested that naked mole-rat sensory neurons are activated by histamine, but that spinal dorsal horn processing of sensory information is not the same as in other rodents. We have previously shown that naked mole-rats naturally lack substance P (SP) in cutaneous C-fibers, but that the neurokinin-1 receptor is expressed in the superficial spinal cord. This led us to investigate if SP deficiency plays a role in the lack of histamine-induced scratching in this species. After intrathecal administration of SP into the spinal cord we observed robust scratching behavior in response to histamine injection. Our data therefore support a model in which TRPV1-expressing sensory neurons are important for histamine-induced itch. In addition, we demonstrate a requirement for active, SP-induced post-synaptic drive to enable histamine sensitive afferents to drive itch-related behavior in the naked mole-rat. These results illustrate that it is altered dorsal horn connectivity of nociceptors that underlies the lack of itch and pain-related behavior in the naked mole-rat.