Papers by Walter Wilczynski
Brain, Behavior and Evolution, 2014
Efforts to understand nervous system structure and function have received new impetus from the fe... more Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene-structure-function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system ‘maps' comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote t...
Comparative Neurobiology: Comparative Neurology of the Optic Tectum
Science, 1984
Frontiers in endocrinology, 2017
Arginine vasotocin (AVT) is the non-mammalian homolog of arginine vasopressin (AVP) and, like vas... more Arginine vasotocin (AVT) is the non-mammalian homolog of arginine vasopressin (AVP) and, like vasopressin, serves as an important modulator of social behavior in addition to its peripheral functions related to osmoregulation, reproductive physiology, and stress hormone release. In amphibians and reptiles, the neuroanatomical organization of brain AVT cells and fibers broadly resembles that seen in mammals and other taxa. Both parvocellular and magnocellular AVT-containing neurons are present in multiple populations located mainly in the basal forebrain from the accumbens-amygdala area to the preoptic area and hypothalamus, from which originate widespread fiber connections spanning the brain with a particularly heavy innervation of areas associated with social behavior and decision-making. As for mammalian AVP, AVT is present in greater amounts in males in many brain areas, and its presence varies seasonally, with hormonal state, and in males with differing social status. AVT's s...
Responses of male cricket frogs (Acris crepitans) to attenuated and degraded advertisement calls
Ethology
We examined the vocal and non-vocal responses of male cricket frogs (Acris crepitans) to conspeci... more We examined the vocal and non-vocal responses of male cricket frogs (Acris crepitans) to conspecific advertisement calls that had been attenuated or degraded by reducing the depth of amplitude modulation (AM). Both are characteristic of changes to the call as it is transmitted through natural habitats. As stimulus calls became more intense or less degraded, male cricket frogs gradually decreased their call rate and increased the number of call groups and pulse groups in their calls, changes indicative of increased aggressive interactions. At the higher intensities and lower degradation levels, the probability that males would shift to one of two non-vocal behavioral responses, attacking the perceived intruder or ceasing calling and abandoning the call site, gradually increased. The results show that differences in signal attenuation and AM degradation levels are perceived by males and trigger both vocal and non-vocal behavioral responses consistent with their use in evaluating the distance to a challenging male. Furthermore, the results indicate that the male responses are graded, increasing as intensity rises and degradation falls, and hierarchical, with vocal responses preceding behavioral responses over the range of intensities and degradation levels presented.
Current Biology
necessary for differentiation of hematopoietic progenitors into gata1-expressing cells [19]. With... more necessary for differentiation of hematopoietic progenitors into gata1-expressing cells [19]. With npas4l, the long-awaited gene responsible for the cloche phenotype has been cloned. Its identification allows for a thorough functional analysis, including the dissection of its upstream regulators and downstream targets, both intra-and extra-embryonic. This will critically further our understanding of the events that take place in the specialization of mesoderm to initiate endothelial, cardiovascular, and hematopoietic differentiation. It will also assist efforts to differentiate pluripotent stem cells into endothelial and hematopoietic cells in vitro for clinical use.
Proceedings of the Royal Society B Biological Sciences, 2007
Social decision making involves the perception and processing of social stimuli, the subsequent e... more Social decision making involves the perception and processing of social stimuli, the subsequent evaluation of that information in the context of the individual's internal and external milieus to produce a decision, and then culminates in behavioural output informed by that decision. We examined brain networks in an anuran communication system that relies on acoustic signals to guide simple, stereotyped motor output. We used egr-1 mRNA expression to measure neural activation in male tú ngara frogs, Physalaemus pustulosus, following exposure to conspecific and heterospecific calls that evoke competitive or aggressive behaviour. We found that acoustically driven activation in auditory brainstem nuclei is transformed into activation related to sensory-motor interactions in the diencephalon, followed by motor-related activation in the telencephalon. Furthermore, under baseline conditions, brain nuclei typically have correlated egr-1 mRNA levels within brain divisions. Hearing conspecific advertisement calls increases correlations between anatomically distant brain divisions; no such effect was observed in response to calls that elicit aggressive behaviour. Neural correlates of social decision making thus take multiple forms: (i) a progressive shift from sensory to motor encoding from lower to higher stages of neural processing and (ii) the emergence of correlated activation patterns among sensory and motor regions in response to behaviourally relevant social cues.
Effects of Steroid Hormones on Hearing and Communication in Frogs
Springer Handbook of Auditory Research, 2016
Acoustic communication in spring peepers: environmental and behavioral aspects
Journal of Comparative Physiology a Sensory Neural and Behavioral Physiology, 1984
Gonadal steroids vary with reproductive stage in a tropically breeding female anuran
General and Comparative Endocrinology, Aug 1, 2005
Tropically breeding anurans that require heavy rainfall in order to reproduce are subject to favo... more Tropically breeding anurans that require heavy rainfall in order to reproduce are subject to favorable breeding conditions that are sporadic. Although there is an increased probability of rain during the rainy season, the probability of local rainfall is unpredictable and this may influence female anuran reproductive strategies. The female túngara frog, a neotropical frog that requires standing water to breed, maintains readiness to breed at any time via asynchronous oogenesis. Although females constantly produce and maintain oocytes during the breeding season, this study shows that they have cyclic fluctuations in gonadal hormone levels. Plasma levels of estrogen significantly change during three reproductive stages within a single reproductive cycle (P=0.03), as do plasma levels of progesterone and androgen (P<0.001 and P=0.001, respectively). Furthermore, elevation in plasma estrogen and progesterone concentrations occurs during the same reproductive stage in which it has been reported that females display the maximum frequency of reproductive behaviors, the amplexed stage. Androgen levels, however, are elevated prior to the reproductive stage in which females display maximal reproductive behavior, that is, the unamplexed stage. Our study suggests that the pattern of gonadal hormone fluctuation in a tropically breeding female anuran is similar to the classic paradigm in which there is a temporal relationship between the appearance of reproductive hormones and reproductive behaviors.
Brain allometry: Correlated variation in cytoarchitectonics and neurochemistry?
Behavioral and Brain Sciences, Apr 1, 2001
Brains vary in characters other than size. We should consider whether Finlay et al.'s argumen... more Brains vary in characters other than size. We should consider whether Finlay et al.'s argument, that developmental shifts responding to selection for change in one area yield correlated changes across the brain, must be extended from size differences to other neural characters responsible for the circuitry or physiological differences distinguishing vertebrate brains.
Developmental structure in brain evolution. Commentary. Authors' reply
Behavioral and Brain Sciences, 2001
The Journal of experimental biology, Jan 4, 2016
One of the major difficulties encountered by animals that select mates using acoustic signals is ... more One of the major difficulties encountered by animals that select mates using acoustic signals is discriminating individual calls from the background noise generated by other conspecifics. Reducing the effects of conspecific masking could improve discrimination of individual calls from background noise. We used auditory evoked potentials to investigate the effects of forward masking on the responses to artificial calls in male and female treefrogs (Hyla cinerea), as well as whether hearing advertisement calls over several nights, as happens in natural frog choruses, could modify the effects of masking. We found that response amplitude decreased with decreasing interstimulus interval when the masker was equal in amplitude to the stimulus. We also found evidence of a priming effect, whereby response amplitude at lower masker amplitudes was greater than when the target stimulus was not preceded by a masker. Finally, we found that the effect of masking was diminished by 10 nights of chor...
Auditory and endocrine inputs to forebrain centers in anuran amphibians
Http Dx Doi Org 10 1080 08927014 1992 9525352, May 19, 2010
ABSTRACT Vertebrate reproduction requires the coordinated expression of somatomotor behavior and ... more ABSTRACT Vertebrate reproduction requires the coordinated expression of somatomotor behavior and visceral responses. Acoustic communication signals and circulating gonadal steroids are two important cues used by anuran amphibians to prime and trigger reproductive behavior. An examination of central nervous system auditory pathways and the binding sites for gonadal steroids shows that somatomotor (striatum) and visceromotor (preoptic area and ventral hypothalamus) control regions of the forebrain each receive an independent, parallel input from auditory relay nuclei in the thalamus, and each contains receptors for gonadal steroid hormones. This suggests that the different aspects of anuran reproductive behavior are coordinated by having the different areas responsible for each aspect concurrently primed by circulating gonadal steroids and simultaneously provided with information regarding the presence of conspecific acoustic communication signals.
Acoustic communication in spring peepers: call characteristics and neurophysiological aspects
Journal of Comparative Physiology a Sensory Neural and Behavioral Physiology, 1984
Journal of Comparative Physiology a Neuroethology Sensory Neural and Behavioral Physiology, Jan 30, 2009
Female behavioral responses to sensory stimuli can be highly variable across the reproductive cyc... more Female behavioral responses to sensory stimuli can be highly variable across the reproductive cycle. Female green treefrogs (Hyla cinerea) use the male vocal signal to locate and choose a mate. Gravid females approach a vocalizing male to mate but do not approach if they have recently mated. Such differences in behavioral response may be due in part to shifts in the neural representation of auditory information in the brain. In this study, we investigated the influence of female reproductive state on neural responses in the auditory midbrain to both communication signals (advertisement calls) and noncommunication sounds (band limited noise bursts). Recently mated females exhibited significantly reduced response strengths compared to females not recently mated. Reduced response strengths in post-mated females were in response to both noise bursts and male advertisement calls but were limited to the lower frequency range corresponding to the amphibian papilla of the peripheral auditory system. Our results therefore show that the ability of social signals to stimulate the auditory system differs in females depending on their reproductive state, and that the differential effect on low versus high spectral sensitivities may influence the way the two spectral peaks of male advertisement calls are represented.
Central Auditory Pathways in Anuran Amphibians: The Anatomical Basis of Hearing and Sound Communication
Springer Handbook of Auditory Research, 2006
Anuran eighth nerve physiology
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Papers by Walter Wilczynski