Nuclear organization of the bullfrog diencephalon

Neary, Timothy J.; Northcutt, R. Glenn

doi:10.1002/cne.902130303

Cited by 342 publications

(198 citation statements)

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“…We located the suprachiasmatic nucleus (SCN) by using the optic chiasm as the rostral landmark, then selected three sections corresponding to figures 2B and 3 A and B in ref. 31 for egr-1 quantification (Fig. 2B) Fig.…”

Section: Methodsmentioning

confidence: 99%

“…We determined borders of hypothalamic subdivisions based on cytoarchitecture following the description of the bullfrog diencephalon (31). We selected sections to be analyzed for each region by using the following criteria.…”

Section: Methodsmentioning

confidence: 99%

“…The fourth POA section resembled figure 1B in ref. 31. We located the suprachiasmatic nucleus (SCN) by using the optic chiasm as the rostral landmark, then selected three sections corresponding to figures 2B and 3 A and B in ref.…”

Section: Methodsmentioning

confidence: 99%

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Social cues shift functional connectivity in the hypothalamus

Hoke

Ryan

Wilczynski

2005

Proc. Natl. Acad. Sci. U.S.A.

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We determined how social stimuli that vary in behavioral relevance differentially activate functional networks in the frog hypothalamus. As measured by egr-1 mRNA levels, activity in three hypothalamic nuclei varied with acoustic stimulus, and these responses were correlated with egr-1 responses in different auditory regions regardless of stimulus. The correlations among hypothalamic nuclei, however, varied as a function of the behavioral relevance of the stimuli. Thus relevant social cues shift the functional connectivity within the hypothalamus, consistent with principles that underlie the simultaneous processing of sensory information in cognitive tasks.amphibian ͉ immediate early gene ͉ mate choice ͉ neural network ͉ tú ngara frog T he complex anatomical connections characteristic of networks in the brain pose a challenge for understanding neural circuits and their dual capacities to motivate and respond to behavior. A traditional approach in studies of neural systems underlying social behavior has been to investigate properties of individual nuclei or centers. Alternatively, cognitive neuroscience studies have more recently focused on variation in the functional relationships among neocortical areas, that is, on network properties indicated by correlated patterns of activity among brain regions, or functional connectivity (1-3). Functional connectivity has been assessed by using metabolic measures such as positron emission tomography (1) or fluorodeoxyglucose incorporation (4) to infer neural activity patterns within brain networks.The limbic and hypothalamic areas are critical candidates for network analyses, because those nuclei are heavily and reciprocally interconnected anatomically and participate in complex ways in multiple aspects of behavior and physiology (5). The brain directs appropriate behavioral and physiological responses to diverse sensory inputs by partitioning interconnected brain regions into independent subnetworks that subserve different tasks (5). Newman (5) described the flexibility of functional connections involved in a variety of aggressive, sexual, and maternal behaviors in the context of a social behavior network of six limbic regions. A similar but not entirely congruent network of limbic regions has been described in geckos (6) in which developmental influences on functional connectivity have been linked to aggressive behaviors (7). Newman (5) predicted that sensory inputs modulate the transient subnetworks that mediate continuously varying behavioral responses to social cues. In this paper, we extend Newman's prediction to consider how socially relevant auditory inputs demarcate subnetworks in the hypothalamus, a brain division that has a critical role in mediating reproductive responses to social cues.Anurans are tractable models for such an investigation. Behavioral responses to conspecific vocal signals are well documented, and we have a rich understanding of how the auditory system differentially responds to behaviorally relevant acoustic stimuli (8,9). Neuroanatomical con...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Social cues shift functional connectivity in the hypothalamus

Hoke

Ryan

Wilczynski

2005

Proc. Natl. Acad. Sci. U.S.A.

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“…In general, frogs have more complex brain morphology than do salamanders, having morphologically distinct nuclei that often lie in migrated positions in the diencephalon, the pretectum, and the mesencephalic tegmentum (2). In addition, multiple lamination (an alternation of cellular and fibrous layers) is found in the tectum opticum (3,4), the torus semicircularis (5), and a number of diencephalic nuclei (2). The brain of salamanders long has been known to be morphologically much simpler than that of frogs and other vertebrates (6,7).…”

Section: Introductionmentioning

confidence: 99%

Cell size predicts morphological complexity in the brains of frogs and salamanders.

Roth

Blanke

Wake

1994

Proc. Natl. Acad. Sci. U.S.A.

138

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The morphological organization of the brain of frogs and salamanders varies greatly in the degree to which it is subdivided and differentiated. Members of these taxa are visually oriented predators, but the morphological complexity of the visual centers in the brain varies interspecifically. We give evidence that the morphological complexity of the amphibian tectum mesencephali, the main visual center, can be predicted from knowledge of cell size, which varies greatly among these taxa. Further, cell size is highiy correlated with genome size. Frogs with small cells have more complex morphologies of the tectum than do those with large cells independent of body and brain size. In contrast, in salamanders brain-body size relationships also are correlated with morphological complexity of the brain. Small salamanders with large cells have the simplest tecta, whereas large salamanders with small cells exhibit the most complex tectal morphologies. Increases in genome, and consequently cell size, are associated with a decrease in the differentiation rate of nervous tissue, which leads to the observed differences in brain morphology. On the basis of these findings we hypothesize that important features of the structure of the brain can arise independently of functional demands, from changes at a lower level of organismal organization this case increase in genome size, which induces simpllifcation of brain morphology.The morphological organization of the brain varies among vertebrates in the degree to which it is subdivided and differentiated. Parts of brains exhibit, among other features, differences in lamination, presence of distinct nuclei, numbers of different cell types, and degree of complexity of neuronal connectivity. There is little understanding of the processes that lead to the observed differences, although the most prevalent explanations are forms of functionalism (i.e., the observed differences are the result of environmental selection regarding the specific function of brain parts) and phylogenetic history (older lineages generally have less complex brains). We have examined an alternative view: that the simple brain morphology of salamanders is secondary, de-rived in large part by pedomorphic evolution associated with increases in genome and cell size (1). We here argue that variation in morphological complexity in the brains of frogs and salamanders is based predominantly on such intrinsic factors and is likely to be independent of direct selection.The brains of frogs (Order Anura) and salamanders (Order Caudata) differ considerably within and among these orders in the degree of morphological complexity. In general, frogs have more complex brain morphology than do salamanders, having morphologically distinct nuclei that often lie in migrated positions in the diencephalon, the pretectum, and the mesencephalic tegmentum (2). In addition, multiple lamination (an alternation of cellular and fibrous layers) is found in the tectum opticum (3, 4), the torus semicircularis (5), and a number of diencephal...

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“…The pallium of frogs also resembles the isocortex of mammals in that this visual activity may be mediated by a direct thalamofugal visual pathway. The anterior nucleus of the dorsal thalamus, a structure that appears to receive direct retinal input [Scalia and Gregory, 1970;Neary and Northcutt, 1983], is known to send ascending efferents to the medial and dorsal pallia [Scalia and Coleman, 1975;Kicliter, 1979;Ronan and Northcutt, 1979;Neary and Northcutt, 1983;Neary, 1984Neary, , 1990Northcutt and Ronan, 1992].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Telencephalic Lesions on Visually Mediated Prey Orienting Behavior in the Leopard Frog <i>(Rana pipiens)</i>

Patton

Grobstein²

1998

Brain Behav Evol

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Unilateral removal of the telencephalon in the leopard frog, Rana pipiens, produces a contralateral deficit in visual prey orienting behavior [Patton and Grobstein, 1997]. In mammals, such deficits are most commonly associated with damage to the isocortex, a pallial derived structure. In contrast, we here report that in leopard frogs, lesions that remove substantial areas of one telencephalic lobe, including virtually the entire pallium, have no discernible effect on visual orienting behavior. Restricted lesions to the ventrocaudal telencephalon, however, produce an effect that closely resembles that produced by the complete removal of one telencephalic lobe. The ‘critical area’ that is both included in all lesions that are effective in producing a severe deficit and excluded from all ineffective lesions includes a portion of the caudal striatum. The striatum is known to play a significant role in anuran vision. It thus seems likely that the deficit produced by unilateral removal of the telencephalon in the leopard frog is due specifically to the removal of the caudal striatum. Unilateral lesions to the striatum have previously been shown to produce a contralateral deficit in visual orienting behavior in cats, and a role for the striatonigral pathway in the production of the visual orienting deficit that follows visual cortex lesions has been proposed. The current findings call attention to the possible general importance of the striatum in the control of vertebrate visual orienting behaviors.

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Nuclear organization of the bullfrog diencephalon

Cited by 342 publications

References 42 publications

Social cues shift functional connectivity in the hypothalamus

Social cues shift functional connectivity in the hypothalamus

Cell size predicts morphological complexity in the brains of frogs and salamanders.

The Effects of Telencephalic Lesions on Visually Mediated Prey Orienting Behavior in the Leopard Frog <i>(Rana pipiens)</i>

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