Structural Changes between Seasons in the Songbird Auditory Forebrain

Groof, Geert De; Verhoye, Marleen; Poirier, Colline; Leemans, Alexander; Eens, Marcel; Darras, Veerle; Linden, Annemie Van der

doi:10.1523/jneurosci.1788-09.2009

Cited by 47 publications

(37 citation statements)

References 81 publications

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“…Conversely, stress can reduce synapse numbers in some systems (for example, in the hippocampus), while increasing them in other systems (for example, in the amygdala) 59 . Synapse dynamics and numbers are further influenced by seasonal changes and developmental age 60 . For environmental enrichment, the increased synapse turnover has been causally related to improved learning 18 .…”

Section: Plasticity Affecting Multiple Systems and Neuronsmentioning

confidence: 99%

Structural plasticity upon learning: regulation and functions

2012

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The contributions of brain networks to information processing and learning and memory are classically interpreted within the framework of Hebbian plasticity and the notion that synaptic weights can be modified by specific patterns of activity. However, accumulating evidence over the past decade indicates that synaptic networks are also structurally plastic, and that connectivity is remodelled throughout life, through mechanisms of synapse formation, stabilization and elimination 1. This has led to the concept of structural plasticity, which can encompass a variety of morphological changes that have functional consequences. These include on the one hand structural rearrangements at pre-existing synapses, and on the other hand the formation or loss of synapses, of neuronal processes that form synapses or of neurons. In this Review we focus on plasticity that involves gains and/or losses of synapses. Its key potential implication for learning and memory is to physically alter circuit connectivity, thus providing long-lasting memory traces that can be recruited at subsequent retrieval. Detecting this form of plasticity and relating it to its possible functions poses unique challenges, which are in part due to our still limited understanding of how structure relates to function in the nervous system.We review recent studies that relate the structural plasticity of neuronal circuits to behavioural learning and memory and discuss conceptual and mechanistic advances, as well as future challenges. The studies establish a number of strong links between specific behavioural learning processes and the assembly and loss of specific synapses. Further areas of substantial progress include molecular and cellular mechanisms that regulate synapse dynamics in response to alterations in synaptic activity, the specific spatial distribution of the syn aptic changes among identified neurons and dendrites and the relative roles of excitation and inhibition in regulating structural plasticity.The new findings provide exciting early vistas of how learning and memory may be implemented at the level of structural circuit plasticity. At the same time, they highlight major gaps in our understanding of plasticity regulation at the cellular, circuit and systems levels. Accordingly, achieving a better mechanistic understanding of learning and memory processes is likely to depend on the development of more effective techniques and models to investigate ensembles of identified synapses longitudinally, both functionally and structurally. Molecular mechanisms of synapse remodellingA remarkable feature of excitatory and inhibitory synapses is their high level of structural variability 2 and the fact that their morphologies and stabilities change over time 3 . This phenomenon is regulated by activity, and the size of spine heads correlates with synaptic strength 4 , presynaptic properties 5 and the long-term stability of the synapse 6 . The morphological characteristics of synapses thus reveal important features of their function and stabilit...

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Section: Plasticity Affecting Multiple Systems and Neuronsmentioning

confidence: 99%

Structural plasticity upon learning: regulation and functions

2012

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“…Some of these changes may be associated with general abilities such as home range size [Sherry et al, 1992] and foodstoring behavior [Smulders et al, 2000;Sherry and Hoshooley, 2010] or very specific skills like learned vocalizations. For instance, the finding that the size of song nuclei in some songbirds exhibits seasonal variations [Nottebohm, 1981;De Groof et al, 2009] suggests that such alterations in brain region size underlie changes in seasonal behaviors. Some of these changes may involve neuronal death, induced changes in postnatal or posthatching neurogenesis, or volumetric changes related to trophic effects, and differential use [Nottebohm, 1981;Kirn, 2010].…”

Section: Other Variations In Brain Region Sizementioning

confidence: 99%

Evo-Devo and Brain Scaling: Candidate Developmental Mechanisms for Variation and Constancy in Vertebrate Brain Evolution

2011

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Biologists have long been interested in both the regularities and the deviations in the relationship between brain, development, ecology, and behavior between taxa. We first examine some basic information about the observed ranges of fundamental changes in developmental parameters (i.e. neurogenesis timing, cell cycle rates, and gene expression patterns) between taxa. Next, we review what is known about the relative importance of different kinds of developmental mechanisms in producing brain change, focusing on mechanisms of segmentation, local and general features of neurogenesis, and cell cycle kinetics. We suggest that a limited set of developmental alterations of the vertebrate nervous system typically occur and that each kind of developmental change may entail unique anatomical, functional, and behavioral consequences for the organism. Thus, neuroecologists who posit a direct mapping of brain size to behavior should consider that not any change in brain anatomy is possible.

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“…Although seasonal changes in overall TELE volume have been reported in oscine songbirds [Van Meir et al, 2006], these likely arise from large increases in the volume of song control nuclei (e.g. 100-200%) and other forebrain regions [Clayton et al, 1997;De Groof et al, 2009]. These seasonal variations underlie behaviours like song learning, food caching and brood parasitism in songbirds, but these behaviours are absent in the ruffed grouse, so a lack of seasonal variation in TELE size was unsurprising.…”

Section: Discussionmentioning

confidence: 99%

Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse <b><i>(Bonasa umbellus)</i></b>

Krilow

Iwaniuk²

2015

Brain Behav Evol

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The song system of songbirds has provided significant insight into the underlying mechanisms and behavioural consequences of seasonal neuroplasticity. The extent to which seasonal changes in brain region volumes occur in non-songbird species has, however, remained largely untested. Here, we tested whether brain region volumes varied with season in the ruffed grouse (Bonasa umbellus), a gallinaceous bird that produces a unique wing-beating display known as ‘drumming' as its primary form of courtship behaviour. Using unbiased stereology, we measured the sizes of the cerebellum, nucleus rotundus, telencephalon, mesopallium, hippocampal formation, striatopallidal complex and arcopallium across spring males, fall males and fall females. The majority of these brain regions did not vary significantly across these three groups. The two exceptions were the striatopallidal complex and arcopallium, both of which were significantly larger in spring males that are actively drumming. These seasonal changes in volume strongly implicate the striatopallidal complex and arcopallium as key structures in the production and/or modulation of the ruffed grouse drumming display and represent the first evidence of seasonal plasticity in the telencephalon underlying a non-vocal courtship behaviour. Our findings also suggest that seasonal plasticity in the striatopallidal complex and arcopallium might be a trait that is shared across many bird species and that both structures are related to the production of multiple forms of courtship and not just learned song.

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Structural Changes between Seasons in the Songbird Auditory Forebrain

Cited by 47 publications

References 81 publications

Structural plasticity upon learning: regulation and functions

Structural plasticity upon learning: regulation and functions

Evo-Devo and Brain Scaling: Candidate Developmental Mechanisms for Variation and Constancy in Vertebrate Brain Evolution

Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse <b><i>(Bonasa umbellus)</i></b>

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