References of "Verhoye, M"
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See detailIn vivo MR imaging of the seasonal volumetric and functional plasticity of song control nuclei in relation to song output in a female songbird
Van Meir, V.; Pavlova, D.; Verhoye, M. et al

in Neuroimage (2006), 31(3), 981-992

In temperate zone songbird species, seasonal plasticity in the morphological and functional state of brain regions involved in song production occurs in association with seasonal changes in song output ... [more ▼]

In temperate zone songbird species, seasonal plasticity in the morphological and functional state of brain regions involved in song production occurs in association with seasonal changes in song output. Following MHCl2-injections in HVC (used as proper name) of female starlings, in vivo tract-tracing by Manganese Enhanced-Magnetic Resonance Imaging (ME-MRI) provided repeated measures of the volume of two HVC targets, the nucleus robustus arcopallii (RA) and area X, along with measures of the activity of the caudal motor pathway and rostral basal-ganglia pathway that control singing. Mn2+- labeling (volume labeled and signal intensity) of both nuclei was dramatically reduced in July (post-breeding season) when birds did not sing, compared to March (breeding season) when birds produced song. Seasonal changes in telencephalon volume did not exceed 4% and were not significant but were surprisingly correlated with individual measures of song rate and song bout length. Although individual song rates were variable in March, all MnCl2-injections led to a reliable labeling of area X and RA. In July, delineation of area X was only possible in two birds and RA could be delineated in 50% of the population; its volume had decreased by 46% as compared to March. The birds in which RA could be delineated in July had in March a higher activity of the HVC to area X projection as reflected by the total amount of Mn2+ accumulated in area X, which suggests unexpected relationships between the two types of HVC projection neurons. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

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See detailSpatiotemporal properties of the BOLD response in the songbirds' auditory circuit during a variety of listening tasks
Van Meir, V.; Boumans, T.; De Groof, G. et al

in Neuroimage (2005), 25(4), 1242-1255

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition ... [more ▼]

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition and development of musical skills. The present study introduces this tool in a well-documented animal model for vocal learning, the songbird, and provides fundamental insight in the main technical issues associated with auditory fMRI in these songbirds. Stimulation protocols with various listening tasks lead to appropriate activation of successive relays in the songbirds' auditory pathway. The elicited BOLD response is also region and stimulus specific, and its temporal aspects provide accurate measures of the changes in brain physiology induced by the acoustic stimuli. Extensive repetition of an identical stimulus does not lead to habituation of the response in the primary or secondary telencephalic auditory regions of anesthetized subjects. The BOLD signal intensity changes during a stimulation and subsequent rest period have a very specific time course which shows a remarkable resemblance to auditory evoked BOLD responses commonly observed in human subjects. This observation indicates that auditory fMRI in the songbird may establish a link between auditory related neuro-imaging studies done in humans and the large body of neuro-ethological research on song learning and neuro-plasticity performed in songbirds. © 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailDifferential effects of testosterone on neuronal populations and their connections in a sensorimotor brain nucleus controlling song production in songbirds: a manganese enhanced-magnetic resonance imaging study
Van Meir, V.; Verhoye, M.; Absil, Philippe ULg et al

in Neuroimage (2004), 21(3), 914-923

Nucleus HVC (formerly called high vocal center) of songbirds contains two types of projecting neurons connecting HVC respectively to the nucleus robustus archistriatalis, RA, or to area X. These two ... [more ▼]

Nucleus HVC (formerly called high vocal center) of songbirds contains two types of projecting neurons connecting HVC respectively to the nucleus robustus archistriatalis, RA, or to area X. These two neuron classes exhibit multiple neurochemical differences and are differentially replaced by new neurons during adult life: high rates of neuronal replacement are observed in RA-projecting neurons only. The activity of these two types of neurons may also be modulated differentially by steroids. We analyzed by magnetic resonance imaging the effect of testosterone on the volume of RA and area X and on the dynamics of Mn2+ accumulation in RA and area X of female starlings that had been injected with MnCl2 through a permanent cannula implanted in HVC. Repeated visualization 6 weeks apart (before and after testosterone treatment) identified a volume increase of both nuclei in testosterone-treated birds associated with a concomitant decrease in controls. Following testosterone treatment, the total amount of Mn2+ transported to RA and area X increased but the dynamics of accumulation, reflecting in part the activity of HVC neurons, was specifically altered in area X but not in RA. These data indicate that testosterone differentially affects the RA- and area X-projecting neurons in HVC. Manganese-enhanced magnetic resonance imaging (ME-MRI) thus provides repeated measures of connected brain areas and demonstrates testosterone-dependent regionally specific changes in brain activity and functional connectivity. The slow time scales investigated by this technique (compared to functional MRI) appear ideally suited for characterizing slow processes such as those involved in brain plasticity and learning. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailIn vivo dynamic ME-MRI reveals differential functional responses of RA- and area X-projecting neurons in the HVC of canaries exposed to conspecific song
Tindemans, I.; Verhoye, M.; Balthazart, Jacques ULg et al

in European Journal of Neuroscience (2003), 18(12), 3352-3360

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by ... [more ▼]

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by electrophysiology. However, immediate-early gene induction cannot be detected in this nucleus following song stimulation. HVC contains neurons projecting either towards the nucleus robustus archistriatalis (RA; motor pathway) or area X (anterior forebrain pathway). Both RA- and area X-projecting cells show auditory responses. The present study analysed these responses separately in the two types of HVC projection neurons of canaries by a new in vivo approach using manganese as a calcium analogue which can be transported anterogradely and used as a paramagnetic contrast agent for magnetic resonance imaging (MRI). Manganese was stereotaxically injected into HVC and taken up by HVC neurons. The anterograde axonal transport of manganese from HVC to RA and area X was then followed by MRI during approximate to 8 h and changes in signal intensity in these targets were fitted to sigmoid functions. Data comparing birds exposed or not to conspecific songs revealed that song stimulation specifically affected the activity of the two types of HVC projection neurons (increase in the sigmoid slope in RA and in its maximum signal intensity in area X). Dynamic manganese-enhanced MRI thus allows assessment of the functional state of specific neuronal populations in the song system of living canaries in a manner reminiscent of functional MRI (but with higher resolution) or of 2-deoxyglucose autoradiography (but in living subjects). [less ▲]

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See detailIn vivo manganese-enhanced magnetic resonance imaging reveals connections and functional properties of the songbird vocal control system
Van der Linden, A.; Verhoye, M.; Van Meir, V. et al

in Neuroscience (2002), 112(2), 467-474

Injection of manganese (Mn2+), a paramagnetic tract tracing agent and calcium analogue, into the high vocal center of starlings labeled within a few hours the nucleus robustus archistriatalis and area X ... [more ▼]

Injection of manganese (Mn2+), a paramagnetic tract tracing agent and calcium analogue, into the high vocal center of starlings labeled within a few hours the nucleus robustus archistriatalis and area X as observed by in vivo magnetic resonance imaging. Structures highlighted by Mn2+ accumulation assumed the expected tri-dimensional shape of the nucleus robustus archistriatalis and area X as identified by classical histological or neurochemical methods. The volume of these nuclei could be accurately calculated by segmentation of the areas highlighted by Mn2+. Besides confirming previously established volumetric sex differences, Mn2+ uptake into these nuclei revealed new functional sex differences affecting Mn2+ transport. A faster transport was observed in males than in females and different relative amounts of Mn2+ were transported to nucleus robustus archistriatalis and area X in males as compared to females. This new in vivo approach, allowing repeated measures, opens new vistas to study the remarkable seasonal plasticity in size and activity of song-control nuclei and correlate neuronal activity with behavior. It also provides new insights on in vivo axonal transport and neuronal activity in song-control nuclei of oscines. (C) 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved. [less ▲]

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