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Functional MRI of auditory responses in the zebra finch forebrain reveals a hierarchical organisation based on signal strength but not selectivity.

Boumans T, Gobes SM, Poirier C, Theunissen FE, Vandersmissen L, Pintjens W, Verhoye M, Bolhuis JJ, Van der Linden A - PLoS ONE (2008)

Bottom Line: Zebra finch males were exposed to conspecific song, BOS and to synthetic variations on BOS that differed in spectro-temporal and/or modulation phase structure.In particular, we have shown that the overall signal strength to song and synthetic variations thereof was different within two sub-regions of Field L2: zone L2a was significantly more activated compared to the adjacent sub-region L2b.Based on our results we suggest that unlike nuclei in the song system, sub-regions in the primary auditory pallium do not show selectivity for the BOS, but appear to show different levels of activity with exposure to any sound according to their place in the auditory processing stream.

View Article: PubMed Central - PubMed

Affiliation: Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium.

ABSTRACT

Background: Male songbirds learn their songs from an adult tutor when they are young. A network of brain nuclei known as the 'song system' is the likely neural substrate for sensorimotor learning and production of song, but the neural networks involved in processing the auditory feedback signals necessary for song learning and maintenance remain unknown. Determining which regions show preferential responsiveness to the bird's own song (BOS) is of great importance because neurons sensitive to self-generated vocalisations could mediate this auditory feedback process. Neurons in the song nuclei and in a secondary auditory area, the caudal medial mesopallium (CMM), show selective responses to the BOS. The aim of the present study is to investigate the emergence of BOS selectivity within the network of primary auditory sub-regions in the avian pallium.

Methods and findings: Using blood oxygen level-dependent (BOLD) fMRI, we investigated neural responsiveness to natural and manipulated self-generated vocalisations and compared the selectivity for BOS and conspecific song in different sub-regions of the thalamo-recipient area Field L. Zebra finch males were exposed to conspecific song, BOS and to synthetic variations on BOS that differed in spectro-temporal and/or modulation phase structure. We found significant differences in the strength of BOLD responses between regions L2a, L2b and CMM, but no inter-stimuli differences within regions. In particular, we have shown that the overall signal strength to song and synthetic variations thereof was different within two sub-regions of Field L2: zone L2a was significantly more activated compared to the adjacent sub-region L2b.

Conclusions: Based on our results we suggest that unlike nuclei in the song system, sub-regions in the primary auditory pallium do not show selectivity for the BOS, but appear to show different levels of activity with exposure to any sound according to their place in the auditory processing stream.

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Related in: MedlinePlus

Data acquisition.Schematical representation of the auditory stimulation design. The entire paradigm was repeated 6 times with alternate presentation of the six different stimuli BOS, reversed BOS, random BOS, familiar CON, BOS ripples, and WN.
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pone-0003184-g002: Data acquisition.Schematical representation of the auditory stimulation design. The entire paradigm was repeated 6 times with alternate presentation of the six different stimuli BOS, reversed BOS, random BOS, familiar CON, BOS ripples, and WN.

Mentions: Auditory signals were presented to the birds with magnetless dynamic speakers as described in Boumans et al. [19]. Stimulus application was controlled by Presentation software (version 0.76; Neurobehavioral Systems, Albany, CA). Images were collected with a block-design paradigm consisting of 6 cycles of 12 images collected during stimulation (30 seconds) and 24 images collected during rest (60 seconds), resulting in 216 functional images (Figure 2). Each experiment, which was preceded by the acquisition of 12 dummy images to allow the signal to reach a steady state, thus took approximately 9.5 minutes. Six consecutive experiments were performed in random order during which the birds were exposed multiple times to the six different stimuli BOS, reversed BOS, random BOS, CON, BOS ripples, and WN. The average song power (average over an entire song) was set at 70 dB SPL (sound pressure level). The magnet noise was measured to be around 63 dB SPL. These sound levels were measured inside the magnet with an electret microphone.


Functional MRI of auditory responses in the zebra finch forebrain reveals a hierarchical organisation based on signal strength but not selectivity.

Boumans T, Gobes SM, Poirier C, Theunissen FE, Vandersmissen L, Pintjens W, Verhoye M, Bolhuis JJ, Van der Linden A - PLoS ONE (2008)

Data acquisition.Schematical representation of the auditory stimulation design. The entire paradigm was repeated 6 times with alternate presentation of the six different stimuli BOS, reversed BOS, random BOS, familiar CON, BOS ripples, and WN.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2527133&req=5

pone-0003184-g002: Data acquisition.Schematical representation of the auditory stimulation design. The entire paradigm was repeated 6 times with alternate presentation of the six different stimuli BOS, reversed BOS, random BOS, familiar CON, BOS ripples, and WN.
Mentions: Auditory signals were presented to the birds with magnetless dynamic speakers as described in Boumans et al. [19]. Stimulus application was controlled by Presentation software (version 0.76; Neurobehavioral Systems, Albany, CA). Images were collected with a block-design paradigm consisting of 6 cycles of 12 images collected during stimulation (30 seconds) and 24 images collected during rest (60 seconds), resulting in 216 functional images (Figure 2). Each experiment, which was preceded by the acquisition of 12 dummy images to allow the signal to reach a steady state, thus took approximately 9.5 minutes. Six consecutive experiments were performed in random order during which the birds were exposed multiple times to the six different stimuli BOS, reversed BOS, random BOS, CON, BOS ripples, and WN. The average song power (average over an entire song) was set at 70 dB SPL (sound pressure level). The magnet noise was measured to be around 63 dB SPL. These sound levels were measured inside the magnet with an electret microphone.

Bottom Line: Zebra finch males were exposed to conspecific song, BOS and to synthetic variations on BOS that differed in spectro-temporal and/or modulation phase structure.In particular, we have shown that the overall signal strength to song and synthetic variations thereof was different within two sub-regions of Field L2: zone L2a was significantly more activated compared to the adjacent sub-region L2b.Based on our results we suggest that unlike nuclei in the song system, sub-regions in the primary auditory pallium do not show selectivity for the BOS, but appear to show different levels of activity with exposure to any sound according to their place in the auditory processing stream.

View Article: PubMed Central - PubMed

Affiliation: Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium.

ABSTRACT

Background: Male songbirds learn their songs from an adult tutor when they are young. A network of brain nuclei known as the 'song system' is the likely neural substrate for sensorimotor learning and production of song, but the neural networks involved in processing the auditory feedback signals necessary for song learning and maintenance remain unknown. Determining which regions show preferential responsiveness to the bird's own song (BOS) is of great importance because neurons sensitive to self-generated vocalisations could mediate this auditory feedback process. Neurons in the song nuclei and in a secondary auditory area, the caudal medial mesopallium (CMM), show selective responses to the BOS. The aim of the present study is to investigate the emergence of BOS selectivity within the network of primary auditory sub-regions in the avian pallium.

Methods and findings: Using blood oxygen level-dependent (BOLD) fMRI, we investigated neural responsiveness to natural and manipulated self-generated vocalisations and compared the selectivity for BOS and conspecific song in different sub-regions of the thalamo-recipient area Field L. Zebra finch males were exposed to conspecific song, BOS and to synthetic variations on BOS that differed in spectro-temporal and/or modulation phase structure. We found significant differences in the strength of BOLD responses between regions L2a, L2b and CMM, but no inter-stimuli differences within regions. In particular, we have shown that the overall signal strength to song and synthetic variations thereof was different within two sub-regions of Field L2: zone L2a was significantly more activated compared to the adjacent sub-region L2b.

Conclusions: Based on our results we suggest that unlike nuclei in the song system, sub-regions in the primary auditory pallium do not show selectivity for the BOS, but appear to show different levels of activity with exposure to any sound according to their place in the auditory processing stream.

Show MeSH
Related in: MedlinePlus