ISSN:
1432-0878
Keywords:
Auditory system
;
Vocal motor system
;
Parvalbumin
;
Cytochrome oxidase
;
2-Deoxyglucose
;
Calcium
;
Plasticity
;
CNS
;
Song birds
;
Zebra finch
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The auditory and vocal motor systems of adult zebra finches were investigated 1) immunocytochemically for the distribution of the Ca2+-binding protein parvalbumin, 2) for the activity of the respiratory enzyme cytochrome oxidase, and 3) for the uptake of 2-deoxyglucose. All auditory nuclei (field L, nucleus ovoidalis, ansa lenticularis, nucleus spiriformis lateralis, nucleus mesencephalicus lateralis-pars dorsalis, nucleus tegmenti pedunculo-pontinus) and vocal motor nuclei (nucleus magnocellularis of the anterior neostriatum, area X, nucleus interfacialis, hyperstriatum ventrale-pars caudalis, nucleus robustus archistriatalis, nucleus intercollicularis) showed high levels of parvalbumin and cytochrome oxidase. Auditory nuclei in addition showed high spontaneous 2-deoxyglucose uptake, while the vocal motor nuclei either remained at background intensity (nucleus magnocellularis of the anterior neostriatum, hyperstriatum ventrale-pars caudalis, nucleus interfacialis and nucleus intercollicularis) or even below background levels (area X, nucleus robustus archistriatalis). Cytochrome oxidase activity supposedly reflects the energy demand of various aspects of metabolism, while 2-deoxyglucose uptake is primarily related to the demands of electrical activity and the Na+-K+ pump. Consequently, it is argued (i) that the congruently high cytochrome oxidase activity and 2-deoxyglucose uptake in the auditory system are due to the high spontaneous electrical activity of neurons, and (ii) that high cytochrome oxidase activity in vocal motor nuclei is related to other than electrical events since 2-deoxyglucose uptake is low. There is evidence of Ca2 + potentials in some parvalbumin-positive neuron types. Ca2+ potentials must lead to Ca2+ flooding of the cytoplasm which could be buffered by parvalbumin thus preventing interference with Ca2+ dependent metabolic reactions or shuttling the ion to sites of such reactions. The unique morphological plasticity reported from the parvalbumin-positive vocal motor nuclei may put a strain on microtubular transport which is Ca2+ dependent. This leads to the idea that parvalbumin reflects local buffering and redistribution mechanisms for Ca2+, and that cytochrome oxidase indicates the underlying energy demand.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00217563
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