Perineuronal nets and vocal plasticity in songbirds: A proposed mechanism to explain the difference between closed-ended and open-ended learning.
Perineuronal nets (PNN) are aggregations of chondroitin sulfate proteoglycans surrounding the soma and proximal processes of neurons, mostly GABAergic interneurons expressing parvalbumin. They limit the plasticity of their afferent synaptic connections. In zebra finches PNN develop in an experience-dependent manner in the song control nuclei HVC and RA (nucleus robustus arcopallialis) when young birds crystallize their song. Because songbird species that are open-ended learners tend to recapitulate each year the different phases of song learning until their song crystallizes at the beginning of the breeding season, we tested whether seasonal changes in PNN expression would be found in the song control nuclei of a seasonally breeding species such as the European starling. Only minimal changes in PNN densities and total number of cells surrounded by PNN were detected. However, comparison of the density of PNN and of PNN surrounding parvalbumin-positive cells revealed that these structures are far less numerous in starlings that show extensive adult vocal plasticity, including learning of new songs throughout the year, than in the closed-ended learner zebra finches. Canaries that also display some vocal plasticity across season but were never formally shown to learn new songs in adulthood were intermediate in this respect. Together these data suggest that establishment of PNN around parvalbumin-positive neurons in song control nuclei has diverged during evolution to control the different learning capacities observed in songbird species. This differential expression of PNN in different songbird species could represent a key cellular mechanism mediating species variation between closed-ended and open-ended learning strategies. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 975-994, 2017.
GIGA Neuroscience, University of Liege, Liege, 4000, Belgium.
Gilles
G
Cornez
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, 21218.|Department of Psychology, University of Maryland, College Park, College Park, Maryland, 20742.
Farrah N
FN
Madison
Bio-imaging Lab, University of Antwerp, Antwerpen, Belgium.
Annemie
A
Van der Linden
GIGA Neuroscience, University of Liege, Liege, 4000, Belgium.
Charlotte
C
Cornil
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, 21218.
Kathleen M
KM
Yoder
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, 21218.|Department of Psychology, University of Maryland, College Park, College Park, Maryland, 20742.
Gregory F
GF
Ball
GIGA Neuroscience, University of Liege, Liege, 4000, Belgium.
Jacques
0000-0001-9492-2126
J
Balthazart
D000818:Animals; D030161:Avian Proteins / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D002171:Canaries / Q000254:growth & development / Q000378:metabolism*; D053145:Cell Nucleus Size / Q000502:physiology; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism; D003423:Critical Period, Psychological; D046369:Finches / Q000254:growth & development / Q000378:metabolism*; D007858:Learning / Q000502:physiology*; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010320:Parvalbumins / Q000378:metabolism; D017440:Photoperiod; D011897:Random Allocation; D012621:Seasons; D013045:Species Specificity; D046749:Starlings / Q000254:growth & development / Q000378:metabolism*; D013739:Testosterone / Q000097:blood; D014828:Vocalization, Animal / Q000502:physiology*
D030161:Avian Proteins; D011508:Chondroitin Sulfate Proteoglycans; D010320:Parvalbumins; D013739:Testosterone
European starling; canary; parvalbumin; perineuronal nets; song control nuclei; song plasticity; zebra finch