Modulation of Perineuronal Nets and Parvalbumin with Developmental Song Learning

Abstract

Neural circuits and behavior are shaped during developmental phases of maximal plasticity known as sensitive or critical periods. Neural correlates of sensory critical periods have been identified, but their roles remain unclear. Factors that define critical periods in sensorimotor circuits and behavior are not known. Birdsong learning in the zebra finch occurs during a sensitive period similar to that for human speech. We now show that perineuronal nets, which correlate with sensory critical periods, surround parvalbumin-positive neurons in brain areas that are dedicated to singing. The percentage of both total and parvalbumin-positive neurons with perineuronal nets increased with development. In HVC (this acronym is the proper name), a song area important for sensorimotor integration, the percentage of parvalbumin neurons with perineuronal nets correlated with song maturity. Shifting the vocal critical period with tutor song deprivation decreased the percentage of neurons that were parvalbumin positive and the relative staining intensity of both parvalbumin and a component of perineuronal nets. Developmental song learning shares key characteristics with sensory critical periods, suggesting shared underlying mechanisms.

Chondroitin Sulfates in Axon Regeneration and Plasticity

“…Injection of ChABC into the visual cortex of monocular deprived rats was able to re-instate ocular dominance plasticity in adult animals, an ability which is lost at the end of critical period (23,24). Similar observations are subsequently reported in other neuronal systems, such as song learning in HVC (this acronym is the proper name) in bird and fear conditioning in amygdala in rat (25)(26). Preventing the formation of PNNs by elimination of a key component, cartilage link protein, has a similar effect to ChABC, demonstrating that PNNs control plasticity (27).…”

Reduction in 50-kHz call-numbers and suppression of tickling-associated positive affective behaviour after lesioning of the lateral hypothalamic parvafox nucleus in rats

“…PV-expression in the songbird is confined to specific neuronal populations that are especially involved in song-learning [80][81][82]. This finding suggests that PV fulfills a specific function in these neurons that is potentially related to their morphological plasticity in the context of vocal learning (see also [83]); or, alternatively, to their protection against Ca 2+ -toxicity from the highly active neurons that control some of the fastest muscles in the body [84]. Furthermore, in avian as well as in primate species, PV is differentially up-regulated in the vocal motor neurons of vocal learners (learned songs or spoken language) compared to nonlearners [85].…”

Primary Hippocampal Neurons, Which Lack Four Crucial Extracellular Matrix Molecules, Display Abnormalities of Synaptic Structure and Function and Severe Deficits in Perineuronal Net Formation

“…However, a potential contribution by a small proportion of neural stem/progenitor cells cannot be excluded in our model. In comparison, astrocytes primarily contributed to the release of brevican and Tnc (Bartsch et al, 1992;Cahoy et al, 2008;Karus et al, 2011). The distinct accumulation of brevican observed around one selected neurite (Fig.…”

“…In contrast, neurondelivered matrix also appeared sufficient to initiate PNN formation in the presence of knock-out astrocytes. The coincidence of PNN formation and the termination of the critical period have led to the hypothesis that PNNs may regulate the plastic potential of the brain (Balmer et al, 2009;Gogolla et al, 2009). Whether the diminished PNN formation and the altered ECM expression also led to enhanced plasticity in our system remains a question for further investigations.…”