Age effect of deafening on stereotyped song maintenance in adult male bengalese finches Lonchura striata domestica

Birdsong is a complex learned vocal behavior that relies on auditory experience for development.However,it appears that among different species of close-ended songbirds,there are some variations in the necessity of auditory feedback for maintaining stereotyped adult song.In zebra finches,the deterioration of adult songs following deafness depends on the birds' age.It is unknown whether this age effect is a general rule in other avian species as well.Therefore,we chose Bengalese finches,whose songs show more complexity and have much heavier dependency on auditory feedback than that of zebra finches,to compare the degree of song degradation after hearing loss in old(over 18 months old)and young adult birds(5-6 months old).We found that both syllable sequence and syllable phonology were much less severely affected by deafening in old adults than that in young ones.Moreover,young adults almost lost their capability to sing trills over 6 months following deafening,while old birds continued to sing plenty of trills and trilled syllables after the same period of deafening.Our results suggest that age plays an important role in affecting the dependency of adult song maintenance on auditory feedback in Bengalese finches.Furthermore,the age dependency may be a general phenomenon in different species of close-ended songbirds.

Temporal and spatial stability of the EM/PM molecular subtypes in adult diffuse glioma

Detailed characterizations of genomic alterations have not identified subtype-specific vulnerabilities in adult gliomas. Mapping gliomas into developmental programs may uncover new vulnerabilities that are not strictly related to genomic alterations. After identifying conserved gene modules co-expressed with EGFR or PDGFRA (EM or PM), we recently proposed an EM/PM classification scheme for adult gliomas in a histological subtype- and grade-independent manner. By using cohorts of bulk samples, paired primary and recurrent samples, multi-region samples from the same glioma, single-cell RNA-seq samples, and clinical samples, we here demonstrate the temporal and spatial stability of the EM and PM subtypes. The EM and PM subtypes, which progress in a subtype-specific mode, are robustly maintained in paired longitudinal samples. Elevated activities of cell proliferation, genomic instability and microenvironment, rather than subtype switching, mark recurrent gliomas. Within individual gliomas, the EM/PM subtype was preserved across regions and single cells. Malignant cells in the EM and PM gliomas were correlated to neural stem cell and oligodendrocyte progenitor cell compartment, respectively. Thus, while genetic makeup may change during progression and/or within different tumor areas, adult gliomas evolve within a neurodevelopmental framework of the EM and PM molecular subtypes. The dysregulated developmental pathways embedded in these molecular subtypes may contain subtype-specific vulnerabilities.

Deafening-induced rapid changes to spine synaptic connectivity in the adult avian vocal basal ganglia

The basal ganglia have been implicated in auditory-dependent vocal learning and plasticity in human and songbirds,but the underlying neural phenotype remains to be clarified.Here,using confocal imaging and three-dimensional electron microscopy,we investigated striatal structural plasticity in response to hearing loss in Area X,the avian vocal basal ganglia,in adult male zebrafinch(Taeniopygia guttata).We observed a rapid elongation of dendritic spines,by approximately 13%,by day 3 after deafening,and a considerable increase in spine synapse density,by approximately 61%,by day 14 after deafening,compared with the controls with an intact cochlea.Thesefind-ings reveal structural sensitivity of Area X to auditory deprivation and suggest that this striatal plasticity might contribute to deafening-induced changes to learned vocal behavior.