Early diagnosis is critical for the effective management of neurodegenerative disorders, and retinal alterations have emerged as promising early biomarkers due to the retina’s close developmental and functional link to the brain. The zebrafish (Danio rerio), with its rapid development, transparent embryos, and evolutionarily conserved visual system, represents a powerful and versatile model for studying retinal degeneration. This review discusses a range of behavioral assays—including visual adaptation, motion detection, and color discrimination—that are employed to evaluate retinal function in zebrafish. These methods enable the detection of subtle visual deficits that may precede overt anatomical damage, providing a non-invasive, efficient strategy for early diagnosis and high-throughput drug screening. Importantly, these behavioral tests also serve as sensitive functional readouts to evaluate the efficacy of pharmacological treatments over time. Compared to traditional murine models, zebrafish offer advantages such as lower maintenance costs, faster development, optical transparency for live imaging, and ethical benefits due to reduced use of higher vertebrates. However, variability in experimental protocols highlights the need for standardization to ensure reliability and reproducibility.

The inaccessibility of human cerebellar tissue and the complexity of its development have historically hindered the study of cerebellar ataxias, a genetically diverse group of neurodegenerative disorders. Induced pluripotent stem cell (iPSC) technology offers a powerful solution, enabling the generation of patient-specific cerebellar models that retain individual genetic backgrounds. This review examines recent progress in iPSC-derived cerebellar models and their application in relation to major hereditary ataxias, including Friedreich’s ataxia, ataxia–telangiectasia, and spinocerebellar ataxias (SCAs). These models have provided valuable insights into disease mechanisms and supported the development of therapeutic strategies, such as gene therapy and high-throughput drug screening. However, challenges remain, particularly in achieving the full maturation of cerebellar cell types and incorporating microglial interactions. Moreover, emerging evidence suggests that neurodevelopmental alterations may act as early contributors to degeneration. Despite the current limitations, the advancement of patient-derived iPSC cerebellar models holds great promise for uncovering novel disease pathways and for driving precision medicine approaches in cerebellar ataxia research.

Hereditary cerebellar ataxias are progressive neurodegenerative disorders for which disease-modifying treatments remain lacking. Although these conditions have traditionally been investigated from a neuron-centered perspective, evidence from several ataxia models indicates that changes in the cerebellar immune microenvironment can arise before overt neuronal loss and may contribute to early circuit dysfunction. This review examines hereditary cerebellar ataxias through the lens of early neuroimmune regulation, with particular attention to the region-specific properties of cerebellar microglia and their roles in synaptic refinement, inflammatory tone modulation and circuit homeostasis. We further discuss zebrafish as a useful experimental system for this question, because they combine in vivo imaging, genetic manipulation, and scalable functional assays in an intact vertebrate model. In this context, flavonoids—and especially naringenin—are not considered as immediate therapeutic candidates, but as mechanistically informative experimental probes to investigate how modulation of neuroimmune signaling affects disease-relevant phenotypes in vivo. By integrating genetic ataxia models with dynamic neuroimmune readouts, functional behavioral assays, and circuit-level analyses, zebrafish-based approaches can help identify early windows during which neuroimmune signaling influences cerebellar resilience and disease progression and can guide subsequent validation in mammalian systems.

Biallelic variants in HPDL cause a severe neurological disorder in childhood, but the mechanisms linking early developmental abnormalities to later cortical degeneration remain unclear. Here, using long-term iPSC-derived human cortical cultures derived from four patients, we investigated the late consequences of HPDL deficiency through quantitative immunofluorescence and bulk RNA-seq. We found that HPDL-deficient cortical cultures undergo progressive synaptic impairment, with marked loss of PSD95-positive postsynaptic puncta despite largely preserved general neuronal maturation markers. This phenotype is accompanied by a profound reduction in astrocytes and oligodendrocytes, together with increased neuronal apoptosis and transcriptional dysregulation of genes linked to extracellular matrix organization, cellular stress, and neurodegeneration. Unexpectedly, late-stage mutant cultures also show reactivation of early developmental programs, including aberrant expression of NEUROD4 and other proneural regulators, suggesting instability of cell identity during cortical maturation. Together, these findings support a model in which HPDL deficiency first perturbs cortical developmental timing and later drives collapse of the neuro-glial unit, linking premature neurogenesis to synaptic failure, glial loss, and progressive neurodegeneration.

Hereditary cerebellar ataxias are progressive neurodegenerative disorders for which diseasemodifying treatments are still lacking. Although these conditions have traditionally been studied from a neuron-centered perspective, evidence from several ataxia models indicates that changes in the cerebellar immune microenvironment can arise before overt neuronal loss and may contribute to early circuit dysfunction. This review examines hereditary cerebellar ataxias through the lens of early neuroimmune regulation, with particular attention to the region-specific properties of cerebellar microglia and their roles in synaptic refinement and circuit homeostasis. We also discuss zebrafish as a useful experimental system for this question, because they combine in vivo imaging, genetic manipulation, and scalable functional assays in an intact vertebrate model. In this context, flavonoids—and especially naringenin—are considered not as immediate therapeutic candidates, but as experimental tools to investigate how modulation of inflammatory balance affects disease-relevant phenotypes in vivo. By integrating genetic ataxia models with dynamic neuroimmune readouts, zebrafish-based approaches can help identify early windows in which neuroimmune signalling influences cerebellar vulnerability and can guide subsequent validation in mammalian systems.