Parkinson’s disease (PD) is known for its motor alterations, but the importance of non-motor symptoms (NMSs), such as olfactory dysfunction (OD), is increasingly recognized. OD may manifest during the prodromal period of the disease, even before motor symptoms appear. Therefore, it is suggested that this symptom could be considered a marker of PD. This article briefly describes PD, the evolution of the knowledge about OD in PD, the prevalence of this NMS and its role in diagnosis and as a marker of PD progression, the assessment of olfaction in patients with PD, the role of α-synuclein and its aggregates in the pathophysiology of PD, and then describes some functional, morphological, and histological alterations observed in different structures related to the olfactory system, such as the olfactory epithelium, olfactory bulb, anterior olfactory nucleus, olfactory tract, piriform cortex, hippocampus, orbitofrontal cortex, and amygdala. In addition, considering the growing evidence that suggests that the cerebellum is also involved in the olfactory system, it has also been included in this work. Comprehending the existing functional and neuroanatomical alterations in PD could be relevant for a better understanding of the mechanisms behind OD in patients with this neurodegenerative disorder.

Autism is a complex alteration in children’s developing nervous system that manifests in behavioral patterns that do not match those of typical subjects. Moreover, starting at puberty, these children may encounter problems regarding social interaction related to sexual encounters. As studies are scarce, we used the valproate model of autism in the zebrafish to contribute to the knowledge related to sexual behavior in this disorder. Young zebrafish were reproduced, embryos collected, and organized in groups of control or treated with valproic acid, as the autism model. Sexual behavior was recorded in fish from these embryos as they became sexually active. The results show that the zebrafish’s sexual behavior is organized into appetitive, preconsummatory, and consummatory behaviors, as in other vertebrates. In the autism model, the patterns of sexual behavior are present but with significant modifications. The behavior of males was the most affected, while in females, the most affected parameter was oviposition. These results show that, in the autism model of zebrafish, sexual behavior is not suppressed, but it seems that critical changes occur in the neuroendocrine system that reduces reproductive success. Furthermore, the enriched environment was beneficial in maintaining the consummatory behaviors of females and males with autism-like behaviors.

Parkinson’s disease is currently a global public health challenge due to the rapid growth of aging populations. To understand its pathophysiology is necessary to study the functional correlation between the basal ganglia (BG) and the cerebellum, which are involved in motor control. Herein, we explored multiunit electrical activity (MUA) in the cerebellum of rats with induced Parkinsonism as a result of lesions following bilateral placement of electrodes and passing of current in the ventrolateral striatum (VLS). In one control group, the electrodes descended without electrical current, and another group was left intact in VLS. MUA was recorded in Sim B and Crus II lobes, and in the dentate nucleus (DN) during the execution of exploration behaviors (horizontal and vertical) and grooming. The lesioned and sham groups showed a decrease in MUA amplitude in the Crus II lobe compared to the intact group in all recorded behaviors. However, Sim B and DN did not express differences. Both electrical and physical insults to the VLS induced Parkinsonism, which results in less MUA in Crus II during the execution of motor behaviors. Thus, this type of Parkinsonism is associated with a decrease in the amplitude of Crus II.

Background: Parkinsonism, characterized by motor symptoms, is typically attributed to basal ganglia dysfunction. Recent evidence suggests that the cerebellum may also influence these symptoms. This study investigated Crus II, the dentate nucleus (DN), and the inferior olive (IO) in a rat model of parkinsonism induced by a bilateral ventrolateral striatal (VLS) lesion. Materials and Methods: Twenty-four male Wistar rats were divided into control (n = 12) and experimental (n = 12) groups. Monopolar electrodes were implanted in target structures. The experimental group received a bilateral VLS lesion. Animals underwent four weekly sessions of electrophysiological recordings and blind behavioral assessments (resting, grooming, locomotion, rearing, sniffing) via video tracking. Power spectral density (PSD) in the 300–500 Hz band was computed. Statistical analyses included Mann–Whitney U, Friedman with Wilcoxon post hoc, and Spearman correlation tests. Results: During weeks one and two, there were significant PSD increases in the experimental group compared to the control, particularly in Crus II—grooming (p = 0.005), locomotion (p = 0.007), and rearing (p = 0.026); in IO—sniffing (p = 0.0167); and in DN—grooming (p < 0.001) and locomotion (p = 0.0008). Additionally, intragroup analysis revealed significant PSD elevations relative to baseline in these structures. Significant correlations were observed only for grooming (negative correlations) and sniffing (positive correlations) across all cerebellar regions. Conclusions: These findings suggest compensatory cerebellar hyperactivity induced by VLS lesion, potentially modulating hypokinetic symptoms and highlighting dynamic network interactions. Interpretation warrants caution due to limitations inherent to the acute lesion model and experimental duration.