What do zebra finches learn besides singing? Systematic mapping of the literature and presentation of an efficient associative learning test.

The process of learning in birds has been extensively studied, with a focus on species such as pigeons, parrots, chickens, and crows. In recent years, the zebra finch has emerged as a model species in avian cognition, particularly in song learning. However, other cognitive domains such as spatial memory and associative learning could also be critical to fitness and survival, particularly during the intensive juvenile period. In this systematic review, we provide an overview of cognitive studies on zebra finches, with a focus on domains other than song learning. Our findings indicate that spatial, associative, and social learning are the most frequently studied domains, while motoric learning and inhibitory control have been examined less frequently over 30 years of research. All of the 60 studies included in this review were conducted on captive birds, limiting the generalizability of the findings to wild populations. Moreover, only two of the studies were conducted on juveniles, highlighting the need for more research on this critical period of learning. To address this research gap, we propose a high-throughput method for testing associative learning performance in a large number of both juvenile and adult zebra finches. Our results demonstrate that learning can occur in both age groups, thus encouraging researchers to also perform cognitive tests on juveniles. We also note the heterogeneity of methodologies, protocols, and subject exclusion criteria applied by different researchers, which makes it difficult to compare results across studies. Therefore, we call for better communication among researchers to develop standardised methodologies for studying each cognitive domain at different life stages and also in their natural conditions.

Variable ambient temperature promotes song learning and production in zebra finches.

Current climate change is leading to increasingly unpredictable environmental conditions and is imposing new challenges to wildlife. For example, ambient conditions fluctuating during critical developmental periods could potentially impair the development of cognitive systems and may therefore have a long-term influence on an individual's life. We studied the impact of temperature variability on zebra finch cognition, focusing on song learning and song quality (N = 76 males). We used a 2 × 2 factorial experiment with two temperature conditions (stable and variable). Half of the juveniles were cross-fostered at hatching to create a mismatch between pre- and posthatching conditions, the latter matching this species' critical period for song learning. We found that temperature variability did not affect repertoire size, syllable consistency, or the proportion of syllables copied from a tutor. However, birds that experienced variable temperatures in their posthatching environment were more likely to sing during recordings. In addition, birds that experienced variable prenatal conditions had higher learning accuracy than birds in stable prenatal environments. These findings are the first documented evidence that variable ambient temperatures can influence song learning in zebra finches. Moreover, they indicate that temperature variability can act as a form of environmental enrichment with net positive effects on cognition.

[Risk Factors of Rapidly Progressive Interstitial Lung Disease in Patients With Anti-Melanoma Differentiation-Associated Gene 5 Antibody-Positive Dermatomyositis].

Objective: To investigate the conditions of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis combined with rapidly progressive interstitial lung disease (RPILD), and to analyze the risk factors. Methods: A total of 145 patients diagnosed with anti-MDA5 antibody-positive dermatomyositis at West China Hospital, Sichuan University between January 2018 and September 2021 were selected, and their general and clinical data were collected. The patients were divided into two groups, a RPILD group of patients with comorbid RPILD and a non-RPILD group of those who did not have comorbid RPILD. Factors that might affect whether patients with anti-MDA5 antibody-positive dermatomyositis also had comorbid RPILD were screened out and binary logistic regression analysis was performed. Results: Among the 145 patients with anti-MDA5 antibody-positive dermatomyositis, 32 (22.07%) patients had comorbid RPILD, while the remaining 113 (77.93%) did not have comorbid RPILD. Binary logistic regression analysis showed that lactate dehydrogenase≥370 IU/L (compared with <370 IU/L, OR=4.066, 95% CI: 1.616-10.230) and carcinoembryo antigen≥5 ng/mL (compared with <5 ng/mL, OR=6.070, 95% CI: 2.013-18.303) were risk factors for comorbid RPILD in patients with anti-MDA5 antibody-positive dermatomyositis ( ß>0, OR>1, P<0.05). Conclusion: It is recommended that close attention be given to changes in high-resolution chest CT and pulmonary functions in patients with lactate dehydrogenase≥370 IU/L and carcinoembryo antigen≥5 ng/mL. If rapid progression of lung disease is detected, it is necessary to strengthen the treatment of the lung disease, thereby improving the prognosis of patients.

Cathodic- and anodic-pulses can alternately activate different sub-populations of neurons during sustained high-frequency stimulation of axons in rat hippocampus.

Objective.Charge-balanced biphasic-pulses are commonly used in neural stimulations to prevent possible damages caused by charge accumulations. The lagging anodic-phases of biphasic-pulses may decrease the activation efficiency of stimulations by counteracting the depolarization effect of the leading cathodic-phases. However, a monophasic anodic-pulse alone can itself activate neurons by depolarizing neuronal membrane through a mechanism of virtual cathode. This study aimed to verify the hypothesis that the anodic-phases/pulses in charge-balanced stimulations could play an activation role during sustained high-frequency stimulations (HFSs).Approach.Two types of antidromic HFS (A-HFS) were applied on the alveus of hippocampal CA1 region of anesthetized rats: monophasic-pulse A-HFS of alternate opposite pulses and biphasic-pulse A-HFS with the same frequency of 100 or 200 Hz. The antidromically-evoked population spike was used as a biomarker to evaluate the activation effects of A-HFS pulses.Main results.Despite a significant difference in the initial abilities of anodic- and cathodic-pulses to activate neurons, an anodic-pulse was able to induce similar amount of neuronal firing as a cathodic-pulse during sustained monophasic-pulse A-HFS. Additionally, the amount of neuronal firing induced by the monophasic-pulse A-HFS was similar to that induced by the biphasic-pulse A-HFS consuming a double amount of electrical energy. Furthermore, the alternate cathodic- and anodic-pulses respectively activated different sub-populations of neurons during steady A-HFS.Significance.The anodic-phases/pulses in charge-balanced HFS at axons can play an activation role in addition to a role of charge balance. The study provides important information for designing charge-balanced stimulations and reveals new mechanisms of neural stimulations.

Adjust Neuronal Reactions to Pulses of High-Frequency Stimulation with Designed Inter-Pulse-Intervals in Rat Hippocampus In Vivo.

Sequences of electrical pulses have been applied in the brain to treat certain disorders. In recent years, altering inter-pulse-interval (IPI) regularly or irregularly in real time has emerged as a promising way to modulate the stimulation effects. However, algorithms to design IPI sequences are lacking. This study proposed a novel strategy to design pulse sequences with varying IPI based on immediate neuronal reactions. Firstly, to establish the correlationship between the neuronal reactions with varying IPIs, high-frequency stimulations with varying IPI in the range of 5-10 ms were applied at the alveus of the hippocampal CA1 region of anesthetized rats in vivo. Antidromically-evoked population spikes (APS) following each IPI were recorded and used as a biomarker to evaluate neuronal reactions to each pulse. A linear mapping model was established to estimate the varied APS amplitudes by the two preceding IPIs. Secondly, the mapping model was used to derive an algorithm for designing an IPI sequence that would be applied for generating a desired neuronal reaction pre-defined by a particular APS distribution. Finally, examples of stimulations with different IPI sequences designed by the algorithm were verified by rat experiments. The results showed that the designed IPI sequences were able to reproduce the desired APS responses of different distributions in the hippocampal stimulations. The novel algorithm of IPI design provides a potential way to obtain various stimulation effects for brain stimulation therapies.