Dual neuromodulatory dynamics underlie birdsong learning.
Although learning in response to extrinsic reinforcement is theorized to be driven by dopamine signals that encode the difference between expected and experienced rewards, skills that enable verbal or musical expression can be learned without extrinsic reinforcement. Instead, spontaneous execution of these skills is thought to be intrinsically reinforcing. Whether dopamine signals similarly guide learning of these intrinsically reinforced behaviours is unknown. In juvenile zebra finches learning from an adult tutor, dopamine signalling in a song-specialized basal ganglia region is required for successful song copying, a spontaneous, intrinsically reinforced process. Here we show that dopamine dynamics in the song basal ganglia faithfully track the learned quality of juvenile song performance on a rendition-by-rendition basis. Furthermore, dopamine release in the basal ganglia is driven not only by inputs from midbrain dopamine neurons classically associated with reinforcement learning but also by song premotor inputs, which act by means of local cholinergic signalling to elevate dopamine during singing. Although both cholinergic and dopaminergic signalling are necessary for juvenile song learning, only dopamine tracks the learned quality of song performance. Therefore, dopamine dynamics in the basal ganglia encode performance quality during self-directed, long-term learning of natural behaviours.
Vibrissa-based object localization in head-fixed mice.
Linking activity in specific cell types with perception, cognition, and action, requires quantitative behavioral experiments in genetic model systems such as the mouse. In head-fixed primates, the combination of precise stimulus control, monitoring of motor output, and physiological recordings over large numbers of trials are the foundation on which many conceptually rich and quantitative studies have been built. Choice-based, quantitative behavioral paradigms for head-fixed mice have not been described previously. Here, we report a somatosensory absolute object localization task for head-fixed mice. Mice actively used their mystacial vibrissae (whiskers) to sense the location of a vertical pole presented to one side of the head and reported with licking whether the pole was in a target (go) or a distracter (no-go) location. Mice performed hundreds of trials with high performance (>90% correct) and localized to <0.95 mm (<6 degrees of azimuthal angle). Learning occurred over 1-2 weeks and was observed both within and across sessions. Mice could perform object localization with single whiskers. Silencing barrel cortex abolished performance to chance levels. We measured whisker movement and shape for thousands of trials. Mice moved their whiskers in a highly directed, asymmetric manner, focusing on the target location. Translation of the base of the whiskers along the face contributed substantially to whisker movements. Mice tended to maximize contact with the go (rewarded) stimulus while minimizing contact with the no-go stimulus. We conjecture that this may amplify differences in evoked neural activity between trial types.
Ih Shapes Pathway-Specific Inhibition in Substantia Nigra Pars Reticulata.
The substantia nigra pars reticulata (SNr) functions as the principal inhibitory output of the basal ganglia, with the timing of its spikes critically controlling downstream disinhibition required for movement initiation. The external globus pallidus (GPe) and D1-expressing medium spiny neurons (D1-MSNs) in the striatum provide GABAergic inputs to the SNr that differ in their amplitude and kinetic properties. How these inputs interact with the intrinsic membrane currents that determine SNr firing is only partially understood. Using optogenetics, computational modeling, and electrophysiology in acute mouse brain slices, 47 animals of either sex were used for measurements, and we found an unexpected interaction between GABAergic inputs and hyperpolarization-activated currents (Ih) that tunes inhibitory efficacy in a pathway-specific manner. GPe inputs evoke fast, large IPSCs that transiently suppress SNr firing within a narrow window but whose rapid decay enables depolarization from Ih to restore firing after only a brief pause. In contrast, the slower decay kinetics of striatal IPSCs enables more sustained inhibition that counters the depolarizing drive from Ih to produce longer pauses, despite their lower conductance amplitudes. Pharmacological blockade of Ih with ZD7288 eliminated the rapid recovery of firing after GPe inhibition and equalized the inhibitory efficacy between GPe and striatal pathways. These findings establish an important interplay between synaptic kinetics and intrinsic membrane conductances in establishing pathway-specific inhibitory balance in the basal ganglia. Our study reveals that inhibitory pathways to the substantia nigra pars reticulata are differentially shaped by the interplay between synaptic kinetics and intrinsic membrane conductances. Using optogenetics, electrophysiology, and modeling, we showed that fast-decaying GABAergic inputs from the external globus pallidus are rapidly overcome by Ih, producing only brief pauses in SNr firing, whereas slower striatal inputs generate longer-lasting inhibition. Blocking Ih abolishes this difference, demonstrating that intrinsic currents tune inhibitory efficacy in a pathway-specific manner. These results identify a biophysical mechanism that helps set the balance of basal ganglia output essential for movement control.
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Basal Ganglia Advances
Basal Ganglia Advances is a collection highlighting research on the structure, function, and disorders of the basal ganglia. It features studies spanning neuroscience, clinical insights, and computational models, serving as a hub for advances in movement, cognition, and behavior.
Progress in Voltage Imaging
Recent advances in the field of Voltage Imaging, with a special focus on new constructs and novel implementations.
Navigation & Localization
Work related to place tuning, spatial navigation, orientation and direction. Mainly includes articles on connectivity in the hippocampus, retrosplenial cortex, and related areas.
Most Popular Recent Articles
Dopamine in the Nucleus Accumbens Signals Salience of Auditory Deviance.
How the brain signals prediction errors for non-rewarding, yet significant, sensory events remains a central question. Although the cortical mismatch negativity provides a well-known signature for deviance detection, the contribution of subcortical dopamine remains unclear. This study tested the hypothesis that phasic dopamine in the nucleus accumbens encodes the salience associated with the violation of an ongoing statistical regularity. Using fiber photometry in freely moving rats, we contrasted an auditory oddball paradigm with a many-standards control. Deviant stimuli elicited a significantly amplified dopamine response compared with standard stimuli. Crucially, this dopamine response enhancement was absent in the control condition, demonstrating that the nucleus accumbens dopamine responds specifically to rule violation rather than mere stimulus rarity. The long latency of this signal (~500 ms) relative to the cortical mismatch negativity argues against a direct role in the initial detection of deviance. Instead, our findings support a model in which subcortical dopamine acts as a distinct salience signal, operating in parallel with cortical deviance detection, to evaluate unexpected events and guide subsequent behavioral adjustments.
Prevention of heart failure.
Heart failure (HF) remains a major cause of morbidity, mortality and costs for the healthcare systems worldwide, despite advances in diagnostic and therapeutic strategies. The enhancement of preventive measures is now a priority, but effective prevention requires a multidisciplinary strategy addressing a broad spectrum of comorbidities and risk factors. It must also consider the changes in the prevailing phenotype of the patients with HF with a lower impact of coronary artery disease and the increasing role of renal and metabolic conditions leading mostly to HF with preserved ejection fraction. Prevention of HF must take into consideration arterial hypertension, chronic kidney disease, diabetes mellitus, sedentary lifestyle, obesity, dyslipidemia, female-specific risk factors, as well as adverse effects of chemotherapy and radiotherapy. Other key factors include infections and the protective role of vaccination, and environmental and socio-economic determinants of health. In 2022, a position paper of the Heart Failure Association and the European Association of Preventive Cardiology of the ESC was published as a complete overview on this topic and as a compendium to the 2021 ESC Guidelines on HF. However, since then, significant evidence has emerged regarding the potential to prevent HF, particularly in the context of metabolic disorders, diabetes and kidney diseases. This scientific statement aims to provide an updated perspective, highlighting the importance of a holistic and tailored approach to managing the multifaceted contributors to this syndrome.
Improved Prediction of Femoral Shortening in Total Hip Arthroplasty for Developmental Dysplasia of the Hip Using the Etfal Classification: A 7-Center Validation Study.
BACKGROUND Developmental dysplasia of the hip (DDH) presents substantial surgical challenges during total hip arthroplasty (THA), particularly in cases of high-riding dislocations, which can require subtrochanteric shortening osteotomy. The newly proposed Etfal classification incorporates the proportional femoral-pelvic ratio and may offer improved preoperative guidance. MATERIAL AND METHODS A retrospective multicenter validity study was conducted across 7 tertiary centers, including 152 patients with 157 hips who underwent THA for DDH. The primary endpoint was the intraoperative requirement for subtrochanteric shortening osteotomy. Preoperative radiographs were classified using the Etfal and Crowe classifications. Diagnostic performance was evaluated using ROC analyses, AUC values, and optimal thresholds determined using the Youden index. Complication associations were assessed using a 2×2 contingency analysis with odds ratios. RESULTS A total of 157 hips from 152 patients were analyzed, with subtrochanteric shortening osteotomy performed in 50 hips (31.8% of hips). Subtrochanteric shortening osteotomy was required in 0% of Etfal type 1; 33% of type 2; 96.4% of type 3; and 100% of type 4 hips. In contrast, only 6.1% of Crowe type 3 hips required subtrochanteric shortening osteotomy, compared with 80% of Crowe type 4 hips. Diagnostic performance favored Etfal over Crowe (AUC, 0.98 vs 0.94). Etfal type 3 or greater demonstrated near-perfect specificity (0.99) and high sensitivity (0.82), outperforming Crowe type 3 or greater (specificity, 0.60; sensitivity, 1.00). Twelve complications occurred, predominantly in Etfal types 3 and 4. CONCLUSIONS Etfal classification demonstrated superior discriminative ability for predicting the intraoperative requirement for subtrochanteric shortening osteotomy and complication risk compared with the Crowe system.