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The use of levodopa to manage Parkinson's disease (PD) symptoms leads to levodopa-induced dyskinesia (LID) and other motor fluctuations, which worsen with disease progression and repeated treatment. Aberrant activity of striatal D1- and D2-expressing medium spiny neurons (D1-/D2-MSNs) underlies LID, but the mechanisms driving its progression remain unclear. Using the 6-OHDA mouse model of PD/LID, we combined and recordings to isolate the effect of repeated treatment in LID worsening and other motor fluctuation-related phenotypes. We found that LID worsening is linked to potentiation of levodopa-evoked responses in both D1-/D2-MSNs, independent of changes in dopamine release or MSN intrinsic excitability. Instead, strengthening of glutamatergic synapses onto D1-MSNs emerged as a key driver. Moreover, we found changes in D2-MSN activity that specifically influenced LID duration, potentially contributing to motor fluctuations, which paralleled a reduction in D2R sensitivity. These findings reveal striatal adaptations contributing to worsening of levodopa-related complications.
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http://dx.doi.org/10.1101/2025.05.16.654598 | DOI Listing |
J Neurosci
September 2025
Faculty of Psychology, Southwest University, Chongqing, China
While the hyper- and hypo- reward or punishment sensitivities (RS, PS) have received considerable attention as prominent transdiagnostic features of psychopathology, the lack of an overarching neurobiological characterization currently limits their early identification and neuromodulation. Here we combined microarray data from the Allen Human Brain Atlas with a multimodal fMRI approach to uncover the neurobiological signatures of RS and PS in a discovery-replication design (N=655 healthy participants, 442 Females). Both RS and PS were mapped separately in the brain, with the functional connectome in the fronto-striatal network encoding reward responsiveness, while the fronto-insular system was particularly engaged in punishment sensitivity.
View Article and Find Full Text PDFBiomolecules
August 2025
School of Psychological Sciences, University of Haifa, Haifa 3498838, Israel.
Cognitive flexibility, the ability to adapt behavior to changing environmental demands, is a core deficit in schizophrenia (SZ), that predicts disease progression. This review synthesizes findings on the neural substates of cognitive flexibility by using a framework that distinguishes animal model tasks by their motivational valence: aversive versus appetitive. While human studies using tasks like the Wisconsin Card Sorting Test (WCST) reveal significant cognitive inflexibility in SZ, particularly in set shifting, rodent models provide important mechanistic insights.
View Article and Find Full Text PDFJ Neurosci
August 2025
Mental Health Service, VA San Diego Healthcare Syst., La Jolla, CA, 92161.
Behavioral outcomes are rarely certain, requiring subjects to discriminate between available choices by using feedback to guide future decisions. Probabilistic reversal learning (PRL) tasks test subjects' ability to learn and flexibly adapt to changes in reward contingencies. Cortico-striatal circuitry has been broadly implicated in flexible decision-making - though what role these circuits play remains complicated.
View Article and Find Full Text PDFAddict Biol
August 2025
Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA.
Adaptive stress coping is often impaired in individuals with alcohol use disorder (AUD). This process relies on neurocircuitry involved in emotional and behavioural regulation, particularly the ventromedial PFC (vmPFC) and orbitofrontal cortex (OFC), along with limbic and ventral striatal regions (e.g.
View Article and Find Full Text PDFImaging Neurosci (Camb)
January 2025
Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry, University of Zurich, Zurich, Switzerland.
Efficient learning of letters-speech sound associations results in the specialization of visual and audiovisual brain regions, which is crucial for the development of proficient reading skills. However, the brain dynamics underlying this learning process remain poorly understood, and the involvement of learning and performance monitoring networks remains underexplored. Here we applied two mutually dependent feedback learning tasks in which novel symbol-speech sound associations were learned by 39 healthy adults.
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