While midbrain DA neurons show phasic activations in response to both reward-predicting and salient non-reward events, activation responses to primary and conditioned rewards are sustained for several hundreds of milliseconds beyond those elicited by salient non-reward-related stimuli. The longer-duration DA reward response and corresponding elevated DA release in striatal target sites may selectively strengthen currently-active corticostriatal synapses, i.e., those associated with the successful reward-procuring behavior. This paper describes how similar models of DA-mediated plasticity of corticostriatal synapses may describe both stimulus-response and response-outcome learning. DA-mediated strengthening of corticostriatal synapses in regions of the dorsolateral striatum receiving afferents from primary sensorimotor cortex is likely to bind corticostriatal inputs representing the previously-emitted movement to striatal outputs contributing to the selection of the next movement segment in a behavioral sequence. Within the striatum, more generally, inputs from distinct regions of the frontal cortex that code independently for movement direction and reward expectation send convergent projections to striatal output cells. DA-mediated strengthening of active corticostriatal synapses promotes the future output of the striatal cell under similar input conditions. This is postulated to promote persistence of neuronal activity in the very cortical cells that drive corticostriatal input, leading to the establishment of sustained reverberatory loops that permit cortical movement-related cells to maintain activity until the appropriate time of movement initiation.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677708 | PMC |
http://dx.doi.org/10.1016/j.bbr.2008.12.014 | DOI Listing |
Eur J Neurosci
January 2025
CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
In corticostriatal nerve terminals, glutamate release is stimulated by adenosine via A receptors (ARs) and simultaneously inhibited by endocannabinoids via CB receptors (CBRs). We previously identified presynaptic AR-CBR heterotetrameric complexes in corticostriatal nerve terminals. We now explored the possible functional interaction between ARs and CBRs in purified striatal GABAergic nerve terminals (synaptosomes) and compared these findings with those on the release of glutamate.
View Article and Find Full Text PDFCell Rep
December 2024
Department of Psychiatry and Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY 10016, USA. Electronic address:
The posterior "tail" region of the striatum receives dense innervation from sensory brain regions and is important for behaviors that require sensorimotor integration. The output neurons of the striatum, D1 and D2 striatal projection neurons (SPNs), which make up the direct and indirect pathways, are thought to play distinct functional roles, although it remains unclear if these neurons show cell-type-specific differences in their response to sensory stimuli. Here, we examine the strength of synaptic inputs onto D1 and D2 SPNs following the stimulation of upstream auditory pathways.
View Article and Find Full Text PDFNeurobiol Dis
December 2024
Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada. Electronic address:
Background: Altered balance between striatal direct and indirect pathways contributes to early motor, cognitive and psychiatric symptoms in Huntington disease (HD). While degeneration of striatal D2-type dopamine receptor (D2)-expressing indirect pathway medium spiny neurons (iMSNs) occurs prior to that of D1-type dopamine receptor (D1)-expressing direct pathway neurons, altered corticostriatal synaptic function precedes degeneration. D2-mediated signaling on iMSNs reduces their excitability and promotes endocannabinoid (eCB) synthesis, suppressing glutamate release from cortical afferents.
View Article and Find Full Text PDFPsychol Med
November 2024
Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.
Background: Major psychiatric disorders (MPDs) are delineated by distinct clinical features. However, overlapping symptoms and transdiagnostic effectiveness of medications have challenged the traditional diagnostic categorisation. We investigate if there are shared and illness-specific disruptions in the regional functional efficiency (RFE) of the brain across these disorders.
View Article and Find Full Text PDFBiomedicines
August 2024
Institute of Clinical Neurobiology, University Hospital Wuerzburg, 97078 Wuerzburg, Germany.
Neurotrophins, particularly brain-derived neurotrophic factor (BDNF), act as key regulators of neuronal development, survival, and plasticity. BDNF is necessary for neuronal and functional maintenance in the striatum and the substantia nigra, both structures involved in the pathogenesis of Parkinson's Disease (PD). Depletion of BDNF leads to striatal degeneration and defects in the dendritic arborization of striatal neurons.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!