Biology subjects

Fuccillo, M. V.

Publications and source records attributed to Fuccillo, M. V..

14 recordsLinked to original sources

bioRxiv2026

Striatal interneuron microcircuits gate reinforcement to stabilize adaptive choice

The dorsomedial striatum guides learning and adaptive decision-making through excitatory synaptic control of its spiny projection neuron outputs. However, the contributions of local inhibitory microcircuitry remain poorly understood. Here, we identify an interneuron circuit in the dorsomedial striatum that links outcome processing to adaptive action selection. During probabilistic push-pull reversal learning, interneurons represented immediate outcomes: somatostatin interneurons were recruited on unrewarded trials and unexpected rewarded trials, whereas tyrosine hydroxylase interneurons were suppressed on unrewarded trials and recruited on rewarded trials. In vivo recruitment of tyrosine hydroxylase interneurons suppressed somatostatin interneuron activity and increased activity in both direct- and indirect-pathway striatal projection neurons, revealing a polysynaptic disinhibitory microcircuit. Transient inhibition of somatostatin interneurons in this pull-tuned region produced a sustained increase in aberrant pull choices and occupancy of a suboptimal pull-preferring behavioral state, whereas inhibition of tyrosine hydroxylase interneurons produced a sustained impairment of pull reinforcement. Longer-term policy changes following somatostatin interneuron inhibition coincided with postsynaptic potentiation of excitatory synapses onto striatal projection neurons, suggesting a potential substrate for the persistence of altered behavioral policies. Together, these findings identify a disinhibitory striatal circuit motif gating reinforcement which transforms individual trial outcomes into temporally broader policy.

neuroscience↗

bioRxiv2026

Comprehensive 3D mapping reveals distinct spatial gradients of SST, PV, and TH interneurons across the mouse caudoputamen

In addition to spatially organized excitatory forebrain inputs along its mediolateral, dorsoventral, and anteroposterior axes, the striatum relies on cellular diversity to subserve its myriad processing functions. Distinct striatal GABAergic interneuron subtypes, including somatostatin (SST), parvalbumin (PV), and tyrosine hydroxylase (TH) interneurons likely subserve complementary computational roles. However, a detailed understanding of how these microcircuit components are distributed across striatal territories remains lacking. To address this gap, we generated a comprehensive three-dimensional atlas of SST, PV, and TH interneurons across the mouse caudoputamen using genetic labeling, brain-wide imaging, and voxel-wise quantification. We found that SST and TH interneurons were relatively enriched in the ventral caudoputamen, whereas PV interneurons were enriched dorsally. In addition, PV and TH interneurons exhibited opposing anteroposterior distribution patterns, with PV interneurons enriched posteriorly and TH interneurons showing a marked decline in density towards the striatal tail. Consequently, while the three interneuron subtypes displayed comparable densities in the functionally defined lateral striatum and anterior ventromedial striatum, PV interneurons predominated in the dorsomedial striatum and tail of striatum. We did not observe major sex differences. Together, these findings reinforce the view that the striatum is not a monolithic structure: in addition to structured excitatory inputs, inhibitory microcircuits themselves are differentially distributed across striatal territories, providing region-specific constraints on circuit computation. By integrating interneuron organization into existing anatomical frameworks, this atlas provides a foundation for linking striatal anatomy to function across behavioral domains.

neuroscience↗

bioRxiv2025

Indirect pathway neurons in the tail of the striatum regulate inhibitory control over sensory driven behavior

Inhibitory control, or the ability to withhold action in certain situations, is behaviorally essential. Disrupted inhibitory control is linked to various neuropsychiatric symptoms, making it critical to understand the underlying neural basis. We examined how the tail of the striatum (TS), a major basal ganglia sensory hub, regulates actions to sensory stimuli. Mice performed an auditory Go/NoGo task where we recorded cell-specific activity of TS neurons. Both major striatal types were active during target sounds, but non-target sounds preferentially engaged indirect pathway neurons. Temporarily silencing this activity increased errors to non-target stimuli, indicating a role in suppressing inappropriate action. In mice deficient for the synaptic adhesion molecule Neurexin1, a gene linked to autism spectrum disorder and ADHD, TS indirect pathway recruitment was reduced, and these mice demonstrated auditory-specific inhibitory control deficits. Altogether, these findings highlight a subcortical target to potentially improve attentional and behavioral regulation in neurodevelopmental disorders. TeaserPosterior striatal circuits control sensory-guided actions and are disrupted in a rodent model of neurodevelopmental disorders.

neuroscience↗

bioRxiv2025

Temporally and Functionally Distinct Contributions to Value Based Choice Along the Anterior-Posterior Dorsomedial Striatal Axis

While the dorsoventral and mediolateral organization of striatum has resolved clear functional distinctions, far less is known about how the anterior-posterior striatal axis contributes to behavioral control. We explore this within the dorsomedial striatum (DMS), a key region for value-based choice, by comparing population neuronal activity and function within anterior (A-DMS) and posterior (P-DMS) subregions while mice operantly seek reward. Neural recordings show that P-DMS encoded action values and strategy information prior to choice selection while A-DMS activity represented recently selected choices and their anticipated values via a dynamic population reorganization immediately following action selection. Optogenetic perturbations were consistent with these temporally distinct coding properties as unilateral manipulation of the P-DMS prior to choice biased choice contralaterally in a value-dependent manner and unilateral inhibition of the A-DMS following choice impaired future value-based action selection. Using anterograde tracing, we found that the A-DMS and P-DMS projected to a common region within the ventromedial substantia nigra pars reticulata (vmSNr), which contained value-related signals combining aspects of upstream DMS processing. Together, our results support a model for temporally distributed influence on value-based choice across the anterior-posterior axis of the DMS.

neuroscience↗

bioRxiv2025

An Open-Source Joystick Platform for Investigating Forelimb Motor Control, Auditory-Motor Integration, and Value-Based Decision-Making in Head-Fixed Mice

Investigation of neural processes underlying motor control requires behavioral readouts that capture the richness of actions, including both categorical (choice-based) information and motor execution (kinematics). We present an open-source platform for behavioral training of head-fixed mice that combines a stationary or retractable forelimb-based joystick, sound-presentation system, capacitive lick sensor, and water reward dispenser. The setup allows for the creation of multiple behavioral paradigms, two of which are highlighted here: a two-alternative forced-choice auditory-motor discrimination paradigm, and a two-armed bandit value-based decision-making task. In the auditory-motor paradigm, mice learn to report high or low frequency tones by pushing or pulling the joystick. In the value-based paradigm, mice learn to push or pull the joystick based on the history of rewarded trials. In addition to reporting categorical choices, this setup provides a rich dataset of motor parameters that reflect components of the underlying learning and decision processes in both of these tasks. These kinematic parameters (including joystick speed and displacement, Frechet similarity of trajectories, tortuosity, angular standard deviation, and movement vigor) provide key additional insights into the motor execution of choices that are not as readily assessed in other paradigms. The systems flexibility of task design, joystick readout, and ease of construction represent an advance compared to currently available manipulandum tasks in mice. We provide detailed schematics for constructing the setup and protocols for behavioral training using both paradigms, with the hope that this open-source resource is readily adopted by neuroscientists interested in mechanisms of sensorimotor integration, motor control, and choice behavior. Significance StatementBehavioral paradigms for experiments in head-restrained mice are important for investigating the relationship between neural activity and behavior. However, behavioral setups are often constrained by high cost, design complexity, and implementation challenges. Here, we present an open-source platform for behavioral training of head-fixed mice using a joystick manipulandum. The setup allows for the creation of multiple behavioral paradigms, including an auditory-motor discrimination paradigm, and a value-based decision-making task. We include detailed instructions for construction and implementation of the entire open-source behavioral platform.

neuroscience↗

bioRxiv2024

A chromosome region linked to neurodevelopmental disorders acts in distinct neuronal circuits in males and females to control locomotor behavior

Biological sex shapes the manifestation and progression of neurodevelopmental disorders (NDDs). These disorders often demonstrate male-specific vulnerabilities; however, the identification of underlying mechanisms remains a significant challenge in the field. Hemideletion of the 16p11.2 region (16p11.2 del/+) is associated with NDDs, and mice modeling 16p11.2 del/+ exhibit sex-specific striatum-related phenotypes relevant to NDDs. Striatal circuits, crucial for locomotor control, consist of two distinct pathways: the direct and indirect pathways originating from D1 dopamine receptor (D1R) and D2 dopamine receptor (D2R) expressing spiny projection neurons (SPNs), respectively. In this study, we define the impact of 16p11.2 del/+ on striatal circuits in male and female mice. Using snRNA-seq, we identify sex- and cell type-specific transcriptomic changes in the D1- and D2-SPNs of 16p11.2 del/+ mice, indicating distinct transcriptomic signatures in D1-SPNs and D2-SPNs in males and females, with a [~]5-fold greater impact in males. Further pathway analysis reveals differential gene expression changes in 16p11.2 del/+ male mice linked to synaptic plasticity in D1- and D2-SPNs and GABA signaling pathway changes in D1-SPNs. Consistent with our snRNA-seq study revealing changes in GABA signaling pathways, we observe distinct changes in miniature inhibitory postsynaptic currents (mIPSCs) in D1- and D2-SPNs from 16p11.2 del/+ male mice. Behaviorally, we utilize conditional genetic approaches to introduce the hemideletion selectively in either D1- or D2-SPNs and find that conditional hemideletion of genes in the 16p11.2 region in D2-SPNs causes hyperactivity in male mice, but hemideletion in D1-SPNs does not. Within the striatum, hemideletion of genes in D2-SPNs in the dorsal lateral striatum leads to hyperactivity in males, demonstrating the importance of this striatal region. Interestingly, conditional 16p11.2 del/+ within the cortex drives hyperactivity in both sexes. Our work reveals that a locus linked to NDDs acts in different striatal circuits, selectively impacting behavior in a sex- and cell type-specific manner, providing new insight into male vulnerability for NDDs. Highlights- 16p11.2 hemideletion (16p11.2 del/+) induces sex- and cell type-specific transcriptomic signatures in spiny projection neurons (SPNs). - Transcriptomic changes in GABA signaling in D1-SPNs align with changes in inhibitory synapse function. - 16p11.2 del/+ in D2-SPNs causes hyperactivity in males but not females. - 16p11.2 del/+ in D2-SPNs in the dorsal lateral striatum drives hyperactivity in males. - 16p11.2 del/+ in cortex drives hyperactivity in both sexes. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=194 HEIGHT=200 SRC="FIGDIR/small/594746v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@19542baorg.highwire.dtl.DTLVardef@4ff570org.highwire.dtl.DTLVardef@17aa1c3org.highwire.dtl.DTLVardef@123e48_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Histone variant H2BE enhances chromatin accessibility in neurons to promote synaptic gene expression and long-term memory

Regulation of histone proteins affects gene expression through multiple mechanisms including exchange with histone variants. However, widely expressed variants of H2B remain elusive. Recent findings link histone variants to neurological disorders, yet few are well studied in the brain. We applied new tools including novel antibodies, biochemical assays, and sequencing approaches to reveal broad expression of the H2B variant H2BE, and defined its role in regulating chromatin structure, neuronal transcription, and mouse behavior. We find that H2BE is enriched at promoters and a single unique amino acid allows it to dramatically enhance chromatin accessibility. Lastly, we show that H2BE is critical for synaptic gene expression and long-term memory. Together, these data reveal a novel mechanism linking histone variants to chromatin regulation, neuronal function, and memory. This work further identifies the first widely expressed H2B variant and uncovers a single histone amino acid with profound effects on genomic structure.

genetics↗

bioRxiv2024

Infralimbic activity during REM sleep facilitates fear extinction memory

Rapid eye movement (REM) sleep is known to facilitate fear extinction and play a protective role against fearful memories. Consequently, disruption of REM sleep after a traumatic event may increase the risk for developing PTSD. However, the underlying mechanisms by which REM sleep promotes extinction of aversive memories remain largely unknown. The infralimbic cortex (IL) is a key brain structure for the consolidation of extinction memory. Using calcium imaging, we found in mice that most IL pyramidal neurons are intensively activated during REM sleep. Optogenetically suppressing the IL activity during REM sleep within a 4-hour window after auditory-cued fear conditioning impaired extinction memory consolidation. In contrast, REM-specific inhibition of the IL cortex after extinction learning did not affect the extinction memory. Whole-cell patch-clamp recordings demonstrated that inactivating IL neurons during REM sleep depresses their excitability. Together, our findings demonstrate that REM sleep after fear conditioning facilitates fear extinction by enhancing IL excitability, and highlight the importance of REM sleep in the aftermath of traumatic events for protecting against traumatic memories.

neuroscience↗

bioRxiv2022

Combined single-cell RNA-seq profiling and enhancer editing reveals critical spatiotemporal controls over thalamic nuclei formation in the murine embryo

The thalamus is the principal information hub of the vertebrate brain, with essential roles in sensory and motor information processing, attention, and memory. The molecular mechanisms regulating the formation of thalamic nuclei are unclear. We apply longitudinal single-cell RNA-sequencing, regional abrogation of Sonic-hedgehog (Shh), and spatial profiling of gene expression to map the developmental trajectories of thalamic progenitors, intermediate progenitors, and post-mitotic neurons as they coalesce into distinct thalamic nuclei. These data reveal that the complex architecture of the thalamus is established early during embryonic brain development through the coordinated action of four cell differentiation lineages derived from Shh-dependent and independent progenitors. We systematically characterize the gene expression programs that define these lineages across time and demonstrate how their disruption upon Shh depletion causes pronounced locomotor impairment resembling infantile Parkinsons disease. These results reveal key principles of thalamic development and provide mechanistic insights into neurodevelopmental disorders resulting from thalamic dysfunction.

neuroscience↗

bioRxiv2021

Distributed processing for action control by prelimbic circuits targeting anterior-posterior dorsal striatal subregions.

Fronto-striatal circuits have been extensively implicated in the cognitive control of behavioral output for both social and appetitive rewards. The functional diversity of prefrontal cortical populations is strongly dependent on their synaptic targets, with control of motor output strongly mediated by connectivity to the dorsal striatum. Despite evidence for functional diversity along the anterior-posterior axis of the dorsomedial striatum (DMS), it is unclear how distinct fronto- striatal sub-circuits support neural computations essential for action selection. Here we identify prefrontal populations targeting distinct DMS subregions and characterize their functional roles. We first performed neural circuit tracing to reveal segregated prefrontal populations defined by anterior/posterior dorsomedial striatal target. We then probed the functional relevance of these parallel circuits via in vivo calcium imaging and temporally precise causal manipulations during a feedback-based 2-alternative choice task. Single-photon imaging revealed circuit-specific representations of task-relevant information with prelimbic neurons targeting anterior DMS (PL::A- DMS) uniquely encoded choices and responses to negative outcomes, while prelimbic neurons targeting posterior DMS (PL::P-DMS) encoded internal representations of value and positive outcomes contingent on prior choice. Consistent with this distributed coding, optogenetic inhibition of PL::A-DMS circuits strongly impacted choice monitoring and behavioral control in response to negative outcomes while perturbation of PL::P-DMS signals impaired task engagement and strategies following positive outcomes. Di-synaptic retrograde tracing uncovered differences in afferent connectivity that may underlie these pathways functional divergence. Together our data uncover novel PL populations engaged in distributed processing for action control. SUMMARYO_LIPrelimbic cortex engages A- and P-DMS via distinct circuits C_LIO_LIPL::A-DMS and PL::P-DMS pathways encode divergent aspects of a simple goal-directed task C_LIO_LIPL::A-DMS pathways shape responding to negative outcomes via multiple mechanisms C_LIO_LIPL::P-DMS pathways guide engagement and choices in response to positive outcomes C_LIO_LIAfferent connectomes of PL neurons defined by A-P DMS target are distinct C_LI

neuroscience↗

bioRxiv2020

Striatal low-threshold spiking interneurons locally gate dopamine during learning

Low-threshold spiking interneurons (LTSIs) in the dorsomedial striatum are potent modulators of goal-directed learning. Here, we uncover a novel function for LTSIs in locally and directly gating striatal dopamine, using in vitro fast scan cyclic voltammetry as well as in vivo GRAB-DA sensor imaging and pharmacology during operant learning. We demonstrate that LTSIs, acting via GABAB signaling, attenuate dopamine release, thereby serving as local coordinators of striatal plasticity.

neuroscience↗

bioRxiv2020

Neurexin1α differentially regulates synaptic efficacy within striatal circuits

Mutations in genes essential for shared aspects of synaptic function throughout the CNS, such as the presynaptic adhesion molecule Neurexin1 (Nrxn1), are strongly implicated in neuropsychiatric pathophysiology. As the input nucleus of the basal ganglia, the striatum integrates diverse excitatory projections governing cognitive and motor control, and its functional impairment underlies neuropsychiatric disorders. While prior work has emphasized Neurexins contributions to synaptic transmission in hippocampus and brainstem, their function in striatal circuits remains unstudied. As Nrxn1 is highly expressed at striatal inputs, we employed optogenetic-mediated afferent recruitment of dorsal prefrontal cortex-dorsomedial striatal (DMS) connections, uncovering a decrease in net synaptic strength specifically onto indirect pathway spiny neurons in both Nrxn1+/- and Nrxn1-/- mice, driven by reductions in transmitter release probability. In contrast, thalamic excitatory inputs to DMS demonstrated relatively normal excitatory synaptic strength. These findings suggest that dysregulation of Nrxn1 modulates striatal function in an input and target-specific manner.

neuroscience↗

bioRxiv2019

Disruption of Nrxn1α within excitatory forebrain circuits drives value-based dysfunction

Goal-directed behaviors, complex action sequences that maximize reward, are essential for normal function and are significantly impaired across neuropsychiatric disorders. Despite extensive associations between genetic mutations and these brain disorders, the mechanisms by which candidate genes contribute to goal-directed dysfunction remains unclear, owing to challenges in (1) describing aspects of reward processing that drive goal-directed dysfunction, (2) localizing these deficits to specific brain circuits and (3) relating changes in physiology to behavioral alterations. Here we examined mice with mutations in Neurexin1, a presynaptically-localized adhesion molecule with widespread neuropsychiatric dis ease association, in value-based decision-making paradigms. We found that Neurexin1 knockout animals exhibited blunted choice bias towards outcomes associated with greater benefits. Mutant mice were similarly impaired in avoiding costlier, benefit-neutral actions. Analysis of trial-by-trial choice data via reinforcement learning models suggested these behavioral patterns were driven largely by deficits in the updating and representation of choice values. Employing conditional gene ablation and region-specific Cre-recombinase strains, we revealed that Neurexin1 disruption within forebrain excitatory projection neurons, but not thalamic population s, recapitulated most aspects of the whole-brain knockout phenotype. Finally, utilizing in vivo recordings of direct pathway spiny neuron population calcium activity, we demonstrated that selective knockout of Neurexin1 within forebrain excitatory neurons disrupts reward-associated neural signals within striatum, a major site of feedback-based learning. By relating deficits in value-based decision-making to region-specific Nrxn1 disruption and changes in reward-associated neural activity, we reveal potential neural substrates for the pathophysiology of neuropsychiatric disease-associated cognitive dysfunction.

neuroscience↗

bioRxiv2017

A cortical pathway modulates sensory input into the olfactory striatum

Sensory cortices process stimuli in manners essential for perception. The piriform primary olfactory cortex (PCX) extends dense association fibers into the ventral striatums olfactory tubercle (OT), yet the function of this cortico-striatal pathway is unknown. We optically stimulated channelrhodopsin-transduced PCX glutamatergic neurons or their association fibers while recording OT neural activity in mice performing an olfactory task. Activation of PCX neurons or their association fibers within the OT controlled the firing of some OT neurons and bidirectionally modulated odor coding dependent upon the neurons intrinsic odor responsivity. Further, patch clamp recordings and retroviral tracing from D1 and D2 dopamine receptor-expressing OT medium spiny neurons revealed this input can be monosynaptic and that both cell types receive most of their input from a specific spatial zone localized within the ventro-caudal PCX. These results demonstrate that the PCX functionally accesses the direct and indirect pathways of the basal ganglia within the OT.

neuroscience↗