Behavioral and Brain Functions最新文献

Background: Visual selective attention can be categorized into top-down (goal-driven) and bottom-up (stimulus-driven) attention, with the fronto-parietal network serving as the primary neural substrate. However, fewer studies have focused on the specific roles of the right dorsolateral prefrontal cortex (DLPFC) and superior parietal lobule (SPL) in top-down and bottom-up attention. This study aimed to investigate the activity and connectivity of the right DLPFC and SPL in top-down and bottom-up attention.

Methods: Visual pop-out task mainly induces bottom-up attention, while the visual search task mainly induces top-down attention. Fifty-four participants completed the pop-out and search tasks during functional magnetic resonance imaging (fMRI) scanning. We used univariate analyses, multivariate pattern analyses (MVPA), and generalized psychophysiological interaction (gPPI) to assess activity and functional connectivity.

Results: Univariate analyses revealed stronger activation in the right DLPFC and SPL during the search > pop-out condition. The activation of the DLPFC was driven by its deactivation in the pop-out task, whereas the SPL showed significant activation in both tasks. MVPA demonstrated that activation patterns in the right DLPFC and SPL could distinguish between the pop-out and search tasks above chance level (0.5), with the right SPL exhibiting higher classification accuracy. The gPPI analyses showed that higher functional connectivity between the two seeds (right DLPFC and SPL) and bilateral precentral gyrus, left SPL, and right insula.

Conclusions: These results indicate that the right DLPFC and SPL showed stronger activity and connectivity under top-down versus bottom-up attention, allowing for neural representation of visual selective attention. This study provides evidence for understanding the role of the fronto-parietal network in visual selective attention.

Recent studies have demonstrated a close association between neuroinflammation and depression. Isoacteoside (ISO) has recently been reported to exhibit anti-inflammatory properties. However, the effects of ISO on neuroinflammation-induced depression and its underlying mechanisms have not been fully elucidated. This study aimed to investigate the mechanism of ISO on neuroinflammation-induced depression from both in vivo and in vitro aspects. In the in vivo experiments, lipopolysaccharide (LPS) was used to induce depressive-like behavior in adult male C57BL/6J mice, which were subsequently detected using the open field test (OFT), forced swim test (FST), and tail suspension test (TST). Quantitative real-time polymerase chain reaction (qPCR) and western blot were employed to measure the expression of inflammatory and polarization markers, as well as related proteins. Immunofluorescence staining was used to detect the expression of glial cell markers. For the in vitro experiments, BV2 and SH-SY5Y cells were selected and treated with LPS for subsequent analysis. The results indicated that mice treated with LPS exhibited depressive-like behaviors, accompanied by significant levels of neuroinflammation and oxidative stress, all of which were effectively reduced by ISO treatment. Furthermore, ISO facilitated the normalization of microglial polarization from the M1 to M2 phenotype, reduced the expression of ionized calcium-binding adaptor 1 (Iba1) and glial fibrillary acidic protein (GFAP), and modulated the CREB/BDNF signaling pathway. These findings suggest that ISO has an ameliorative effect on LPS-induced depressive-like behavior in mice, which may be achieved by attenuating neuroinflammation and oxidative stress as well as modulating the phenotype of microglia.

The TWIK-related K⁺ channel (TREK-1), a member of the two-pore domain potassium(K2P) family, is characterized as a "leaky potassium channel" and is integral to the maintenance of the resting membrane potential. As the most abundant cell type in the central nervous system, astrocytes play important roles in the development of epilepsy by regulating the release of glutamate and the function of potassium channels. Previous studies have revealed that TREK-1 is involved in a range of neurological diseases, including epilepsy. In astrocytes, TREK-1 acts as a crucial regulator of the rapid release of glutamate and passive conductance. However, controversy remains about the expression levels of TREK-1-binding receptors in the process of the release and recycling of glutamate in tripartite synapses. Thus, elucidating the pathological mechanisms involving TREK-1 in epilepsy could significantly increase our understanding of the pathophysiological basis of diseases and facilitate the identification of potential targets for novel therapeutic interventions. Here, we review the physiological function of TREK-1 and studies examining the role of TREK-1 in epilepsy, with a particular emphasis on its interactions with glutamate at tripartite synapses. Furthermore, we provide an analysis of the associated molecular mechanisms of this channel and conclude with an outlook on impending studies on TREK-1 as a novel therapeutic target for epilepsy.

Background: Although creativity is an essential cognitive function to adapt to an ever-changing world, its neurocognitive and cerebral bases still need clarification. Current models highlight the interaction between associative and executive processes underpinned by the default mode (DMN), executive control (ECN) and salience networks (SN). Furthermore, recent neuroimaging studies highlight the key role of the prefrontal cortex (PFC), located at the crossroads of these networks. Hence, behavioral variant frontotemporal dementia (bvFTD), characterized by progressive neurodegeneration principally impacting the prefrontal cortex and the intrinsic connectivity of these three creativity-related networks, represents a unique model to study creativity. In this study involving 14 bvFTD patients and 20 matched controls, we used a simple word-to-word association task (FGAT) to explore the specific cognitive processes involved in remote thinking, i.e., the production of creative semantic associations. Using voxel-based morphometry, we uncovered critical brain regions for each component and then characterized these regions' intrinsic connectivity profiles using resting-state functional connectivity in healthy controls.

Results: We dissociated four key cognitive components underlying remote thinking: spontaneous associative thinking, inhibition of unoriginal responses, intentional remote associative thinking, and verbal initiation; and replicated them in three independent datasets. Spontaneous associative thinking relied on temporal and cerebellar regions involved in low-order and automatic semantic processing, connected with the DMN, ECN and SN. Inhibition of prepotent unoriginal responses depended on key nodes of the SN. The ability to intentionally generate remote semantic associations was underpinned by key regions of the DMN. Finally, initiation of verbal responses relied on the right dorsolateral PFC, connected to the ECN. BvFTD patients were impaired in the last three components. Two components, cognitive inhibition and intentional remote thinking, mediated the link between atrophy in critical regions and an independent measure of creative abilities.

Conclusions: These findings advance our understanding of creative neurocognition, distinguishing components of creative thinking and clarifying their critical cerebral bases, and participate in the characterization of creativity impairment in patients with bvFTD.

Background: Parkinson's disease (PD) is an incurable neurological disorder, and current pharmacological therapies primarily address symptoms without halting disease progression. Emerging evidence highlights PD as a neuroinflammatory disease, with chronic brain inflammation preceding the onset of motor dysfunction. This study investigates the role of C18:0 GM3, a long-chain fatty acids-containing ganglioside, in modulating inflammatory responses in PD, exploring its therapeutic potential in mitigating LPS-induced parkinsonism.

Methods: Male C57BL/6 mice were utilized in an LPS-induced PD model to evaluate the neuroprotective effects of C18:0 GM3 ganglioside. Pre-treatment with C18:0 GM3 was assessed through behavioral tests, including rotarod and beam-walking, to determine motor function improvements. Dopaminergic neurotoxicity was quantified using [¹⁸F]FE-PE2I positron emission tomography (PET) imaging and tyrosine hydroxylase (TH) staining. The anti-inflammatory and anti-gliosis effects of C18:0 GM3 were analyzed by measuring cytokine levels (IL-1β, TNF-α) and by assessing Iba1 and GFAP immunoreactivity as indicators of microglial and astrocytic changes, respectively.

Results: Pre-treatment with C18:0 GM3 ganglioside significantly enhanced motor coordination and balance, as evidenced by improved performance in rotarod and beam-walking tests. Furthermore, C18:0 GM3 ganglioside effectively attenuated LPS-induced dopaminergic neurotoxicity, evidenced by increased striatal dopamine transporter availability on [¹⁸F]FE-PE2I PET imaging and the preservation of TH-positive neurons in the striatum. In addition, C18:0 GM3 markedly suppressed the expression of pro-inflammatory cytokines, including IL-1β and TNF-α, along with cyclooxygenase-2 levels. C18:0 GM3 also reduced gliosis, as demonstrated by a decrease in Iba1-positive microglial cells and GFAP-positive astrocytes.

Conclusion: Our data indicate that C18:0 GM3 primarily attenuates the TLR4-driven inflammatory cascade initiated by intrastriatal LPS, thereby secondarily preserving striatal dopaminergic terminals and improving motor deficits. Although these results highlight anti-inflammatory neuroprotection, additional studies are required to determine whether GM3 also modulates downstream Parkinson-specific processes such as α-synuclein aggregation or progressive neurodegeneration.

Background: Mu-opioid receptors (MORs) are critical regulators mediating the modulation of several behavioral reactions, including analgesia, addiction, and sedation. Recent studies have reported that MORs are closely associated with mood disorders or anxiety behaviors; however, the underlying neural mechanisms remain unclear. The periaqueductal gray (PAG), a key brain area, participates in the modulation of aversive emotional behaviors. MORs show a high expression in the ventrolateral PAG (vlPAG) region. This study explored the preliminary role of MORs expressed in the vlPAG in modulating emotional behaviors.

Results: Bilateral administration of DAMGO, an MOR-specific agonist, into the vlPAG of male mice elicited anxiety-like behaviors in elevated plus maze tests. This phenotype was reversed by conditional knockdown of astrocytic MORs. In contrast, glutamatergic or GABAergic MORs were not involved in vlPAG MOR-dependent anxiety-like behaviors. By using in vitro calcium imaging of vlPAG astrocytes and chemical genetic technologies, we found that vlPAG astrocytic MORs can promote astrocytic calcium signaling, which can efficiently induce anxiety-like behaviors. Accordingly, the interference of astrocytic calcium signaling by viral infection reversed vlPAG-dependent anxiety-like behaviors.

Conclusion: Our findings demonstrated that vlPAG astrocytic, but not glutamatergic or GABAergic, MORs are involved in modulating emotional reactions, and these effects are accomplished by MOR-elicited astrocytic calcium signaling mechanisms. The present study provides a theoretical basis for treating emotional dysfunctions during MOR-targeted management.

Background: Chronic neuroinflammation is a pivotal pathogenesis in neurodegenerative diseases (NDDs). Transient receptor potential canonical protein 6 (TRPC6) has an essential role in the maintenance of calcium homeostasis in cells. Our previous study indicated that TRPC6 signaling is involved in Aβ deposition and NLRP1 inflammasome activation in type 2 diabetes mellitus-associated cognitive dysfunction. However, whether TRPC6 signaling contributes to chronic lipopolysaccharide (LPS)-induced neuroinflammatory injury and the mechanism remain unclear.

Methods: In this study, male mice received intraperitoneal injections of LPS (200 µg/kg) for 21 days to induce a chronic neuroinflammation model. The open field test, hole-board test, and Morris water maze were conducted to evaluate cognitive function. The H&E and Nissl staining was employed to examine neuronal injury. The immunofluorescence, western blotting, or q-PCR were used to analyze TRPC6, AIM2 inflammasome expression, and Nrf2 activation. The fluorescent probes and calcium imaging were performed to assess ROS accumulation and calcium dysregulation in LPS-induced HT22 neuron cells.

Results: Chronic LPS exposure induced behavioral deficits in locomotion, exploratory behavior, and learning and memory, and neuronal damages with less expressions of PSD95 and Synaptophysin in mice. Mechanistically, LPS exposure significantly increased ROS production, TRPC6 expression and calcium overload, and induced AIM2 inflammasome activation in vivo or in vitro. While Trpc6 knockout could significantly improve LPS-induced cognitive dysfunction and neuronal injuries, inhibit TRPC6-mediated calcium overload, and downregulate the expressions of AIM2, caspase-1, IL-1β, IL-6, caspase-3 and Bax in vivo or in vitro. Additionally, Rg1 treatment significantly inhibited calcium overload and AIM2 inflammasome activation in LPS-induced HT22 cells. More importantly, Rg1 significantly activated Nrf2 signaling and reduced ROS production in LPS-induced mice or HT22 cells.

Conclusions: Trpc6 knockout can improve chronic LPS-induced neuroinflammation and injury by inhibiting TRPC6-AIM2 inflammasomes. While Rg1 treatment can alleviate LPS-induced neuroinflammation and injury not only by inhibiting TRPC6-AIM2 inflammasomes activation but also activating Nrf2 signaling.

Background: The central circadian clock coordinates daily oscillations in physiology, metabolism and behavior. Disruptions to core circadian clock genes not only perturb sleep-wake rhythms but also contribute to psychiatric disorders. While dopaminergic dysfunction is strongly associated with mental illnesses, the mechanistic connection between circadian clock genes and dopamine signaling remains elusive. In the current study, we directly examine the role of the core circadian gene Bmal1 in dopamine neurons, investigating its effects on behavioral outcomes and dopamine signaling.

Results: Bmal1 conditional knockout (cKO) mice specific to dopamine neuron were generated by crossing Bmal1-flox strain with the Dat-Cre strain, with knockout efficiency validated through immunofluorescence. BMAL1 deficiency in dopaminergic neurons induces attention-deficit hyperactivity disorder (ADHD)-like phenotypes, including hyperactivity, impairments in attention and working memory. Dopamine sensor detection revealed increased dopamine release in Bmal1-cKO mice. Additionally, electrophysiological recording showed that striatal neurons in Bmal1 knockout mice exhibited increased neuronal excitability. Amphetamine and dopamine D1 receptor antagonist SCH23390 treatment attenuated the hyperactivity behavior in cKO mice.

Conclusions: This study finds that BMAL1 ablation in dopaminergic neurons induces ADHD-like phenotypes in male mice, identifying hyperactive dopamine signaling as a potential mediator of these phenotypes. It unveils a novel role for BMAL1 in regulating dopamine signaling and provide insights into circadian gene-driven psychiatric pathophysiology.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline. Working memory impairment, a hallmark of early-stage AD, is hypothesized to arise from deficits in encoding processes. Given the critical role of hippocampal-prefrontal interactions in working memory, we investigated whether disrupted encoding mechanisms in this circuit contribute to AD-related deficits. We performed simultaneous local field potential (LFP) recordings in the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC) of APP/PS1 transgenic mice during a spatial working memory task. We analyzed oscillatory dynamics and directed information flow between these two regions across distinct task phases. Wild-type mice exhibited task-phase-specific enhancement of theta (4-12 Hz) and low-gamma (30-40 Hz) information flow from vHPC to mPFC during encoding, which correlated with performance accuracy. APP/PS1 mice showed a significant reduction in the theta and low-gamma flow and impaired task performance. Decoding analyses revealed a robust correlation between the strength of directed information flow and performance accuracy. These findings provide compelling evidence for a neurophysiological mechanism linking vHPC-mPFC circuit dynamics to encoding processes, offering new insights into the neural basis of working memory impairment in AD.