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Monosynaptic Inputs to Ventral Tegmental Area Glutamate and GABA Co-transmitting Neurons

A unique population of ventral tegmental area (VTA) neurons co-transmits glutamate and GABA. However, the circuit inputs to VTA VGluT2+VGaT+ neurons are unknown, limiting our understanding of their functional capabilities. By coupling monosynaptic rabies tracing with intersectional genetic targeting in male and female mice, we found that VTA VGluT2+VGaT+ neurons received diverse brainwide inputs. The largest numbers of monosynaptic inputs to VTA VGluT2+VGaT+ neurons were from superior colliculus (SC), lateral hypothalamus (LH), midbrain reticular nucleus, and periaqueductal gray, whereas the densest inputs relative to brain region volume were from the dorsal raphe nucleus, lateral habenula, and VTA. Based on these and prior data, we hypothesized that LH and SC inputs were from glutamatergic neurons. Optical activation of glutamatergic LH neurons activated VTA VGluT2+VGaT+ neurons regardless of stimulation frequency and resulted in flee-like ambulatory behavior. In contrast, optical activation of glutamatergic SC neurons activated VTA VGluT2+VGaT+ neurons for a brief period of time at high frequency and resulted in head rotation and arrested ambulatory behavior (freezing). Stimulation of glutamatergic LH neurons, but not glutamatergic SC neurons, was associated with VTA VGluT2+VGaT+ footshock-induced activity and inhibition of LH glutamatergic neurons disrupted VTA VGluT2+VGaT+ tailshock-induced activity. We interpret these results such that inputs to VTA VGluT2+VGaT+ neurons may integrate diverse signals related to the detection and processing of motivationally salient outcomes.




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Behavioral and Neural Mechanisms of Face-Specific Attention during Goal-Directed Visual Search

Goal-directed visual attention is a fundamental cognitive process that enables animals to selectively focus on specific regions of the visual field while filtering out irrelevant information. However, given the domain specificity of social behaviors, it remains unclear whether attention to faces versus nonfaces recruits different neurocognitive processes. In this study, we simultaneously recorded activity from temporal and frontal nodes of the attention network while macaques performed a goal-directed visual search task. V4 and inferotemporal (IT) visual category-selective units, selected during cue presentation, discriminated fixations on targets and distractors during the search but were differentially engaged by face and house targets. V4 and IT category-selective units also encoded fixation transitions and search dynamics. Compared with distractors, fixations on targets reduced spike–LFP coherence within the temporal cortex. Importantly, target-induced desynchronization between the temporal and prefrontal cortices was only evident for face targets, suggesting that attention to faces differentially engaged the prefrontal cortex. We further revealed bidirectional theta influence between the temporal and prefrontal cortices using Granger causality, which was again disproportionate for faces. Finally, we showed that the search became more efficient with increasing target-induced desynchronization. Together, our results suggest domain specificity for attending to faces and an intricate interplay between visual attention and social processing neural networks.




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Monocyte Invasion into the Retina Restricts the Regeneration of Neurons from Müller Glia

Endogenous reprogramming of glia into neurogenic progenitors holds great promise for neuron restoration therapies. Using lessons from regenerative species, we have developed strategies to stimulate mammalian Müller glia to regenerate neurons in vivo in the adult retina. We have demonstrated that the transcription factor Ascl1 can stimulate Müller glia neurogenesis. However, Ascl1 is only able to reprogram a subset of Müller glia into neurons. We have reported that neuroinflammation from microglia inhibits neurogenesis from Müller glia. Here we found that the peripheral immune response is a barrier to CNS regeneration. We show that monocytes from the peripheral immune system infiltrate the injured retina and negatively influence neurogenesis from Müller glia. Using CCR2 knock-out mice of both sexes, we found that preventing monocyte infiltration improves the neurogenic and proliferative capacity of Müller glia stimulated by Ascl1. Using scRNA-seq analysis, we identified a signaling axis wherein Osteopontin, a cytokine highly expressed by infiltrating immune cells is sufficient to suppress mammalian neurogenesis. This work implicates the response of the peripheral immune system as a barrier to regenerative strategies of the retina.




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A Prefrontal->Periaqueductal Gray Pathway Differentially Engages Autonomic, Hormonal, and Behavioral Features of the Stress-Coping Response

The activation of autonomic and hypothalamo-pituitary-adrenal (HPA) systems occurs interdependently with behavioral adjustments under varying environmental demands. Nevertheless, laboratory rodent studies examining the neural bases of stress responses have generally attributed increments in these systems to be monolithic, regardless of whether an active or passive coping strategy is employed. Using the shock probe defensive burying test (SPDB) to measure stress-coping features naturalistically in male and female rats, we identify a neural pathway whereby activity changes may promote distinctive response patterns of hemodynamic and HPA indices typifying active and passive coping phenotypes. Optogenetic excitation of the rostral medial prefrontal cortex (mPFC) input to the ventrolateral periaqueductal gray (vlPAG) decreased passive behavior (immobility), attenuated the glucocorticoid hormone response, but did not prevent arterial pressure and heart rate increases associated with rats’ active behavioral (defensive burying) engagement during the SPDB. In contrast, inhibition of the same pathway increased behavioral immobility and attenuated hemodynamic output but did not affect glucocorticoid increases. Further analyses confirmed that hemodynamic increments occurred preferentially during active behaviors and decrements during immobility epochs, whereas pathway manipulations, regardless of the directionality of effect, weakened these correlational relationships. Finally, neuroanatomical evidence indicated that the influence of the rostral mPFC->vlPAG pathway on coping response patterns is mediated predominantly through GABAergic neurons within vlPAG. These data highlight the importance of this prefrontal->midbrain connection in organizing stress-coping responses and in coordinating bodily systems with behavioral output for adaptation to aversive experiences.




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Dynamics of Saccade Trajectory Modulation by Distractors: Neural Activity Patterns in the Frontal Eye Field

The sudden appearance of a visual distractor shortly before saccade initiation can capture spatial attention and modulate the saccade trajectory in spite of the ongoing execution of the initial plan to shift gaze straight to the saccade target. To elucidate the neural correlates underlying these curved saccades, we recorded from single neurons in the frontal eye field of two male rhesus monkeys shifting gaze to a target while a distractor with the same eccentricity appeared either left or right of the target at various delays after target presentation. We found that the population level of presaccadic activity of neurons representing the distractor location encoded the direction of the saccade trajectory. Stronger activity occurred when saccades curved toward the distractor, and weaker when saccades curved away. This relationship held whether the distractor was ipsilateral or contralateral to the recorded neurons. Meanwhile, visually responsive neurons showed asymmetrical patterns of excitatory responses that varied with the location of the distractor and the duration of distractor processing relating to attentional capture and distractor inhibition. During earlier distractor processing, neurons encoded curvature toward the distractor. During later distractor processing, neurons encoded curvature away from the distractor. This was observed when saccades curved away from distractors contralateral to the recording site and when saccades curved toward distractors ipsilateral to the recording site. These findings indicate that saccadic motor planning involves dynamic push–pull hemispheric interactions producing attraction or repulsion for potential but unselected saccade targets.




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Deciphering Peripheral Taste Neuron Diversity: Using Genetic Identity to Bridge Taste Bud Innervation Patterns and Functional Responses

Peripheral taste neurons exhibit functional, genetic, and morphological diversity, yet understanding how or if these attributes combine into taste neuron types remains unclear. In this study, we used male and female mice to relate taste bud innervation patterns to the function of a subset of proenkephalin-expressing (Penk+) taste neurons. We found that taste arbors (the portion of the axon within the taste bud) stemming from Penk+ neurons displayed diverse branching patterns and lacked stereotypical endings. The range in complexity observed for individual taste arbors from Penk+ neurons mirrored the entire population, suggesting that taste arbor morphologies are not primarily regulated by the neuron type. Notably, the distinguishing feature of arbors from Penk+ neurons was their propensity to come within 110 nm (in apposition with) different types of taste-transducing cells within the taste bud. This finding is contrary to the expectation of genetically defined taste neuron types that functionally represent a single stimulus. Consistently, further investigation of Penk+ neuron function revealed that they are more likely to respond to innately aversive stimuli—sour, bitter, and high salt concentrations—as compared with the full taste population. Penk+ neurons are less likely to respond to nonaversive stimuli—sucrose, umami, and low salt—compared with the full population. Our data support the presence of a genetically defined neuron type in the geniculate ganglion that is responsive to innately aversive stimuli. This implies that genetic expression might categorize peripheral taste neurons into hedonic groups, rather than simply identifying neurons that respond to a single stimulus.




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The Role of the Rat Prefrontal Cortex and Sex Differences in Decision-Making

The prefrontal cortex is critical for decision-making across species, with its activity linked to choosing between options. Drift diffusion models (DDMs) are commonly employed to understand the neural computations underlying this behavior. Studies exploring the specific roles of regions of the rodent prefrontal cortex in controlling the decision process are limited. This study explored the role of the prelimbic cortex (PLC) in decision-making using a two-alternative forced-choice task. Rats first learned to report the location of a lateralized visual stimulus. The brightness of the stimulus indicated its reward value. Then, the rats learned to make choices between pairs of stimuli. Sex differences in learning were observed, with females responding faster and more selectively to high-value stimuli than males. DDM analysis found that males had decreased decision thresholds during initial learning, whereas females maintained a consistently higher drift rate. Pharmacological manipulations revealed that PLC inactivation reduced the decision threshold for all rats, indicating that less information was needed to make a choice in the absence of normal PLC processing. μ-Opioid receptor stimulation of the PLC had the opposite effect, raising the decision threshold and reducing bias in the decision process toward high-value stimuli. These effects were observed without any impact on the rats’ choice preferences. Our findings suggest that PLC has an inhibitory role in the decision process and regulates the amount of evidence that is required to make a choice. That is, PLC activity controls "when," but not "how," to act.




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Neural Predictors of Fear Depend on the Situation

The extent to which neural representations of fear experience depend on or generalize across the situational context has remained unclear. We systematically manipulated variation within and across three distinct fear-evocative situations including fear of heights, spiders, and social threats. Participants (n = 21; 10 females and 11 males) viewed ~20 s clips depicting spiders, heights, or social encounters and rated fear after each video. Searchlight multivoxel pattern analysis was used to identify whether and which brain regions carry information that predicts fear experience and the degree to which the fear-predictive neural codes in these areas depend on or generalize across the situations. The overwhelming majority of brain regions carrying information about fear did so in a situation-dependent manner. These findings suggest that local neural representations of fear experience are unlikely to involve a singular pattern but rather a collection of multiple heterogeneous brain states.




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Orbitofrontal Cortex Mediates Sustained Basolateral Amygdala Encoding of Cued Reward-Seeking States

Basolateral amygdala (BLA) neurons are engaged by emotionally salient stimuli. An area of increasing interest is how BLA dynamics relate to evolving reward-seeking behavior, especially under situations of uncertainty or ambiguity. Here, we recorded the activity of individual BLA neurons in male rats across the acquisition and extinction of conditioned reward seeking. We assessed ongoing neural dynamics in a task where long reward cue presentations preceded an unpredictable, variably time reward delivery. We found that, with training, BLA neurons discriminated the CS+ and CS– cues with sustained cue-evoked activity that correlated with behavior and terminated only after reward receipt. BLA neurons were bidirectionally modulated, with a majority showing prolonged inhibition during cued reward seeking. Strikingly, population-level analyses revealed that neurons showing cue-evoked inhibitions and those showing excitations similarly represented the CS+ and behavioral state. This sustained population code rapidly extinguished in parallel with conditioned behavior. We next assessed the contribution of the orbitofrontal cortex (OFC), a major reciprocal partner to the BLA. Inactivation of the OFC while simultaneously recording in the BLA revealed a blunting of sustained cue-evoked activity in the BLA that accompanied reduced reward seeking. Optogenetic disruption of BLA activity and OFC terminals in the BLA also reduced reward seeking. Our data indicate that the BLA represents reward-seeking states via sustained, bidirectional cue-driven neural encoding. This code is regulated by cortical input and is important for the maintenance of vigilant reward-seeking behavior.




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Youth experience persecution

OM teaches East London youth about the persecuted Christians in the world, as well as trains them in street ministry.




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Preparing for missions

Engage, OM South Africa’s bi-annual conference, provides a challenge and a channel for joining missions with OM.




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Without a vision people perish

Participants of a poverty simulation activity hosted by AIDSLink International discover that it’s very different to minister to the poor than to be the poor.




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Coaching for life in Randfontein

Community leaders in South Africa met with SportsLink to discuss how coaches can impact the fatherless in Randfontein.




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Once and for all

A Missions Discipleship Training participant discovers that his sins were dealt with by Jesus on the cross, making him free and forgiven, once and for all.




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Sharing the gospel in a hair salon

Logos Hope crew members share the Gospel in a hair salon with someone who has never before heard about Jesus.




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MDT: A springboard into missions

Missions Discipleship Training in South Africa is not a wasted six months--it's a springboard into your calling, preparing and equipping you for the real deal.




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Passing on the baton

After leading AIDS Hope for the past 11 years, Nico and Alma hand over the leadership of Meetse a Bophelo centre in Mamelodi.




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Missions Discipleship Training in OM

OM has trained thousands of young people into a stronger relationship with Christ and prepared them for the mission field.




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Connecting with God in prayer

During an outreach to Lesotho an MDT team meets an older man during door-to-door ministry and invites him to their daily prayer meeting.




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Convincing or conversing?

An Australian working with OM Russia shares about seeing God work in the lives of the students of OM Russia’s Discipleship Centre.




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'Why shouldn't we get involved in world mission?'

How OM Founder George Verwer's visit to Siberia impacted local churches.




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Internet evangelism, Internet dating and the Internet in world mission

A young couple who met on the Internet answers God’s call to missions to help others find Christ using their IT and web design skills.




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OM Russia: A mission team for families

OM Russia leader Colin Cleaver discusses why he values the involvement of families in OM Russia’s ministry and encourages other families to consider missions.




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Rehabilitation through love and action

The church in Russia is facing a new threat-HIV/AIDS. OM Russia works in rehab-centres to show God's love and compassion.




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Imprisoned to be free

The story of Yury, who came to Christ in prison.




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Mission trip outside Russia

A group of Russians participates in an OM Moldova summer outreach for children.




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Abandoning ruinous traditions

A woman from a least-reached group of people accepted Christ during Discipleship Centre student outreach.




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Floods and earthquakes shake up a nation

Although a flash flood inundated most of Metro Manila, Central and North Luzon in the Philippines, recent earthquakes have shaken up the nation even more.




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In the aftermath of Typhoon Pablo

OM Philippines sees signs of hope in the midst of tragic loss while extending help to churches wrecked by Typhoon Pablo (Bopha).




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Three million and counting…

OM Ships’ vessel Logos Hope welcomes her three millionth visitor on board while in Puerto Princesa, Philippines.




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Serving beyond their comfort zones

Marie Reyes from Australia led the Out of the Comfort Zone Cebu team, and shares lessons she learnt during the two-week outreach.




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Typhoon Haiyan slams the Philippines

One of the strongest typhoons ever to hit land slammed the Philippines on Friday, 15 November, forcing millions to take shelter. OM Philippines responds.




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Fully operational this week

After taking inventory of the relief effort, OM Philippines workers, in partnership with churches, distribute relief necessities to some of the least-reached disaster sites.




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OM starts reconstruction in three locations

As local markets begin to re-establish themselves, the OM Philippines crisis response team takes steps towards reconstruction in Tacloban, Bohol and Northern Cebu.




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Running the relief marathon

How OM Philippines is making a long-term difference in the aftermath of Typhoon Haiyan.




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Into the last frontier

From 8-26 April, OM Philippines will host their annual short-term missions conference GO EXTRA MILE in Palawan for the first time ever.




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Operation Safe multiplied

OM Philippines hosts camps for children affected by recent trauma that facilitate emotional restoration through dance, songs, crafts, Bible stories and more.




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School drop-outs receive holistic education

OM Philippines’ Alternative Learning System teachers visit the homes of students in an effort to connect with their parents and encourage further education.




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Construction of 20 homes unites people

20 A-frame houses and a Sunday School building destroyed by Typhoon Haiyan have been built by OM Philippines these past three months.




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Intentional relationships open doors

Three boys who sell fish become “men of peace” for the DreamAsia+ team in three of the poorest Muslim communities in the Philippines.




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ALS gradutation inspires

OM Philippines helps train and provide school drop-outs with the opportunity to earn their elementary or high school diploma.




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Tropical cyclone reopens conflict area

OM responded to the needs of people affected by Typhoon Vinta, relying on military accompaniment to reach the location and deliver aid.




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The missionary goats

A shepherd from a Muslim background comes to Jesus thanks to a goat ministry started by OM Mozambique.




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By the beautiful stones

Antonio Nipueda (Mozambique) recollects his journey to ministry with OM in Mozambique and the ways their prayers have impacted one village there.




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Concentrate on one

Focusing on one person at a time, John uses everyday life as a way to meet people where they are and journey alongside them.




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'You can do missions'

"...if they don’t believe you, you have to keep on talking and talking and talking until it gets stuck in their head," said Lansipe.




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On the 'wings' of worship

Kanat, which means 'wings' in Turkish, is the biannual worship arts camp run by the Taco team in Turkey.




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Old and new creation

A Turkish believer remains strong in his faith through persecution.




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Acceleration in Turkey

Ministries in Turkey experience acceleration through wide sowing, building projects, and church planting.




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One sows, one waters, God gives the growth

Church planters with the BCC in Turkey are encouraged by growth in a city where the gospel was previously unknown.