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Nature Communications May 2024Unified visual perception requires integration of bottom-up and top-down inputs in the primary visual cortex (V1), yet the organization of top-down inputs in V1 remains...
Unified visual perception requires integration of bottom-up and top-down inputs in the primary visual cortex (V1), yet the organization of top-down inputs in V1 remains unclear. Here, we used optogenetics-assisted circuit mapping to identify how multiple top-down inputs from higher-order cortical and thalamic areas engage V1 excitatory and inhibitory neurons. Top-down inputs overlap in superficial layers yet segregate in deep layers. Inputs from the medial secondary visual cortex (V2M) and anterior cingulate cortex (ACA) converge on L6 Pyrs, whereas ventrolateral orbitofrontal cortex (ORBvl) and lateral posterior thalamic nucleus (LP) inputs are processed in parallel in Pyr-type-specific subnetworks (Pyr and Pyr) and drive mutual inhibition between them via local interneurons. Our study deepens understanding of the top-down modulation mechanisms of visual processing and establishes that V2M and ACA inputs in L6 employ integrated processing distinct from the parallel processing of LP and ORBvl inputs in L5.
Topics: Animals; Primary Visual Cortex; Optogenetics; Male; Thalamus; Visual Pathways; Neurons; Visual Cortex; Gyrus Cinguli; Interneurons; Visual Perception; Mice; Female; Brain Mapping
PubMed: 38802410
DOI: 10.1038/s41467-024-48924-8 -
Nature Communications May 2024How the spike output of the retina enables human visual perception is not fully understood. Here, we address this at the sensitivity limit of vision by correlating human...
How the spike output of the retina enables human visual perception is not fully understood. Here, we address this at the sensitivity limit of vision by correlating human visual perception with the spike outputs of primate ON and OFF parasol (magnocellular) retinal ganglion cells in tightly matching stimulus conditions. We show that human vision at its ultimate sensitivity limit depends on the spike output of the ON but not the OFF retinal pathway. Consequently, nonlinear signal processing in the retinal ON pathway precludes perceptual detection of single photons in darkness but enables quantal-resolution discrimination of differences in light intensity.
Topics: Animals; Humans; Retinal Ganglion Cells; Retina; Photons; Photic Stimulation; Visual Perception; Contrast Sensitivity; Male; Adult; Female; Primates; Visual Pathways; Macaca mulatta; Vision, Ocular
PubMed: 38802354
DOI: 10.1038/s41467-024-48750-y -
Translational Psychiatry May 2024Interoception is the perception of afferent information that arises from anywhere and everywhere within the body. Recently, interoceptive accuracy could be enhanced by...
Interoception is the perception of afferent information that arises from anywhere and everywhere within the body. Recently, interoceptive accuracy could be enhanced by cognitive training. Given that the anterior insula cortex (AIC) is a key node of interoception, we hypothesized that resting functional connectivity (RSFC) from AIC was involved in an effect of interoceptive training. To address this issue, we conducted a longitudinal intervention study using interoceptive training and obtained RSFC using fMRI before and after the intervention. A heartbeat perception task evaluated interoceptive accuracy. Twenty-two healthy volunteers (15 females, age 19.9 ± 2.0 years) participated. After the intervention, interoceptive accuracy was enhanced, and anxiety levels and somatic symptoms were reduced. Also, RSFC from AIC to the dorsolateral prefrontal cortex (DLPFC), superior marginal gyrus (SMG), anterior cingulate cortex (ACC), and brain stem, including nucleus tractus solitarius (NTS) were enhanced, and those from AIC to the visual cortex (VC) were decreased according to enhanced interoceptive accuracy. The neural circuit of AIC, ACC, and NTS is involved in the bottom-up process of interoception. The neural circuit of AIC, DLPFC, and SMG is involved in the top-down process of interoception, which was thought to represent the cognitive control of emotion. The findings provided a better understanding of neural underpinnings of the effect of interoceptive training on somatic symptoms and anxiety levels by enhancing both bottom-up and top-down processes of interoception, which has a potential contribution to the structure of psychotherapies based on the neural mechanism of psychosomatics.
Topics: Humans; Female; Interoception; Male; Magnetic Resonance Imaging; Insular Cortex; Young Adult; Adult; Anxiety; Longitudinal Studies; Neural Pathways; Cerebral Cortex; Gyrus Cinguli
PubMed: 38782961
DOI: 10.1038/s41398-024-02933-9 -
The Journal of Pharmacology and... May 2024Following colonic inflammation, the uninjured bladder afferent neurons are also activated. The mechanisms and pathways underlying this sensory neuron cross-activation...
Following colonic inflammation, the uninjured bladder afferent neurons are also activated. The mechanisms and pathways underlying this sensory neuron cross-activation (from injured neurons to uninjured neurons) are not fully understood. Colonic and bladder afferent neurons reside in the same spinal segments and are separated by satellite glial cells (SGCs) and extracellular matrix in dorsal root ganglia (DRG). SGCs communicate with sensory neurons in a bidirectional fashion. In this review, I summarize the differentially regulated genes/proteins in the injured and uninjured DRG neurons and explore the role of SGCs in regulation of sensory neuron crosstalk in visceral cross-organ sensitization. I also highlight the paracrine pathways in mediating neuron-SGC and SGC-neuron coupling with an emphasis on the neurotrophins and purinergic systems. Finally, I discuss the results from recent RNAseq profiling of SGCs to reveal useful molecular markers for characterization, functional study, and therapeutic targets of SGCs. Satellite glial cells (SGCs) are the largest glial subtypes in sensory ganglia and play a critical role in mediating sensory neuron crosstalk, an underlying mechanism in colon-bladder cross-sensitization. Identification of novel and unique molecular markers of SGCs can advance the discovery of therapeutics targets in treatment of chronic pain including visceral pain comorbidity.
PubMed: 38777604
DOI: 10.1124/jpet.123.002061 -
Brain Research Bulletin May 2024The medial prefrontal cortex (mPFC) forms output pathways through projection neurons, inversely receiving adjacent and long-range inputs from other brain regions....
INTRODUCTION
The medial prefrontal cortex (mPFC) forms output pathways through projection neurons, inversely receiving adjacent and long-range inputs from other brain regions. However, how afferent neurons of mPFC are affected by chronic stress needs to be clarified. In this study, the effects of chronic restraint stress (CRS) on the distribution density of mPFC dendrites/dendritic spines and the projections from the cortex and subcortical brain regions to the mPFC were investigated.
METHODS
In the present study, C57BL/6 J transgenic (Thy1-YFP-H) mice were subjected to CRS to establish an animal model of depression. The infralimbic (IL) of mPFC was selected as the injection site of retrograde AAV using stereotactic technique. The effects of CRS on dendrites/dendritic spines and afferent neurons of the mPFC IL were investigaed by quantitatively assessing the distribution density of green fluorescent (YFP) positive dendrites/dendritic spines and red fluorescent (retrograde AAV recombinant protein) positive neurons, respectively.
RESULTS
The results revealed that retrograde tracing virus labeled neurons were widely distributed in ipsilateral and contralateral cingulate cortex (Cg1), second cingulate cortex (Cg2), prelimbic cortex (PrL), infralimbic cortex, medial orbital cortex (MO), and dorsal peduncular cortex (DP). The effects of CRS on the distribution density of mPFC red fluorescence positive neurons exhibited regional differences, ranging from rostral to caudal or from top to bottom. Simultaneously, CRS resulted a decrease in the distribution density of basal, proximal and distal dendrites, as well as an increase in the loss of dendritic spines of the distal dendrites in the IL of mPFC. Furthermore, varying degrees of red retrograde tracing virus fluorescence signals were observed in other cortices, amygdala, hippocampus, septum/basal forebrain, hypothalamus, thalamus, mesencephalon, and brainstem in both ipsilateral and contralateral brain. CRS significantly reduced the distribution density of red fluorescence positive neurons in other cortices, hippocampus, septum/basal forebrain, hypothalamus, and thalamus. Conversely, CRS significantly increased the distribution density of red fluorescence positive neurons in amygdala.
CONCLUSION
Our results suggest a possible mechanism that CRS leads to disturbances in synaptic plasticity by affecting multiple inputs to the mPFC, which is characterized by a decrease in the distribution density of dendrites/dendritic spines in the IL of mPFC and a reduction in input neurons of multiple cortices to the IL of mPFC as well as an increase in input neurons of amygdala to the IL of mPFC, ultimately causing depression-like behaviors.
PubMed: 38777132
DOI: 10.1016/j.brainresbull.2024.110981 -
Scientific Reports May 2024The ventral visual stream is organized into units, or functional regions of interest (fROIs), specialized for processing high-level visual categories. Task-based fMRI...
The ventral visual stream is organized into units, or functional regions of interest (fROIs), specialized for processing high-level visual categories. Task-based fMRI scans ("localizers") are typically used to identify each individual's nuanced set of fROIs. The unique landscape of an individual's functional activation may rely in large part on their specialized connectivity patterns; recent studies corroborate this by showing that connectivity can predict individual differences in neural responses. We focus on the ventral visual stream and ask: how well can an individual's resting state functional connectivity localize their fROIs for face, body, scene, and object perception? And are the neural processors for any particular visual category better predicted by connectivity than others, suggesting a tighter mechanistic relationship between connectivity and function? We found, among 18 fROIs predicted from connectivity for each subject, all but one were selective for their preferred visual category. Defining an individual's fROIs based on their connectivity patterns yielded regions that were more selective than regions identified from previous studies or atlases in nearly all cases. Overall, we found that in the absence of a domain-specific localizer task, a 10-min resting state scan can be reliably used for defining these fROIs.
Topics: Humans; Magnetic Resonance Imaging; Male; Female; Brain Mapping; Adult; Visual Cortex; Visual Perception; Young Adult; Photic Stimulation; Visual Pathways
PubMed: 38762549
DOI: 10.1038/s41598-024-62098-9 -
BMC Ophthalmology May 2024The inconsistency in terminology for Cortical Visual Impairment or Cerebral Visual Impairment presents challenges: (1) different levels of changes in visual pathway and...
The inconsistency in terminology for Cortical Visual Impairment or Cerebral Visual Impairment presents challenges: (1) different levels of changes in visual pathway and other cerebral areas do not allow discrimination; (2) different visual and oculomotor aspects are not adequately considered. We open a debate to consider a more appropriate diagnosis.
Topics: Humans; Terminology as Topic; Vision Disorders; Visual Cortex; Visual Pathways
PubMed: 38755573
DOI: 10.1186/s12886-024-03469-8 -
Proceedings of the National Academy of... May 2024The mammalian brain implements sophisticated sensory processing algorithms along multilayered ("deep") neural networks. Strategies that insects use to meet similar...
The mammalian brain implements sophisticated sensory processing algorithms along multilayered ("deep") neural networks. Strategies that insects use to meet similar computational demands, while relying on smaller nervous systems with shallow architectures, remain elusive. Using as a model, we uncover the algorithmic role of odor preprocessing by a shallow network of compartmentalized olfactory receptor neurons. Each compartment operates as a ratiometric unit for specific odor-mixtures. This computation arises from a simple mechanism: electrical coupling between two differently sized neurons. We demonstrate that downstream synaptic connectivity is shaped to optimally leverage amplification of a hedonic value signal in the periphery. Furthermore, peripheral preprocessing is shown to markedly improve novel odor classification in a higher brain center. Together, our work highlights a far-reaching functional role of the sensory periphery for downstream processing. By elucidating the implementation of powerful computations by a shallow network, we provide insights into general principles of efficient sensory processing algorithms.
Topics: Animals; Odorants; Olfactory Receptor Neurons; Smell; Drosophila melanogaster; Algorithms; Drosophila; Olfactory Pathways; Models, Neurological; Nerve Net
PubMed: 38753511
DOI: 10.1073/pnas.2316799121 -
Nature Communications May 2024Visual information is important for accurate spatial coding and memory-guided navigation. As a crucial area for spatial cognition, the medial entorhinal cortex (MEC)...
Visual information is important for accurate spatial coding and memory-guided navigation. As a crucial area for spatial cognition, the medial entorhinal cortex (MEC) harbors diverse spatially tuned cells and functions as the major gateway relaying sensory inputs to the hippocampus containing place cells. However, how visual information enters the MEC has not been fully understood. Here, we identify a pathway originating in the secondary visual cortex (V2) and directly targeting MEC layer 5a (L5a). L5a neurons served as a network hub for visual processing in the MEC by routing visual inputs from multiple V2 areas to other local neurons and hippocampal CA1. Interrupting this pathway severely impaired visual stimulus-evoked neural activity in the MEC and performance of mice in navigation tasks. These observations reveal a visual cortical-entorhinal pathway highlighting the role of MEC L5a in sensory information transmission, a function typically attributed to MEC superficial layers before.
Topics: Animals; Entorhinal Cortex; Visual Cortex; Spatial Navigation; Mice; Neurons; Male; Mice, Inbred C57BL; Photic Stimulation; CA1 Region, Hippocampal; Visual Pathways; Visual Perception
PubMed: 38750027
DOI: 10.1038/s41467-024-48483-y -
Science Advances May 2024The world is undergoing massive atmospheric and ecological change, driving unprecedented challenges to human well-being. Olfaction is a key sensory system through which... (Review)
Review
The world is undergoing massive atmospheric and ecological change, driving unprecedented challenges to human well-being. Olfaction is a key sensory system through which these impacts occur. The sense of smell influences quality of and satisfaction with life, emotion, emotion regulation, cognitive function, social interactions, dietary choices, stress, and depressive symptoms. Exposures via the olfactory pathway can also lead to (anti-)inflammatory outcomes. Increased understanding is needed regarding the ways in which odorants generated by nature (i.e., natural olfactory environments) affect human well-being. With perspectives from a range of health, social, and natural sciences, we provide an overview of this unique sensory system, four consensus statements regarding olfaction and the environment, and a conceptual framework that integrates the olfactory pathway into an understanding of the effects of natural environments on human well-being. We then discuss how this framework can contribute to better accounting of the impacts of policy and land-use decision-making on natural olfactory environments and, in turn, on planetary health.
Topics: Humans; Smell; Olfactory Pathways; Odorants; Nature; Environment
PubMed: 38748806
DOI: 10.1126/sciadv.adn3028