Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglio...Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglion cells and their axons,leading to axonal transport dysfuntion,subsequently causing secondary damage to anterior or posterior ends of the visual system.Accordingly,recent evidence indicates that glaucoma is a degenerative disease of the central nervous system that causes damage throughout the visual pathway.However,the effects of glaucoma on synaptic plasticity in the primary visual cortex remain unclear.In this study,we established a mouse model of unilateral chronic ocular hypertension by injecting magnetic microbeads into the anterior chamber of one eye.We found that,after 4 weeks of chronic ocular hypertension,the neuronal somas were smaller in the superior colliculus and lateral geniculate body regions of the brain contralateral to the affected eye.This was accompanied by glial cell activation and increased expression of inflammatory factors.After 8 weeks of ocular hypertension,we observed a reduction in the number of excitatory and inhibitory synapses,dendritic spines,and activation of glial cells in the primary visual cortex contralateral to the affected eye.These findings suggest that glaucoma not only directly damages the retina but also induces alterations in synapses and dendritic spines in the primary visual cortex,providing new insights into the pathogenesis of glaucoma.展开更多
AIM:To investigate the postnatal development of parvalbumin(PV)-positive gamma-aminobutyric acid(GABA)interneurons and the co-expression of perineuronal nets(PNNs)and PV in the visual cortex of rats,as well as the reg...AIM:To investigate the postnatal development of parvalbumin(PV)-positive gamma-aminobutyric acid(GABA)interneurons and the co-expression of perineuronal nets(PNNs)and PV in the visual cortex of rats,as well as the regulatory effects of fluoxetine(FLX)treatment and binocular form deprivation(BFD)on these indices.METHODS:Wistar rats were assigned to three experimental cohorts:1)Age-related groups:postnatal week(PW)1,PW3,PW5,PW7,and PW9;2)FLX treatment duration groups:FLX 0W,FLX 2W,FLX 4W,FLX 6W,and FLX 8W;3)Intervention groups:control(Cont),FLX,BFD,and BFD+FLX.The levels of PNNs,PV,and PNNs/PV coexpression in the visual cortex were detected and analyzed.RESULTS:The density of PV-positive cells and the coexpression of PNNs and PV increased gradually with the maturation of the visual cortex(b=0.960,P<0.01).The ratio of PV-positive cells surrounded by PNNs to total PV-positive cells(PNNs+/PV+/total PV+)was significantly decreased in the FLX 4W group(χ^(2)=9.03,P=0.003).There was no significant difference in the PNNs+/PV+/total PV+ratio between the FLX and BFD groups(χ^(2)=1.08,P=0.161),but a significant difference was observed between the BFD+FLX group and the BFD group(χ^(2)=5.82,P<0.01).CONCLUSION:The number of PV-positive neurons and PNNs-surrounded PV neurons in the rat visual cortex increases postnatally and reaches adult levels by postnatal week 7.Chronic FLX treatment downregulates these expressions.Combined 4-week FLX treatment and BFD exerts a more significant inhibitory effect on the PNNs+/PV+/total PV+ratio than either intervention alone.展开更多
Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the pr...Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the primary visual cortex(V1)is altered in glaucoma.This study used DBA/2J mice as a model for spontaneous secondary glaucoma.The aim of the study was to compare the electrophysiological and histomorphological chara cteristics of neurons in the V1between 9-month-old DBA/2J mice and age-matched C57BL/6J mice.We conducted single-unit recordings in the V1 of light-anesthetized mice to measure the visually induced responses,including single-unit spiking and gamma band oscillations.The morphology of layerⅡ/Ⅲneurons was determined by neuronal nuclear antigen staining and Nissl staining of brain tissue sections.Eighty-seven neurons from eight DBA/2J mice and eighty-one neurons from eight C57BL/6J mice were examined.Compared with the C57BL/6J group,V1 neurons in the DBA/2J group exhibited weaker visual tuning and impaired spatial summation.Moreove r,fewer neuro ns were observed in the V1 of DBA/2J mice compared with C57BL/6J mice.These findings suggest that DBA/2J mice have fewer neurons in the VI compared with C57BL/6J mice,and that these neurons have impaired visual tuning.Our findings provide a better understanding of the pathological changes that occur in V1 neuron function and morphology in the DBA/2J mouse model.This study might offer some innovative perspectives regarding the treatment of glaucoma.展开更多
When presented with visual stimuli of face images,the ventral stream visual cortex of the human brain exhibits face-specific activity that is modulated by the physical properties of the input images.However,it is stil...When presented with visual stimuli of face images,the ventral stream visual cortex of the human brain exhibits face-specific activity that is modulated by the physical properties of the input images.However,it is still unclear whether this activity relates to conscious face perception.We explored this issue by using the human intracranial electroencephalography technique.Our results showed that face-specific activity in the ventral stream visual cortex was significantly higher when the subjects subjectively saw faces than when they did not,even when face stimuli were presented in both conditions.In addition,the face-specific neural activity exhibited a more reliable neural response and increased posterior-anterior direction information transfer in the“seen”condition than the“unseen”condition.Furthermore,the face-specific neural activity was significantly correlated with performance.These findings support the view that face-specific activity in the ventral stream visual cortex is linked to conscious face perception.展开更多
Recent studies show that a reduced effect of inhibitory transmitter system in the visual cortex may underlie aged visual function degradation. Whether excitatory transmitter system changes with age and hence affects i...Recent studies show that a reduced effect of inhibitory transmitter system in the visual cortex may underlie aged visual function degradation. Whether excitatory transmitter system changes with age and hence affects intracortical excitation-inhibition balance is not clear. To explore this issue, we used Nissl staining and immunohistochemical methods as well as Image-Pro Express software to examine the density of Nissl-stained neurons, Glutamie acid-immunoreactive （Glu-IR） neurons and T-Aminobutyric acid-immunoreactive （GABA-IR） neurons in the primary visual cortex of young adult and aged cats. The results showed that there was no significant difference in the density of Nissl-stained neurons between young and old cats （2〉0.05）. However, the density of Glu-IR neurons and GABA-IR neurons in the primary visual cortex of aged cats was significantly lower than that of young ones （P〈0.01）. The ratio between Glu-IR neurons and GABA-IR neurons was significantly increased in old cats compared to that in young adult ones （P〈0.01）. These results indicated that the effect of excitatory transmitter system in the old visual cortex was increased relative to the inhibitory transmitter system, which might cause an imbalance between cortical excitation and inhibition and might be an important factor mediating the visual function decline during aging.展开更多
Visual functions undergo an age-related degradation. However, the neural mechanisms underlying these changes are not yet clear. This study was designed to investigate the influence of age and sex on the anatomy of the...Visual functions undergo an age-related degradation. However, the neural mechanisms underlying these changes are not yet clear. This study was designed to investigate the influence of age and sex on the anatomy of the rat＇s visual cortex. Dendritic tree extent and spine density were examined in young adult rats （2-3 months） and aged male and female rats （22-24 months） using a modified Golgi-Cox staining method. A sex difference in dendritic branching of the pyramidal cells was found among young adults. However, this difference disappeared during aging, due to a reduction in branching with age for males but not for females. Moreover, the pyramidal cells of young males also have a greater spine density. Although there was a reduction in spine density with age for both sexes, this reduction was more pronounced for males, resulting in a disappearance of sex difference with age. Thus these results suggest that aging could lead to the degeneration of dendrites, which might contribute to the degradation of age-related visual functions. Also the results indicate that age-related degeneration of dendrites is more severe for males than for females.展开更多
Major depressive disorder(MDD)is a highly heterogeneous mental disorder,and its complex etiology and unclear mechanism are great obstacles to the diagnosis and treatment of the disease.Studies have shown that abnormal...Major depressive disorder(MDD)is a highly heterogeneous mental disorder,and its complex etiology and unclear mechanism are great obstacles to the diagnosis and treatment of the disease.Studies have shown that abnormal functions of the visual cortex have been reported in MDD patients,and the actions of several antidepressants coincide with improvements in the structure and synaptic functions of the visual cortex.In this review,we critically evaluate current evidence showing the involvement of the malfunctioning visual cortex in the pathophysiology and therapeutic process of depression.In addition,we discuss the molecular mechanisms of visual cortex dysfunction that may underlie the pathogenesis of MDD.Although the precise roles of visual cortex abnormalities in MDD remain uncertain,this undervalued brain region may become a novel area for the treatment of depressed patients.展开更多
Diffusion-weighted magnetic resonance imaging（d MRI） is widely used to study white and gray matter（GM） micro-organization and structural connectivity in the brain. Super-resolution track-density imaging（TDI） is ...Diffusion-weighted magnetic resonance imaging（d MRI） is widely used to study white and gray matter（GM） micro-organization and structural connectivity in the brain. Super-resolution track-density imaging（TDI） is an image reconstruction method for d MRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains. In this study, we used short track TDI（st TDI）, a variation of TDI with enhanced contrast for GM structures, to reconstruct directionencoded color maps of fixed tree shrew brain. The results were compared with those obtained with the traditional diffusion tensor imaging（DTI） method. We demonstrated that fine microstructures in the tree shrew brain, such as Baillarger bands in the primary visual cortex and the longitudinal component of the mossy fibers within the hippocampal CA3 subfield, were observable with st TDI,but not with DTI reconstructions from the same d MRI data.The possible mechanisms underlying the enhanced GM contrast are discussed.展开更多
AIM： To evaluate the differences in the functional connectivity（FC） of the primary visual cortex（V1） between the youth comitant exotropia（CE） patients and health subjects using resting functional magnetic reson...AIM： To evaluate the differences in the functional connectivity（FC） of the primary visual cortex（V1） between the youth comitant exotropia（CE） patients and health subjects using resting functional magnetic resonance imaging（f MRI） data.METHODS： Totally, 32 CEs（25 males and 7 females） and 32 healthy control subjects（HCs）（25 males and 7 females） were enrolled in the study and underwent the MRI scanning. Two-sample t-test was used to examine differences in FC maps between the CE patients and HCs. RESULTS： The CE patients showed significantly less FC between the left brodmann area（BA17） and left lingual gyrus/cerebellum posterior lobe, right middle occipital gyrus, left precentral gyrus/postcentral gyrus and right inferior parietal lobule/postcentral gyrus. Meanwhile, CE patients showed significantly less FC between right BA17 and right middle occipital gyrus（BA19, 37）.CONCLUSION： Our findings show that CE involves abnormal FC in primary visual cortex in many regions, which may underlie the pathologic mechanism of impaired fusion and stereoscopic vision in CEs.展开更多
Studies have shown that spatial attention remarkably affects the trial-to-trial response variability shared between neurons.Difficulty in the attentional task adjusts how much concentration we maintain on what is curr...Studies have shown that spatial attention remarkably affects the trial-to-trial response variability shared between neurons.Difficulty in the attentional task adjusts how much concentration we maintain on what is currently important and what is filtered as irrelevant sensory information.However,how task difficulty mediates the interactions between neurons with separated receptive fields(RFs)that are attended to or attended away is still not clear.We examined spike count correlations between single-unit activities recorded simultaneously in the primary visual cortex(V1)while monkeys performed a spatial attention task with two levels of difficulty.Moreover,the RFs of the two neurons recorded were non-overlapping to allow us to study fluctuations in the correlated responses between competing visual inputs when the focus of attention was allocated to the RF of one neuron.While increasing difficulty in the spatial attention task,spike count correlations were either decreased to become negative between neuronal pairs,implying competition among them,with one neuron(or none)exhibiting attentional enhancement of firing rate,or increased to become positive,suggesting inter-neuronal cooperation,with one of the pair showing attentional suppression of spiking responses.Besides,the modulation of spike count correlations by task difficulty was independent of the attended locations.These findings provide evidence that task difficulty affects the functional interactions between different neuronal pools in V1 when selective attention resolves the spatial competition.展开更多
Nogo-A and Nogo receptor （NgR） expression in the visual cortex following a critical developmental period （postnatal days 20-60） has been previously shown. However, little is known regarding Nogo-A and NgR expressi...Nogo-A and Nogo receptor （NgR） expression in the visual cortex following a critical developmental period （postnatal days 20-60） has been previously shown. However, little is known regarding Nogo-A and NgR expression between postnatal day 0 and initiation of the critical period. The present study analyzed Nogo-A and NgR expression at four different time points： postnatal day 0 （P0）, before critical period （P14）, during critical period （P28）, and after critical period （P60）. Results showed significantly increased Nogo-A mRNA and protein expression levels in the visual cortex following birth, and expression levels remained steady between P28 and P60. NgR mRNA or protein expression was dramatically upregulated with age and peaked at P14 or P28, respectively, and maintained high expression to P60. In addition, Nogo-A and NgR expression was analyzed in each visual cortex layer in normal developing rats and rats with monocular deprivation. Monocular deprivation decreased Nogo-A and NgR mRNA and protein expression in the rat visual cortex, in particular in layers Ⅱ-Ⅲ and Ⅳ in the visual cortex contralateral to the deprived eye. These findings suggested that Nogo-A and NgR regulated termination of the critical period in experience- dependent visual cortical plasticity.展开更多
Nitric oxide is an important neuromodulator in the brain and is involved in the development of visual system. But it is not clear how nitric oxide and nitric oxide synthase （NOS） are involved in the developing visua...Nitric oxide is an important neuromodulator in the brain and is involved in the development of visual system. But it is not clear how nitric oxide and nitric oxide synthase （NOS） are involved in the developing visual cortex of rodents. Thus we examined the expression of NOS activity in the postnatal developing visual cortex of the golden hamster by using histochemical technique for NADPH-diaphorase （NADPH-d）. A heavily stained NADPH-d band was observed in the neuropil of the visual cortex. This NADPH-d band initially appeared in the cortical plate from the day of birth （P0） to postnatal day 4 （P4）. From P7 to P21, this band was confined to area 17 and migrated to the deeper layers Ill IV and V VI before it eventually disappeared at P28. Such developmental trends of the band correlated well with the process of formation and establishment of the geniculo-cortical projection patterns. Thus, the areal specific development of the band suggests that NOS is closely related to the cortical differentiation and synaptic formation of the primary visual cortex. On the other hand, monocular eye enucleation on P1 could not alter the appearance of this NADPH-d positive band, indicating a non-activity dependant role of NOS. In addition, differences in the laminar distributions and developmental sequence between the heavily and lightly stained NADPH-d positive neurons during development suggest that they play different roles in the development.展开更多
Several recent studies using either viral or transgenic mouse models have shown different results on whether the activation of parvalbumin-positive（PV~＋）neurons expressing channelrhodopsin-2（ChR2） in the primary ...Several recent studies using either viral or transgenic mouse models have shown different results on whether the activation of parvalbumin-positive（PV~＋）neurons expressing channelrhodopsin-2（ChR2） in the primary visual cortex（V1） improves the orientation-and direction-selectivity of V1 neurons. Although this discrepancy was thoroughly discussed in a follow-up communication, the issue of using different models to express ChR2 in V1 was not mentioned. We found that ChR2 was expressed in retinal ganglion cells（RGCs） and V1 neurons in ChR2fl/~＋; PV-Cre mice. Our results showed that the activation of PV~＋RGCs using white drifting gratings alone significantly decreased the firing rates of V1 neurons and improved their direction-and orientation-selectivity. Longduration activation of PV~＋interneurons in V1 further enhanced the feature-selectivity of V1 neurons in anesthetized mice, confirming the conclusions from previous findings. These results suggest that the activation of both PV~＋RGCs and V1 neurons improves feature-selectivity in mice.展开更多
AIM: To explore changes and possible communication relationship of local potential signals recorded simultaneously from retina and visual cortex I(V1).·METHODS: Fourteen C57BL/6J mice were measured with pattern e...AIM: To explore changes and possible communication relationship of local potential signals recorded simultaneously from retina and visual cortex I(V1).·METHODS: Fourteen C57BL/6J mice were measured with pattern electroretinogram(PERG) and pattern visually evoked potential(PVEP) and fast Fourier transform has been used to analyze the frequency components of those signals.· RESULTS: The amplitude of PERG and PVEP was measured at about 36.7 μV and 112.5 μV respectively and the dominant frequency of PERG and PVEP, however,stay unchanged and both signals do not have second, or otherwise, harmonic generation.· CONCLUSION: The results suggested that retina encodes visual information in the way of frequency spectrum and then transfers it to primary visual cortex.The primary visual cortex accepts and deciphers the input visual information coded from retina. Frequency spectrum may act as communication code between retina and V1.展开更多
Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized...Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex（the implant area） is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine（LSVM） as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.展开更多
Fear memory contextualization is critical for selecting adaptive behavior to survive.Contextual fear conditioning(CFC)is a classical model for elucidating related underlying neuronal circuits.The primary visual cortex...Fear memory contextualization is critical for selecting adaptive behavior to survive.Contextual fear conditioning(CFC)is a classical model for elucidating related underlying neuronal circuits.The primary visual cortex(V1)is the primary cortical region for contextual visual inputs,but its role in CFC is poorly understood.Here,our experiments demonstrated that bilateral inactivation of V1 in mice impaired CFC retrieval,and both CFC learning and extinction increased the turnover rate of axonal boutons in V1.The frequency of neuronal Ca^(2+)activity decreased after CFC learning,while CFC extinction reversed the decrease and raised it to the naïve level.Contrary to control mice,the frequency of neuronal Ca^(2+)activity increased after CFC learning in microglia-depleted mice and was maintained after CFC extinction,indicating that microglial depletion alters CFC learning and the frequency response pattern of extinction-induced Ca^(2+)activity.These findings reveal a critical role of microglia in neocortical information processing in V1,and suggest potential approaches for cellular-based manipulation of acquired fear memory.展开更多
a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form ...a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eye- opening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.展开更多
The aim of this study was to examine the secondary visual cortex functional disorder in patients with glaucoma and large pituitary adenoma by functional magnetic resonance imaging, and to determine the correlation bet...The aim of this study was to examine the secondary visual cortex functional disorder in patients with glaucoma and large pituitary adenoma by functional magnetic resonance imaging, and to determine the correlation between visual field defect and primary visual cortex activation. Results showed that single eye stimulation resulted in bilateral visual cortex activation in patients with glaucoma or large pituitary adenoma. Compared with the normal control group, the extent and intensity of visual cortex activation was decreased after left and right eye stimulation, and functional magnetic resonance imaging revealed a correlation between visual field defects and visual cortex activation in patients with glaucoma and large pituitary adenoma. These functional magnetic resonance imaging data suggest that anterior optic pathway lesions can cause secondary functional disorder of the visual cortex, and that visual defects are correlated with visual cortex activation.展开更多
In the present study, a feline model of strabismic amblyopia was established during a sensitive developmental period, and the influence of levodopa methyl ester and levodopa on nerve growth factor expression in the vi...In the present study, a feline model of strabismic amblyopia was established during a sensitive developmental period, and the influence of levodopa methyl ester and levodopa on nerve growth factor expression in the visual cortex （area 17） was compared. Pattern visual-evoked potential and immunohistochemistry results showed that levodopa methyl ester and levodopa treatment shortened P10o wave latency, increased Pleo amplitude, and increased the number of endogenous nerve growth factor-positive cells in visual cortex levels. In particular, the effects of levodopa methyl ester were superior to levodopa treatment.展开更多
Totally three articles focusing on “the expression of Nogo-A, Nogo receptor and NADPH-diaphorase in the developing rat visual cortex and the effects of levodopa methyl ester on nerve growth factor expression in visua...Totally three articles focusing on “the expression of Nogo-A, Nogo receptor and NADPH-diaphorase in the developing rat visual cortex and the effects of levodopa methyl ester on nerve growth factor expression in visual cortex area 17 in strabismic amblyopia” are published in three issues. We hope that our readers find these papers useful to their research.展开更多
基金supported by the National Natural Science Foundation of China,No.82271115(to MY).
文摘Synaptic plasticity is essential for maintaining neuronal function in the central nervous system and serves as a critical indicator of the effects of neurodegenerative disease.Glaucoma directly impairs retinal ganglion cells and their axons,leading to axonal transport dysfuntion,subsequently causing secondary damage to anterior or posterior ends of the visual system.Accordingly,recent evidence indicates that glaucoma is a degenerative disease of the central nervous system that causes damage throughout the visual pathway.However,the effects of glaucoma on synaptic plasticity in the primary visual cortex remain unclear.In this study,we established a mouse model of unilateral chronic ocular hypertension by injecting magnetic microbeads into the anterior chamber of one eye.We found that,after 4 weeks of chronic ocular hypertension,the neuronal somas were smaller in the superior colliculus and lateral geniculate body regions of the brain contralateral to the affected eye.This was accompanied by glial cell activation and increased expression of inflammatory factors.After 8 weeks of ocular hypertension,we observed a reduction in the number of excitatory and inhibitory synapses,dendritic spines,and activation of glial cells in the primary visual cortex contralateral to the affected eye.These findings suggest that glaucoma not only directly damages the retina but also induces alterations in synapses and dendritic spines in the primary visual cortex,providing new insights into the pathogenesis of glaucoma.
基金Supported by the Suzhou Science and Technology Bureau(No.SKY2023175)the Project of State Key Laboratory of Radiation Medicine and Protection+6 种基金Soochow University(No.GZK1202309)the Advantage Subject Lifting Project(No.XKTJ-XK202412)the Suzhou Science and Education for Strengthening Healthcare(No.MSXM2024010)the Suzhou Medical Key Supported Disciplines(No.SZFCXK202118)the Youth Scientific Research Fund Project of Kunshan Hospital of Traditional Chinese Medicine(No.2024QNJJ06)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_1673)the Undergraduate Training Program for Innovation and Entrepreneurship,Soochow University(No.202310285162Y).
文摘AIM:To investigate the postnatal development of parvalbumin(PV)-positive gamma-aminobutyric acid(GABA)interneurons and the co-expression of perineuronal nets(PNNs)and PV in the visual cortex of rats,as well as the regulatory effects of fluoxetine(FLX)treatment and binocular form deprivation(BFD)on these indices.METHODS:Wistar rats were assigned to three experimental cohorts:1)Age-related groups:postnatal week(PW)1,PW3,PW5,PW7,and PW9;2)FLX treatment duration groups:FLX 0W,FLX 2W,FLX 4W,FLX 6W,and FLX 8W;3)Intervention groups:control(Cont),FLX,BFD,and BFD+FLX.The levels of PNNs,PV,and PNNs/PV coexpression in the visual cortex were detected and analyzed.RESULTS:The density of PV-positive cells and the coexpression of PNNs and PV increased gradually with the maturation of the visual cortex(b=0.960,P<0.01).The ratio of PV-positive cells surrounded by PNNs to total PV-positive cells(PNNs+/PV+/total PV+)was significantly decreased in the FLX 4W group(χ^(2)=9.03,P=0.003).There was no significant difference in the PNNs+/PV+/total PV+ratio between the FLX and BFD groups(χ^(2)=1.08,P=0.161),but a significant difference was observed between the BFD+FLX group and the BFD group(χ^(2)=5.82,P<0.01).CONCLUSION:The number of PV-positive neurons and PNNs-surrounded PV neurons in the rat visual cortex increases postnatally and reaches adult levels by postnatal week 7.Chronic FLX treatment downregulates these expressions.Combined 4-week FLX treatment and BFD exerts a more significant inhibitory effect on the PNNs+/PV+/total PV+ratio than either intervention alone.
基金supported by the STI 2030-Major Projects 2022ZD0208500(to DY)the National Natural Science Foundation of China,Nos.82072011(to YX),82121003(to DY),82271120(to YS)+2 种基金Sichuan Science and Technology Program,No.2022ZYD0066(to YS)a grant from Chinese Academy of Medical Science,No.2019-12M-5-032(to YS)the Fundamental Research Funds for the Central Universities,No.ZYGX2021YGLH219(to KC)。
文摘Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the primary visual cortex(V1)is altered in glaucoma.This study used DBA/2J mice as a model for spontaneous secondary glaucoma.The aim of the study was to compare the electrophysiological and histomorphological chara cteristics of neurons in the V1between 9-month-old DBA/2J mice and age-matched C57BL/6J mice.We conducted single-unit recordings in the V1 of light-anesthetized mice to measure the visually induced responses,including single-unit spiking and gamma band oscillations.The morphology of layerⅡ/Ⅲneurons was determined by neuronal nuclear antigen staining and Nissl staining of brain tissue sections.Eighty-seven neurons from eight DBA/2J mice and eighty-one neurons from eight C57BL/6J mice were examined.Compared with the C57BL/6J group,V1 neurons in the DBA/2J group exhibited weaker visual tuning and impaired spatial summation.Moreove r,fewer neuro ns were observed in the V1 of DBA/2J mice compared with C57BL/6J mice.These findings suggest that DBA/2J mice have fewer neurons in the VI compared with C57BL/6J mice,and that these neurons have impaired visual tuning.Our findings provide a better understanding of the pathological changes that occur in V1 neuron function and morphology in the DBA/2J mouse model.This study might offer some innovative perspectives regarding the treatment of glaucoma.
基金supported by the Science and Technology Innovation 2030-Brain Science and Brain-Inspired Intelligence Project (2021ZD0200200)the National Natural Science Foundation of China (62327805,82151307,and 32271085)the Beijing Natural Science Foundation (5244049).
文摘When presented with visual stimuli of face images,the ventral stream visual cortex of the human brain exhibits face-specific activity that is modulated by the physical properties of the input images.However,it is still unclear whether this activity relates to conscious face perception.We explored this issue by using the human intracranial electroencephalography technique.Our results showed that face-specific activity in the ventral stream visual cortex was significantly higher when the subjects subjectively saw faces than when they did not,even when face stimuli were presented in both conditions.In addition,the face-specific neural activity exhibited a more reliable neural response and increased posterior-anterior direction information transfer in the“seen”condition than the“unseen”condition.Furthermore,the face-specific neural activity was significantly correlated with performance.These findings support the view that face-specific activity in the ventral stream visual cortex is linked to conscious face perception.
基金Natural Science Fund of Anhui Province (070413138)Key Laboratory Foundation of Anhui Province for Researches on the Conservation and Utilization of Important Biological ResourceKey Laboratory Foundation for Universities and Colleges in Anhui
文摘Recent studies show that a reduced effect of inhibitory transmitter system in the visual cortex may underlie aged visual function degradation. Whether excitatory transmitter system changes with age and hence affects intracortical excitation-inhibition balance is not clear. To explore this issue, we used Nissl staining and immunohistochemical methods as well as Image-Pro Express software to examine the density of Nissl-stained neurons, Glutamie acid-immunoreactive （Glu-IR） neurons and T-Aminobutyric acid-immunoreactive （GABA-IR） neurons in the primary visual cortex of young adult and aged cats. The results showed that there was no significant difference in the density of Nissl-stained neurons between young and old cats （2〉0.05）. However, the density of Glu-IR neurons and GABA-IR neurons in the primary visual cortex of aged cats was significantly lower than that of young ones （P〈0.01）. The ratio between Glu-IR neurons and GABA-IR neurons was significantly increased in old cats compared to that in young adult ones （P〈0.01）. These results indicated that the effect of excitatory transmitter system in the old visual cortex was increased relative to the inhibitory transmitter system, which might cause an imbalance between cortical excitation and inhibition and might be an important factor mediating the visual function decline during aging.
基金This project was supported by grants fromthe National Natural Science Foundation of China(30520120072)National Basic Research Program(2006CB500804)Foundation of New Century Excellent Talents(NCET-04-0586).
文摘Visual functions undergo an age-related degradation. However, the neural mechanisms underlying these changes are not yet clear. This study was designed to investigate the influence of age and sex on the anatomy of the rat＇s visual cortex. Dendritic tree extent and spine density were examined in young adult rats （2-3 months） and aged male and female rats （22-24 months） using a modified Golgi-Cox staining method. A sex difference in dendritic branching of the pyramidal cells was found among young adults. However, this difference disappeared during aging, due to a reduction in branching with age for males but not for females. Moreover, the pyramidal cells of young males also have a greater spine density. Although there was a reduction in spine density with age for both sexes, this reduction was more pronounced for males, resulting in a disappearance of sex difference with age. Thus these results suggest that aging could lead to the degeneration of dendrites, which might contribute to the degradation of age-related visual functions. Also the results indicate that age-related degeneration of dendrites is more severe for males than for females.
基金This review was supported by grants from the National Natural Science Key Foundation of China(81830040 and 82130042)the China Science and Technology Innovation 2030-Major Project(2022ZD0211701 and 2021ZD0200700)+1 种基金the Science and Technology Program of Guangdong(2018B030334001)the Science and Technology Program of Shenzhen(GJHZ20210705141400002,KCXFZ20211020164543006,JCYJ20220818101615033,and 202206063000055).
文摘Major depressive disorder(MDD)is a highly heterogeneous mental disorder,and its complex etiology and unclear mechanism are great obstacles to the diagnosis and treatment of the disease.Studies have shown that abnormal functions of the visual cortex have been reported in MDD patients,and the actions of several antidepressants coincide with improvements in the structure and synaptic functions of the visual cortex.In this review,we critically evaluate current evidence showing the involvement of the malfunctioning visual cortex in the pathophysiology and therapeutic process of depression.In addition,we discuss the molecular mechanisms of visual cortex dysfunction that may underlie the pathogenesis of MDD.Although the precise roles of visual cortex abnormalities in MDD remain uncertain,this undervalued brain region may become a novel area for the treatment of depressed patients.
基金supported by grants from the National Basic Research Development Program of China (2011CB707800)the National Natural Science Foundation of China (21790390, 21790392, and 61371014)
文摘Diffusion-weighted magnetic resonance imaging（d MRI） is widely used to study white and gray matter（GM） micro-organization and structural connectivity in the brain. Super-resolution track-density imaging（TDI） is an image reconstruction method for d MRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains. In this study, we used short track TDI（st TDI）, a variation of TDI with enhanced contrast for GM structures, to reconstruct directionencoded color maps of fixed tree shrew brain. The results were compared with those obtained with the traditional diffusion tensor imaging（DTI） method. We demonstrated that fine microstructures in the tree shrew brain, such as Baillarger bands in the primary visual cortex and the longitudinal component of the mossy fibers within the hippocampal CA3 subfield, were observable with st TDI,but not with DTI reconstructions from the same d MRI data.The possible mechanisms underlying the enhanced GM contrast are discussed.
基金Supported by the National Natural Science Foundation of China(No.81660158No.81160118No.81400372)
文摘AIM： To evaluate the differences in the functional connectivity（FC） of the primary visual cortex（V1） between the youth comitant exotropia（CE） patients and health subjects using resting functional magnetic resonance imaging（f MRI） data.METHODS： Totally, 32 CEs（25 males and 7 females） and 32 healthy control subjects（HCs）（25 males and 7 females） were enrolled in the study and underwent the MRI scanning. Two-sample t-test was used to examine differences in FC maps between the CE patients and HCs. RESULTS： The CE patients showed significantly less FC between the left brodmann area（BA17） and left lingual gyrus/cerebellum posterior lobe, right middle occipital gyrus, left precentral gyrus/postcentral gyrus and right inferior parietal lobule/postcentral gyrus. Meanwhile, CE patients showed significantly less FC between right BA17 and right middle occipital gyrus（BA19, 37）.CONCLUSION： Our findings show that CE involves abnormal FC in primary visual cortex in many regions, which may underlie the pathologic mechanism of impaired fusion and stereoscopic vision in CEs.
基金This work was supported by the National Natural Science Foundation of China(61773259,31471081,61773256,62073221,and 61971280).
文摘Studies have shown that spatial attention remarkably affects the trial-to-trial response variability shared between neurons.Difficulty in the attentional task adjusts how much concentration we maintain on what is currently important and what is filtered as irrelevant sensory information.However,how task difficulty mediates the interactions between neurons with separated receptive fields(RFs)that are attended to or attended away is still not clear.We examined spike count correlations between single-unit activities recorded simultaneously in the primary visual cortex(V1)while monkeys performed a spatial attention task with two levels of difficulty.Moreover,the RFs of the two neurons recorded were non-overlapping to allow us to study fluctuations in the correlated responses between competing visual inputs when the focus of attention was allocated to the RF of one neuron.While increasing difficulty in the spatial attention task,spike count correlations were either decreased to become negative between neuronal pairs,implying competition among them,with one neuron(or none)exhibiting attentional enhancement of firing rate,or increased to become positive,suggesting inter-neuronal cooperation,with one of the pair showing attentional suppression of spiking responses.Besides,the modulation of spike count correlations by task difficulty was independent of the attended locations.These findings provide evidence that task difficulty affects the functional interactions between different neuronal pools in V1 when selective attention resolves the spatial competition.
基金supported by the Graduate Degree Thesis Innovation Foundation of Central South University, No.2009BSXT050
文摘Nogo-A and Nogo receptor （NgR） expression in the visual cortex following a critical developmental period （postnatal days 20-60） has been previously shown. However, little is known regarding Nogo-A and NgR expression between postnatal day 0 and initiation of the critical period. The present study analyzed Nogo-A and NgR expression at four different time points： postnatal day 0 （P0）, before critical period （P14）, during critical period （P28）, and after critical period （P60）. Results showed significantly increased Nogo-A mRNA and protein expression levels in the visual cortex following birth, and expression levels remained steady between P28 and P60. NgR mRNA or protein expression was dramatically upregulated with age and peaked at P14 or P28, respectively, and maintained high expression to P60. In addition, Nogo-A and NgR expression was analyzed in each visual cortex layer in normal developing rats and rats with monocular deprivation. Monocular deprivation decreased Nogo-A and NgR mRNA and protein expression in the rat visual cortex, in particular in layers Ⅱ-Ⅲ and Ⅳ in the visual cortex contralateral to the deprived eye. These findings suggested that Nogo-A and NgR regulated termination of the critical period in experience- dependent visual cortical plasticity.
基金the Fundamental Research Funds for the Central Universities,No.21609101the National Basic Research Program of China (973 Program),No.2011CB707501
文摘Nitric oxide is an important neuromodulator in the brain and is involved in the development of visual system. But it is not clear how nitric oxide and nitric oxide synthase （NOS） are involved in the developing visual cortex of rodents. Thus we examined the expression of NOS activity in the postnatal developing visual cortex of the golden hamster by using histochemical technique for NADPH-diaphorase （NADPH-d）. A heavily stained NADPH-d band was observed in the neuropil of the visual cortex. This NADPH-d band initially appeared in the cortical plate from the day of birth （P0） to postnatal day 4 （P4）. From P7 to P21, this band was confined to area 17 and migrated to the deeper layers Ill IV and V VI before it eventually disappeared at P28. Such developmental trends of the band correlated well with the process of formation and establishment of the geniculo-cortical projection patterns. Thus, the areal specific development of the band suggests that NOS is closely related to the cortical differentiation and synaptic formation of the primary visual cortex. On the other hand, monocular eye enucleation on P1 could not alter the appearance of this NADPH-d positive band, indicating a non-activity dependant role of NOS. In addition, differences in the laminar distributions and developmental sequence between the heavily and lightly stained NADPH-d positive neurons during development suggest that they play different roles in the development.
基金supported by the grants of National Natural Science Foundation of China(31271158,31421091,and 31422025)the Science and Technology Commission of Shanghai Municipality,China(13PJ1401000)the Young 1000 Plan and the Ministry of Science and Technology of China(2015AA020512)
文摘Several recent studies using either viral or transgenic mouse models have shown different results on whether the activation of parvalbumin-positive（PV~＋）neurons expressing channelrhodopsin-2（ChR2） in the primary visual cortex（V1） improves the orientation-and direction-selectivity of V1 neurons. Although this discrepancy was thoroughly discussed in a follow-up communication, the issue of using different models to express ChR2 in V1 was not mentioned. We found that ChR2 was expressed in retinal ganglion cells（RGCs） and V1 neurons in ChR2fl/~＋; PV-Cre mice. Our results showed that the activation of PV~＋RGCs using white drifting gratings alone significantly decreased the firing rates of V1 neurons and improved their direction-and orientation-selectivity. Longduration activation of PV~＋interneurons in V1 further enhanced the feature-selectivity of V1 neurons in anesthetized mice, confirming the conclusions from previous findings. These results suggest that the activation of both PV~＋RGCs and V1 neurons improves feature-selectivity in mice.
基金Supported by 973 Program of the Ministry of Science and Technology of China (No.2013CB967101)Shanghai Science Committee Foundation (No.13PJ1433200)
文摘AIM: To explore changes and possible communication relationship of local potential signals recorded simultaneously from retina and visual cortex I(V1).·METHODS: Fourteen C57BL/6J mice were measured with pattern electroretinogram(PERG) and pattern visually evoked potential(PVEP) and fast Fourier transform has been used to analyze the frequency components of those signals.· RESULTS: The amplitude of PERG and PVEP was measured at about 36.7 μV and 112.5 μV respectively and the dominant frequency of PERG and PVEP, however,stay unchanged and both signals do not have second, or otherwise, harmonic generation.· CONCLUSION: The results suggested that retina encodes visual information in the way of frequency spectrum and then transfers it to primary visual cortex.The primary visual cortex accepts and deciphers the input visual information coded from retina. Frequency spectrum may act as communication code between retina and V1.
基金supported by the National Natural Science Foundation of China,No.31070758,31271060the Natural Science Foundation of Chongqing in China,No.cstc2013jcyj A10085
文摘Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex（the implant area） is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine（LSVM） as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.
基金supported by the National Natural Science Foundation of China(61735016)the Natural Science Foundation of Zhejiang Province(LR20F050002)+3 种基金the Key R&D Program of Zhejiang Province(2020C03009 and 2021C03001)the Zhejiang Leading Innovation and Entrepreneurship Team(202099144)the CAMS Innovation Fund for Medical Sciences(2019-I2M-5-057)Fundamental Research Funds for the Central Universities.
文摘Fear memory contextualization is critical for selecting adaptive behavior to survive.Contextual fear conditioning(CFC)is a classical model for elucidating related underlying neuronal circuits.The primary visual cortex(V1)is the primary cortical region for contextual visual inputs,but its role in CFC is poorly understood.Here,our experiments demonstrated that bilateral inactivation of V1 in mice impaired CFC retrieval,and both CFC learning and extinction increased the turnover rate of axonal boutons in V1.The frequency of neuronal Ca^(2+)activity decreased after CFC learning,while CFC extinction reversed the decrease and raised it to the naïve level.Contrary to control mice,the frequency of neuronal Ca^(2+)activity increased after CFC learning in microglia-depleted mice and was maintained after CFC extinction,indicating that microglial depletion alters CFC learning and the frequency response pattern of extinction-induced Ca^(2+)activity.These findings reveal a critical role of microglia in neocortical information processing in V1,and suggest potential approaches for cellular-based manipulation of acquired fear memory.
基金the National Natural Science Foundation of China, No.30772350
文摘a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eye- opening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.
文摘The aim of this study was to examine the secondary visual cortex functional disorder in patients with glaucoma and large pituitary adenoma by functional magnetic resonance imaging, and to determine the correlation between visual field defect and primary visual cortex activation. Results showed that single eye stimulation resulted in bilateral visual cortex activation in patients with glaucoma or large pituitary adenoma. Compared with the normal control group, the extent and intensity of visual cortex activation was decreased after left and right eye stimulation, and functional magnetic resonance imaging revealed a correlation between visual field defects and visual cortex activation in patients with glaucoma and large pituitary adenoma. These functional magnetic resonance imaging data suggest that anterior optic pathway lesions can cause secondary functional disorder of the visual cortex, and that visual defects are correlated with visual cortex activation.
基金the National Natural Science Foundation of China, No. 30760285the Education Innovation Plan Program for Postgraduate in Guangxi Zhuang Autonomous Region, No. 2008105981007D27
文摘In the present study, a feline model of strabismic amblyopia was established during a sensitive developmental period, and the influence of levodopa methyl ester and levodopa on nerve growth factor expression in the visual cortex （area 17） was compared. Pattern visual-evoked potential and immunohistochemistry results showed that levodopa methyl ester and levodopa treatment shortened P10o wave latency, increased Pleo amplitude, and increased the number of endogenous nerve growth factor-positive cells in visual cortex levels. In particular, the effects of levodopa methyl ester were superior to levodopa treatment.
文摘Totally three articles focusing on “the expression of Nogo-A, Nogo receptor and NADPH-diaphorase in the developing rat visual cortex and the effects of levodopa methyl ester on nerve growth factor expression in visual cortex area 17 in strabismic amblyopia” are published in three issues. We hope that our readers find these papers useful to their research.
