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Functional imaging of visual cortical layers and subplate in awake mice with optimized three-photon microscopy
摘要： Two-photon microscopy is used to image neuronal activity, but has severe limitations for studying deeper cortical layers. Here, we developed a custom three-photon microscope optimized to image a vertical column of the cerebral cortex > 1 mm in depth in awake mice with low (<20 mW) average laser power. Our measurements of physiological responses and tissue-damage thresholds define pulse parameters and safety limits for damage-free three-photon imaging. We image functional visual responses of neurons expressing GCaMP6s across all layers of the primary visual cortex (V1) and in the subplate. These recordings reveal diverse visual selectivity in deep layers: layer 5 neurons are more broadly tuned to visual stimuli, whereas mean orientation selectivity of layer 6 neurons is slightly sharper, compared to neurons in other layers. Subplate neurons, located in the white matter below cortical layer 6 and characterized here for the first time, show low visual responsivity and broad orientation selectivity.
关键词： subplate neurons,deep brain imaging,visual cortex,neuronal activity,three-photon microscopy,GCaMP6s
更新于2025-09-23 15:23:52
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The Human Connectome Project 7 Tesla retinotopy dataset: Description and population receptive field analysis
摘要： About a quarter of human cerebral cortex is dedicated mainly to visual processing. The large-scale spatial organization of visual cortex can be measured with functional magnetic resonance imaging (fMRI) while subjects view spatially modulated visual stimuli, also known as 'retinotopic mapping.' One of the datasets collected by the Human Connectome Project involved ultrahigh-field (7 Tesla) fMRI retinotopic mapping in 181 healthy young adults (1.6-mm resolution), yielding the largest freely available collection of retinotopy data. Here, we describe the experimental paradigm and the results of model-based analysis of the fMRI data. These results provide estimates of population receptive field position and size. Our analyses include both results from individual subjects as well as results obtained by averaging fMRI time series across subjects at each cortical and subcortical location and then fitting models. Both the group-average and individual-subject results reveal robust signals across much of the brain, including occipital, temporal, parietal, and frontal cortex as well as subcortical areas. The group-average results agree well with previously published parcellations of visual areas. In addition, split-half analyses show strong within-subject reliability, further demonstrating the high quality of the data. We make publicly available the analysis results for individual subjects and the group average, as well as associated stimuli and analysis code. These resources provide an opportunity for studying fine-scale individual variability in cortical and subcortical organization and the properties of high-resolution fMRI. In addition, they provide a set of observations that can be compared with other Human Connectome Project measures acquired in these same participants.
关键词： retinotopy,population receptive fields,topography,visual cortex,fMRI,parcellation
更新于2025-09-23 15:22:29
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In Vivo Two-photon Calcium Imaging in Dendrites of Rabies Virus-labeled V1 Corticothalamic Neurons
摘要： Monitoring neuronal activity in vivo is critical to understanding the physiological or pathological functions of the brain. Two-photon Ca2? imaging in vivo using a cranial window and speci?c neuronal labeling enables real-time, in situ, and long-term imaging of the living brain. Here, we constructed a recombinant rabies virus containing the Ca2? indicator GCaMP6s along with the ?uorescent protein DsRed2 as a baseline reference to ensure GCaMP6s signal reliability. This functional tracer was applied to retrogradely label speci?c V1–thalamus circuits and detect spontaneous Ca2? activity in the dendrites of V1 corticothalamic neurons by in vivo two-photon Ca2? imaging. Notably, we were able to record single-spine spontaneous Ca2? activity in speci?c circuits. Distinct spontaneous Ca2? dynamics in dendrites of V1 corticothalamic neurons were found for different V1–thalamus circuits. Our method can be applied to monitor Ca2? dynamics in speci?c input circuits in vivo, and contribute to functional studies of de?ned neural circuits and the dissection of functional circuit connections.
关键词： Corticothalamic projection,In vivo Ca2? imaging,Two-photon microscopy,Primary visual cortex,Neural circuit tracing,Cranial window,Rabies virus,Dendrite
更新于2025-09-11 14:15:04
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A flexible 202-channel epidural ECoG array with PEDOT: PSS coated electrodes for chronic recording of the visual cortex
摘要： Electrocorticography (ECoG) electrode arrays for epidural implantation allow establishing neural interfaces, which promote investigation of complex distributed brain functions and development of neuroprosthetic systems, while having reduced invasiveness in comparison to intracortical or subdural electrode placement. In this work, we present the design, fabrication, and both in-vitro and in-vivo evaluation of a flexible ECoG array with 202 closely spaced electrodes of 560 μm diameter, each coated with the polymer poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) for chronic recording in two visual cortical areas V1 and V4 of macaque monkeys. The specific layout of the array provides a close fit to the curved surface of the brain. We confirm its chronic recording functionality in-vivo by estimating visual receptive fields for the individual electrodes.
关键词： electrical stimulation,BMI,visual cortex,ECoG,PEDOT: PSS,epidural implantation,chronic recording
更新于2025-09-09 09:28:46