Macaque V1 responses to 2nd-order contrast-modulated stimuli and the possible subcortical and cortical contributions.

Natural images comprise contours and boundaries defined by 1st-order luminance-modulated (LM) cues that are readily encoded by V1 neurons, and 2nd-order contrast-modulated (CM) cues that carry local, but not over-the-space, luminance changes. The neurophysiological foundations for CM processing remain unsolved. Here we used two-photon calcium imaging to demonstrate that V1 superficial-layer neurons respond to both LM and CM gratings in awake, fixating, macaques, with overall LM responses stronger than CM responses.

Connectomic comparison of mouse and human cortex.

The human cerebral cortex houses 1000 times more neurons than that of the cerebral cortex of a mouse, but the possible differences in synaptic circuits between these species are still poorly understood. We used three-dimensional electron microscopy of mouse, macaque, and human cortical samples to study their cell type composition and synaptic circuit architecture. The 2.

Perceptual hue, lightness, and chroma are represented in a multidimensional functional anatomical map in macaque V1.

Humans perceive millions of colors along three dimensions of color space: hue, lightness, and chroma. A major gap in knowledge is where the brain represents these specific dimensions in cortex, and how they relate to each other. Previous studies have shown that brain areas V4 and the posterior inferotemporal cortex (PIT) are central to computing color dimensions.

Functional organization of spatial frequency tuning in macaque V1 revealed with two-photon calcium imaging.

V1 neurons are functionally organized in orientation columns in primates. Whether spatial frequency (SF) columns also exist is less clear because mixed results have been reported. A definitive solution would be SF functional maps at single-neuron resolution.

Orientation Tuning and End-stopping in Macaque V1 Studied with Two-photon Calcium Imaging.

Orientation tuning is a fundamental response property of V1 neurons and has been extensively studied with single-/multiunit recording and intrinsic signal optical imaging. Long-term 2-photon calcium imaging allows simultaneous recording of hundreds of neurons at single neuron resolution over an extended time in awake macaques, which may help elucidate V1 orientation tuning properties in greater detail. We used this new technology to study the microstructures of orientation functional maps, as well as population tuning properties, in V1 superficial layers of 5 awake macaques.

Spatiotemporal functional organization of excitatory synaptic inputs onto macaque V1 neurons.

The integration of synaptic inputs onto dendrites provides the basis for neuronal computation. Whereas recent studies have begun to outline the spatial organization of synaptic inputs on individual neurons, the underlying principles related to the specific neural functions are not well understood. Here we perform two-photon dendritic imaging with a genetically-encoded glutamate sensor in awake monkeys, and map the excitatory synaptic inputs on dendrites of individual V1 superficial layer neurons with high spatial and temporal resolution.

Advanced Circuit and Cellular Imaging Methods in Nonhuman Primates.

Novel genetically encoded tools and advanced microscopy methods have revolutionized neural circuit analyses in insects and rodents over the last two decades. Whereas numerous technical hurdles originally barred these methodologies from success in nonhuman primates (NHPs), current research has started to overcome those barriers. In some cases, methodological advances developed with NHPs have even surpassed their precursors.

Long-term all-optical interrogation of cortical neurons in awake-behaving nonhuman primates.

Whereas optogenetic techniques have proven successful in their ability to manipulate neuronal populations-with high spatial and temporal fidelity-in species ranging from insects to rodents, significant obstacles remain in their application to nonhuman primates (NHPs). Robust optogenetics-activated behavior and long-term monitoring of target neurons have been challenging in NHPs. Here, we present a method for all-optical interrogation (AOI), integrating optical stimulation and simultaneous two-photon (2P) imaging of neuronal populations in the primary visual cortex (V1) of awake rhesus macaques.

A model-based analysis of physiological properties of the striatal medium spiny neuron.

As the principal cell of the striatum, medium spiny neurons (MSNs) are closely associated with various motor dysfunctional diseases. In this paper, we describe an electric compartment model constructed in NEURON with a realistic morphology. Based on a 554-compartment computational model, we researched the influence of external current stimuli, different ions conductance, and the removal of partial dendrites on the physiological properties of the MSN.