Inferotemporal face patches are histo-architectonically distinct.

An interconnected group of cortical regions distributed across the primate inferotemporal cortex forms a network critical for face perception. Understanding the microarchitecture of this face network can refine mechanistic accounts of how individual areas function and interact to support visual perception. To address this, we acquire a unique dataset in macaque monkeys combining fMRI to localize face patches in vivo and then ex vivo histology to resolve their histo-architecture across cortical depths in the same individuals.

Weak evidence for neural correlates of task-switching in macaque V1.

A central goal of systems neuroscience is to understand how populations of sensory neurons encode and relay information to the rest of the brain. Three key quantities of interest are ) how mean neural activity depends on the stimulus (sensitivity), ) how neural activity (co)varies around the mean (noise correlations), and ) how predictive these variations are of the subject's behavior (choice probability). Previous empirical work suggests that both choice probability and noise correlations are affected by task training, with decision-related information fed back to sensory areas and aligned to neural sensitivity on a task-by-task basis.

Anatomical correlates of face patches in macaque inferotemporal cortex.

Primate brains typically have regions within the ventral visual stream that are selectively responsive to faces. In macaques, these face patches are located in similar parts of inferotemporal cortex across individuals although correspondence with particular anatomical features has not been reported previously. Here, using high-resolution functional and anatomical imaging, we show that small "bumps," or buried gyri, along the lower bank of the superior temporal sulcus are predictive of the location of face-selective regions.

Gene Transfer with AAV9-PHP.B Rescues Hearing in a Mouse Model of Usher Syndrome 3A and Transduces Hair Cells in a Non-human Primate.

Hereditary hearing loss often results from mutation of genes expressed by cochlear hair cells. Gene addition using AAV vectors has shown some efficacy in mouse models, but clinical application requires two additional advances. First, new AAV capsids must mediate efficient transgene expression in both inner and outer hair cells of the cochlea.

Evolution of Osteocrin as an activity-regulated factor in the primate brain.

Sensory stimuli drive the maturation and function of the mammalian nervous system in part through the activation of gene expression networks that regulate synapse development and plasticity. These networks have primarily been studied in mice, and it is not known whether there are species- or clade-specific activity-regulated genes that control features of brain development and function. Here we use transcriptional profiling of human fetal brain cultures to identify an activity-dependent secreted factor, Osteocrin (OSTN), that is induced by membrane depolarization of human but not mouse neurons.

A direct GABAergic output from the basal ganglia to frontal cortex.

The basal ganglia are phylogenetically conserved subcortical nuclei necessary for coordinated motor action and reward learning. Current models postulate that the basal ganglia modulate cerebral cortex indirectly via an inhibitory output to thalamus, bidirectionally controlled by direct- and indirect-pathway striatal projection neurons (dSPNs and iSPNs, respectively). The basal ganglia thalamic output sculpts cortical activity by interacting with signals from sensory and motor systems.

Vesicular stomatitis virus enables gene transfer and transsynaptic tracing in a wide range of organisms.

Current limitations in technology have prevented an extensive analysis of the connections among neurons, particularly within nonmammalian organisms. We developed a transsynaptic viral tracer originally for use in mice, and then tested its utility in a broader range of organisms. By engineering the vesicular stomatitis virus (VSV) to encode a fluorophore and either the rabies virus glycoprotein (RABV-G) or its own glycoprotein (VSV-G), we created viruses that can transsynaptically label neuronal circuits in either the retrograde or anterograde direction, respectively.

Segregation of feedforward and feedback projections in mouse visual cortex.

Hierarchical organization is a common feature of mammalian neocortex. Neurons that send their axons from lower to higher areas of the hierarchy are referred to as "feedforward" (FF) neurons, whereas those projecting in the opposite direction are called "feedback" (FB) neurons. Anatomical, functional, and theoretical studies suggest that these different classes of projections play fundamentally different roles in perception.

Broadly tuned response properties of diverse inhibitory neuron subtypes in mouse visual cortex.

Different subtypes of GABAergic neurons in sensory cortex exhibit diverse morphology, histochemical markers, and patterns of connectivity. These subtypes likely play distinct roles in cortical function, but their in vivo response properties remain unclear. We used in vivo calcium imaging, combined with immunohistochemical and genetic labels, to record visual responses in excitatory neurons and up to three distinct subtypes of GABAergic neurons (immunoreactive for parvalbumin, somatostatin, or vasoactive intestinal peptide) in layer 2/3 of mouse visual cortex.

Comparison of fiber tracts derived from in-vivo DTI tractography with 3D histological neural tract tracer reconstruction on a macaque brain.

Since the introduction of diffusion weighted imaging (DWI) as a method for examining neural connectivity, its accuracy has not been formally evaluated. In this study, we directly compared connections that were visualized using injected neural tract tracers (WGA-HRP) with those obtained using in-vivo diffusion tensor imaging (DTI) tractography. First, we injected the tracer at multiple sites in the brain of a macaque monkey; second, we reconstructed the histological sections of the labeled fiber tracts in 3D; third, we segmented and registered the fibers (somatosensory and motor tracts) with the anatomical in-vivo MRI from the same animal; and last, we conducted fiber tracing along the same pathways on the DTI data using a classical diffusion tracing technique with the injection sites as seeds.

3D histological reconstruction of fiber tracts and direct comparison with diffusion tensor MRI tractography.

A classical neural tract tracer, WGA-HRP, was injected at multiple sites within the brain of a macaque monkey. Histological sections of the labeled fiber tracts were reconstructed in 3D, and the fibers were segmented and registered with the anatomical post-mortem MRI from the same animal. Fiber tracing along the same pathways was performed on the DTI data using a classical diffusion tracing technique.