Current Projects

The short-term goals of our current projects are to (1) resolve aspects of neural coding of binocular signals across cortical layers, (2) determine the underpinnings of functional magnetic resonance imaging (fMRI) using rodent and non-rodent animal model systems, and (3) build microcircuits for neurovascular coupling. Access to deeper cortical layers (especially in non-rodent mammals), has been made possible with our adoption of three-photon microscopy, e.g., see movie below and our Lab Technology section.

In essence, we study the spatial precision of neural and vascular circuits in the brain. We assay synaptic and spiking activity (see movie above) along with the responses of individual blood vessels (see movie below) to sensory stimuli. In addition to resolving aspects of neural coding and the ways in which neurons talk to blood vessels (neuro-vascular coupling), our advanced optical imaging methods helps us to understand fMRI signals. The brain has a mechanism for locally increasing blood flow to regions with increased neural activity and fMRI tracks increases in blood flow. But fMRI cannot tell us exactly how many neurons are firing at any given time, and which neurons are triggering the changes in blood flow. This is where optical imaging (two-photon and three-photon microscopy) can provide insights.

Most fundamentally, we examine which brain circuit elements retain general-purpose features vs. those that are super-specialized. These need not be different classes of cells (excitatory vs. inhibitory) but could be occurring within single neurons, e.g., at apical vs. basal dendrites or even the arterioles that supply blood to these domains. At a coarse anatomical scale, the neocortex seems very similar across different mammalian species. Yet functionally, there are some remarkable differences in the micro-architecture and the degree of selectivity for certain stimulus attributes. Thus, we have a comparative approach, performing similar tests across a few different mammalian species. Finally, brain circuits are not just neurons but include other critical signaling compartments—glia and blood vessels. Therefore, we include these non-neuronal components in our lab research to obtain a comprehensive view of how the neocortex encodes sensory signals.

Our lab is located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. Members in the Kara lab interact with (a) Thomas Naselaris on computational models and (b) the ultra-high field fMRI group (Wei Chen, Kamil Ugurbil) to perform fMRI imaging on the same subjects used for multi-photon imaging.