Dr. Nielsen's laboratory investigates the neural circuits in the visual cortex that are responsible for encoding objects. In the primate brain, a series of visual areas are involved in object recognition, with different areas extracting different features from the objects in a visual scene. These areas are organized in a hierarchical manner: While lower level areas encode simpler object features such as the orientation of edges, higher level areas respond to more complex features such as parts of objects or even entire objects such as faces.
To a large extent, researchers know which features are represented where, but to understand how object features are encoded, they need to understand the organization of the neural circuits that comprise and connect these areas. Dr. Nielson's lab aims to reveal the fine-scale organization of these circuits, with an emphasis on higher-level visual areas. They use two-photon microscopy to perform high-resolution functional imaging of visual areas in the non-human primate. They also investigate how the function of higher visual areas changes over the course of brain development in ferrets, by measuring the activity of single neurons in these areas, as well as determining the animal’s visual capabilities at various developmental stages.
Lab Website: Kristina Nielsen Laboratory
Nauhaus I, Nielsen KJ, Disney AA, Callaway EM. "Orthogonal micro-organization of orientation and spatial frequency in primate primary visual cortex." Nat Neurosci. 2012 Dec;15(12):1683-90. doi: 10.1038/nn.3255. Epub 2012 Nov 11. Erratum in: Nat Neurosci. 2013 Dec;16(12):1907.
Nielsen KJ, Callaway EM, Krauzlis RJ. "Viral vector-based reversible neuronal inactivation and behavioral manipulation in the macaque monkey." Front Syst Neurosci. 2012 Jun 19;6:48. doi: 10.3389/fnsys.2012.00048. eCollection 2012.
Nauhaus I, Nielsen KJ, Callaway EM. "Nonlinearity of two-photon Ca2+ imaging yields distorted measurements of tuning for V1 neuronal populations." J Neurophysiol. 2012 Feb;107(3):923-36. doi: 10.1152/jn.00725.2011. Epub 2011 Nov 23.
Marshel JH, Mori T, Nielsen KJ, Callaway EM. "Targeting single neuronal networks for gene expression and cell labeling in vivo." Neuron. 2010 Aug 26;67(4):562-74. doi: 10.1016/j.neuron.2010.08.001.
Nielsen KJ, Logothetis NK, Rainer G. "Object features used by humans and monkeys to identify rotated shapes." J Vis. 2008 Feb 22;8(2):9.1-15. doi: 10.1167/8.2.9.