Kristina Nielsen PhD

Assistant Professor of Neuroscience
Telephone Number: 410-516-5833
Fax Number: 410-516-8648

The Zanvyl Krieger Mind/Brain Institute
The Johns Hopkins University
3400 N. Charles Street
338 Krieger Hall
Baltimore, MD 21218
Room: Krieger Hall 352
Areas of Research
Systems, Cognitive + Computational Neuroscience
Neural Circuits, Ensembles + Connectomes

Graduate Program Affiliations

Neuroscience Training Program

Neural Circuits Underlying Object Recognition

Object recognition is central to our interaction with the world. It is how we recognize our car in the parking lot or a familiar face in a coffee shop.  This process seems effortless to us, but is, in truth, a difficult computational problem that the visual system of our brains is confronted with.  Not only is our environment filled with a vast number of objects, but the appearance of those objects may change when viewed from different angles or in different contexts.  Despite this complexity, the visual system is able to solve the problem of object recognition.  To understand how the visual system performs this remarkable feat, my laboratory investigates the neural circuits in 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, we know which features are represented where, but to understand howobject features are encoded we need to understand the organization of the neural circuits that comprise and connect these areas.  Our lab aims to reveal the fine scale organization of these circuits, with an emphasis on higher level visual areas.  Towards this aim, we use two-photon microscopy to perform high resolution functional imaging of visual areas in the non-human primate.  We 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.  In both types of investigations, we also rely on detailed anatomical techniques to precisely observe how the function of neuronal circuits is related to their structure.

Questions addressed in our experiments include: (1) How are the feature representations in a visual area organized on a fine scale basis? Do neighboring neurons prefer similar object features, for example?  (2) What information is sent from one brain area to another? Do neurons that are located within the same area, but that send their axons to different brain areas, respond differently to object features? (3) At which time point is an animal able to detect certain stimuli, and how is the behavioral development mirrored in terms of brain development?

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