A fundamental mystery of brain science is to understand how networks of
neurons assemble during development and function in circuits to enable
perception and behavior. Unraveling this mystery requires an
understanding of the relationships between the cellular-level
properties of circuits -- the anatomical "wiring diagram" of
connectivity on the one hand, and the functional properties of single
neurons and synapses on the other -- and the systems-level properties
such as sensory responses or motor outputs.
In the Neural Circuits Lab, we apply a new generation of optical and
optogenetic tools to observe both fine-scale circuit features and
systems-level responses at the same time, in the living brain. We
combine these optical approaches with advanced physiological and
anatomical techniques to address previously inaccessible questions
about neural circuitry and its development in mammalian visual cortex.
Our current research is focused on 2 themes:
1) The role of experience in the development and maturation of neural
As a postdoc in David Fitzpatrick's lab at Duke, my colleagues and I
identified a fertile model system for exploring the impact of
experience on the development of neural circuits using ferret visual
cortex, where motion selectivity develops in an experience-dependent
manner. At the time of eye opening, cortical neurons exhibit
orientation selectivity but they respond equally to stimulation in
either of two opposite directions of motion. In the weeks after eye
opening, most neurons develop a strong preference for motion in a
single direction. We are interested in understanding whether experience
merely permits the completion of developmental programs that are fully
seeded prior to visual experience, or rather if experience alters the
trajectory of circuit construction. In addition, we would like to
understand which circuit elements are modified by experience and the
learning rules that govern these changes.
2) Operating principles of cortical circuits
Owing to 50 years of intense research, the field of neuroscience
probably knows more about sensory response properties, functional
architecture, and anatomical connections in primary visual cortex than
in any other mammalian brain structure. While progress has been made
towards understanding some of the circuit mechanisms underlying these
receptive field properties, many fundamental circuit mechanisms have
remained out of experimental reach. Do large neural circuits operate
using feed forward or recurrent processing? How do cells maintain
selectivity as signal strength changes? Is there a common functional
plan for cortical circuits, or has evolution crafted unique circuits
for each species and cortical region (see Van Hooser, 2007).
"Firing rate homeostasis in visual cortex of freely behaving rodents" Hengen KB, Lambo ME, Van Hooser SD, Katz DB, Turrigiano GG. Firing rate homeostasis in visual cortex of freely behaving rodents. Neuron. 2013;80(2):335-42.
"Transformation of receptive field properties from lateral geniculate nucleus to superficial v1 in the tree shrew." Van Hooser SD, Roy A, Rhodes HJ, Culp JH, Fitzpatrick D. J Neurosci. 2013 Jul 10;33(28):11494-505.
"The laminar development of direction selectivity in ferret visual cortex." Clemens JM, Ritter NJ, Roy A, Miller JM, Van Hooser SD. J Neurosci. 2012 Dec 12;32(50):18177-85.
"Initial neighborhood biases and the quality of motion stimulation jointly influence the rapid emergence of direction preference in visual cortex." Van Hooser SD, Li Y, Christensson M, Smith GB, White LE, Fitzpatrick D.
J Neurosci. 2012 May 23;32(21):7258-66.
"Molecular compartmentalization of lateral geniculate nucleus in the gray squirrel (Sciurus carolinensis)." Felch DL, Van Hooser SD. Front Neuroanat. 2012 Apr 10;6:12. doi: 10.3389/fnana.2012.00012.The representation of S-cone signals in primary visual cortex. Johnson EN, Van Hooser SD, Fitzpatrick D. J Neurosci. 2010 Aug 4;30(31):10337-50.
Last review: August 14, 2013