Research Abstract:
Visual information is encoded in multiple cortical areas that are connected to hierarchically organized processing streams, specialized for object recognition and spatial relationships. How areas develop and form specific processing networks is incompletely understood. One reason for this is the lack of experimental models, accessible to manipulations by molecular genetics. To close this gap we are studying the mouse visual cortex. We are interested whether, similar to primates, mouse visual cortex contains multiple areas that are linked to functionally distinct streams and how circuits between lower and higher cortical areas are synaptically connected.
To investigate these questions we are employing a combination of anatomical and physiological techniques. For delineating area maps we are studying regional distributions of molecular markers and use topographic mapping of anatomical connections and physiological recording of receptive fields. Multi-color axonal tracing methods are employed to study the anatomical organization of cortical streams and areal hierarchies. Single unit recordings are used to determine whether the streams process different visual information. To study the neuronal composition of feedforward and feedback circuits between lower and higher cortical areas we are using neuronal tracers and cell-type specific markers for excitatory and inhibitory neurons and analyses in the electron microscope. For determining the mechanisms of synaptic transmission in interareal circuits we are using whole cell recording of GFP labeled inhibitory and excitatory neurons in brain slices. The goal of these experiments is to determine how during development the strengths of excitatory and inhibitory synaptic connections are adjusted so that mature circuits generate circuit-specific balances of excitation and inhibition. This information is important for understanding how the visual inputs are amplified by top-down influences which may play a role in the selection of inputs and attentional modulation.
Selected Publications:
Burkhalter A. Many specialists for suppressing cortical excitation. Front Neurosci 2008 2:155-167.
Gonchar Y, Wang Q, Burkhalter A. Multiple distinct subtypes of GABAergic neurons in mouse visual cortex identified by triple immunostaining. Front Neurosci 2008 1: 1-11.
Nerbonne JM, Gerber BR, Norris A, Burkhalter. Electrical remodelling maintains firing properties in cortical pyramidal neurons lacking KCND2-encoded A-types K+ currents. J Physiol 2008 586.6:1565-1579.
Wang Q, Burkhalter A. Area map of mouse visual cortex. J Comp Neurol 2007 502:339-357.
Wang Q, Gao E, Burkhalter A. In vibvo trasncranial imaging of connections i ouse visual cortex. J Neurosci Meth 2007 159:268-276.
Last Updated: 09/10/2009 |