The Bickford lab studies synaptic circuits involved in transmitting visual signals and initiating appropriate motor responses to visual stimuli. We are particularly interested in pathways that involve the pulvinar nucleus (a large region of the human dorsal thalamus), or its rodent homologue, the lateral posterior nucleus (LPN). Since virtually all neocortical sensory signals originate from cells in the dorsal thalamus, it is viewed as the major site for regulating attention to specific sensory stimuli, a function accomplished through the selective damping or amplification of thalamocortical signals. The pulvinar and LPN are of particular interest in the study of attention mechanisms because they appear to be involved both in mechanisms that enhance salient visual signals, and those that direct movements to attend to such stimuli.

We use complementary anatomical and physiological approaches to examine the synaptic organization, development, and plasticity of visual pathways. The goal of these studies is to elucidate the normal mechanisms underlying visual signal transmission, as a first step toward understanding visual deficits associated with disorders of attention. Techniques used in our lab include anatomical tract tracing using traditional tracers and viral vectors, electron microscopy, immunocytochemistry, optogenetics, and whole cell recording from neurons in an in vitro slice preparation.

Current Projects

Identification of cortical circuits targeted by the LPN. In vitro whole cell recording from identified cell populations and optogenetic activation of terminals that originate from the LPN are being used to determine which cortical cell types are directly innervated by the LPN and to characterize the electrophysiological properties of these synapses (supported by the National Eye Institute).

Identification of superior colliculus circuits targeted by striate versus lateral extrastriate cortex. In vitro whole cell recording from identified cell populations and optogenetic activation of terminals that originate from the striate or extrastriate cortex are being used to determine which superior colliculus cell types are directly innervated and to characterize the electrophysiological properties of these synapses (supported by the National Eye Institute).

Pretectogeniculate circuits. We are using in vitro whole cell recording from identified cell populations in the dorsal lateral geniculate nucleus (dLGN) and optogenetic activation of GABAergic projections to determine how the pretectum modifies dLGN activity patterns.

Tectothalamic circuits. We are using dual viral tracing techniques as well as in vitro whole cell recording from identified cell populations in the LPN to determine how superior colliculus inputs affect LPN cells that project to the striatum, amygdala and/or extrastriate cortex.

Key Publications

Bickford ME, Zhou N, Krahe TE, Govindaiah G, Guido W (2015) Retinal and tectal "driver-like" inputs converge in the shell of the mouse dorsal lateral geniculate nucleus. J. Neuroscience 35(29):10523-10534.

Vanni MP, Thomas S, Petry HM, Bickford ME, Casanova C (2015) Spatiotemporal profile of voltage-sensitive dye responses in the visual cortex of tree shrews evoked by electrical microstimulation of the dorsal lateral geniculate and pulvinar nuclei. J. Neuroscience 35(34): 11891-11896.

Wei H, Bonjean M, Petry HM, Sejnowski TJ, Bickford ME (2011) Thalamic burst firing propensity: a comparison of the dorsal lateral geniculate and pulvinar nuclei in the tree shrew (Tupaia belangeri) J Neuroscience 31(47):17287-17299. PMC3236686

Chomsung RD, Wei H, Day-Brown JD, Petry HM, Bickford ME (2010) Synaptic organization of connections between the temporal cortex and pulvinar nucleus of the tree shrew. Cerebral Cortex 20(4):997-1011. PMC2837095

Masterson SP, Li J, Bickford ME (2010) Frequency-dependent release of substance P mediates heterosynaptic potentiation of glutamatergic synaptic responses in the rat visual thalamus. J. Neurophysiology 104(3):1758-67. PMC2944677

Day-Brown JD, Wei H, Chomsung RD, Petry HM, Bickford ME (2010) Pulvinar projections to the striatum and amygdala. Frontiers in Neuroanatomy Special Issue: Basal Ganglia Circuits 4 (143):1-11. PMC2991220

Bickford ME, Slusarczyk A, Dilger EK, Krahe TE, Kucuk C, Guido W (2010) Synaptic development of the mouse dorsal lateral geniculate nucleus. J. Comparative Neurology 518(5):622-635.