Scholars@Duke
David Fitzpatrick

David Fitzpatrick

James B. Duke Distinguished Professor Emeritus of Medicine
Neurobiology
fitzpat@neuro.duke.edu
Box 3209 Med Ctr, Durham, NC 27710
427C Bryan Res Bldg, Durham, NC 27710

Selected Publications

A morphological basis for orientation tuning in primary visual cortex.

Journal Article Nat Neurosci · August 2004 Featured Publication Feedforward connections are thought to be important in the generation of orientation-selective responses in visual cortex by establishing a bias in the sampling of information from regions of visual space that lie along a neuron's axis of preferred orienta ... Full text Link to item Cite

The contribution of vertical and horizontal connections to the receptive field center and surround in V1.

Journal Article Neural Netw · 2004 Here we review the results of anatomical and physiological studies in tree shrew visual cortex which focus on the contribution of vertical and horizontal inputs to receptive field center and surround properties of layer 2/3 neurons. A fundamental feature o ... Full text Link to item Cite

Mapping multiple features in the population response of visual cortex.

Journal Article Nature · June 26, 2003 Featured Publication Stimulus features such as edge orientation, motion direction and spatial frequency are thought to be encoded in the primary visual cortex by overlapping feature maps arranged so that the location of neurons activated by a particular combination of stimulus ... Full text Link to item Cite

Emergent properties of layer 2/3 neurons reflect the collinear arrangement of horizontal connections in tree shrew visual cortex.

Journal Article J Neurosci · April 1, 2003 Featured Publication The superficial layers of primary visual cortex, unlike layer 4, have an extensive network of long-range horizontal connections linking sites of similar orientation preference. To identify possible functional consequences of this distinct anatomy, we compa ... Full text Link to item Cite

Spatial coding of position and orientation in primary visual cortex.

Journal Article Nat Neurosci · September 2002 Featured Publication We examined the spatial distribution of population activity in primary visual cortex (V1) of tree shrews with optical imaging and electrophysiology. A line stimulus, thinner than the average V1 receptive field, evoked a broad strip of neural activity of ne ... Full text Link to item Cite

The contribution of sensory experience to the maturation of orientation selectivity in ferret visual cortex.

Journal Article Nature · June 28, 2001 Featured Publication Sensory experience begins when neural circuits in the cerebral cortex are still immature; however, the contribution of experience to cortical maturation remains unclear. In the visual cortex, the selectivity of neurons for oriented stimuli at the time of e ... Full text Link to item Cite

Consistent mapping of orientation preference across irregular functional domains in ferret visual cortex.

Journal Article Vis Neurosci · 2001 The mammalian visual cortex harbors a number of functional maps that represent distinct attributes of stimuli in the visual environment. How different functional maps are accommodated within the same cortical space, especially in species that show marked i ... Full text Link to item Cite

Development of a fluorescent ligand-binding assay using the AcroWell filter plate.

Journal Article J Biomol Screen · December 2000 One of the most powerful tools for receptor research and drug discovery is the use of receptor-ligand affinity screening of combinatorial libraries. Early work involved the use of radioactive ligands to identify a binding event; however, there are numerous ... Full text Link to item Cite

Seeing beyond the receptive field in primary visual cortex.

Journal Article Curr Opin Neurobiol · August 2000 Recent studies on the response properties of neurons in primary visual cortex emphasize the dynamics and the complexities of facilitatory and suppressive interactions between the receptive field center and surrounding areas of visual space. These observati ... Full text Link to item Cite

Functional specificity of callosal connections in tree shrew striate cortex.

Journal Article J Neurosci · March 15, 2000 Although callosal connections have been shown to link extensive regions of primary visual cortex, the distribution of these connections with respect to the map of visual space and the map of orientation preference remains unclear. Here we combine optical i ... Full text Link to item Cite

Cortical imaging: capturing the moment.

Journal Article Curr Biol · March 9, 2000 Recent advances in optical imaging techniques using voltage-sensitive dyes have provided new insights into the dynamic of neural processing in distributed cortical networks. ... Full text Link to item Cite

Maps of central visual space in ferret V1 and V2 lack matching inputs from the two eyes.

Journal Article J Neurosci · August 15, 1999 In the visual cortex, the representation of central visual space is supplied by matching geniculate inputs that are driven exclusively by one eye or the other. In layer 4 of early visual areas (V1 in primates and V1 and V2 in cat), these inputs form a near ... Full text Link to item Cite

Unequal representation of cardinal and oblique contours in ferret visual cortex.

Journal Article Proc Natl Acad Sci U S A · March 3, 1998 We have measured the amount of cortical space activated by differently oriented gratings in 25 adult ferrets by optical imaging of intrinsic signal. On average, 7% more area of the exposed visual cortex was preferentially activated by vertical and horizont ... Full text Link to item Cite

Orientation selectivity and the arrangement of horizontal connections in tree shrew striate cortex.

Journal Article J Neurosci · March 15, 1997 Featured Publication Horizontal connections, formed primarily by the axon collaterals of pyramidal neurons in layer 2/3 of visual cortex, extend for millimeters parallel to the cortical surface and form patchy terminations. Previous studies have provided evidence that the patc ... Full text Link to item Cite

A systematic map of direction preference in primary visual cortex.

Journal Article Nature · February 22, 1996 Featured Publication Neurons in the primary visual cortex respond selectively to the orientation of edges and their direction of motion. Orientation preference is mapped in a systematic fashion across the cortical surface, such that neurons in adjacent columns have similar but ... Full text Link to item Cite

Specificity in the axonal connections of layer VI neurons in tree shrew striate cortex: evidence for distinct granular and supragranular systems.

Journal Article J Neurosci · February 1, 1996 Pyramidal neurons in layer VI of striate cortex are the source of descending projections to the lateral geniculate nucleus (LGN) as well as a major source of axon terminals in the layers of striate cortex that receive LGN projections. This study examines h ... Full text Link to item Cite

The functional organization of local circuits in visual cortex: insights from the study of tree shrew striate cortex.

Journal Article Cereb Cortex · 1996 We have used a combination of anatomical and physiological techniques to explore the functional organization of vertical and horizontal connections in tree shrew striate cortex. Our studies of vertical connections reveal a remarkable specificity in the lam ... Full text Link to item Cite

Patterns of excitation and inhibition evoked by horizontal connections in visual cortex share a common relationship to orientation columns.

Journal Article Neuron · September 1995 Combined optical imaging and electrophysiological techniques were used to assess directly the functional nature of long-range excitatory and inhibitory synaptic interactions between orientation columns in area 17 of ferret visual cortex. A significant corr ... Full text Link to item Cite

The sublaminar organization of corticogeniculate neurons in layer 6 of macaque striate cortex.

Journal Article Vis Neurosci · 1994 We examined the laminar distribution of corticogeniculate neurons in the macaque striate cortex labeled by axonal transport following injections of retrograde tracers into the lateral geniculate nucleus (LGN). Large injections of retrograde tracers involvi ... Full text Link to item Cite

Calcium binding proteins distinguish large and small cells of the ventral posterior and lateral geniculate nuclei of the prosimian galago and the tree shrew (Tupaia belangeri).

Journal Article Proc Natl Acad Sci U S A · February 15, 1993 Two different cell types were identified in the thalamus of galago and Tupaia by using antibodies to two calcium binding proteins, calbindin and parvalbumin. In each species studied, the lateral geniculate nucleus consists of six layers, two of which have ... Full text Link to item Cite

Lateral geniculate projections to the superficial layers of visual cortex in the tree shrew.

Journal Article J Comp Neurol · May 1, 1992 Our recent studies of tree shrew striate cortex have focused on the organization of lateral geniculate projections to layer IV and the projections from IV to layer III. Although these pathways play an important role in determining the response properties o ... Full text Link to item Cite

The morphological basis for binocular and ON/OFF convergence in tree shrew striate cortex.

Journal Article J Neurosci · April 1992 We used retrograde and anterograde transport methods and single-cell reconstructions to examine the projection from layer IV to supragranular layers in the tree shrew's striate cortex. We found that neurons in the ON and OFF subdivisions of layer IV (IVa a ... Full text Link to item Cite

A projection from the parabigeminal nucleus to the pulvinar nucleus in Galago.

Journal Article J Comp Neurol · February 15, 1992 A projection from the parabigeminal nucleus (Pbg) to the striate-recipient zone of the pulvinar nucleus in the prosimian Galago was identified by anterograde and retrograde transport methods. In addition to the pulvinar nucleus, Pbg projections were found ... Full text Link to item Cite

Evidence for separate pathways within the tecto-geniculate projection in the tree shrew.

Journal Article Proc Natl Acad Sci U S A · February 15, 1991 Two layers (3 and 6) in the dorsal lateral geniculate nucleus (GLd) of the tree shrew (Tupaia belangeri) receive projections from the superficial layers of the superior colliculus. The goal of this study was to determine whether the same or different cells ... Full text Link to item Cite

Distribution and morphology of area 17 neurons that project to the cat's extrastriate cortex.

Journal Article J Comp Neurol · January 1, 1991 We used intracellular dye injections in lightly fixed cortical slices to examine the distribution and morphology of area 17 neurons that project to extrastriate cortex. Both the projection to the medial bank of the posterior lateral suprasylvian sulcus (PM ... Full text Link to item Cite

Terminal arbors of individual, physiologically identified geniculocortical axons in the tree shrew's striate cortex.

Journal Article J Comp Neurol · December 15, 1990 We studied the terminal patterns of single, physiologically identified geniculocortical axons in the striate cortex of the tree shrew by using intracellular recording and labeling methods. Axons were classified by their response to the onset (ON-center) or ... Full text Link to item Cite

Innervation patterns of single physiologically identified geniculocortical axons in the striate cortex of the tree shrew.

Journal Article Proc Natl Acad Sci U S A · January 1990 We examined the termination patterns of single geniculocortical axons in the striate cortex of the tree shrew by using intracellular recording and horseradish peroxidase staining methods. Axons were classified by whether they responded to light onset (ON c ... Full text Link to item Cite

Organization of cholinergic synapses in the cat's dorsal lateral geniculate and perigeniculate nuclei.

Journal Article J Comp Neurol · October 22, 1989 In the preceding article, we showed that cholinergic fibers originating from the brainstem reticular formation provide a dense innervation of the lateral geniculate nucleus. In this report we describe the ultrastructure of these fibers and their relations ... Full text Link to item Cite

Cholinergic and monoaminergic innervation of the cat's thalamus: comparison of the lateral geniculate nucleus with other principal sensory nuclei.

Journal Article J Comp Neurol · October 22, 1989 The cholinergic and monoaminergic innervation of the lateral geniculate nucleus (GL) and other thalamic nuclei in the cat was examined by using immunocytochemical and tract-tracing techniques. Cholinergic fibers, identified with an antibody to choline acet ... Full text Link to item Cite

Cholinergic innervation of the superior colliculus in the cat.

Journal Article J Comp Neurol · September 22, 1989 The superficial and intermediate gray layers of the superior colliculus are heavily innervated by fibers that utilize the neurotransmitter acetylcholine. The distribution, ultrastructure, and sources of the cholinergic innervation of these layers have been ... Full text Link to item Cite

Morphology of retinogeniculate axons in the macaque.

Journal Article Vis Neurosci · 1989 The size, pattern of terminal arborizations, and laminar specificity of individual retinogeniculate axons were studied in the macaque following injections of HRP into the optic tract. Axons that terminated in the magnocellular layers had significantly larg ... Full text Link to item Cite

Cholinergic projections from the midbrain reticular formation and the parabigeminal nucleus to the lateral geniculate nucleus in the tree shrew.

Journal Article J Comp Neurol · June 1, 1988 The distribution and sources of putative cholinergic fibers within the lateral geniculate nucleus (GL) of the tree shrew have been examined by using the immunocytochemical localization of choline acetyltransferase (ChAT). ChAT-immunoreactive fibers are fou ... Full text Link to item Cite

Distribution of GABAergic neurons and axon terminals in the macaque striate cortex.

Journal Article J Comp Neurol · October 1, 1987 Antisera to glutamic acid decarboxylase (GAD) and gamma-aminobutyric acid (GABA) have been used to characterize the morphology and distribution of presumed GABAergic neurons and axon terminals within the macaque striate cortex. Despite some differences in ... Full text Link to item Cite

Laminar asymmetry in the distribution of choline acetyltransferase-immunoreactive neurons in the retina of the tree shrew (Tupaia belangeri).

Journal Article Brain Res · December 10, 1986 Cholinergic neurons in the retina of the tree shrew were identified immunocytochemically using a monoclonal antibody directed against choline acetyltransferase (ChAT). The chief result is that roughly 4 times as many ChAT-immunoreactive neurons are found i ... Full text Link to item Cite

Laminar organization of geniculocortical projections in Galago senegalensis and Aotus trivirgatus.

Journal Article J Comp Neurol · December 22, 1985 The projections of the lateral geniculate nucleus to striate cortex were traced by anterograde and retrograde transport of WGA-HRP in two primates, Galago and Aotus. The goal was to determine the laminar organization of the terminals of individual layers o ... Full text Link to item Cite

Intrinsic connections of macaque striate cortex: axonal projections of cells outside lamina 4C.

Journal Article J Neurosci · December 1985 We have exploited a technique for making small injections of horseradish peroxidase into single cortical laminae in order to study axonal projections in macaque striate cortex. In the preceding paper (Fitzpatrick, D., J. S. Lund, and G. G. Blasdel (1985) J ... Full text Link to item Cite

Intrinsic connections of macaque striate cortex: afferent and efferent connections of lamina 4C.

Journal Article J Neurosci · December 1985 We have studied the intrinsic organization of macaque striate cortex by tracing the pattern of horseradish peroxidase (HRP)-labeled axons and cell bodies produced by microinjections of HRP into single cortical laminae. Both anterograde and retrograde trans ... Full text Link to item Cite

Glutamic acid decarboxylase-immunoreactive neurons and terminals in the lateral geniculate nucleus of the cat.

Journal Article J Neurosci · July 1984 We have examined the distribution of neurons and terminals that are immunoreactive for glutamic acid decarboxylase (GAD), the synthesizing enzyme for the inhibitory neurotransmitter gamma-aminobutyric acid within the lateral geniculate nucleus of the cat. ... Full text Link to item Cite

GABAergic neurons of mammalian cerebral cortex: widespread subclass defined by somatostatin content.

Journal Article Neurosci Lett · June 29, 1984 GABAergic neurons are found in all layers of cerebral cortex and display many types of non-pyramidal morphology. Most are intensely immunoreactive for neuron-specific enolase, suggesting a high rate of metabolic activity. The molecular layer and subcortica ... Full text Link to item Cite

Physiological organization of layer 4 in macaque striate cortex.

Journal Article J Neurosci · March 1984 Numerous highly angled electrode penetrations through the opercular region of macaque striate cortex reveal that layers 4A, 4C alpha, and 4C beta--the primary input sublaminae for axons from the lateral geniculate nucleus (LGN)--are retinotopically organiz ... Full text Link to item Cite

The laminar organization of the lateral geniculate body and the striate cortex in the tree shrew (Tupaia glis).

Journal Article J Neurosci · January 1984 The organization of geniculostriate projections in Tupaia was studied using three separate methods, anterograde transport from the lateral geniculate, retrograde transport from the striate cortex, and reconstruction of single geniculostriate axons. The res ... Full text Link to item Cite

Glutamic acid decarboxylase-containing neurons in the dorsal column nuclei of the cat.

Journal Article Somatosens Res · 1984 The retrograde transport of horseradish peroxidase (HRP) and immunocytochemistry for glutamic acid decarboxylase (GAD) have been employed to examine whether local circuit neurons (LCNs) exist in the dorsal column nuclei (DCN) and whether these neurons may ... Full text Link to item Cite

Glutamic acid decarboxylase-immunoreactive neurons and horseradish peroxidase-labeled projection neurons in the ventral posterior nucleus of the cat and Galago senegalensis.

Journal Article J Neurosci · September 1983 Immunocytochemical methods were used to identify neurons in the ventral posterior nucleus of the cat and Galago senegalensis that contain glutamic acid decarboxylase (GAD), the synthetic enzyme for the inhibitory neurotransmitter, GABA. In both species GAD ... Full text Link to item Cite

Improved visualization of neurons labeled with horseradish peroxidase: silver-intensification of the pyrocatechol/p-phenylenediamine reaction product.

Journal Article J Neurosci Methods · June 1983 A silver intensification procedure suitable for use with pyrocatechol/p-phenylenediamine (PC-PPD) product of the horseradish peroxidase (HRP) reaction is described. Qualitative and quantitative results from retrogradely labeled neurons in the cat cortex af ... Full text Link to item Cite

The laminar organization of the lateral geniculate body and the striate cortex in the squirrel monkey (Saimiri sciureus).

Journal Article J Neurosci · April 1983 The organization of the projection from the lateral geniculate body to the striate cortex in the squirrel monkey has been re-examined using the anterograde and retrograde transport of horseradish peroxidase (HRP) and wheat germ agglutinin conjugated to HRP ... Full text Link to item Cite

Distribution of acetylcholinesterase in the geniculo striate system of Galago senegalensis and Aotus trivirgatus: evidence for the origin of the reaction product in the lateral geniculate body.

Journal Article J Comp Neurol · December 15, 1980 This inquiry began with the discovery that just two layers of the lateral geniculate nucleus (GL) of Galago contain large amounts of acetylcholinesterase (AChE). These two layers (layers 3 and 6) are similar in cell size and Nissl-staining characteristics ... Full text Link to item Cite

Layer I of striate cortex of Tupaia glis and Galago senegalensis: projections from thalamus and claustrum revealed by retrograde transport of horseradish peroxidase.

Journal Article J Comp Neurol · August 1, 1979 We have examined the origin of the subcortical projections to the superficial layers of the striate cortex in Tupaia glis and Galago senegalensis by using the retrograde transport of HRP. Crystals of HRP were laid directly on the moist pial surface of the ... Full text Link to item Cite

Thalamic projections to layer I of striate cortex shown by retrograde transport of horseradish peroxidase.

Journal Article Science · February 9, 1979 The diffusion of horseradish peroxidase was restricted to layers I and II of the striate cortex in Tupaia glis and Galago senegalensis. In the lateral geniculate body of Tupaia labeled cells were found only in layer 3; some labeled cells were also found in ... Full text Link to item Cite