Fig 1.
Flowchart showing the processing steps for 3-D reconstruction of histological images. See text for details.
Fig 2.
3-D reconstructed injections combined in atlas template.
Analysis of the spatial location of tracer injection sites in the four cases investigated. (A) Coronal, sagittal, and horizontal slices through the injection site centers at the level of cortical layer V, facilitating comparison of the spatial location and extent of the four tracer injections. Dashed lines indicate slice locations in corresponding images. (B) Cartoon representations of the primary somatosensory cortex (redrawn and modified from [34] with permission) showing the estimated locations of the tracer injection sites. (C) Horizontal slice through the 3-D reconstructed atlas (at level of layer V) showing the relative location and extent of the co-registered delineations of the four injection sites. (D) Estimated stereotaxic positions of injection sites projected onto a composite map of M1 and S1 based on several earlier electrophysiological studies (redrawn and modified from [59] with permission). This map indicates that the stereotaxic location of the tracer injection in case R601 to a larger degree involves the forelimb representation in M1, rather than S1. C, cingulate cortex; FBP, furry buccal pad; FL, forelimb; HL, hindlimb; LJ, lower jaw; M, motor cortex; N, nose; P, parietal cortex; PO, perioral; R, retrosplenical cortex; S, somatosensory cortex; TR, trunk; UZ, unresponsive zone; V, visual cortex; W, whisker; Scale bar, 1 mm.
Fig 3.
3-D shape and distribution of corticostriatal projections.
Visualization of axonal labeling in three-plane slices centered on clusters with highest labeling density in the striatum of the four cases investigated. Insets (left) indicate the location of tracer injections in S1 (presentation as in Fig 2). Dashed lines indicate slice locations in corresponding images. ac, anterior commissure; cc, corpus callosum; ec, external capsule; ic, internal capsule; Cpu, caudate-putamen complex (striatum). Scale bar, 0.5 mm.
Fig 4.
3-D shape and distribution of corticothalamic projections.
Visualization of axonal labeling in three-plane slices centered on clusters with highest labeling density in the thalamus of the four cases investigated (A-L). Insets (left) indicate the location of tracer injections in the primary somatosensory cortex (presentation as in Fig 2). Dashed lines indicate slice locations in corresponding images. ic, internal capsule. (M) Oblique horizontal slice through a volumetric rat brain atlas [57] indicating the orientation of an arbitrary slice through an image volume (N), showing an almost continuous ring of axonal labeling in the thalamus (case R602). Scale bars, 0.5 mm.
Fig 5.
3-D surface models of corticostriatal and corticothalamic projections.
3-D visualization of topographical organization in corticostriatal and corticothalamic pathways. (A-D) Stereo-image pairs showing color coded 3-D surface models of the delineated axonal clusters in the striatum (A,B) and thalamus (C,D), in slightly offset views from anterior (A), medial (B,D), and posterior (C), as indicated in the inset figures (right column). To perceive the 3-D images the viewer must cross the eye axis to let the image pairs merge. (A,B) Clusters representing corticostriatal axons are distributed within a narrow, laminar subspace, extending in an anteroposterior direction through the dorsolateral striatum. (C,D) Clusters representing corticothalamic axons are distributed within a narrow, spherical shell-like subspace in the thalamus. A, anterior; D, dorsal; M, medial; P, posterior.