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Figure 4f. Coronal serial, consecutive, color-coded images of myelin-stained brain slices and corresponding T2-weighted fast spin-echo magnetic resonance (MR) images obtained in vivo of the left hemisphere. The orbitofrontal circuit is shown in red, the dorsolateral in blue, and the anterior cingulate in yellow. Arabic numbers in blue zones show the predominant flow of information in the dorsolateral circuit (Fig 1). Letters in red zones show the connections of the orbitofrontal circuit (Fig 2). Roman numerals in yellow zones show the predominant connections of the anterior cingulate circuit (Fig 3). The appropriately colored dots indicate the incoming and outgoing fibers of each circuit. All MR images were acquired by using a fast spin-echo sequence with a repetition time of 6,000 msec, an echo time of 105 msec, a section thickness of 3 mm, an intersection gap of 0.6 mm, a field of view of 24 cm, a matrix of 512 x 512, and two signals acquired. Caudate = caudate nucleus. (a, b) Coronal images of the anterior frontal lobe immediately rostral to the genu of the corpus callosum. (a) The left frontal lobe cortex is the source and termination of the orbitofrontal circuit (A, red) and the dorsolateral circuit (1, blue). (b) The Brodmann areas and gyri are labeled on the in vivo MR image corresponding to a. (c, d) Coronal images of the frontal lobe at the tip of the frontal horn and genu of the corpus callosum. (c) Anterior cingulate (I, yellow), orbitofrontal (A, red), and dorsolateral (1, blue) cortices are shown in the left frontal lobe. (d) The Brodmann areas and gyri are labeled on the in vivo MR image corresponding to c. (e, f) Coronal images at the midbody of the head of the caudate nucleus. (e) The most caudal extent of the anterior cingulate (I, yellow) and orbitofrontal (A, red) cortices are shown in the left cerebral hemisphere. The left caudate nucleus is colored to indicate the dorsolateral circuit (2, blue) and the orbitofrontal circuit (B, red). The anterior cingulate circuit (II, yellow) in the ventral putamen, ventral caudate nucleus, and nucleus accumbens is also shown. (f) The Brodmann areas and deep structures are labeled on the in vivo MR image corresponding to e. (g, h) Coronal images at the caudal head of the caudate nucleus. (g) The left caudate nucleus is colored to indicate the dorsolateral (2, blue), orbitofrontal (B, red), and anterior cingulate (II, yellow) circuits. The anterior cingulate circuit (yellow) in the rostral part of the anterior perforated substance (II, olfactory tubercle) and the globus pallidus (III) are also shown. The dorsolateral circuit (3, blue) and the orbitofrontal circuit (C, red) in the globus pallidus are shown. The presence of fibers from all three circuits in the genu of the internal capsule explains why there are motor and sensory deficits, as well as "frontal lobe" symptoms, after damage to this area. (h) The important structures are labeled on the in vivo MR image corresponding to g. (i, j) Coronal images at the anterior thalamus. (i) The left hemisphere is colored to indicate the anterior cingulate fibers (yellow) in the dorsomedial thalamus (IV), globus pallidus (III), and caudate nucleus (II). The orbitofrontal circuit (red) is seen in the ventral anterior thalamic and dorsomedial thalamic nuclei (D), the globus pallidus (C), and the caudate nucleus (B). The dorsolateral circuit (blue) is seen in the ventral anterior thalamic and dorsomedial thalamic nuclei (4), globus pallidus (3), and caudate nucleus (2). (j) The deep gray matter structures are labeled on the in vivo MR image corresponding to i. Dorsomedial and ventral anterior refer to the thalamic nuclei.