Maps of the adult human hypothalamus

Abstract

The human hypothalamus is a small deeply located region placed at the crossroad of neurovegetative, neuroendocrine, limbic, and optic systems. Although deep brain stimulation techniques have proven that it could be feasible to modulate these systems, targeting the hypothalamus and in particular specific nuclei and white bundles, is still challenging. Our goal was to make a synthesis of relevant topographical data of the human hypothalamus, under the form of magnetic resonance imaging maps useful for mastering its elaborated structure as well as its neighborhood. As from 1.5 Tesla, Inversion-Recovery sequence allows locating the hypothalamus and most of its components. Spotting hypothalamic compartments is possible according to specific landmarks: the anterior commissure, the mammillary bodies, the preoptic recess, the infundibular recess, the crest between the preoptic and the infundibular recesses, the optical tract, the fornix, and the mammillo-thalamic bundle. The identification of hypothalamus and most of its components could be useful to allow the quantification of local pathological processes and to target specific circuitry to alleviate severe symptoms, using physical or biological agents.

Keywords: Brain mapping; hypothalamus; inversion-recovery sequence; magnetic resonance imaging; stereotaxy.

Figure 1

3D reconstruction of the adult human hypothalamus displayed on three orthogonal (a. Frontal view; b. Left lateral view; c. Inferior view) T1-weighted MRI slices crossing the mammillary bodies (light blue): hypothalamus (green plus light blue), anterior white commissure (purple), thalamus (brown), pallidum (purple), third ventricle (yellow; the brain aqueduct and the ventricular foramen are also reconstructed), and optical system (dark blue)

Figure 2

MRI coronal slices (white matter attenuated inversion recovery sequence; joined slices, matri × 0.56 × 0.56 mm, 2-mm thickness) from posterior (a) to anterior (g): third ventricle (1), mammillary body (2), fornix (3), thalamus (4), mammillo-thalamic bundle or Vicq d’Azyr fascicle (5), nucleus entopedoncularis or nucleus of ansa lenticularis (6), zona incerta (7), optical tract (8), pallidum (9), hypothalamus (10), anterior white commissure (11), optic chiasma (12), internal capsule posterior limb (13), internal capsule anterior limb (14)

Figure 3

(a) Schematic drawing of hypothalamic nuclei, lateral view from the midline; left, nuclei directly located under the wall of the third ventricle; right, more deeply located nuclei up to the lateral region. (b) 3D overview of hypothalamic nuclei, constructed from a 3D high-field MRI data set; left, frontal view; intermediate, lateral view; right, medial view; the ventral tegmental area (VTA) is located within the retro hypothalamic region. Anterior commissure, Ac; dorsal or posterior nucleus, D; dorsomedial nucleus, Dm; fornix, Fx; fornix nuclei F; infundibular (arcuate) nucleus, If; lateral nucleus, L; mammillary body, Mb; mammillo - thalamic bundle, Mtb; optic chiasma, Cx; paraventricular nucleus, Pv; preoptic nuclei, Pr; suprachiasmatic (ovoid) nucleus, Sc; ventricular foramen, Vf; supraoptic (tangential) nucleus, So; tuberomamillaris (mamilloinfundibularis) nucleus, Tm; ventromedial (tuber principal) nucleus, Vm

Figure 4

Overview of structures neighboring the hypothalamus (Hyp), 3D reconstruction from a high - field MRI data set merged with schematic drawing; left, frontal view; right, superior view: amygdala, Am; ansa lenticularis nucleus, Nal; basal forebrain bundle, Bfb (and *); diagonal band of Broca, Bd; epithalamus, Ep; fornix, Fx; globus pallidum intern, GPi; mammillo-thalamic bundle, Mtb; red nucleus, RN; septum, Se; stria medullaris, Sm; stria terminalis, St; sublenticular radiations, SLr; substantia innominata (of Reichert), Sir; translenticular radiations, TLr; supraoptic commissure, Soc; thalamus, Tha

Figure 5

MRI landmarks and line used to spot hypothalamic compartments and nuclei (projection on 3D reconstruction from a high-field MRI data set; lateral view. (a) The hypothalamus is lined posteriorly by the vertical line (Post) placed behind the mammillary body and perpendicular to an anterior commissure posterior commissure (ACPC) segment. The anterior line (Ant) rises from the preoptic recess (Por), perpendicular to ACPC. Two intermediate lines, anterior (IntAnt) and posterior (IntPost), respectively, goes from the dorsal region of the optic chiasma (Cx) to the anterior point of the intermediate third of the ACPC line and from the crest (c) placed between the optical recess and the infundibular recess (Ir), to the posterior point of the intermediate third of the ACPC line. The anterior horizontal line (LineP; doted black line) goes parallel to ACPC (toward the posterior point at the origin of Post). The intermediate horizontal line (LineP2) is parallel to ACPC and origins at the midpoint of the segment of IntAnt between the point where IntAnt crosses LineP and the point where IntAnt crosses ACPC. The ventral line (Vent) goes from C to the intersection of LineP2 and IntPost. (b) The fornix limits the medial border of the lateral nucleus (l), which is visible in the background; the mammillo-thalamic bundle (Mtb) is displayed. (c) The area limited by the LineP2, LineP and IntAnt and IntPost projects on the lateral nucleus

Figure 6

MRI landmarks and lines used to spot hypothalamic compartments and nuclei (projection on 3D reconstruction from a high-field MRI data set. From A to F: left, frontal view; intermediate, sagittal slice, right, coronal slice; gray dotted lines show section plans. (a) Preoptic nuclei (Pr) and supraoptic plus suprachiasmatic nuclei (Soc). (b) Dorsomedial nucleus (Dm) lined laterally by the fornix. (c) Ventromedial nucleus (Vm) lined laterally by the tuberomamillaris nucleus (Tm). (d) Tuberomamillaris nucleus (Tm); placed below the fornix extending laterally to the optical tract (Ot). (e) Lateral nucleus (l), lined medially by the fornix; the inferior region overlaps with the tuberomamillaris nucleus. (f) Dorsal nucleus (d), placed behind the fornix (not visible here) and lined posteriorly by the mammillo-thalamic bundle (Mtb)