White matter tracts connect cortical areas to other parts of the cortex, to basal ganglia and to the brain stem and spinal cord. These tracts form the internal part of the brain and transmit the nervous impulses. Changes in brain white matter may serve as biomarkers for numerous neurological diseases.

Diffusion Weighted Imaging (DWI) is a non-invasive MRI (Magnetic Resonance Imaging) technique providing information on white matter tracts (tractography) by studying water diffusion. Since it is based on complex mathematical models that only indirectly evaluates the underlying anatomy, tractography need to be validated before being used for research and clinical purposes. Several validation techniques were previously proposed, none of them being fully convincing in human.

Inclusion Criteria:

• Prior enrollment in a body donation program
• Age ≥ 82 years
• Absence of major cognitive impairment as demonstrated by independent living skills in 4 fields evaluated by the IADL (4 items) (Lawton and Brody, 1969)
• Distance to one of the participating laboratories ≤ 120km
• Able to remain supine in the MR scanner for acquisition duration (60 min),
• Affiliation to Social Security
• Informed and written consent

Non Inclusion Criteria:

• Past or present Neurological or Neurosurgical diseases (excluding trauma or degenerative spinal lesions)
• Uncontrolled: High blood pressure, diabetes (types I or II), or dyslipemia
• Contraindications to MRI
• Contraindication to body donation

Exclusion criteria

• Diagnosis on MRI of brain lesions, excepted common age-related changes