Cerebral Substrates of Prospective Memory in Young and Its Disruption in Normal Aging and in Alzheimer's Disease: A Study in Anatomical MRI, Diffusion Tensor MRI and Functional MRI

Inclusion Criteria: * All participants: * Normal Education\> 7 years * French mother tongue * right-handed (Edinburgh Inventory) * score on the scale of Beck \<7 (depression scale) * signing the informed consent of the protocol in agreement with the Committee to Protect People * Medical examinations, neurological, neuropsychological and neuroimaging depth in accordance with the specific inclusion and exclusion criteria for each population, that is to say: * Young healthy subjects aged between 18 and 44 years * Healthy subjects intermediate age: between 45 and 69 years * score on the Mattis Dementia Scale higher than 137, in order to exclude any potential dementia * Performance "normal" to test RI RL-16 (that is to say, not differing by more than 1.65 standard deviation from the norm for age and cultural level \[see normative values published Van der Linden et al., 2004\]), test conventionally used to assess the verbal episodic memory. * Healthy elderly subjects aged 70 and over, living at home * score on the Mattis Dementia Scale higher than 137, in order to exclude any potential dementia * Performance "normal" to test RI RL-16 (that is to say, not differing by more than 1.65 standard deviation from the norm for age and cultural level \[see normative values published Van der Linden et al., 2004\]), test conventionally used to assess the verbal episodic memory. * MCI patients: older than 50 years and recruited from memory clinics and meet the current criteria and recognized including amnestic MCI * memory complaint * targets deficits of episodic memory (lower performance of at least 1 standard deviation from the norm for age and cultural level to one or more (sub) episodic memory scores of diagnostic battery - cf. . Tables 1 and infra) * performance in the standards for age and cultural level in all tests of diagnostic battery measuring other cognitive functions as memory, including the evaluation of overall cognitive ability tests. * Alzheimer's patients: older than 50 years were recruited from the clinics and memory satisfying the standards NINCDS-ADRDA criteria for probable AD which include * abnormal global cognitive functioning and deficits in two or more cognitive domains identified by the diagnostic battery * mild to moderate AD (MMSE ≥ 18). Exclusion Criteria: * Cognitive disorders of sudden onset (contrary to their slow and progressive onset in AD), which could reflect a stroke; a modified Hachinski ischemic score ≤ 2 (Loeb \& Gandolfo, 1983); history of head trauma with loss of consciousness for more than 1 hour, or encephalitis; * Chronic neurological disease, psychiatric, endocrine, hepatic, infectious; * A history of major illness (chronic lung disease, heart disorder, metabolic, hematologic, endocrine or immunological severe, cancer); * A medication that may interfere with the mnemonic or metabolic measures (psychotropics, hypnotics, anxiolytics, neuroleptics, anti-Parkinson, benzodiazepines, anti-inflammatory drugs, antiepileptics, antihistamines, analgesics and muscle relaxants central, as is usual The investigating doctor deems the annoying character for the study of the regular intake of certain medications). Taking anticholinesterase treatment will also be a criterion for non-inclusion. * Chronic intake of alcohol or drugs;