Francis Eustache

Transient global amnesia: implicit/explicit memory dissociation and PET assessment of brain perfusion and oxygen metabolism in the acute stage

OBJECTIVES To assess explicit memory and two components of implicit memory—that is, perceptual-verbal skill learning and lexical-semantic priming effects—as well as resting cerebral blood flow (CBF) and oxygen metabolism (CMRO2) during the acute phase of transient global amnesia. METHODS In a 59 year old woman, whose amnestic episode fulfilled all current criteria for transient global amnesia, a neuropsychological protocol was administered, including word learning, story recall, categorical fluency, mirror reading, and word stem completion tasks. PET was performed using the 15O steady state inhalation method, while the patient still exhibited severe anterograde amnesia and was interleaved with the cognitive tests. RESULTS There was a clear cut dissociation between impaired long term episodic memory and preserved implicit memory for its two components. Categorical fluency was significantly altered, suggesting word retrieval strategy—rather than semantic memory—impairment. The PET study disclosed a reduced CMRO2with relatively or fully preserved CBF in the left prefrontotemporal cortex and lentiform nucleus, and the reverse pattern over the left occipital cortex. CONCLUSIONS The PET alterations with patchy CBF-CMRO2 uncoupling would be compatible with a migraine-like phenomenon and indicate that the isolated assessment of perfusion in transient global amnesia may be misleading. The pattern of metabolic depression, with sparing of the hippocampal area, is one among the distinct patterns of brain dysfunction that underlie the (apparently) uniform clinical presentation of transient global amnesia. The finding of a left prefrontal hypometabolism in the face of impaired episodic memory and altered verbal fluency would fit present day concepts from PET activation studies about the role of this area in episodic and semantic memory encoding/retrieval. Likewise, the changes affecting the lenticular nucleus but sparing the caudate would be consistent with the normal performance in perceptual-verbal skill learning. Finally, unaltered lexical-semantic priming effects, despite left temporal cortex hypometabolism, suggest that these processes are subserved by a more distributed neocortical network.

Right motor neglect associated with dynamic aphasia, loss of drive and amnesia: Case report and cerebral blood flow study

A 30-year-old right-handed man had right motor neglect, amnesia, aphasia and loss of drive following bilateral thalamic and subthalamic infarctions. Serial resting cerebral blood flow (CBF) measurements with either Xenon 133 inhalation or positron emission tomography at 1, 8 and 10 months post-onset showed a widespread and long-lasting low CBF in the cortex. An additional CBF measurement, during motor tasks, showed a marked interhemispheric asymmetry in the pattern of activation: whereas left hand movement resulted in a CBF increase in contralateral superior rolandic and prerolandic areas, no significant regional CBF changes were seen during right hand movement, despite recovery from motor neglect. This loss of CBF increase in cortical motor and premotor areas during voluntary movement of the previously neglected side points to a disruption of cortico-subcortical pathways subserving motor activation. The pathophysiology of aphasia, loss of drive and amnesia as well as their relationships to motor neglect, may also be discussed on the basis of thalamo-cortical disconnections.

Infarct of the anterior limb of the right internal capsule causing left motor neglect: case report and cerebral blood flow study.

A sixty-nine year old hypertensive man had left motor neglect following an infarct of the anterior limb of the right internal capsule. He also had left auditory extinction on verbal dichotic listening and a sligh constructional apraxia. Regional cerebral blood flow (CBF) was measured at rest with Xenon 133 inhalation and was found to be slightly decreased in a diffuse fashion. Motor activation of the right hand resulted in an increase of CBF in the contralateral superior rolandic area, whereas no such increase was found during motor activation of the left hand. This lack of cortical CBF increase on contralateral motor activation is interpreted as a consequence of the failure of some corticosubcortical connexions involved in motor arousal. The specifically dynamic appearance of regional CBF abnormalities, i.e. during selective activation as opposed to rest measurements, is consistent with the functional character of neglect.

Brain glucose utilisation in a patient with "athymhormia" from a family with autosomal dominant parkinsonism and psychic disturbances.

2 Sellal F, Hirsch E, Lisovoski F, Mutschler V, Collard M, Marescaux C. Contralateral disappearance of parkinsonian signs after subthalamic hematoma. Neurology 1992;42: 255-6. 3 Bergman H, Wichmann T, DeLong MR. Reversal of experimental parkinsonism by lesions of the subthalamic nucleus. Science 1 990;249: 1436-8. 4 Aziz TZ, Peggs D, Sambrook MA, Crossman AR. Lesion of the subthalamic nucleus for the alleviation of 1-methyl-4-phenyl-1,2,3,6tetrahydropyridine (MPTP) induced parkinsonism in the primate. Mov Disord 1991;6:288-92.

Le XXIe siècle sera neuropsychologique ou ne sera pas !The Twenty-First Century as a Neuropsychology Era

Cet article rend compte de levolution de la neuropsychologie depuis la fondation institutionnelle de cette discipline dans les domaines de la recherche, de lenseignement et des soins. Laccent est mis sur les evolutions constatees au cours des 30 dernieres annees (1977-2007), depuis la naissance de la Societe de Neuropsychologie de Langue Francaise (SNLF). La neuropsychologie cognitive et limagerie fonctionnelle ont contribue a faconner limage actuelle de la neuropsychologie. La creation de journaux specialises, lorganisation de congres, la mise en place de filieres denseignement et de soins ainsi que laugmentation de la production scientifique sont autant dindicateurs de lidentite et de limportance de cette discipline. Lexemple quebecois est developpe car il propose une structuration originale de lenseignement qui mene a un Doctorat dexercice en neuropsychologie repondant a des normes nationales. Les auteurs soulignent enfin limportance sociale et societale que devra jouer cette discipline dans les prochaines annees.This article reviews how neuropsychology, in the French-speaking world, has evolved as a discipline focused on research, teaching and clinical work. The article targets the last 30 years as this corresponds to the time at which the Société de Neuropsychologie de Langue Française (French-Speaking Neuropsychological Society) was created. The review addresses how the cognitive neuropsychology approach and the advent of brain imaging have shaped the field of neuropsychology in recent years. It presents the status of the discipline in the main French-speaking countries (where neuropsychology is currently developed) including France, Belgium, Switzerland and Canada. It also analyzes a number of indicators that reflect the vitality of the discipline and its cohesion as a science and as a clinical domain. These indicators include the creation of specialized journals, organization of scientific meetings, accessibility to training programs in neuropsychology, development of discipline-oriented clinical programs, and the increase in scientific productivity. The Quebec academic environment is used as an illustration, whereby structured clinical doctoral training programs that meet national standards in neuropsychology were implemented to train clinical neuropsychologists. Finally, the authors emphasize the major role that the discipline is likely to play at different levels of society in the near future.

De mémoire d’homme. Mémoire, oubli et pathologies

L’etude des maladies de la memoire a peu a peu permis de poser les bases des concepts et des theories qui renseignent sur sa structure et son fonctionnement. De la psychologie cognitive aux neurosciences, le spectre des disciplines est large. Beatrice Desgranges et Francis Eustache retracent le cheminement scientifique et l’historique des recherches menees sur differentes pathologies.