Thalamic amnesia after infarct

Abstract

Objective:To improve current understanding of the mechanisms behind thalamic amnesia, as it is unclear whether it is directly related to damage to specific nuclei, in particular to the anterior or mediodorsal nuclei, or indirectly related to lesions of the mammillothalamic tract (MTT).Methods:We recruited 12 patients with a left thalamic infarction and 25 healthy matched controls. All underwent a comprehensive neuropsychological assessment of verbal and visual memory, executive functions, language, and affect, and a high-resolution structural volumetric MRI scan. Thalamic lesions were manually segmented and automatically localized with a computerized thalamic atlas. As well as comparing patients with controls, we divided patients into subgroups with intact or damaged MTT.Results:Only one patient had a small lesion of the anterior nucleus. Most of the lesions included the mediodorsal (n = 11) and intralaminar nuclei (n = 12). Patients performed worse than controls on the verbal memory tasks, but the 5 patients with intact MTT who showed isolated lesions of the mediodorsal nucleus (MD) only displayed moderate memory impairment. The 7 patients with a damaged MTT performed worse on the verbal memory tasks than those whose MTT was intact.Conclusions:Lesions in the MTT and in the MD result in memory impairment, severely in the case of MTT and to a lesser extent in the case of MD, thus highlighting the roles played by these 2 structures in memory circuits.

Medial thalamic stroke and its impact on familiarity and recollection

“…We had previously compared the performance of the damaged and intact MTT subgroups to a standard verbal memory task. This study showed more severe impairment of both recall and recognition of the damaged MTT subgroup ( Danet et al, 2015 ).…”

“…All participants underwent a series of three verbal recognition memory tasks, each measuring recollection and familiarity in a different way, thus allowing us to assess these processes independently of the method used ( Yonelinas, 2001 ; Bowles et al, 2007 ). An automated atlas was used to identify the location and extent of the damage to thalamus nuclei on the patients’ high-resolution 3D MRI ( Danet et al, 2015 ). Two complementary methods were used to assess damage to the MTT.…”

Secondary Bithalamic Ischemic Vascular Accident Has an Occlusion of the Artery of Percheron

“…Hypersomnia can be explained by the involvement of the intralaminar thalamic nucleus which forms with the posterior hypothalamus and the basal telencephalon the executive network of awakening under the control of three modulatory systems: the reticulo-hypothalamic-cortical pathway, the baso-cortical reticulo and the reticulo-thalamo-cortical pathway [12]. Memory disorders (anterograde and retrograde) are present in 63% of cases, explained by the loss of connection between the anterior thalamus nucleus and the hippocampus connected by the Mamillo-thalamic tract when the vascularization of the tubero-thalamic territory is dependent on the vascularization of the paramedian territory [13]. In addition, other thalamus territories such as the dorsomedial nucleus and the medullary medulla oblongata of the thalamus can cause memory disorders.…”

Assessment of serotonergic system in formation of memory and learning

“…On the other hand, animal with B7 and B9 serotonergic nuclei damaged, showed a tendency to worse its response in implicit test, but results did not show significance between the 1 st and 3 rd day of execution. Many disorders seen in patients without an effective treatment have encouraged basic researchers to look for novel approaches in the use of animal models of cognitive impairment, which is important for the understanding of its physiopathology and also the development of new therapies (Gornicka-Pawlak et al, 2015;Dalrymple-Alford et al, 2015;Huijgen and Samson, 2015;Danet et al, 2015). This work suggests that serotonergic nuclei together with Papez's circuit might be an important target in the study and understanding of the mechanisms involved in memory impairment.…”