Thalamic contributions to anterograde, retrograde, and implicit memory: a case study.
ABSTRACT Learning and memory deficits are typically associated with damage or dysfunction of medial temporal lobe structures; however, diencephalic lesions are another common cause of severe and persistent memory deficits. We focus specifically on the thalamus and review the pathological and neuropsychological characteristics of two common causes of such damage: Korsakoff's syndrome and stroke. We then present a patient who had sustained bilateral medial thalamic infarctions that affected the medial dorsal nucleus and internal medullary lamina. This patient demonstrated the characteristic temporally graded retrograde amnesia and a profound anterograde memory (i.e., explicit memory) deficit within the context of relatively preserved implicit memory. Implications of this explicit-implicit discrepancy are discussed within the context of cognitive rehabilitation techniques that hold promise for more severely impaired patients.
- SourceAvailable from: Christian H Nolte[show abstract] [hide abstract]
ABSTRACT: The thalamus comprises numerous nuclei that can be grouped into five major functional domains: (1) the reticular and intralaminar nuclei influence arousal and nociception, (2) sensory nuclei handle afferent pathways, (3) the effector nuclei are involved in motor function and language, (4) associative nuclei participate in higher cognitive functions and (5) limbic nuclei influence mood and motivation. The thalamic nuclei are mainly supplied by the following four cerebral arteries: paramedian artery, anterior thalamoperforating artery, thalamogeniculate artery and posterior choroidal artery (lateral branches). Occlusions of these arteries affect the thalamic nuclei to varying degrees and produce partly characteristic and partly overlapping deficits. This article describes the clinical pictures.Der Nervenarzt 12/2010; 82(2):231-41. · 0.80 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The thalamus plays a crucial role in memory, executive functioning and attention. It remains, however, unclear whether thalamic structures have specific roles in each of these functions. We tested 22 cases of thalamic infarction, proven with MR imaging, using experimental and established neuropsychological tests. We performed a lesion-overlap study in standardised stereotactic space of patients sharing a certain deficit, corrected for the lesion distribution of patients without such deficits and determined the regions of interest using an atlas of the human thalamus. We checked for additional, non-thalamic, damage and for deficient comprehension and perception that would preclude interpretation of the results. Non-thalamic damage such as white matter lesions, hippocampal atrophy, sulcal widening and infarctions occur significantly more often in patients aged over 60. The patients with additional damage overlapped to a major degree with those who showed loss of orientation, or lack of comprehension of the test requirements. In the 10 patients judged 'clean', we observed a deficit of episodic long-term memory with relative sparing of intellectual capacities and short-term memory when the mammillo-thalamic tract was damaged. Lesions including the medial dorsal nucleus, midline nuclei and/or intralaminar nuclei accompany executive dysfunctioning. Reduced simple processing speed and attention are associated with age, but not with a particular structure in the thalamus. Complex attention deficits follow damage to the intralaminar nuclei.We conclude that the analysis of structure-function relationships must take into account extra-structure damage which may explain cognitive deficits. Separate thalamic structures are involved in memory, executive functioning and attention.Neuropsychologia 02/2003; 41(10):1330-44. · 3.48 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Relatively few studies have examined the use of cognitive rehabilitation in patients with mild cognitive impairment (MCI), largely due to the assumption that training will not improve functioning in patients with progressive conditions. Face-name association, an ecologically valid task, is both dependent on the explicit memory system and difficult for MCI patients. During three hour-long sessions, eight patients diagnosed with MCI were trained in the use of explicit memory strategies with 45 face-name pairs. For each pair, they were taught to visually identify a facial feature, link a phonological cue to that feature, and recall the associated name. There was significant improvement in recognition accuracy, along with faster reaction times, for trained face-name pairs. Improved accuracy persisted when tested one month after training. Significant, but less, improvement was also found on untrained stimuli, raising the possibility of generalization of training strategies. Preliminary results suggest strategy-based cognitive rehabilitation may be beneficial in patients with MCI, though these results must be replicated with a control group to rule out practice effects.Journal of the International Neuropsychological Society 10/2008; 14(5):883-9. · 2.70 Impact Factor