A Contribution to the Anatomical Basis of Thalamic Amnesia

Abstract

Damage to diencephalic structures is stated to give rise to memory dysfunction. Amnesia is likely to occur following vascular lesions in the ventral portion of the thalamus. The CT findings of 6 of our own cases and 5 patients reported in the literature, all with selective vascular lesions of the thalamus, were studied to determine the critical structures involved in human memory processes more closely. Thalamic amnesia probably depends on intrathalamic white matter lesions more than on nuclear lesions. The mamillothalamic tract and the ventral portion of the lamina medullaris interna are the most likely candidates in the mediation of memory processes and a combined lesion of these structures may be responsible for thalamic amnesia in man. Two patients without significant memory dysfunction had lesions in the ventrobasal portion of the mediodorsal nucleus sparing the mamillothalamic tract and the ventral part of the lamina medullaris interna. Our findings correspond well with the understanding of amnesia as a 'disconnection syndrome' stressed recently by Warrington and Weiskrantz (1982) and with Mishkin's (1982) model of the memory system in monkeys.

The anatomy of amnesia: Neurohistological analysis of three new cases

“…of brain injury in patient PN (damage to the mammillary nuclei, mammillothalamic tracts, and anterior nuclei of the thalamus) differs from the pattern of brain injury reported in the two previous neurohistological studies of patients with wellcharacterized amnesia due to Korsakoff's syndrome (Mair et al 1979;Mayes et al 1988) but is consistent with reports that emphasize the importance of the mammillothalamic tract and the anterior thalamic nuclei (e.g., von Cramon et al 1985;Markowitsch 1988;Harding et al 2000). MG had damage to the mediodorsal nucleus and the internal medullary lamina, consistent with reports that emphasize the importance of these structures (von Cramon et al 1985;Victor et al 1989). It has only rarely been possible to study the anatomy of memory by carrying out extensive neuropsychological testing during life followed by detailed post-mortem neurohistological analysis.…”

Distribution of Dopamine D3 Receptor Expressing Neurons in the Human Forebrain Comparison with D2 Receptor Expressing Neurons

“…The AV also receives massive projections from the MM through the mtt, the former enriched with D 3 mRNA and the latter with binding sites. Although functions of the AV remain little understood, it has been implicated in mechanisms of memory and attention (von Cramon et al 1985). Its connections with the prefrontal, temporal, cingulate, and entorhinal cortex and hippocampal formation (for review see Armstrong 1990) suggest its importance for processing of information within the limbic circuit.…”

Acquired aphasia in children after surgical resection of left‐thalamic tumors

“…Most often the right hemisphere is implicated (Kawahara et al 1986). The dorsomedial thalamus (Squire and Moore 1979), the superior/posterior thalamic peduncles, the mamillothalamic tracts (von Cramon 1985, Gentilini et al 1987, and anterior intrathalamic fiber projections (Plets et al 1970, von Cramon 1985, Kritchevsky et al 1987) have all been implicated. Some investigators suggest that the language problems seen in adults after thalamic injury reflect predominantly memory problems or semantic-memory access, rather than language function alone (Wallesch et al 1983, Crossen 1984, Wallesch and Papagno 1988, Alexander et al 1989, Nadeau and Crosson 1997.…”