Preserved Memory Abilities in Thalamic Amnesia

Abstract

The pattern of preserved learning abilities is described in a severely amnesic patient after bilateral thalamic infarction. Experimental findings cannot be accounted for both by the view that only episodic memory is impaired in amnesia, while semantic memory is spared, and by the theory that what is spared in amnesia is procedural learning contrasted with impaired declarative memory. In agreement with Warrington and Weiskrantz (1982), diencephalic amnesia is considered to be a disconnection syndrome between the frontal and temporal lobes. The conditions for showing spared and impaired memory in amnesics are specified on the basis of the performance of the patient and of the data available in the literature. This allows us to derive practical suggestions for programmes aimed at remediation of memory defects.

Task-specific contribution of the human striatum to perceptual–motor skill learning

“…This type of learning does not depend on the integrity of the mesial temporal area, diencephalic brain structures, or basal forebrain, which are crucial for the acquisition of new declarative information (e.g., Bondi, Kaszniak, Rapcsak, & Butters, 1993;Brooks & Baddeley, 1976;Cavaco, Anderson, Allen, Castro-Caldas, & Damasio, 2004;Milner, 1962;Nichelli, Gentilini, & Vecchi, 1988;Tranel, Damasio, Damasio, & Brandt, 1994).…”

Effects of Temporal Lobe Lesions on Retrograde Memory: A Critical Review

“…Nevertheless, scientific interest in retrograde memory and its neurological underpinnings has grown considerably over the last two decades. Deficits in retrograde memory have been recorded in patients with lesions involving frontal (e.g., Baddley and Wilson 1986;Levine et al 1998;O'Connor and Lafleche 2004), posterior cerebral (Hunkin et al 1995) or thalamic regions (Barbizet et al 1981;Hodges and McCarthy 1993;Isaac et al 1998;Luchelli et al 1995;Markowitsch et al 1993;Miller et al 2001;Nichelli et al 1988;Stuss et al 1988), but most attention has been paid to the consequences of temporal lobe lesions (Table 1). Retrograde memory deficits of different severity and type have been reported in patients with lesions in different locations, and the way in which lesion site influences the pattern of retrograde memory loss has been considered by many authors.…”

Implicit and explicit memory after focal thalamic lesions

“…Diencephalic global amnesia is characterized by severe anterograde memory deficits. [1][2][3][4][5][6][7] Retrograde amnesia occurs less frequently and is less pronounced 4,5 but it has rarely been formally assessed. Retrograde amnesia tends to improve with time whereas anterograde deficits persist.…”

“…Retrograde amnesia tends to improve with time whereas anterograde deficits persist. 6 Global amnesia after thalamic infarction mostly requires bilateral lesions. Unilateral damage to thalamic structures only rarely leads to global amnesia but frequently causes less pronounced memory deficits.…”