Impairment of short-term memory associated with low iron stores in a volunteer multidose plateletpheresis donor.

A platelet donor may lose 80-100 mL of blood both in the harness and by blood sampling at each donation, the equivalent of four to five whole blood donations per annum for a donor attending at 2-weekly intervals. A 54-year-old male multidose platelet donor had donated platelets at regular 2-weekly intervals for 6 years. He developed an impairment of anterograde memory (new learning). A self-rating scale revealed a moderate degree of depression [Beck Depression Inventory (BDI) score 22]. Memory testing (Doors and People Memory Battery) showed low scores, particularly for verbal recall and verbal recognition memory. He was found to have a normal haemoglobin of 157 g L(-1) with normal red blood cell indices, but a low serum ferritin (15 ng mL(-1)) and a low serum iron (8.1 mmol L(-1)). Following iron therapy and a return of his iron stores to normal levels, there was an improved BDI score of 13 (minimal level of depression) and a marked improvement in memory test scores. This has been maintained even though he has resumed platelet donation but at reduced intervals.

Lost for words or loss of memories? Autobiographical memory in semantic dementia.

Recent reports have suggested that patients with semantic dementia show a loss of early (remote) auto-biographical memories with pronounced sparing of recent memories (Graham & Hodges, 1997; Snowden, Griffiths, & Neary, 1996), i.e., a 'reversed' temporal gradient or 'Ribot effect'. At first sight, these findings suggest that the deficits in 'semantic' dementia go beyond the semantic domain, involving aspects of autobiographical (episodic) memory. It has also been proposed that there is a 'step-like' function with personal memories preserved for 18 months to 2 years in the immediate past. This view is consistent with the theory that the hippocampal complex/medial temporal lobe (relatively intact in semantic dementia) plays a time-limited role in the acquisition and storage of memories, while the temporal neocortex (damaged in semantic dementia) is required for long-term storage and retrieval. In this study we ask whether (a) previous tests have underestimated the integrity of remote memory in semantic dementia as a result of not allowing for these patients' comprehension and language production difficulties, and (b) whether a recency effect, if obtained, is genuinely step-like or more graded. We used a cued autobiographical memory interview with semantic dementia patient, IH, to examine the effect of providing increasingly specific lexical cues to probe salient events throughout his lifespan. Results demonstrated that the provision of specific cues enabled IH to access and express memories from his childhood and early adulthood as well as from more recent times. There was a gentle recency effect only for intermediate levels of cueing, indicating that recent memories were easier to retrieve and/or express in the absence of specific cues, but this effect was graded, with no evidence of a step-like cut-off at 18 months or 2 years before testing. In brief, our findings are consistent with the view that the deficits in semantic dementia are predominantly or exclusively semantic, rather than involving the storage of autobiographical memories per se.

Amnesic syndrome and severe ataxia following the recreational use of 3,4-methylene-dioxymethamphetamine (MDMA, 'ecstasy') and other substances.

A 26-year-old woman suffered disseminated intravascular coagulation (DIC) and a brief respiratory arrest following recreational use of 3,4-methylene-dioxymethamphetamine (MDMA; 'ecstasy'), together with amyl nitrate, lysergic acid (LSD), cannabis and alcohol. She was left with residual cognitive and physical deficits, particularly severe anterograde memory disorder, mental slowness, severe ataxia and dysarthria. Follow-up investigations have shown that these have persisted, although there has been some improvement in verbal recognition memory and in social functioning. Magnetic resonance imaging and quantified positron emission tomography investigations have revealed: (i) severe cerebellar atrophy and hypometabolism accounting for the ataxia and dysarthria; (ii) thalamic, retrosplenial and left medial temporal hypometabolism to which the anterograde amnesia can be attributed; and (iii) some degree of fronto-temporal-parietal hypometabolism, possibly accounting for the cognitive slowness. The putative relationship of these abnormalities to the direct and indirect effects of MDMA toxicity, hypoxia and ischaemia is considered.

Imitation in rats (Rattus norvegicus): The role of demonstrator action.

In a bidirectional control procedure, rats had their first opportunity to push a joystick immediately after observing, from an adjacent compartment, the joystick moving 50 times either to the right or to the left, with each movement signalling the delivery of inaccessible food. Half of these animals observed the joystick moving automatically, and half observed a conspecific demonstrator pushing the joystick. When they were given direct access to the joystick, the observers were rewarded for both left and right pushes. Rats that had observed the joystick moving through the action of a conspecific demonstrator showed a response bias in favour of the observed direction of joystick movement (Experiment 1), while rats that had observed the joystick moving automatically, either in the presence or absence of a passive conspecific, did not show observation-consistent responding (Experiments 1 and 2). These results apparently confirm that rats are capable of imitation or observational learning.

Performance on two fixed-interval schedules in the absence of neocortex in rats.

Rats with complete surgical removal of the neocortex (neodecorticates) were trained, with milk as the reinforcer, on a 40-s fixed-interval (FI-40) schedule, then on an FI-120, and finally reexposed to the FI-40. Like controls, neodecorticates developed and appropriately adjusted their postreinforcement pauses and response distributions and showed scallop-type responding on the FI-120 and a positive correlation between running rate and the preceding postreinforcement pause on both FI-40 schedules but not on the FI-120. On some variables neodecorticates reached asymptotic levels of performance more slowly than controls. Extended training on the first FI-40 did not differentially affect neodecorticates' performance. The results suggest that neodecorticates retain a functional timing mechanism.