Preservation of long-term memory and synaptic plasticity despite short-term impairments in the Tc1 mouse model of Down syndrome

Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of the human chromosome 21 (Hsa21). Recently, O’Doherty and colleagues in an earlier study generated a new genetic mouse model of DS (Tc1) that carries an almost complete Hsa21. Since DS is the most common genetic cause of mental retardation, we have undertaken a detailed analysis of cognitive function and synaptic plasticity in Tc1 mice. Here we show that Tc1 mice have impaired spatial working memory (WM) but spared long-term spatial reference memory (RM) in the Morris watermaze. Similarly, Tc1 mice are selectively impaired in short-term memory (STM) but have intact long-term memory (LTM) in the novel object recognition task. The pattern of impaired STM and normal LTM is paralleled by a corresponding phenotype in long-term potentiation (LTP). Freely-moving Tc1 mice exhibit reduced LTP 1 h after induction but normal maintenance over days in the dentate gyrus of the hippocampal formation. Biochemical analysis revealed a reduction in membrane surface expression of the AMPAR (α-amino-3-hydroxy-5-methyl-4-propionic acid receptor) subunit GluR1 in the hippocampus of Tc1 mice, suggesting a potential mechanism for the impairment in early LTP. Our observations also provide further evidence that STM and LTM for hippocampus-dependent tasks are subserved by parallel processing streams.     

Information available In brief tactile presentations

Two experiments investigated characteristics of Immediate recall for brief tactile stimuli applied to the 24 interjoint regions of the fingers of both hands (thumbs excluded) The obtained Immediate-memory span varied from 35 to 7,5 stimulus positions correct after correction for guessing, similar to the results In analogous visual studies, Properties of any hypothetical tactile short-term memory were studied by requiring subjects to report only a specified portion of the stimuli presented, and by varying the time of occurrence of the marker specifying which portion of the stimuli to report, In this partial-report condition, subjects had more stimulus information available at the time of reporting than their immediate memory spans indicated, provided that the stimulus marker occurred within 0.8 sec after stimulus termination, The data suggest that at least for the amount of training employed here, any tactile short-term memory has much less capacity than an analogous visual short-term memory.     

Tactile perception of sequentially presented spatial patterns

Tactile pattern recognition was studied by presenting pairs of alphabetic shapes in rapid succession at the same anatomical location, the subject being required on each trial to identify bath of the patterns. Experimental variables were the duration of each stimulus and the time between stimuli. Three aspects of the observed interaction were (1) an increase in letter reversals for very short interstimulus intervals; (2) a greater percentage of first-response errors for short-stimulus onset intervals and a greater percentage of second-response errors for long-stimulus onset intervals; and (3) a crossover in the first- and second-response error rates in the range of 100 to 200 msec. after the onset of the first stimulus. These results are consistent with some of the temporal properties of models proposed for analogous visual tasks.     

Communality of videogame performances with tracking tasks

Performances on three videogames were compared with two different tracking tasks and a third dual tracking task, after stability of performance was achieved by 40 male subjects. The six tasks were performed in succession for three weeks each, and one year separated administration of the tracking tasks from the videogames. Convergence of the cross-correlations among these tasks occurred such that higher correlations were attained for scores obtained late in practice (late/late) of two tasks (even when they were performed a year apart) rather than for scores obtained earlier in training (viz., early/early). High communality between these two types of tasks was observed as indicated by virtual overlap between the videogames and the tracking tasks, even though different control media (joysticks, knobs), control orders (zero/first), and control inputs (displacement/force transducer) were required. Because these tasks apparently index similar abilities, there may be advantages to measuring tracking skills with videogames, which include low cost, wide availability, inherent interest to subjects and motivation, rapid approach to stable levels, and, in many cases greater apparent face validity relative to real world performance requirements.     

Transference and “The Rebbe” Idiographic and Nomothetic Factors in the Psychoanalysis of Lubavitch Chassidim

The Lubavitch Chassidim are one of several ultra-orthodox groups within Judaism. Their central focus is on their leader or Rebbe, who is seen as not only the possessor of all wisdom but also having supernatural powers. In working therapeutically with Lubavitch, one needs to distinguish if the beliefs of the individual are unique to them or reflect the belief system of the community. If the former, then it obviously needs to be analyzed. If the latter, then it is seen as an identification with the group and reflective of the need for group cohesion and often a regulator of self-esteem. The following article demonstrates these factors.     

Central executive function in mild cognitive impairment: a PET activation study

Using positron emission tomography (PET), we explored the neural correlates of an executive function, dual tasking, in patients with amnestic mild cognitive impairment (aMCI) and in elderly controls. The experiment employed simple auditory and visual tasks that were presented both in isolation and simultaneously to create a task condition requiring enhanced attentional control. Behaviorally, both groups performed well, albeit the patients made more errors on the visual task. The PET analysis focused at prefrontal regions where group differences in task-related activation patterns were expected. During dual task performance, the patients showed attenuated activity in the left inferior frontal region when compared to the controls. This suggests abnormalities in the neural processes underlying attentional control in aMCI.