Clara Calia

Visuospatial bootstrapping: Binding useful visuospatial information during verbal working memory encoding does not require set-shifting executive resources

Immediate serial recall of digits is better when the digits are shown by highlighting them in a familiar array, such as a phone keypad, compared with presenting them serially in a single location, a pattern referred to as “visuospatial bootstrapping.” This pattern implies the establishment of temporary links between verbal and spatial working memory, alongside access to information in long-term memory. However, the role of working memory control processes like those implied by the “Central Executive” in bootstrapping has not been directly investigated. Here, we report a study addressing this issue, focusing on executive processes of attentional shifting. Tasks in which information has to be sequenced are thought to be heavily dependent on shifting. Memory for digits presented in keypads versus single locations was assessed under two secondary task load conditions, one with and one without a sequencing requirement, and hence differing in the degree to which they invoke shifting. Results provided clear evidence that multimodal binding (visuospatial bootstrapping) can operate independently of this form of executive control process.

Refining understanding of working memory buffers through the construct of binding: Evidence from a single case informs theory and clinical practise

Binding operations carried out in working memory enable the integration of information from different sources during online performance. While available evidence suggests that working memory may involve distinct binding functions, whether or not they all involve the episodic buffer as a cognitive substrate remains unclear. Similarly, knowledge about the neural underpinnings of working memory buffers is limited, more specifically regarding the involvement of medial temporal lobe structures. In the present study, we report on the case of patient KA, with developmental amnesia and selective damage to the whole hippocampal system. We found that KA was unable to hold shape-colours associations (relational binding) in working memory. In contrast, he could hold integrated coloured shapes (conjunctive binding) in two different tasks. Otherwise, and as expected, KA was impaired on three relational memory tasks thought to depend on the hippocampus that are widely used in the early detection of Alzheimers disease. Our results emphasize a dissociation between two binding processes within working memory, suggesting that the visuo-spatial sketchpad could support conjunctive binding, and may rely upon a large cortical network including sub-hippocampal structures. By contrast, we found evidence for a selective impairment of relational binding in working memory when the hippocampal system is compromised, suggesting that the long-term memory deficit observed in amnesic patients may be related to impaired short-term relational binding at encoding. Finally, these findings may inform research on the early detection of Alzheimers disease as the preservation of conjunctive binding in KA is in sharp contrast with the impaired performance demonstrated very early in this disease.

TOWARD HARMONISATION OF NEUROPSYCHOLOGICAL ASSESSMENT OF ALZHEIMER’S DISEASE IN EUROPE: EVIDENCE FROM NOVEL COGNITIVE MAKERS

Background: Prior research links vascular risk factors and depression to cognitive functioning; however, few studies have examined this phenomenon in Mexican Americans. Mexican Americans report higher rates of depression symptomology and prevalence of cardiovascular risk factors, both of which put them at risk for cognitive impairment in later life. The goal of this study was to examine the relationship between vascular risk and depression on executive functioning among Mexican American adults and elders. Methods:Data was analyzed from 352 Mexican American women (NC1⁄4289; MCI1⁄449), enrolled in the Health and Aging Brain among Latino Elders (HABLE) study. The HABLE study is an epidemiological study of cognitive aging among Mexican Americans. Participants underwent an interview, neuropsychological testing, blood draw, medical examination, and informant interviews. Cognitive diagnosis were assigned via consensus review using standard published criteria. Vascular risk (BMI-Framingham 10 year Cardiovascular Risk Scores) and depression (Geriatric Depression Scale) were entered into the model as predictors. Executive function was assessed via Trails B scaled scores, and the EXIT. Linear regression analyses were split by cognitive status. Follow up logistic regression analyses were carried out to examine the relationship between vascular risk and depression on MCI diagnosis. Results: For normal control women, the average age was 58.0(SD1⁄4 5.9) and the BMI-Framingham risk score was 17.0 (SD1⁄49.2). For MCI women, the average age was 61.4 (SD1⁄46.8), and Framingham risk score was 20.6(SD1⁄48.2). Among normal controls, higher depression (p1⁄4.003) and higher vascular risk (p1⁄4.002) were significantly associated with low Trails B scaled scores. High vascular risk (p1⁄4.010) and GDS (p1⁄4.011) scores were significantly associated with higher EXIT scores. For MCI, there were no significant findings for Trails B or Exit. Higher GDS scores (OR1⁄41.10; 95% CI 1⁄41.030-1.115, p1⁄4 .001), and higher vascular risk scores (OR1⁄41.04; 95%CI1⁄41.01-1.10, p1⁄4.020) significantly predicted MCI status in Mexican American women. Conclusions: Vascular risk and depression were significantly associated with poorer executive dysfunction, and increased risk for MCI in Mexican American women. These findings suggest a vascular depression may contribute to cognitive dysfunction among in Mexican Americans.

DO SEMANTIC CLUSTERING DEFICITS UNDERPIN LONG-TERM MEMORY BINDING IMPAIRMENTS IN PRODROMAL AD?

greater cost than their e3 counterparts. This pattern was reversed in young adulthood, with e4s tending towards a smaller cost. Across both genotypes, cost decreased with increasing WM load suggesting everybody was being forced to switch to a more focal strategy. Under WM load the e3s performed more like the e4s, which may suggest mid-age e4s were already working harder in the no load block. This differencewas supported by subjective report measures. Conclusions:Age-associated increases in prospective memory cost in e4 carriers are consistent with reduced processing in this group by mid-adulthood. Additionally, we identified age and genotype differences in the use of strategies to support PM performance. Further research is needed to understand the mechanisms of these early genotype differences in PM.