Effect of Encoding on Prospective Memory.

Event-based prospective memory (ProM) refers to remembering to execute planned actions in response to a target ProM cues. Encoding modality influences ProM performance; visual encoding has been studied more than auditory encoding. Further, it has not yet been examined whether different encoding may influence ProM performance in different encoding modalities. This study examines the effects of encoding modality (visual vs. auditory), cue-encoding specificity (specific cue vs. non-specific cue), and encoding modes (standard vs. implementation intention) on event-based ProM tasks. In Experiment 1, cue specificity and encoding modality were manipulated as a within-groups encoding of visual cues is more commonly and between-groups variable. Results revealed the facilitative effect of cue specificity on ProM performance. Also, with respect to encoding modality, participants showed better performance when receiving auditory instructions compared with the visual encoding condition. In Experiment 2, as in Experiment 1, cue specificity and encoding modality were manipulated. Encoding mode was added as a new between-group variable. Result revealed that there was a significant interaction between encoding modality and encoding modes. Visual implementation intention encoding was a more effective method for improving ProM performance compared with visual standard encoding. Furthermore, there was a significant interaction between cue-encoding specificity and encoding modes. Implementation intention encoding enhances ProM performance in non-specific cue-encoding conditions. Overall, the present study found that (1) auditory encoding modality showed superior ProM performance compared with visual encoding, although implementation intention had facilitative on ProM performance regardless of the encoding modalities, and (2) there was better ProM performance under specific encoding compared with non-specific encoding, and implementation intention had a facilitative effect on ProM performance in the non-specific condition.

Working Memory Load and Reminder Effect on Event-Based Prospective Memory of High- and Low-Achieving Students in Math.

The effects of working memory (WM) demand and reminders on an event-based prospective memory (PM) task were compared between students with low and high achievement in math. WM load (1- and 2-back tasks) was manipulated as a within-subject factor and reminder (with or without reminder) as a between-subject factor. Results showed that high-achieving students outperformed low-achieving students on all PM and n-back tasks. Use of a reminder improved PM performance and thus reduced prospective interference; the performance of ongoing tasks also improved for all students. Both PM and n-back performances in low WM load were better than in high WM load. High WM load had more influence on low-achieving students than on high-achieving students. Results suggest that low-achieving students in math were weak at PM and influenced more by high WM load. Thus, it is important to train these students to set up an obvious reminder for their PM and improve their WM.

Rac1 modulates the vitreous-induced plasticity of mesenchymal movement in retinal pigment epithelial cells.

BACKGROUND: The vitreous has been shown to induce epithelial-mesenchymal transdifferentiation because it induces fibroblast-like morphology, enhanced migration and invasion in retinal pigment epithelial cells in proliferative vitreoretinopathy. Rac1 is the principal mediator of cell migration. In the current study, the relationship between Rac1 and cell migration, and invasion in vitreous-transformed retinal pigment epithelial cells was investigated using NSC23766, a specific inhibitor of Rac guanosine-5'-triphosphatase activity, and the involvement of a Rac1 guanosine-5'-triphosphatase-dependent pathway was detected. DESIGN: One-way design with multiple levels and repeated measurement design. PARTICIPANTS AND SAMPLES: The vitreous humor was collected from 20 healthy donor eyes and the retinal pigment epithelial cells were obtained from 9 healthy donor eyes. METHODS: Human low-passage retinal pigment epithelial cells were treated with normal medium or 25% vitreous medium. Rac1 activity was measured using a pull-down assay. The cytotoxicity of NSC23766 was measured using the trypan blue dye exclusion test. Cell migration was measured using a wound healing assay. Cell invasion was determined using a transwell invasion assay. Protein expression of Rac1 and phosphorylation of LIM kinase 1 and cofilin were detected by Western blot analysis. MAIN OUTCOME MEASURES: Cell migration, invasion, Rac1 activity and phosphorylation of LIM kinase 1 and cofilin. RESULTS: Rac1guanosine-5'-triphosphatase was activated in vitreous-transformed retinal pigment epithelial cells. A Rac inhibitor suppressed vitreous-induced migration and invasion in retinal pigment epithelial cells. Cofilin phosphorylation was activated by vitreous treatment but blocked by NSC23766. CONCLUSIONS: Rac1 mediates vitreous-transformed retinal pigment epithelial cells' plasticity of mesenchymal movement via Rac1 guanosine-5'-triphosphatase-dependent pathways that modulate LIM kinase 1 and cofilin activity. Rac inhibition may be considered a novel treatment for proliferative vitreoretinopathy.

Effect of characteristics of target cues on task interference from prospective memory.

Event-related potential technique was used to examine the effect of characteristics of target cues on brain activity related to task interference during event-based prospective memory (PM). Three conditions were tested. In the control condition participants had no PM task and merely performed a shape decision task. In one PM condition the task of PM was to respond to a salient cue, whereas in the other PM condition the task of PM was to respond to a nonsalient cue. The results seemed to support preparatory attentional and memory processes theory and suggested frontal lobe involvement in monitoring, which caused task interference effects, and those characteristics of cues modulated the amount of task interference and the extent to which the frontal lobe was engaged.

Task interference from event-based prospective memory: an event-related potentials study.

Event-related potentials (ERPs) technique was used to examine brain activity related to task interference during event-based prospective memory. The behavioral data indicated that there existed task interference. Data from ERPs record on non-prospective memory trials suggested that there were significant differences in the time windows of 200-300, 300-350, and 350-400 ms after the onset of stimulus. The ERP difference wave showed the maximum amplitude over the central site (Fz) with a peak latency of 250 ms (N250). The topographical map in the time window of 200-300 ms indicated that the components reflected activation mainly in the frontal lobe. The results seemed to support preparatory attentional processes and memory processes theory and revealed that frontal lobe was involved in monitoring, which caused task interference effect.

Infertility in mice induced by the rhesus monkey chorionic gonadotropin beta-subunit glycoprotein (rmCGbeta) using DNA immunization.

The recombinant eukaryotic expression vector pCMV4-rmCGbeta, inserted full-length cDNA of the beta-subunit of rhesus monkey chorionic gonadotropin (rmCGbeta), as DNA immuno-contraceptive against CGbeta glycoprotein, has previously demonstrated the biological expression of rmCGbeta in vitro and in vivo. The plasmid DNA of pCMV4-rmCGbeta was inoculated into BALB/c mice at different doses and routes as DNA immuno-contraceptive to understand its antifertility effect. The results of immune responses indicated that the intradermal inoculation is the optimal pCMV4-rmCGbeta DNA delivery method for BALB/c mice, and the dose of 10 microg should be enough to elicit immune response. With different doses from 10-50 microg, marked reductions in the fertility of the female mice after two intramuscular inoculations of pCMV4-rmCGbeta DNA were seen, while the similar level of humoral immune responses were induced. With the dose of 20 microg of pCMV4-rmCGbeta DNA, the mice showed reduction in fertility from intraperitoneal, and intradermal to intramuscular inoculating method. The antifertility effect of antiserum from immunized mice confirmed that the antibodies elicited by pCMV4-rmCGbeta DNA could prevent pregnancy in female mice. At the same time, the full-length cDNA of beta-subunit of mouse chorionic gonadotropin (muCGbeta) was cloned from placenta and sequenced for the first time (GenBank Accession No. AF333067). Sequence analysis showed that muCGbeta shares 99.6% homology with rmCGbeta and 90.6% with hCGbeta respectively. The results indicated that the infertility of BALB/c mice induced by pCMV4-rmCGbeta contraceptive should be further studied as a CGbeta DNA contraceptive. (Mol Cell Biochem 231: 89-96, 2002)