Cross-cultural differences in the neural correlates of specific and general recognition

Effects of Age on Cross-Cultural Differences in the Neural Correlates of Memory Retrieval

Culture can shape memory, but little research investigates age effects. The present study examines the neural correlates of memory retrieval for old, new, and similar lures in younger and older Americans and Taiwanese. Results show that age and culture impact discrimination of old from new items. Taiwanese performed worse than Americans, with age effects more pronounced for Taiwanese. Americans activated the hippocampus for new more than old items, but pattern of activity for the conditions did not differ for Taiwanese, nor did it interact with age. The engagement of left inferior frontal gyrus (LIFG) differed across cultures. Patterns of greater activity for old (for Americans) or new (for Taiwanese) items were eliminated with age, particularly for older Americans. The results are interpreted as reflecting cultural differences in orientation to novelty vs. familiarity for younger, but not older, adults, with the LIFG supporting interference resolution at retrieval. Support is not as strong for cultural differences in pattern separation processes. Although Americans had higher levels of memory discrimination than Taiwanese and engaged the LIFG for correct rejections more than false alarms, the patterns of behavior and neural activity did not interact with culture and age. Neither culture nor age impacted hippocampal activity, which is surprising given the region's role in pattern separation. The findings suggest ways in which cultural life experiences and concomitant information processing strategies can contribute to consistent effects of age across cultures or contribute to different trajectories with age in terms of memory.

Do cultural differences emerge at different levels of representational hierarchy?

In prior research, Eastern and Western culture groups differ in memory specificity for objects. However, these studies used concrete object stimuli, which carry semantic information that may be confounded with culture. Additionally, the perceptual properties of the stimuli were not tightly controlled. Therefore, it cannot be precisely determined whether the observed cross-cultural differences are generalizable across different stimulus types and memory task demands. In prior studies, Americans demonstrated higher memory specificity than East Asians, but this may be due to Americans being more attuned to the low-level features that distinguish studied items from similar lures, rather than general memory differences. To determine whether this pattern of cross-cultural memory differences emerges irrespective of stimulus properties, we tested American and East Asian young adults using a recognition memory task employing abstract stimuli for which attention to conjunctions of features was critical for discrimination. Additionally, in order to more precisely determine the influence of stimulus and task on culture differences, participants also completed a concrete objects memory task identical to the one used in prior research. The results of the abstract objects task mirror the pattern seen in prior studies with concrete objects: Americans showed generally higher levels of recognition memory performance than East Asians for studied abstract items, whether discriminating them from similar or entirely new items. Results from the current concrete object task generally replicated this pattern. This suggests cross-cultural memory differences generalize across stimulus types and task demands, rather than reflecting differential sensitivity to low-level features or higher-level conjunctions.

Cross-cultural comparison of the neural correlates of true and false memory retrieval

Prior work has shown Americans have higher levels of memory specificity than East Asians. Neuroimaging studies have not investigated mechanisms that account for cultural differences at retrieval. In this study, we use fMRI to assess whether mnemonic discrimination, distinguishing novel from previously encountered stimuli, accounts for cultural differences in memory. Fifty-five American and 55 Taiwanese young adults completed an object recognition paradigm testing discrimination of old targets, similar lures and novel foils. Mnemonic discrimination was tested by comparing discrimination of similar lures from studied targets, and results showed the relationship between activity in left fusiform gyrus and behavioural discrimination between target and lure objects differed across cultural groups. Parametric modulation analyses of activity during lure correct rejections also indicated that groups differed in left superior parietal cortex response to variations in lure similarity. Additional analyses of old vs. new activity indicated that Americans and Taiwanese differ in the neural activity supporting general object recognition in the hippocampus, left inferior frontal gyrus and middle frontal gyrus. Results are juxtaposed against comparisons of the regions activated in common across the two cultures. Overall, Americans and Taiwanese differ in the extent to which they recruit visual processing and attention modulating brain regions.

Functional connectivity with medial temporal regions differs across cultures during post-encoding rest

Connectivity of the brain at rest can reflect individual differences and impact behavioral outcomes, including memory. The present study investigated how culture influences functional connectivity with regions of the medial temporal lobe. In this study, 46 Americans and 59 East Asians completed a resting state scan after encoding pictures of objects. To investigate cross-cultural differences in resting state functional connectivity, left parahippocampal gyrus (anterior and posterior regions) and left hippocampus were selected as seed regions. These regions were selected, because they were previously implicated in a study of cultural differences during the successful encoding of detailed memories. Results revealed that left posterior parahippocampal gyrus had stronger connectivity with temporo-occipital regions for East Asians compared with Americans and stronger connectivity with parieto-occipital regions for Americans compared with East Asians. Left anterior parahippocampal gyrus had stronger connectivity with temporal regions for East Asians than Americans and stronger connectivity with frontal regions for Americans than East Asians. Although connectivity did not relate to memory performance, patterns did relate to cultural values. The degree of independent self-construal and subjective value of tradition were associated with functional connectivity involving left anterior parahippocampal gyrus. Findings are discussed in terms of potential cultural differences in memory consolidation or more general trait or state-based processes, such as holistic versus analytic processing.

An Introduction to Musical Interactions

The article presents a contextual survey of eight contributions in the special issue Musical Interactions (Volume I) in Multimodal Technologies and Interaction. The presentation includes (1) a critical examination of what it means to be musical, to devise the concept of music proper to MTI as well as multicultural proximity, and (2) a conceptual framework for instrumentation, design, and assessment of musical interaction research through five enabling dimensions: Affordance; Design Alignment; Adaptive Learning; Second-Order Feedback; Temporal Integration. Each dimension is discussed and applied in the survey. The results demonstrate how the framework provides an interdisciplinary scope required for musical interaction, and how this approach may offer a coherent way to describe and assess approaches to research and design as well as implementations of interactive musical systems. Musical interaction stipulates musical liveness for experiencing both music and technologies. While music may be considered ontologically incomplete without a listener, musical interaction is defined as ontological completion of a state of music and listening through a listener’s active engagement with musical resources in multimodal information flow.

Cross-Cultural Differences in Memory Specificity: Investigation of Candidate Mechanisms

Previous research has revealed that people from Western cultures tend to remember more details of objects and events in autobiographical memory compared to people from Eastern cultures. The present experiments tested whether differences in pattern separation - the process by which new, but potentially similar, exemplars are discriminated from previously-encountered exemplars - account for these cultural difference in object memory. In two experiments, we investigated the extent to which North Americans and East Asians differ in pattern separation and whether these effects are related to cultural values. We also examined the role of response bias. These results revealed it is unlikely that pattern separation is the sole mechanism underlying cross-cultural memory specificity differences, as broader memory mechanisms, such as differences in memory resolution for previously-encoded items, could account for the differences observed between groups.

Cross-Cultural Comparison of Rural Healthy Adults: Russian and American Groups

OBJECTIVE

The Russian-speaking population is among the largest European-born in the U.S., yet Russian-American cross-cultural research is scarce. Two studies compared neuropsychological test performance in Russian and American urban adults. However, rural populations of the two nations have never been compared. Cross-cultural neuropsychological differences in rural populations might present differently than in urban dwellers. The present study provides a cross-sectional comparison of neuropsychological test performance in Russian and American rural adults.

METHODS

Neuropsychological test performance of 51 American (67% female) and 52 Russian (60% female) healthy rural adults age 18-89 was compared using t-test with Bonferroni correction for education-adjusted z-scores for the following tests: Rey Complex Figure Test (RCFT), Rey Auditory Verbal Learning Test (RAVLT), Trail Making Test A and B (TMT A&B), Stroop Neuropsychological Screening Test, Benton Judgment of Line Orientation Test (JLO), Brief Visuospatial Memory Test-Revised (BVMT-R), Color Trails Test 1 and 2 (CTT 1&2), WMS-IV Logical Memory Test (LMT), WAIS-IV Digit Span Forward (DSF) and Backward Test (DSB), and Symbol Digit Modalities Test (SDMT).

RESULTS

Age and sex distribution did not differ in the two groups, but the Russian group was more highly educated. The American group outperformed the Russian group on TMT B, CTT 2, recognition trials of RCFT, BVMT-R, LMT, and on DSF.

CONCLUSIONS

Cultural differences in attitudes to timed activities, experience with timed tests and multiple-choice format, attention to details, and length of digit-words that put differential demand on short-term memory in Russian and in English may mediate observed between-group differences.

Healthy individuals vs patients with bipolar or unipolar depression in gray matter volume

BACKGROUND

Previous studies using voxel-based morphometry (VBM) revealed changes in gray matter volume (GMV) of patients with depression, but the differences between patients with bipolar disorder (BD) and unipolar depression (UD) are less known.

AIM

To analyze the whole-brain GMV data of patients with untreated UD and BD compared with healthy controls.

METHODS

Fourteen patients with BD and 20 with UD were recruited from the Mental Health Center of Shantou University between August 2014 and July 2015, and 20 non-depressive controls were recruited. After routine three-plane positioning, axial T2WI scanning was performed. The connecting line between the anterior and posterior commissures was used as the scanning baseline. The scanning range extended from the cranial apex to the foramen magnum. Categorical data are presented as frequencies and were analyzed using the Fisher exact test.

RESULTS

There were no significant intergroup differences in gender, age, or years of education. Disease course, age at the first episode, and Hamilton depression rating scale scores were similar between patients with UD and those with BD. Compared with the non-depressive controls, patients with BD showed smaller GMVs in the right inferior temporal gyrus, left middle temporal gyrus, right middle occipital gyrus, and right superior parietal gyrus and larger GMVs in the midbrain, left superior frontal gyrus, and right cerebellum. In contrast, UD patients showed smaller GMVs than the controls in the right fusiform gyrus, left inferior occipital gyrus, left paracentral lobule, right superior and inferior temporal gyri, and the right posterior lobe of the cerebellum, and larger GMVs than the controls in the left posterior central gyrus and left middle frontal gyrus. There was no difference in GMV between patients with BD and UD.

CONCLUSION

Using VBM, the present study revealed that patients with UD and BD have different patterns of changes in GMV when compared with healthy controls.

Common and unique effects of HD-tDCS to the social brain across cultural groups

Cultural background influences social cognition, however no study has examined brain stimulation differences attributable to cultural background. 104 young adults [52 South-East Asian Singaporeans (SEA); 52 Caucasian Australians (CA)] received anodal high-definition transcranial direct current stimulation (HD-tDCS) to the dorsomedial prefrontal cortex (dmPFC) or the right temporoparietal junction (rTPJ). Participants completed tasks with varying demands on self-other processing including visual perspective taking (VPT)and episodic memory with self and other encoding. At baseline, SEA showed greater self-other integration than CA in the level one (line-of-sight) VPT task as indexed by greater interference from the alternate perspective. Anodal HD-tDCS to the dmPFC resulted in the CA performing closer to the SEA during egocentric perspective judgements. Baseline performance on level two (embodied rotation) VPT task and the self-reference effect (SRE) in episodic memory was comparable between the two groups. In the combined sample, HD-tDCS to the rTPJ decreased the interference from the egocentric perspective during level two VPT and dmPFC HD-tDCS removed the SRE in episodic memory. Stimulation effects were comparable when baseline performance was comparable. When baseline performance differed, stimulation differences were identified. Therefore, social cognitive differences due to cultural background are an important consideration in social brain stimulation studies.

Cultural specialization of visual cortex

A growing body of evidence suggests culture influences how individuals perceive the world around them. This study investigates whether these cultural differences extend to a simple object viewing task and visual cortex by examining voxel pattern representations with multi-voxel pattern analysis (MVPA). During functional magnetic resonance imaging scanning, 20 East Asian and 20 American participants viewed photos of everyday items, equated for familiarity and conceptual agreement across cultures. Whole brain searchlight mapping with non-parametric statistical evaluation tested whether these stimuli evoked multi-voxel patterns that were distinct between cultural groups. We found that participants' cultural identities were successfully predicted from stimuli representations in visual cortex Brodmann areas 18 and 19. This result demonstrates culturally specialized visual cortex during a basic perceptual task ubiquitous to everyday life.

Directional associations between memory impairment and depressive symptoms: data from a longitudinal sample and meta-analysis

BACKGROUND

Previous cross-lagged studies on depression and memory impairment among the elderly have revealed conflicting findings relating to the direction of influence between depression and memory impairment. The current study aims to clarify this direction of influence by examining the cross-lagged relationships between memory impairment and depression in an Asian sample of elderly community dwellers, as well as synthesizing previous relevant cross-lagged findings via a meta-analysis.

METHODS

A total of 160 participants (Mage = 68.14, s.d. = 5.34) were assessed across two time points (average of 1.9 years apart) on measures of memory and depressive symptoms. The data were then fitted to a structural equation model to examine two cross-lagged effects (i.e. depressive symptoms→memory; memory→depressive symptoms). A total of 14 effect-sizes for each of the two cross-lagged directions were extracted from six studies (including the present; total N = 8324). These effects were then meta-analyzed using a three-level mixed effects model.

RESULTS

In the current sample, lower memory ability at baseline was associated with worse depressive symptoms levels at follow-up, after controlling for baseline depressive symptoms. However, the reverse effect was not significant; baseline depressive symptoms did not predict subsequent memory ability after controlling for baseline memory. The results of the meta-analysis revealed the same pattern of relationship between memory and depressive symptoms.

CONCLUSIONS

These results provide robust evidence that the relationship between memory impairment and depressive symptoms is unidirectional; memory impairment predicts subsequent depressive symptoms but not vice-versa. The implications of these findings are discussed.

Influence of encoding instructions and response bias on cross-cultural differences in specific recognition

Prior cross-cultural research has reported cultural variations in memory. One study revealed that Americans remembered images with more perceptual detail than East Asians (Millar et al. in Cult Brain 1(2-4):138-157, 2013). However, in a later study, this expected pattern was not replicated, possibly due to differences in encoding instructions (Paige et al. in Cortex 91:250-261, 2017). The present study sought to examine when cultural variation in memory-related decisions occur and the role of instructions. American and East Asian participants viewed images of objects while making a Purchase decision or an Approach decision and later completed a surprise recognition test. Results revealed Americans had higher hit rates for specific memory, regardless of instruction type, and a less stringent response criterion relative to East Asians. Additionally, a pattern emerged where the Approach decision enhanced hit rates for specific memory relative to the Purchase decision only when administered first; this pattern did not differ across cultures. Results suggest encoding instructions do not magnify cross-cultural differences in memory. Ultimately, cross-cultural differences in response bias, rather than memory sensitivity per se, may account for findings of cultural differences in memory specificity.