Takashi Tsukiura

Thinking of the future and past: the roles of the frontal pole and the medial temporal lobes

Human lesion data have indicated that the frontal polar area might be critically involved in having an insight into ones future. Retrospective memory mediated by medial temporal lobes and related structures, on the other hand, could be used to extract ones future prospects efficiently. In the present study, we investigated the roles of these two brain structures in thinking of the future and past by using positron emission tomography (PET) and a naturalistic task setting. We measured regional cerebral blood flow (rCBF) in healthy subjects while they were talking about their future prospects or past experiences, with regard to two different temporal windows (in years or days). Many areas in the frontal and the medial temporal lobes were activated during the future and past tasks compared with a control task requiring semantic retrieval. Among these, areas in anteromedial frontal pole showed greater activation during the future tasks than during the past tasks, showing significant effect of temporal distance from the present. Most areas in the medial temporal lobes showed greater or equivalent level of activations during the future tasks compared with the past tasks. The present results suggest that thinking of the future is closely related to retrospective memory, but that specific areas in the frontal pole and the medial temporal lobes are more involved with thinking of the future than that of the past.

Participation of the prefrontal cortices in prospective memory: evidence from a PET study in humans

Prospective memory is a memory feature in humans which involves activities for remembering to do something in the future. The present study provides functional neuroanatomy of prospective memory for the first time. We used positron emission tomography (PET) and found several localized brain activations in relation to a prospective memory task required to retain and remember a planned action while performing an ongoing routine activity. Activations were identified in the right dorsolateral and ventrolateral prefrontal cortices, the left frontal pole and anterior cingulate gyrus, the left parahippocampal gyrus, and midline medial frontal lobe. We attributed these activations to several cognitive processes involved in prospective memory, such as holding an intention toward future behavior, checking target items within presented stimuli, and dividing attention between the planned action and the routine activity.

Brain Training Game Improves Executive Functions and Processing Speed in the Elderly: A Randomized Controlled Trial

Background The beneficial effects of brain training games are expected to transfer to other cognitive functions, but these beneficial effects are poorly understood. Here we investigate the impact of the brain training game (Brain Age) on cognitive functions in the elderly. Methods and Results Thirty-two elderly volunteers were recruited through an advertisement in the local newspaper and randomly assigned to either of two game groups (Brain Age, Tetris). This study was completed by 14 of the 16 members in the Brain Age group and 14 of the 16 members in the Tetris group. To maximize the benefit of the interventions, all participants were non-gamers who reported playing less than one hour of video games per week over the past 2 years. Participants in both the Brain Age and the Tetris groups played their game for about 15 minutes per day, at least 5 days per week, for 4 weeks. Each group played for a total of about 20 days. Measures of the cognitive functions were conducted before and after training. Measures of the cognitive functions fell into four categories (global cognitive status, executive functions, attention, and processing speed). Results showed that the effects of the brain training game were transferred to executive functions and to processing speed. However, the brain training game showed no transfer effect on any global cognitive status nor attention. Conclusions Our results showed that playing Brain Age for 4 weeks could lead to improve cognitive functions (executive functions and processing speed) in the elderly. This result indicated that there is a possibility which the elderly could improve executive functions and processing speed in short term training. The results need replication in large samples. Long-term effects and relevance for every-day functioning remain uncertain as yet. Trial Registration UMIN Clinical Trial Registry 000002825

Shared brain activity for aesthetic and moral judgments: implications for the Beauty-is-Good stereotype

The Beauty-is-Good stereotype refers to the assumption that attractive people possess sociably desirable personalities and higher moral standards. The existence of this bias suggests that the neural mechanisms for judging facial attractiveness and moral goodness overlap. To investigate this idea, we scanned participants with functional magnetic resonance imaging while they made attractiveness judgments about faces and goodness judgments about hypothetical actions. Activity in the medial orbitofrontal cortex increased as a function of both attractiveness and goodness ratings, whereas activity in the insular cortex decreased with both attractiveness and goodness ratings. Within each of these regions, the activations elicited by attractiveness and goodness judgments were strongly correlated with each other, supporting the idea of similar contributions of each region to both judgments. Moreover, activations in orbitofrontal and insular cortices were negatively correlated with each other, suggesting an opposing relationship between these regions during attractiveness and goodness judgments. These findings have implications for understanding the neural mechanisms of the Beauty-is-Good stereotype.

Neural Basis of the Retrieval of People's Names: Evidence from Brain-Damaged Patients and fMRI

The aim of this study was to identify the neuroanatomical basis of the retrieval of peoples names. Lesion data showed that patients with language-dominant temporal lobectomy had impairments in their ability to retrieve familiar and newly learned peoples names, whereas patients with language-nondominant temporal lobectomy had difficulty retrieving newly learned peoples names. Functional magnetic resonance imaging experiments revealed activations in the left temporal polar region during the retrieval of familiar and newly learned peoples names, and in the right superior temporal and bilateral prefrontal cortices during the retrieval of newly learned information from face cues. These data provide new evidence that the left anterior temporal region is crucial for the retrieval of peoples names irrespective of their familiarity and that the right superior temporal and bilateral prefrontal areas are crucial for the process of associating newly learned peoples faces and names.

Neural Basis of Temporal Context Memory: A Functional MRI Study

Temporal context information is crucial to understanding human episodic memory. Human lesion and neuroimaging data indicate that prefrontal regions are important for retrieving temporal context memory, although the exact nature of their involvement is still unclear. We employed functional magnetic resonance imaging (fMRI) to elucidate the neural basis of two kinds of temporal context memory: the temporal order of items between lists and within a list. On the day of the fMRI experiment, subjects memorized a list of 30 pictures in the morning and another list of 30 pictures in the afternoon. During the scanning session, the subjects performed three tasks. In a between-lists task, they were asked to judge the temporal order between two items that had been presented in different lists. In a within-list task, they were asked to judge the temporal order between two items that had been presented in a single list. We found bilateral prefrontal activities during these two temporal context memory tasks compared with a simple item-recognition task. Furthermore, in direct comparison between these two tasks, we found differential prefrontal activities. Thus, right prefrontal activity was associated with temporal order judgment of items between lists, whereas left prefrontal activity was related to temporal order judgment of items within a list. These results indicate that retrieval processes of two kinds of temporal context memory are supported by different, but overlapping, sets of cerebral regions. We speculate that this reflects different cognitive processes for retrieving temporal context memory between separate episodes and within a single episode.

Neuroanatomical discrimination between manipulating and maintaining processes involved in verbal working memory; a functional MRI study

We used functional magnetic resonance imaging (fMRI) to investigate neural correlates of processes concerning store and manipulation in verbal working memory. We prepared a revised lag 1 digit span, digit span and a simple number detection task. Specific activities in association with manipulating process were identified in the right middle (BA 9/46) and left precentral gyrus (BA 6). Activated areas specific to maintaining process were detected in the right middle (right BA 11/10) and medial (BA 6) frontal gyri, the right inferior parietal lobule (BA 40), and the left middle (BA 9) and inferior frontal gyri (BA 44). The process-nonspecific activated areas common to two processes were identified in the right inferior frontal gyrus (BA 47) and the left superior parietal lobule (BA 7). Using the signal percent change of each subject, we calculated the correlation coefficients among each activated area. The results of this analysis showed that two processes of verbal working memory were clearly discriminated. The two essential processes of manipulation and maintenance in working memory seem to activate process-specific and overlapping (process-nonspecific) areas, but the patterns of combination were definitely different.

Remembering beauty: Roles of orbitofrontal and hippocampal regions in successful memory encoding of attractive faces

Behavioral data have shown that attractive faces are better remembered but the neural mechanisms of this effect are largely unknown. To investigate this issue, female participants were scanned with event-related functional MRI (fMRI) while rating the attractiveness of male faces. Memory for the faces was tested after fMRI scanning and was used to identify successful encoding activity (subsequent memory paradigm). As expected, attractive faces were remembered better than other faces. The study yielded three main fMRI findings. First, activity in the right orbitofrontal cortex increased linearly as a function of attractiveness ratings. Second, activity in the left hippocampus increased as a function of subsequent memory (subsequent misses<low confidence hits<high confidence hits). Third, functional connectivity between these orbitofrontal and hippocampal regions was stronger during the encoding of attractive than neutral or unattractive faces. These results suggest that better memory for attractive faces reflects greater interaction between a region associated with reward, the orbitofrontal cortex, and a region associated with successful memory encoding, the hippocampus.

Proper name anomia after left temporal lobectomy: A patient study

Article abstract A patient with a selective deficit in retrieving proper names after left temporal lobectomy is reported. He showed proper name anomia in conversation, in response to photographs, and in verbal descriptions, despite being able to provide semantic information about the people he was unable to name. This report provides evidence that the rostral part of the left temporal lobe plays a crucial role in processing proper names without involvement of other verbal functions.

Distinguishing the Neural Correlates of Episodic Memory Encoding and Semantic Memory Retrieval

Episodic memory and semantic memory interact very closely. In particular, episodic memory encoding (EE) tends to elicit semantic memory retrieval (SR), and vice versa. Thus, similar activations for EE and SR in functional neuroimaging studies may reflect shared memory processes, or they may reflect the fact that EE and SR are usually confounded. To address this issue, we used a factorial functional magnetic resonance imaging approach to disentangle the neural correlates of EE and SR. Within the left temporal lobe, the hippocampus was associated with successful EE, whereas a posterior lateral region was associated with successful SR. Within the left inferior prefrontal cortex, a posterior region was involved in SR, a mid region was involved in both SR and EE, and an anterior region was involved in EE, but only when SR was also high. Thus, the neural correlates of EE and SR are dissociable but interact in specific brain regions.