There is a growing interest in the parietal cortical role for episodic memory retrieval. Previous functional magnetic resonance imaging (fMRI) studies of recency judgments, judgments of the relative temporal order of two studied items, have highlighted the involvement of the lateral prefrontal and medial temporal regions. However, the parietal cortical contribution to recency judgments has rarely been highlighted. To examine the parietal involvement, in this study, we conducted a re-analysis to increase the statistical power using three data sets (N=73) from our previous fMRI studies of recency judgments. Recency judgments can be achieved by at least two mechanisms, relational and item-based ones. It has been revealed that the left hippocampus/parahippocampal region is related to relational recency judgments, and that the right anterior temporal region is related to item-based recency judgments. We examined whether the parietal cortex is involved in these two types of recency judgments. Significant brain activity related to relational recency judgments was observed in the left ventral parietal region and, as reported previously, the left parahippocampal region. On the other hand, significant brain activity related to item-based recency judgments was observed in the left dorsal parietal region and, as reported previously, the right anterior temporal region. Furthermore, correlation analyses of resting-state BOLD signals detected significant correlations between the ventral parietal region and the parahippocampal region, as well as between the dorsal parietal region and anterior temporal region. These results suggest that the two temporo-parietal networks differentially contribute to relational and item-based recency judgments.

Flexible adaptation to changing environments requires shifting of a cognitive set, one basic function of the prefrontal cortex. Set shifting, as instantiated in the Wisconsin Card Sorting Task (WCST) administered in a neuropsychological testing room, is typically achieved when subjects have no prior experiences of updating one WCST behavior to another. By contrast, earlier neuroimaging studies typically involved examination of repeated transitions between particular behaviors, to which situation subjects are far from naive. Naive subjects with no prior knowledge of the WCST were recruited in the present functional magnetic resonance imaging study to test set shifting under unknown situations that they experienced for the first time. Prominent activation was revealed in the left superior prefrontal cortex selectively on the initial shifts. On the other hand, the inferior prefrontal cortex was significantly activated on both the initial and subsequent shifts. The superior prefrontal activation distinguishable from the conventional inferior prefrontal activation suggests a selective role of this region in performance of the WCST in naive subjects.

Interference by amygdalar activity in perceptual processes has been reported in many previous studies. Consistent with these reports, previous clinical studies have shown amygdalar volume change in multiple types of psychotic disease presenting with unusual perception. However, the relationship between variation in amygdalar volume in the normal population and the tendency toward unusual or unique perception has never been investigated. To address this issue, we defined an index to represent the tendency toward unique perception using ambiguous stimuli: subjects were instructed to state what the figures looked like to them, and "unique responses" were defined depending on the appearance frequency of the same responses in an age- and gender-matched control group. The index was defined as the ratio of unique responses to total responses per subject. We obtained structural brain images and values of the index from sixty-eight normal subjects. Voxel-based morphometry analyses revealed a positive correlation between amygdalar volume and the index. Since previous reports have indicated that unique responses were observed at higher frequency in the artistic population than in the nonartistic normal population, this positive correlation suggests that amygdalar enlargement in the normal population might be related to creative mental activity.

The mammalian tongue contains gustatory receptors tuned to basic taste types, providing an evolutionarily old hedonic compass for what and what not to ingest. Although representation of these distinct taste types is a defining feature of primary gustatory cortex in other animals, their identification has remained elusive in humans, leaving the demarcation of human gustatory cortex unclear. Here we used distributed multivoxel activity patterns to identify regions with patterns of activity differentially sensitive to sweet, salty, bitter, and sour taste qualities. These were found in the insula and overlying operculum, with regions in the anterior and middle insula discriminating all tastes and representing their combinatorial coding. These findings replicated at super-high 7 T field strength using different compounds of sweet and bitter taste types, suggesting taste sensation specificity rather than chemical or receptor specificity. Our results provide evidence of the human gustatory cortex in the insula.

Functional areas in sensory/motor cortices are usually organized, on a finer scale, in a seamless manner along related functional units that represent, for example, certain visual fields to analyze and certain body parts to control. However, fine-scale functional organization in the prefrontal cortex has rarely been reported. In the present functional magnetic resonance imaging study, we show an example of sub-centimeter scale functional organization in the posterior part of the inferior frontal gyrus (IFG) in the right hemisphere. The spatial relationship was examined in the same subjects with regard to the activations associated with response inhibition and negative feedback processing, which are known to activate similar right IFG regions. We found that these activations were segregated, the activation during response inhibition being more caudal than that during feedback processing, and that the distance between the two activations was only 8.7 mm. Examination of the two-dimensional surface mapping of individual subjects confirmed that the two activations were located in adjacent but different regions. These results provide a specific example of a pair of functionally characterized regions that are located in the close vicinity within the right IFG.

Multivoxel pattern analysis (MVPA) has become a standard tool for decoding mental states from brain activity patterns. Recent studies have demonstrated that MVPA can be applied to decode activity patterns of a certain region from those of the other regions. By applying a similar region-to-region decoding technique, we examined whether the information represented in the visual areas can be explained by those represented in the other visual areas. We first predicted the brain activity patterns of an area on the visual pathway from the others, then subtracted the predicted patterns from their originals. Subsequently, the visual features were derived from these residuals. During the visual perception task, the elimination of the top-down signals enhanced the simple visual features represented in the early visual cortices. By contrast, the elimination of the bottom-up signals enhanced the complex visual features represented in the higher visual cortices. The directions of such modulation effects varied across visual perception/imagery tasks, indicating that the information flow across the visual cortices is dynamically altered, reflecting the contents of visual processing. These results demonstrated that the distillation approach is a useful tool to estimate the hidden content of information conveyed across brain regions.

Functional MRI (fMRI) has been instrumental in understanding how cognitive processes are spatially mapped in the brain, yielding insights about brain regions and functions. However, in case the orthogonality of behavioral or stimulus timing is not guaranteed, the estimated brain maps fail to dissociate each cognitive process, and the resultant maps become unstable. Also, the brain mapping exercise can not provide temporal information on the cognitive process. Here we propose a qualitatively different approach to fMRI analysis, named Cognitive Dynamics Estimation (CDE), that estimates how multiple cognitive processes change over time even when behavior or stimulus logs are unavailable. This method transposes the conventional brain mapping; the brain activity pattern at each time point is subject to regression analysis with data-driven maps of cognitive processes as regressors, resulting in the time series of cognitive processes. The estimated time series captured the fluctuation of intensity and timing of cognitive processes on a trial-by-trial basis, which conventional analysis could not capture. Notably, the estimated time series predicted participants' cognitive ability to perform each psychological task. As an addition to our fMRI analytic toolkit, these results suggest the potential for CDE to elucidate underexplored cognitive phenomena, especially in the temporal domain.

It remains unclear how the brain represents external objective sensory events alongside our internal subjective impressions of them--affect. Representational mapping of population activity evoked by complex scenes and basic tastes in humans revealed a neural code supporting a continuous axis of pleasant-to-unpleasant valence. This valence code was distinct from low-level physical and high-level object properties. Although ventral temporal and anterior insular cortices supported valence codes specific to vision and taste, both the medial and lateral orbitofrontal cortices (OFC) maintained a valence code independent of sensory origin. Furthermore, only the OFC code could classify experienced affect across participants. The entire valence spectrum was represented as a collective pattern in regional neural activity as sensory-specific and abstract codes, whereby the subjective quality of affect can be objectively quantified across stimuli, modalities and people.

Application of multivoxel pattern analysis (MVPA) to functional magnetic resonance imaging (fMRI) data enables reconstruction and classification of cognitive status from brain activity. However, previous studies using MVPA have extracted information about cognitive status that is experienced simultaneously with fMRI scanning, but not one that will be observed after the scanning. In this study, by focusing on activity in the medial temporal lobe (MTL), we demonstrate that MVPA on fMRI data is capable of predicting subsequent recognition performance. In this experiment, six runs of fMRI signals were acquired during encoding of phonogram stimuli. In the analysis, using data acquired in runs 1-3, we first conducted MVPA-based voxel-wise search for the clusters in the MTL whose signals contained the most information about subsequent recognition performance. Next, using the fMRI signals acquired in runs 1-3 from the selected clusters, we trained a classifier function in MVPA. Finally, the trained classifier function was applied to fMRI signals acquired in runs 4-6. Consequently, we succeeded in predicting the subsequent recognition performance for stimuli studied in runs 4-6 with significant accuracy. This accurate prediction suggests that MVPA can extract information that is associated not only with concurrent cognitive status, but also with behavior in the near future.

Unique mode of perception, or the ability to see things differently from others, is one of the psychological resources required for creative mental activities. Behavioral studies using ambiguous visual stimuli have successfully induced diverse responses from subjects, and the unique responses defined in this paradigm were observed in higher frequency in the artistic population as compared to the nonartistic population. However, the neural substrates that underlie such unique perception have yet to be investigated. In the present study, ten ambiguous figures were used as stimuli. The subjects were instructed to say what the figures looked like during functional MRI scanning. The responses were classified as "frequent", "infrequent" or "unique" responses based on the appearance frequency of the same response in an independent age- and gender-matched control group. An event-related analysis contrasting unique vs. frequent responses revealed the greatest activation in the right temporal pole, which survived a whole brain multiple comparison. An alternative parametric modulation analysis was also performed to show that potentially confounding perceptual effects deriving from differences in visual stimuli make no significant contribution to this temporopolar activation. Previous neuroimaging and neuropsychological studies have shown the involvement of the temporal pole in perception-emotion linkage. Thus, our results suggest that unique perception is produced by the integration of perceptual and emotional processes, and this integration might underlie essential parts of creative mental activities.

The non-stationarity of resting-state brain activity has received increasing attention in recent years. Functional connectivity (FC) analysis with short sliding windows and coactivation pattern (CAP) analysis are two widely used methods for assessing the dynamic characteristics of brain activity observed with functional magnetic resonance imaging (fMRI). However, the statistical nature of the dynamics captured by these techniques needs to be verified. In this study, we found that the results of CAP analysis were similar for real fMRI data and simulated stationary data with matching covariance structures and spectral contents. We also found that, for both the real and simulated data, CAPs were clustered into spatially heterogeneous modules. Moreover, for each of the modules in the real data, a spatially similar module was found in the simulated data. The present results suggest that care needs to be taken when interpreting observations drawn from CAP analysis as it does not necessarily reflect non-stationarity or a mixture of states in resting brain activity.