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Background: Subjective Cognitive Decline (SCD) is the early preclinical stage of Alzheimer's Disease (AD). Previous study provided an invaluable contribution by showing that a tactile angle discrimination system can be used to distinguish between healthy older individuals and patients with mild cognitive impairment and AD. However, that study paid little attention to the relationship between tactile angle discrimination and SCD. Therefore, a means of differentiating Normal Controls (NCs), elderly subjects with SCD, patients with amnestic Mild Cognitive Impairment (aMCI), and AD is urgently needed. Methods: In the present study, we developed a novel tactile discrimination device that uses angle stimulation applied to the index finger pad to identify very small differences in angle discrimination between the NC (n = 30), SCD (n = 30), aMCI (n = 30), and AD (n = 30) groups. Using a three-alternative forced-choice and staircase method, we analyzed the average accuracy and threshold of angle discrimination. Results: We found that accuracy significantly decreased while thresholds of angle discrimination increased in the groups in the following order: NC, SCD, aMCI, and AD. The area under the receiver operating characteristic curve also indicated that the tactile angle discrimination threshold was better than Mini-Mental State Examination scores in distinguishing NC individuals and SCD patients. Conclusion: These findings emphasize the importance of tactile working memory dysfunction in explaining the cognitive decline in angle discrimination that occurs in SCD to AD patients and offer further insight into the very early detection of subjects with AD.

The frontoparietal network (FPN), including bilateral frontal eye field, inferior parietal sulcus, and supplementary motor area, has been linked to attention processing, including spatiotemporal and sensory modality domains. However, it is unclear whether FPN encodes representations of these domains that are generalizable across subdomains. We decomposed multivariate patterns of functional magnetic resonance imaging activity from 20 participants into domain-specific components and identified latent multivariate representations that generalized across subdomains. The 30 experimental conditions were organized into unimodal–bimodal and spatial–temporal models. We found that brain areas in the FPN, form the primary network that modulated during attention across domains. However, the activation patterns of areas within the FPN were reorganized according to the specific attentional demand, especially when pay attention to different sensory, suggesting distinct regional neural representations associated with specific attentional processes within FPN. In addition, there were also other domain-specific areas outside the FPN, such as the dorsolateral prefrontal cortex. Our conclusion is that, according to the results of the analysis of representation similarity, 2 types of activated brain regions, related to attention domain detailed information processing and general information processing, can be revealed.

Haptic object perception is still poorly understood up to now. This study investigated the ability of human fingers to discriminate the volume of objects by passive touch. Experiments measured the discrimination threshold of volume using three tasks: passive tactile volume perception, passive tactile area perception, and active tactile volume perception. In each trial, we utilized two plastic cubes to successively stimulate the fingers, and participants were instructed to make comparisons between the stimulus objects’ volume and area. Results showed that there was no significant difference in the discrimination thresholds of tactile volume perception between passive touch and active touch, whereas significant differences in the discrimination thresholds between fingertips, such as the thumb versus the pinky finger. In passive touch, the discrimination thresholds of volume perception were larger than that with surface area perception. We found that the discrimination of the volume of objects is more difficult than the discrimination of the area of the objects.

Auditory sensory memory indexed by mismatch negativity has been broadly studied over the past century, but far less attention has been directed to tactile sensory memory. To investigate whether tactile sensory memory is affected by attention, we recorded somatosensory mismatch negativity (sMMN) from 24 healthy adults in two experiments to distinguish sustained attention from non-sustained attention. Using the roving somatosensory oddball paradigm, we analyzed the average dynamic changes in the amplitude and latency of sMMN amplitude and found a clear sMMN component at the central region at a 100–300 ms interval. The sMMN amplitude, which indexes the early detection of tactile stimuli with the sensory memory trace, was larger in the tactile attentional task. Additionally, the sMMN latency increased with the increasing visual attentional load, which indicates a decay of tactile sensory memory. Our results indicate that the more attention resources are allocated for a tactile sensation, the more favorable it is to the generation of tactile sensory memory.

For early detection of dementia, the aging effect between young people and the elderly was studied by angle chip rearrangement experiments. As a comparison method, an error score was used. However, because it took time and effort to calculate the error score, we studied to develop a device that can automatically output error scores using a computer. The content of the experiment is to touch the angular stimulus with the fingertip and rearrange them in the order of magnitude of the angle. Experiments were conducted for young people and the elderly. We conducted two types of experiments, a small angular interval and a large angular interval. Angles of 20 ° to 32 ° were presented at 2 ° intervals, 20 ° to 44 ° at 4 ° intervals, angle stimulation at the left end (minimum) and right end (maximum) respectively fixed. As a result of experiments, the elderly people got bigger errors than young people. From this result, aging effect can be confirmed, time can be shortened compared to the conventional error score calculation method, and it was possible to gather a lot of data easily. Furthermore, in order to make this device one of the methods of diagnosing dementia, further improvements will need to be made and examined in the future.

Tactile stimuli can be distinguished based on their temporal features (e.g., duration, local frequency, and number of pulses), which are fundamental for vibrotactile frequency perception. Characterizing how the hemodynamic response changes in shape across experimental conditions is important for designing and interpreting fMRI studies on tactile information processing. In this study, we focused on periodic tactile stimuli with different temporal structures and explored the hemodynamic response function (HRF) induced by these stimuli. We found that HRFs were stimulus‐dependent in tactile‐related brain areas. Continuous stimuli induced a greater area of activation and a stronger and narrower hemodynamic response than intermittent stimuli with the same duration. The magnitude of the HRF increased with increasing stimulus duration. By normalizing the characteristics into topographic matrix, nonlinearity was obvious. These results suggested that stimulation patterns and duration within a cycle may be key characters for distinguishing different stimuli. We conclude that different temporal structures of tactile stimuli induced different HRFs, which are essential for vibrotactile perception and should be considered in fMRI experimental designs and analyses., We found that HRFs were stimulus‐dependent in tactile‐related brain areas. Stimulation patterns and duration within a cycle may be key characters for distinguishing different stimuli.

Humans exhibit a remarkable ability to discriminate variations in object volume based on natural haptic perception. The discrimination thresholds for the haptic volume perception of the whole hand are well known, but the discrimination thresholds for haptic volume perception of fingers and phalanges are still unknown. In the present study, two psychophysical experiments were performed to investigate haptic volume perception in various fingers and phalanges. The configurations of both experiments were completely dependent on haptic volume perception from the fingers and phalanges. The participants were asked to blindly discriminate the volume variation of regular solid objects in a random order by using the distal phalanx, medial phalanx, and proximal phalanx of their index finger, middle finger, ring finger, and little finger. The discrimination threshold of haptic volume perception gradually decreases from the little finger to the index finger as well as from the proximal phalanx to the distal phalanx. Overall, both the shape of the target and the part of the finger in contact with the target significantly influence the precision of haptic perception of volume. This substantial data set provides detailed and compelling perspectives on the haptic system, including for discrimination of the spatial size of objects and for performing more general perceptual processes.

A Correction to this paper has been published: https://doi.org/ https://doi.org/10.3758/s13414-020-02211-y

Schizophrenia patients exhibited a psychological abnormal appearance when they recognized objects related to themselves. This cognitive process is associated with self-referential processing. In this study, the self-referential memory (SRM) task was performed by 18 schizophrenia patients and 18 healthy controls. In the encoding stage of the SRM task, the behavioral experiment data and electroencephalogram (EEG) data were recorded in three experimental conditions (self-referential condition, other-referential condition, and physical condition). For data analysis, the electrophysiological performance of the time-frequency distribution, phase lag index (PLI) strengths, phase synchronization connectivity, and brain-network properties were assessed in schizophrenia patients compared to healthy controls. We found that schizophrenia patients exhibited abnormal alpha oscillation characteristics at the time of 100-300 ms poststimulus during the self-referential condition, which consisted of diminished time-frequency distributions over the prefrontal, parietal, and occipital regions; lower functional connectivity strengths of the PLI in the parietal and occipital areas; higher global efficiency and the lower characteristic path length; and nodal efficiency of local areas (increased nodal efficiency in temporal regions and decreased nodal efficiency in occipital region) for dynamic network topology properties. Furthermore, the evoked power of the alpha band during the self-referential condition was significantly correlated with the SRM bias score in the patients (r = 0.595, p = 0.009). These results provided electrophysiological evidence and supported the hypothesis that an abnormal alpha rhythm might be the principal factor of dysfunctional self-referential processing in schizophrenia patients.

Supplemental material, PEC878560 Supplemental Material for Discrimination Thresholds for Passive Tactile Volume Perception by Fingertips by Jian Zhang, Zhilin Zhang, Ritsu Go, Chunlin Li and Jinglong Wu in Perception

To investigate gender differences in functional connectivity during the unattended processing of facial expressions, we recorded visual mismatch negativity (vMMN) in 34 adults using a deviant-standard reverse oddball paradigm. Using wavelet analysis, we calculated the time-frequency (TF) power at each electrode associated with happy-deviant, sad-deviant, happy-standard and sad-standard conditions. We also calculated the phase lag index (PLI) between electrode pairs and analyzed the dynamic network topologies of the functional connectivity for happy and sad vMMNs in the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8–13 Hz), beta (13–30 Hz), and gamma (30–45 Hz) bands. The results showed that females induced stronger TF power and PLI values than males in only the alpha band over the whole brain regarding the vMMN. Moreover, females had a higher ratio of the number of connections between long-distance electrode pairs than males. While theoretical analysis of dynamic network topologies indicated that high node degree values were found in local brain regions of males and in almost the entire female brain, our findings suggested that female brain activation and connections between brain regions are not only stronger but also more widely distributed during the unattended processing of facial expressions than those in males.

Although it is well known about the position of attention in many cases from the gaze, the covert attention which showed that attention and position of gaze may different is still not clear. In order to understand where people are paying attention, it is necessary to think from something other than gaze information. Microsaccades are rapid eye movements that occur with extremely fine amplitude within fixation microtremor. Therefore, Microsaccades can be used there, as it is likely to occur when a stimulus is presented in the direction. However, since the relationship between spatial attention and microsaccades has not been studied sufficiently, we also confirmed spatial attention and microsaccades incidence by using classical posner task in this study. As a result, it was confirmed that there was a significant difference in reaction time when the viewing angle was 7 deg. Further comparison showed that the response time with valid conditions were significant faster than that with invalid conditions. However, no significant difference was found at a viewing angle of 20 deg, which might relate with the presentation rate. Therefore, it became clear that there is relevance to the occurrence frequency of microsaccades and the presence or absence of spatial attention.

Dementia is a kind of cognitive impairment, diagnostic methods and therapies are not well established at present. For the early detection of dementia, this study investigated the aging effect between young people and the elderly in sorting experiment of angular chips which is simpler than conventional angle discriminating devices. The content of the experiment is to touch the angle chip with the fingertips and rearrange them in the order of the degree of the angle. There are two types experiments in this study, small angles and large angles. Angles of 20° to 60° were presented at 2° intervals, angles of 60° to 150° were presented at 5° intervals, and angle chips at the left and right ends were fixed, respectively. Experiments showed that the elderly had greater errors than younger people. According to the results of the experiment, the aging effect was confirmed. In addition, it was possible to shorten the experimental time as compared with the conventional apparatus. Also, by targeting patients with dementia, it can be expected that the error will be further larger than in healthy elderly people. In order to make this device one of the methods of dementia diagnosis, it is necessary to further experiment and study in the future.

Humans exhibit a remarkable ability to discriminate variations in object volume based on natural haptic perception. The discrimination thresholds for the haptic volume perception of the whole hand are well known, but the discrimination thresholds for haptic volume perception of fingers and phalanges are still unknown. In the present study, two psychophysical experiments were performed to investigate haptic volume perception in various fingers and phalanges. The configurations of both experiments were completely dependent on haptic volume perception from the fingers and phalanges. The participants were asked to blindly discriminate the volume variation of regular solid objects in a random order by using the distal phalanx, medial phalanx, and proximal phalanx of their index finger, middle finger, ring finger, and little finger. The discrimination threshold of haptic volume perception gradually decreases from the little finger to the index finger as well as from the proximal phalanx to the distal phalanx. Overall, both the shape of the target and the part of the finger in contact with the target significantly influence the precision of haptic perception of volume. This substantial data set provides detailed and compelling perspectives on the haptic system, including for discrimination of the spatial size of objects and for performing more general perceptual processes.

In this paper, we constructed a novel stimulator system that can present quantitatively controllable air puffs for the research of the human somatosensory system with functional magnetic imaging (fMRI). The developed stimulator system consists of an adjustable stimulus regulating apparatus, and a control box, which is synchronized with fMRI. The system allows regulation of 1mm aperture position in both horizontal and vertical plane by using a special customized adjuster. In addition, the stimulus regulating apparatus can suit different experimental requirements and easily be fixed to and untied from the digits. This new adjustable pneumatic air-jet stimulator system is portable, easy-to-assemble, and economical. A validation fMRI experiment indicated that stimulate different phalanx were induced in activation of different somatosensory areas. The developed device is expected to be utilized for fMRI studies of the tactile system.

Audiovisual integration occurs frequently and has been shown to exhibit age-related differences via behavior experiments or time-frequency analyses. In the present study, we examined whether functional connectivity influences audiovisual integration during normal aging. Visual, auditory, and audiovisual stimuli were randomly presented peripherally; during this time, participants were asked to respond immediately to the target stimulus. Electroencephalography recordings captured visual, auditory, and audiovisual processing in 12 old (60–78 years) and 12 young (22–28 years) male adults. For non-target stimuli, we focused on alpha (8–13 Hz), beta (13–30 Hz), and gamma (30–50 Hz) bands. We applied the Phase Lag Index to study the dynamics of functional connectivity. Then, the network topology parameters, which included the clustering coefficient, path length, small-worldness global efficiency, local efficiency and degree, were calculated for each condition. For the target stimulus, a race model was used to analyze the response time. Then, a Pearson correlation was used to test the relationship between each network topology parameters and response time. The results showed that old adults activated stronger connections during audiovisual processing in the beta band. The relationship between network topology parameters and the performance of audiovisual integration was detected only in old adults. Thus, we concluded that old adults who have a higher load during audiovisual integration need more cognitive resources. Furthermore, increased beta band functional connectivity influences the performance of audiovisual integration during normal aging.