A novel method for estimating connectivity‐based parcellation of the human brain from diffusion MRI: Application to an aging cohort

Connectivity‐based parcellation (CBP) methods are used to define homogenous and biologically meaningful parcels or nodes—the foundations of brain network fingerprinting—by grouping voxels with similar patterns of brain connectivity. However, we still lack a gold standard method and the use of CBPs to study the aging brain remains scarce. Our study proposes a novel CBP method from diffusion MRI data and shows its potential to produce a more accurate characterization of the longitudinal alterations in brain network topology occurring in aging. For this, we constructed whole‐brain connectivity maps from diffusion MRI data of two datasets: an aging cohort evaluated at two timepoints (mean interval time: 52.8 ± 7.24 months) and a normative adult cohort—MGH‐HCP. State‐of‐the‐art clustering techniques were used to identify the best performing technique. Furthermore, we developed a new metric (connectivity homogeneity fingerprint [CHF]) to evaluate the success of the final CBP in improving regional/global structural connectivity homogeneity. Our results show that our method successfully generates highly homogeneous parcels, as described by the significantly larger CHF score of the resulting parcellation, when compared to the original. Additionally, we demonstrated that the developed parcellation provides a robust anatomical framework to assess longitudinal changes in the aging brain. Our results reveal that aging is characterized by a reorganization of the brain''s structural network involving the decrease of intra‐hemispheric, increase of inter‐hemispheric connectivity, and topological rearrangement. Overall, this study proposes a new methodology to perform accurate and robust evaluations of CBP of the human brain.     

Comparison of cerebral activation between motor execution and motor imagery of self-feeding activity

Motor imagery is defined as an act wherein an individual contemplates a mental action of motor execution without apparent action. Mental practice executed by repetitive motor imagery can improve motor performance without simultaneous sensory input or overt output. We aimed to investigate cerebral hemodynamics during motor imagery and motor execution of a self-feeding activity using chopsticks. This study included 21 healthy right-handed volunteers. The self-feeding activity task comprised either motor imagery or motor execution of eating sliced cucumber pickles with chopsticks to examine eight regions of interest: pre-supplementary motor area, supplementary motor area, bilateral prefrontal cortex, premotor area, and sensorimotor cortex. The mean oxyhemoglobin levels were detected using near-infrared spectroscopy to reflect cerebral activation. The mean oxyhemoglobin levels during motor execution were significantly higher in the left sensorimotor cortex than in the supplementary motor area and the left premotor area. Moreover, significantly higher oxyhemoglobin levels were detected in the supplementary motor area and the left premotor area during motor imagery, compared to motor execution. Supplementary motor area and premotor area had important roles in the motor imagery of self-feeding activity. Moreover, the activation levels of the supplementary motor area and the premotor area during motor execution and motor imagery are likely affected by intentional cognitive processes. Levels of cerebral activation differed in some areas during motor execution and motor imagery of a self-feeding activity. This study was approved by the Ethical Review Committee of Nagasaki University(approval No. 18110801) on December 10, 2018.     

Saliency-guided neural prosthesis for visual attention: Design and simulation

Recently the authors showed that a computational model of visual saliency could account for changes in gaze behavior of monkeys with damage in the primary visual cortex. Here we propose a neural prosthesis to restore eye gaze behavior by electrically stimulating the superior colliculus to drive visual attention. The saliency computational model is used to calculate the stimulation parameters from a real-time camera stream. Our simulations demonstrate that electrodes implanted in the superior colliculus at 1.0 mm spacing are, in principle, able to recover specifically those visual attention behaviors which are lost when the primary visual cortex is damaged.     

The Muscle Sensor for on-site neuroscience lectures to pave the way for a better understanding of brain–machine-interface research

Neuroscience is an expanding field of science to investigate enigmas of brain and human body function. However, the majority of the public have never had the chance to learn the basics of neuroscience and new knowledge from advanced neuroscience research through hands-on experience. Here, we report that we produced the Muscle Sensor, a simplified electromyography, to promote educational understanding in neuroscience. The Muscle Sensor can detect myoelectric potentials which are filtered and processed as 3-V pulse signals to shine a light bulb and emit beep sounds. With this educational tool, we delivered “On-Site Neuroscience Lectures” in Japanese junior-high schools to facilitate hands-on experience of neuroscientific electrophysiology and to connect their text-book knowledge to advanced neuroscience researches. On-site neuroscience lectures with the Muscle Sensor pave the way for a better understanding of the basics of neuroscience and the latest topics such as how brain–machine-interface technology could help patients with disabilities such as spinal cord injuries.     

Event‐related potentials in response to cheating and cooperation in a social dilemma game

A sequential prisoner's dilemma game was combined with psychophysiological measures to examine the cognitive underpinnings of reciprocal exchange. Participants played four rounds of the game with partners who either cooperated or cheated. In a control condition, the partners’ faces were shown, but no interaction took place. The partners’ behaviors were consistent in the first three rounds of the game, but in the last round some of the partners unexpectedly changed strategies. In the first round of the game, the feedback about a partner's decision elicited a feedback P300, which was more pronounced for cooperation and cheating in comparison to the control condition, but did not vary as a function of feedback valence. In the last round, both the feedback negativity and the feedback P300 were sensitive to expectancy violations. There was no consistent evidence for a negativity bias, that is, enhanced allocation of attention to feedback about another person's cheating in comparison to feedback about another person's cooperation. Instead, participants focused on both positive and negative information, and flexibly adjusted their processing biases to the diagnosticity of the information. This conclusion was corroborated by the ERP correlates of memory retrieval. Successful retrieval of a partner's reputation was associated with an anterior positivity between 400 and 600 ms after face onset. This anterior positivity was more pronounced for both cooperator and cheater faces in comparison to control faces. The results suggest that it is not the negativity of social information, but rather its motivational and behavioral relevance that determines its processing.     

II. A Brief Introduction to the thought of Armando B. Ferrari

This paper describes the work of Armando Bianco Ferrari whose central tenet is the very direct relationship between the body (Concrete Original Object) and the mind to which it gives rise, but which is also mind's first and essentially only real object. Ferrari's approach offers an important avenue of approach to the treatment of psychosis, psychosomatic illness and anorexia, for instance, as is recorded in a by now growing Anglophone literature. The direct relationship between body and mind is in contrast to the object relations model in which this relationship is mediated through the breast. The paper starts with a short biological sketch of Ferrari's life before describing his theoretical position. This is largely concerned with the relationship between the mind and its body, the so‐called ‘vertical axis’, and that with the external world which he calls, the ‘horizontal axis’. The relationship between body and mind is achieved through the means of a ‘contact net’ (as opposed to Bion's contact barrier) and the evolution of ‘language registers’ out of patterns of bodily experience. Ferrari's formulation also involves modifications of the ways he conceives the ego and the oedipal situation (‘Oedipal constellation’), especially in the light of what he takes to be an innate femininity and masculinity in either sex, as well as the way in which he frames ideas about health and illness. The fact that the emphasis is directed towards the subject's direct apperception of the sensational and emotional life of his body rather than one mediated exclusively via the object involves a parallel shift away from the transference as always necessarily central to interpretation, without of course dispensing with it or suggesting that it is not ubiquitous. This is one of the various clinical implications of Ferrari's model which is discussed before offering an illustrative clinical vignette, and finally relating Ferrari's thought to some other current theoretical and clinical formulations.     

Inactivation of prefrontal cortex abolishes cortical acetylcholine release evoked by sensory or sensory pathway stimulation in the rat

Sensory stimulation and electrical stimulation of sensory pathways evoke an increase in acetylcholine release from the corresponding cortical areas. The pathways by which such sensory information reaches the cholinergic neurons of the basal forebrain that are responsible for this release are unclear, but have been hypothesized to pass through the prefrontal cortex (PFC). This hypothesis was tested in urethane-anesthetized rats using microdialysis to collect acetylcholine from somatosensory, visual, or auditory cortex, before and after the PFC was inactivated by local microdialysis delivery of the GABA-A receptor agonist muscimol (0.2% for 10 min at 2 microl/min). Before PFC inactivation, peripheral sensory stimulation and ventral posterolateral thalamic stimulation evoked 60 and 105% increases, respectively, in acetylcholine release from somatosensory cortex. Stimulation of the lateral geniculate nucleus evoked a 57% increase in acetylcholine release from visual cortex and stimulation of the medial geniculate nucleus evoked a 72% increase from auditory cortex. Muscimol delivery to the PFC completely abolished each of these evoked increases (overall mean change from baseline = -7%). In addition, the spontaneous level of acetylcholine release in somatosensory, visual, and auditory cortices was reduced by 15-59% following PFC inactivation, suggesting that PFC activity has a tonic facilitatory influence on the basal forebrain cholinergic neurons. These experiments demonstrate that the PFC is necessary for sensory pathway evoked cortical ACh release and strongly support the proposed sensory cortex-to-PFC-to-basal forebrain circuit for each of these modalities.     

共聚焦激光扫描显微镜及其在神经科学研究中的应用

目的:共聚焦激光扫描显微镜(confocal laser scanning microscopy,CLSM)是一种新兴的显微图像检测技术,能够进行光学切片、活体检测、三维重构等,并且能够获得较之普通光学显微镜更高的空间分辨率。本文旨在讨论CLSM及其在神经科学中的应用。方法:通过大量调研文献,从细胞、亚细胞及分子水平上详细阐述了CLSM在神经科学领域中的应用。结果:相比传统光学显微镜,CLSM更适合在神经科学的细胞等层次上进行成像和活体观测试验。结论:CLSM作为一种精密的观察工具,已广泛应用于神经科学研究,为推动神经科学的发展做出了贡献。新的双光子共聚焦显微镜由于其自身的优点在神经科学研究中将具有很大的发展空间。     

My face in yours: Visuo-tactile facial stimulation influences sense of identity

Abstract

Self-face recognition is crucial for sense of identity and self-awareness. Finding self-face recognition disorders mainly in neurological and psychiatric diseases suggests that modifying sense of identity in a simple, rapid way remains a “holy grail” for cognitive neuroscience. By touching the face of subjects who were viewing simultaneous touches on a partner's face, we induced a novel illusion of personal identity that we call “enfacement”: The partner's facial features became incorporated into the representation of the participant's own face. Subjects reported that morphed images of themselves and their partner contained more self than other only after synchronous, but not asynchronous, stroking. Therefore, we modified self-face recognition by means of a simple psychophysical manipulation. While accommodating gradual change in one's own face is an important form of representational plasticity that may help maintaining identity over time, the surprisingly rapid changes induced by our procedure suggest that sense of facial identity may be more malleable than previously believed. “Enfacement” correlated positively with the participant's empathic traits and with the physical attractiveness the participants attributed to their partners. Thus, personality variables modulate enfacement, which may represent a marker of the tendency to be social and may be absent in subjects with defective empathy.     

Comparing different pre-processing routines for infant fNIRS data

Functional Near Infrared Spectroscopy (fNIRS) is an important neuroimaging technique in cognitive developmental neuroscience. Nevertheless, there is no general consensus yet about best pre-processing practices. This issue is highly relevant, especially since the development and variability of the infant hemodynamic response (HRF) is not fully known. Systematic comparisons between analysis methods are thus necessary. We investigated the performance of five different pipelines, selected on the basis of a systematic search of the infant NIRS literature, in two experiments. In Experiment 1, we used synthetic data to compare the recovered HRFs with the true HRF and to assess the robustness of each method against increasing levels of noise. In Experiment 2, we analyzed experimental data from a published study, which assessed the neural correlates of artificial grammar processing in newborns. We found that with motion artifact correction (as opposed to rejection) a larger number of trials were retained, but HRF amplitude was often strongly reduced. By contrast, artifact rejection resulted in a high exclusion rate but preserved adequately the characteristics of the HRF. We also found that the performance of all pipelines declined as the noise increased, but significantly less so than if no pre-processing was applied. Finally, we found no difference between running the pre-processing on optical density or concentration change data. These results suggest that pre-processing should thus be optimized as a function of the specific quality issues a give dataset exhibits.