- Prism adaptation enhances decoupling between the default mode network and the attentional networks. [Journal Article]
- NNeuroimage 2019 Jun 21
- Prism adaptation (PA) is a procedure used for studying visuomotor plasticity in healthy individuals, as well as for alleviating spatial neglect in patients. The adaptation is achieved by performing g…
Prism adaptation (PA) is a procedure used for studying visuomotor plasticity in healthy individuals, as well as for alleviating spatial neglect in patients. The adaptation is achieved by performing goal-directed movements while wearing prismatic lenses that induce a lateral displacement of visual information. This results in an initial movement error that is compensated by a recalibration of sensory-motor coordinates; consequently, a lateral bias in both motor and perceptual measurements occurs after prism removal, i.e., after effects. Neuroimaging studies have shown that a brief exposure to rightward prism changes the activations in the inferior parietal lobule (IPL) and modulates interhemispheric balance during attention tasks. However, it is yet unknown how PA changes global interplay between cortical networks as evident from task-free resting state connectivity. Thus we compared resting state functional connectivity patterns before ('Pre') and after ('Post') participants performed session of pointing movements with rightward-shifting prism (N = 14) or with neutral lenses (as a control condition; N = 12). Global connectivity analysis revealed significant decreases in functional connectivity following PA in two nodes of the Default Mode Network (DMN), and the left anterior insula. Further analyses of these regions showed specific connectivity decrease between either of the DMN nodes and areas within the attentional networks, including the inferior frontal gyrus, the anterior insula and the right superior temporal sulcus. On the other hand, the anterior insula decreased its connectivity to a large set of areas, all within the boundaries of the DMN. These results demonstrate that a brief exposure to PA enhances the decoupling between the DMN and the attention networks. The change in interplay between those pre-existing networks might be the basis of the rapid and wide-ranged behavioural changes induce by PA in healthy individuals.
- Gray matter volume changes following antipsychotic therapy in first-episode schizophrenia patients: A longitudinal voxel-based morphometric study. [Journal Article]
- JPJ Psychiatr Res 2019 Jun 15; 116:126-132
- Despite evidence of structural brain abnormalities in schizophrenia, the current study aimed to explore the effects of antipsychotic treatment on gray matter (GM) volume using structural magnetic res…
Despite evidence of structural brain abnormalities in schizophrenia, the current study aimed to explore the effects of antipsychotic treatment on gray matter (GM) volume using structural magnetic resonance imaging (MRI) and investigate the relationship between brain structure and treatment response. The GM volumes of 33 patients with first-episode schizophrenia were calculated with voxel-based morphometry (VBM), with 33 matched healthy controls. Longitudinal volume changes within subjects after 4-month antipsychotic treatment were also evaluated. Correlation between volumetric changes and clinical symptoms derived from the Positive and Negative Syndrome Scale (PANSS) were further investigated. Compared with healthy controls, decreased GM volumes in the frontal gyrus were observed in schizophrenia patients. After 4-month treatment, patients showed significantly decreased GM volume primarily in the bilateral frontal, temporal and left parietal brain regions. In addition, the GM volume changes of the left postcentral gyrus was positively correlated with negative symptoms improvement, and the correlation analysis revealed the total PANSS scores changes were associated with GM volume changes in the right inferior frontal gyrus and the right superior temporal gyrus. Besides, non-responders had reduced GM volume in the bilateral middle frontal gyrus and the right superior frontal gyrus compared with responders and healthy controls. Our results suggest that the abnormality in the right frontal gyrus exists in the early stage of schizophrenia. Moreover, the relationship between antipsychotics and structural changes was identified. The GM volume might have the potential to reflect the symptom improvement in schizophrenia patients. And MRI may assist in predicting the antipsychotic treatment response in first-episode schizophrenia patients.
- Brain Entropy is Associated with Divergent Thinking. [Journal Article]
- CCCereb Cortex 2019 Jun 24
- Creativity is the ability to generate original and useful products, and it is considered central to the progression of human civilization. As a noninherited emerging process, creativity may stem from…
Creativity is the ability to generate original and useful products, and it is considered central to the progression of human civilization. As a noninherited emerging process, creativity may stem from temporally dynamic brain activity, which, however, has not been well studied. The purpose of this study was to measure brain dynamics using entropy and to examine the associations between brain entropy (BEN) and divergent thinking in a large healthy sample. The results showed that divergent thinking was consistently positively correlated with regional BEN in the left dorsal anterior cingulate cortex/pre-supplementary motor area and left dorsolateral prefrontal cortex, suggesting that creativity is closely related to the functional dynamics of the control networks involved in cognitive flexibility and inhibitory control. Importantly, our main results were cross-validated in two independent cohorts from two different cultures. Additionally, three dimensions of divergent thinking (fluency, flexibility, and originality) were positively correlated with regional BEN in the left inferior frontal gyrus and left middle temporal gyrus, suggesting that more highly creative individuals possess more flexible semantic associative networks. Taken together, our findings provide the first evidence of the associations of regional BEN with individual variations in divergent thinking and show that BEN is sensitive to detecting variations in important cognitive abilities in healthy subjects.
- The Dentate Gyrus and Temporal Lobe Epilepsy: An "Exciting" Era. [Journal Article]
- ECEpilepsy Curr 2019 Jun 24; :1535759719855952
- This review describes developments in epilepsy research during the last 3 to 4 decades that focused on the dentate gyrus (DG) and its role in temporal lobe epilepsy (TLE). The emphasis is on basic re…
This review describes developments in epilepsy research during the last 3 to 4 decades that focused on the dentate gyrus (DG) and its role in temporal lobe epilepsy (TLE). The emphasis is on basic research in laboratory animals and is chronological, starting with hypotheses that attracted a lot of attention in the 1980s. Then experiments are described that addressed the questions, as well as new methods that often made the experiments possible. In addition, where new questions arose and the implications for clinical epilepsy are discussed.
- Alterations of cerebral perfusion and functional brain connectivity in medication-naïve male adults with attention-deficit/hyperactivity disorder. [Journal Article]
- CNCNS Neurosci Ther 2019 Jun 23
- CONCLUSIONS: The present findings suggested alterations of both cerebral perfusion and functional connectivity for the left amygdala in aADHD. The combination of CBF and RSFCs may help to interpret the neuropathogenesis of ADHD more comprehensively.
- Three Weeks of rTMS Treatment Maintains Clinical Improvement But Not Electrophysiological Changes in Patients With Depression: A 6-Week Follow-Up Pilot Study. [Journal Article]
- FPFront Psychiatry 2019; 10:351
- Our previous study demonstrated that 3 weeks of repetitive transcranial magnetic stimulation (rTMS) increases P200 amplitudes and improves the symptoms of depression and anxiety in depression patient…
Our previous study demonstrated that 3 weeks of repetitive transcranial magnetic stimulation (rTMS) increases P200 amplitudes and improves the symptoms of depression and anxiety in depression patients. In the present study, we investigated whether 3 weeks of rTMS treatment maintained the P200 amplitude in patients with depression at 6 weeks of follow-up. We measured the 6-week maintenance effects of rTMS using clinical questionnaires and an auditory oddball paradigm. Twenty-one patients with medication-resistant major depression participated in this pilot study. All patients underwent rTMS treatment for 3 weeks; they completed clinical ratings and performed the auditory oddball task at the pre-treatment, post-treatment, and 6-week follow-up visit (3 weeks after finishing rTMS treatment). The results revealed an increase in P200 amplitudes as well as improvements in the symptoms of depression and anxiety by 3 weeks of rTMS treatment. Furthermore, the results demonstrated maintenance effects on clinical ratings at 6-week follow-up. Depression and anxiety scales showed improvements in post-treatment and maintenance effects at the 6-week follow-up. Although P200 amplitude showed a significant main effect for 3 time points (baseline, post-treatment, and 6-week follow-up visit), at 2 time point comparisons, P200 amplitudes significantly increased in post-treatment compared to those of the baseline condition but did not show the maintenance effects of long-term rTMS at the 6-week follow-up compared to those of the baseline condition (p = .173, Bonferroni correction). Standardized low-resolution brain electromagnetic tomography (sLORETA) for P200 showed significant activation in the left middle frontal gyrus in post-treatment but no significant activation at the 6-week follow-up. Moreover, the amplitudes of overall topographic distribution were reduced at 6 weeks of follow-up. The 3 weeks of rTMS treatment induced the maintenance of the improvements in the symptoms of depression and anxiety. However, considering the results of the event-related potential (ERP) and sLORETA, 3 weeks of rTMS treatment may not be sufficient to maintain this improvement, implying that a treatment period of more than 3 weeks may be required to reveal the electrophysiological maintenance effect of rTMS.
- Common Neural Network for Different Functions: An Investigation of Proactive and Reactive Inhibition. [Journal Article]
- FBFront Behav Neurosci 2019; 13:124
- Successful behavioral inhibition involves both proactive and reactive inhibition, allowing people to prepare for restraining actions, and cancel their actions if the response becomes inappropriate. I…
Successful behavioral inhibition involves both proactive and reactive inhibition, allowing people to prepare for restraining actions, and cancel their actions if the response becomes inappropriate. In the present study, we utilized the stop-signal paradigm to examine whole-brain contrasts and functional connectivity for proactive and reactive inhibition. The results of our functional magnetic resonance imaging (fMRI) data analysis show that the inferior frontal gyrus (IFG), the supplementary motor area (SMA), the subthalamic nucleus (STN), and the primary motor cortex (M1) were activated by both proactive and reactive inhibition. We then created 70 dynamic causal models (DCMs) representing the alternative hypotheses of modulatory effects from proactive and reactive inhibition in the IFG-SMA-STN-M1 network. Bayesian model selection (BMS) showed that causal connectivity from the IFG to the SMA was modulated by both proactive and reactive inhibition. To further investigate the possible brain circuits involved in behavioral control, including proactive inhibitory processes, we compared 13 DCMs representing the alternative hypotheses of proactive modulation in the dorsolateral prefrontal cortex (DLPFC)-caudate-IFG-SMA neural circuits. BMS revealed that the effective connectivity from the caudate to the IFG is modulated only in the proactive inhibition condition but not in the reactive inhibition. Together, our results demonstrate how fronto-basal ganglia pathways are commonly involved in proactive and reactive inhibitory control, with a "longer" pathway (DLPFC-caudate-IFG-SMA-STN-M1) playing a modulatory role in proactive inhibitory control, and a "shorter" pathway (IFG-SMA-STN-M1) involved in reactive inhibition. These results provide causal evidence for the roles of indirect and hyperdirect pathways in mediating proactive and reactive inhibitory control.
- Modulation of creativity by transcranial direct current stimulation. [Journal Article]
- BSBrain Stimul 2019 Jun 05
- CONCLUSIONS: The findings provide new insights into ways of modulating creativity, whereby a deactivation of the left and an activation of the right prefrontal cortex with tDCS is associated with increased creativity. Potential future applications might include tDCS for patients with mental disorders and for healthy individuals in creative professions.
- What can we learn about human individual face recognition from experimental studies in monkeys? [Journal Article]
- VRVision Res 2019; 157:142-158
- Typical human adults recognize numerous individuals from their faces accurately, rapidly and automatically, reaching a level of expertise at individual face recognition that is important for the qual…
Typical human adults recognize numerous individuals from their faces accurately, rapidly and automatically, reaching a level of expertise at individual face recognition that is important for the quality of their social interactions. A non-human species of primates, the rhesus monkey, has been used for decades as a model of human face processing, in particular for understanding the neural basis of individual face recognition. However, despite responding specifically to faces behaviourally and neurally, this species, as well as other Old World and New World monkeys, is remarkably poor at individuating faces of conspecifics. Following extensive conditioning, monkeys only achieve moderate performance at individual face matching tasks where image-based cues are available. Contrary to humans, monkeys do not show a systematic inversion effect in such tasks, or an advantage for matching face pictures of familiar versus unfamiliar individuals, indicating that they do not rely on qualitatively similar individual face recognition processes as humans. These observations concur with the characteristics of the rhesus monkey cortical face processing system, which lacks two critical aspects for human expertise at individual face recognition: a distinct ventral face-selective pathway and a right hemispheric specialization. While the rhesus monkey brain is undoubtedly an informative non-human model for studying the neural basis of social behaviour and visual cognition, it does not provide an adequate model of human individual face recognition. More generally, this review urges for caution when drawing direct inferences across species without sufficient homologies in behaviour and anatomico-functional landmarks.
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- Microglia-mediated synaptic pruning is impaired in sleep-deprived adolescent mice. [Journal Article]
- NDNeurobiol Dis 2019 Jun 20; :104517
- The detrimental effects of sleep insufficiency have been extensively explored. However, only a few studies have addressed this issue in adolescents. In the present study, we examined and compared the…
The detrimental effects of sleep insufficiency have been extensively explored. However, only a few studies have addressed this issue in adolescents. In the present study, we examined and compared the effects of 72 h paradoxical sleep deprivation (SD) on adolescent (5 weeks old) and adult (~12 weeks old) mice. Following 72 h of SD, induced by a modified multiple-platform method, mice were subjected to behavioral, histological and neurochemical examinations. In both adolescent and adult mice, SD adversely affected short-term memory in a novel object recognition test. Compared with normal-sleep controls, sleep-deprived adolescent mice had an increased density of excitatory synapses in the granule cells of the dentate gyrus, but no such pattern was observed in the adult group. The engulfment of postsynaptic components within the microglia after SD was reduced in adolescents but not in adults, suggesting an impaired microglia-mediated synaptic pruning in adolescent SD mice. Possible contributing factors included the decreases in CX3CR1, CD11b and P2Y12, closely associated with the synaptic pruning via microglial phagocytosis. In adult SD mice, microglia-associated inflammatory reactions were noted. In sum, sleep deprivation induces age-dependent microglial reactions in adolescent and adult mice, respectively; yet results in similar defects in short-term recognition memory. Sufficient sleep is indispensable for adolescents and adults.