Even though retinal images of objects change their locations following each eye movement, we perceive a stable and continuous world. One possible mechanism by which the brain achieves such visual stability is to construct a craniotopic coordinate by integrating retinal and extraretinal information. There have been several proposals on how this may be done, including eye-position modulation (gain fields) of retinotopic receptive fields (RFs) and craniotopic RFs. In the present study, we investigated coordinate systems used by RFs in the lateral intraparietal (LIP) cortex and frontal eye fields (FEF) and compared the two areas. We mapped the two-dimensional RFs of neurons in detail under two eye fixations and analyzed how the RF of a given neuron changes with eye position to determine its coordinate representation. The same recording and analysis procedures were applied to the two brain areas. We found that, in both areas, RFs were distributed from retinotopic to craniotopic representations. There was no significant difference between the distributions in the LIP and FEF. Only a small fraction of neurons was fully craniotopic, whereas most neurons were between the retinotopic and craniotopic representations. The distributions were strongly biased toward the retinotopic side but with significant craniotopic shifts. These results suggest that there is only weak evidence for craniotopic RFs in the LIP and FEF, and that transformation from retinotopic to craniotopic coordinates in these areas must rely on other factors such as gain fields.
Animals ; Macaca ; Visual Fields ; Frontal Lobe/physiology* ; Eye Movements ; Brain

OBJECTIVE: To investigate the changes in gray matter volume in depressive-like mice and explore the possible mechanism. METHODS: Twenty-four 6-week-old C57 mice were randomized equally into control group and model group, and the mice in the model group were subjected to chronic unpredictable mild stimulation (CUMS) for 35 days. Magnetic resonance imaging was performed to examine structural changes of the grey matter volume in depressive-like mice. The expression of brain-derived neurotrophic factor (BDNF) in the grey matter of the mice was detected using Western blotting and immunofluorescence staining. RESULTS: Compared with the control mice, the mice with CUMS showed significantly decreased central walking distance in the open field test (P < 0.05) and increased immobile time in forced swimming test (P < 0.05). Magnetic resonance imaging showed that the volume of the frontal cortex was significantly decreased in CUMS mice (P < 0.001, when the mass level was greater than or equal to 10 756, the FDRc was corrected with P=0.05). Western blotting showed that the expression of mature BDNF in the frontal cortex was significantly decreased in CUMS mice (P < 0.05), and its expression began to decrease after the exposure to CUMS as shown by immunofluorescence staining. The volume of different clusters obtained by voxel-based morphometry (VBM) analysis was correlated with the expression level of mature BDNF detected by Western blotting (P < 0.05). CONCLUSION The decrease of frontal cortex volume after CUMS is related with the reduction of mature BDNF expression in the frontal cortex.
Animals ; Mice ; Blotting, Western ; Brain-Derived Neurotrophic Factor ; Cerebral Cortex ; Depression/physiopathology* ; Frontal Lobe/pathology*

BACKGROUND: Patients with schizophrenia (SCZ) and major depressive disorder (MDD) share significant clinical overlap, although it remains unknown to what extent this overlap reflects shared neural profiles. To identify the shared and specific abnormalities in SCZ and MDD, we performed a whole-brain voxel-based meta-analysis using magnetization transfer imaging, a technique that characterizes the macromolecular structural integrity of brain tissue in terms of the magnetization transfer ratio (MTR). METHODS: A systematic search based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted in PubMed, EMBASE, International Scientific Index (ISI) Web of Science, and MEDLINE for relevant studies up to March 2022. Two researchers independently screened the articles. Rigorous scrutiny and data extraction were performed for the studies that met the inclusion criteria. Voxel-wise meta-analyses were conducted using anisotropic effect size-signed differential mapping with a unified template. Meta-regression was used to explore the potential effects of demographic and clinical characteristics. RESULTS: A total of 15 studies with 17 datasets describing 365 SCZ patients, 224 MDD patients, and 550 healthy controls (HCs) were identified. The conjunction analysis showed that both disorders shared higher MTR than HC in the left cerebellum ( P =0.0006) and left fusiform gyrus ( P =0.0004). Additionally, SCZ patients showed disorder-specific lower MTR in the anterior cingulate/paracingulate gyrus, right superior temporal gyrus, and right superior frontal gyrus, and higher MTR in the left thalamus, precuneus/cuneus, posterior cingulate gyrus, and paracentral lobule; and MDD patients showed higher MTR in the left middle occipital region. Meta-regression showed no statistical significance in either group. CONCLUSIONS The results revealed a structural neural basis shared between SCZ and MDD patients, emphasizing the importance of shared neural substrates across psychopathology. Meanwhile, distinct disease-specific characteristics could have implications for future differential diagnosis and targeted treatment.
Humans ; Depressive Disorder, Major/drug therapy* ; Schizophrenia/pathology* ; Brain/pathology* ; Prefrontal Cortex ; Frontal Lobe ; Magnetic Resonance Imaging/methods*

Obstructive sleep apnea syndrome (OSAS), a prevalent sleep disorder in children, is characterized by recurring upper airway obstruction during sleep. OSAS in children can cause intermittent hypoxia and sleep fragmentation, ultimately affect brain development and further lead to cognitive impairment if lack of timely effective intervention. In recent years, magnetic resonance imaging (MRI) and electroencephalogram (EEG) have been employed to investigate brain structure and function abnormalities in children with OSAS. Previous studies have indicated that children with OSAS showed extensive gray and white matter damage, abnormal brain function in regions such as the frontal lobe and hippocampus, as well as a significant decline in general cognitive function and executive function. However, the existing studies mainly focused on the regional activity, and the mechanism of pediatric OSAS affecting brain networks remains unknown. Moreover, it's unclear whether the alterations in brain structure and function are associated with their cognitive impairment. In this review article, we proposed two future research directions: 1) future studies should utilize the multimodal neuroimaging techniques to reveal the alterations of brain networks organization underlying pediatric OSAS; 2) further investigation is necessary to explore the relationship between brain network alteration and cognitive dysfunction in children with OSAS. With these efforts, it will be promising to identify the neuroimaging biomarkers for monitoring the brain development of children with OSAS as well as aiding its clinical diagnosis, and ultimately develop more effective strategies for intervention, diagnosis, and treatment.
Humans ; Child ; Sleep Apnea, Obstructive/complications* ; Cognition ; Hypoxia/complications* ; Hippocampus ; Frontal Lobe

Active exploratory behaviors have often been associated with theta oscillations in rodents, while theta oscillations during active exploration in non-human primates are still not well understood. We recorded neural activities in the frontal eye field (FEF) and V4 simultaneously when monkeys performed a free-gaze visual search task. Saccades were strongly phase-locked to theta oscillations of V4 and FEF local field potentials, and the phase-locking was dependent on saccade direction. The spiking probability of V4 and FEF units was significantly modulated by the theta phase in addition to the time-locked modulation associated with the evoked response. V4 and FEF units showed significantly stronger responses following saccades initiated at their preferred phases. Granger causality and ridge regression analysis showed modulatory effects of theta oscillations on saccade timing. Together, our study suggests phase-locking of saccades to the theta modulation of neural activity in visual and oculomotor cortical areas, in addition to the theta phase locking caused by saccade-triggered responses.
Animals ; Frontal Lobe/physiology* ; Macaca mulatta ; Neurons/physiology* ; Saccades ; Theta Rhythm ; Visual Fields

Transcranial direct current stimulation (tDCS) is a non-invasive low-current brain stimulation technique, which is mainly based on the different polarity of electrode stimulation to make the activation threshold of neurons different, thereby regulating the excitability of the cerebral cortex. In this paper, healthy subjects were randomly divided into three groups: anodal stimulation group, cathodal stimulation group and sham stimulation group, with 5 subjects in each group. Then, the performance data of the three groups of subjects were recorded before and after stimulation to test their mental rotation ability, and resting state and task state electroencephalogram (EEG) data were collected. Finally, through comparative analysis of the behavioral data and EEG data of the three groups of subjects, the effect of electrical stimulation of different polarities on the three-dimensional mental rotation ability was explored. The results of the study found that the correct response time/accuracy rate and the accuracy rate performance of the anodal stimulation group were higher than those of the cathodal stimulation and sham stimulation groups, and there was a significant difference (
Electric Stimulation ; Electroencephalography ; Frontal Lobe ; Humans ; Reaction Time ; Transcranial Direct Current Stimulation

Mental fatigue is the subjective state of people after excessive consumption of information resources. Its impact on cognitive activities is mainly manifested as decreased alertness, poor memory and inattention, which is highly related to the performance after impaired working memory. In this paper, the partial directional coherence method was used to calculate the coherence coefficient of scalp electroencephalogram (EEG) of each electrode. The analysis of brain network and its attribute parameters was used to explore the changes of information resource allocation of working memory under mental fatigue. Mental fatigue was quickly induced by the experimental paradigm of adaptive N-back working memory. Twenty-five healthy college students were randomly recruited as subjects, including 14 males and 11 females, aged from 20 to 27 years old, all right-handed. The behavioral data and resting scalp EEG data were collected simultaneously. The results showed that the main information transmission pathway of the brain changed under mental fatigue, mainly in the frontal lobe and parietal lobe. The significant changes in brain network parameters indicated that the information transmission path of the brain decreased and the efficiency of information transmission decreased significantly. In the causal flow of each electrode and the information flow of each brain region, the inflow of information resources in the frontal lobe decreased under mental fatigue. Although the parietal lobe region and occipital lobe region became the main functional connection areas in the fatigue state, the inflow of information resources in these two regions was still reduced as a whole. These results indicated that mental fatigue affected the information resources allocation of working memory, especially in the frontal and parietal regions which were closely related to working memory.
Adult ; Aged ; Brain ; Female ; Frontal Lobe ; Humans ; Male ; Memory, Short-Term ; Mental Fatigue ; Resource Allocation ; Young Adult

To investigate the association between chronic unpredictable mild stress (CUMS)-induced depressive-like behavior in rats and expressions of brain-derived neurotrophic factor (BDNF) and S100β in the hippocampal and prefrontal cortex. Rats were randomly assigned to three groups:saline control group,saline+CUMS group,and citalopram +CUMS group. CUMS was used for depression modeling in rats. Depressive-like behavior in rats were evaluated by open-field test,sucrose preference test,and novel object recognition test. S100β and BDNF expressions were tested by enzyme-linked immunosorbent assay. Rats in the saline+CUMS group had significantly lower score in sucrose preference [(52.48±13.14)%],basic motor tasks [(845.8±371.4)s],fine motor tasks [(565.6±211.9)s],and longer resting time [(282.6±11.8)s] compared to the control group [(84.30±6.15)% (=7.49,=0.000),(1239.1±281.6)s (=2.83,=0.008),(801.8±150.9)s (=3.05,=0.003),(268.2±12.8)s (=2.72,=0.001)]. Compared with the citalopram+CUMS group,rats from the saline+CUMS group also showed significantly lower results in sucrose preference [(80.55±11.31)%,=5.39,=0.000],basic motor tasks [(1156.4±314.7)s,=2.13,=0.031],and fine motor tasks [(736.1±150.0)s,=2.21,=0.008]. There were no significant differences in the expression of hippocampal and prefrontal BDNF between these two groups,but rats from the saline+CUMS group expressed significantly higher levels of S100β compared to rats from the citalopram+CUMS group [(13.22±2.23) ng/g (10.55±2.72) ng/g,=2.67,=0.014]. Pearson correlation analysis revealed that the expression of S100β was positively correlated with the expression of BDNF in the prefrontal cortex and hippocampus (=0.35,=0.034;=0.36,=0.034).The novel object recognition index was positively correlated with the expression of BDNF in the hippocampus(=0.38,=0.021),and the duration of fine-motor activities was negatively correlated with S100β in the prefrontal cortex (=-0.36,=0.037). Different types of depressive behaviors in rats induced by CUMS are associated with the selective expression of S100β and BDNF in two different brain cortex. S100β protein and BDNF may independently participate in the pathogenesis of depression.
Animals ; Antidepressive Agents ; Brain-Derived Neurotrophic Factor ; metabolism ; Citalopram ; Depression ; metabolism ; Disease Models, Animal ; Frontal Lobe ; metabolism ; Hippocampus ; metabolism ; Random Allocation ; Rats ; S100 Calcium Binding Protein beta Subunit ; metabolism ; Stress, Psychological

Mindfulness is a process in which all thoughts, feelings, sensations, and all phenomena that happen to me are uncritically recognized as they are, so that they are eventually accepted and released without identifying or automatically responding to them. The clinical effects of mindfulness-based therapy have already been demonstrated in several studies. However, consistent results have not been reported for the mechanism of mindfulness-based treatment. Thus, this review aimed to describe a systematic review of the literature and research on the mechanisms of mindfulness-based interventions. Experienced meditators showed a physiological change in a ‘wakeful hypometabolic state’ during mindfulness meditation. In mindfulness meditation, it is known that certain areas other than brain activation during relaxation are additionally activated, particularly activation of fronto-limbic and fronto-parietal neural networks. The psychological mechanisms include meta-cognitive awareness, emotion regulation, reduction of automatic and self-referential thinking, concentration control, self-compassion, improvement of value clarification and self-regulation, exposure, extinction, and reconsolidation. Of the brain regions with changes in activity associated with mindfulness meditation, prefrontal cortex, the default mode network including cortical midline structures were associated with emotion regulation, concentration control, and reduction of automatic and self-referential thinking. In addition, brain regions associated with mindfulness meditation have been reported in the hippocampus, amygdala, and medical frontal cortices associated with memory reconsolidation and fear extinction. Thus, mindfulness-based interventions have a psychological and neurobiological effect with a special mechanism different from other psychological interventions, so that mindfulness based intervention can be an effective therapeutic intervention with a different mechanism from other psychological techniques.
Amygdala ; Brain ; Frontal Lobe ; Hippocampus ; Meditation ; Memory ; Mindfulness ; Prefrontal Cortex ; Psychological Techniques ; Relaxation ; Self-Control ; Sensation ; Thinking

OBJECTIVE: Alternate ascending/descending directional navigation (ALADDIN) is a novel arterial spin labeling technique that does not require a separate spin preparation pulse. We sought to compare the normalized cerebral blood flow (nCBF) values obtained by ALADDIN and dynamic susceptibility contrast (DSC) perfusion magnetic resonance imaging (MRI) in patients with primary brain tumors. MATERIALS AND METHODS: Sixteen patients with primary brain tumors underwent MRI scans including contrast-enhanced T1-weighted imaging, DSC perfusion MRI, and ALADDIN. The nCBF values of normal gray matter (GM) and tumor areas were measured by both DSC perfusion MRI and ALADDIN, which were compared by the Wilcoxon signed rank test. Subgroup analyses according to pathology were performed with the Wilcoxon signed rank test. RESULTS: Higher mean nCBF values of GM regions in the bilateral frontal lobe, temporal lobe, and caudate were detected by ALADDIN than by DSC perfusion MRI (p <0.05). In terms of the mean or median nCBF values and the mean of the top 10% nCBF values from tumors, DSC perfusion MRI and ALADDIN did not statistically significantly differ either overall or in each tumor group. CONCLUSION: ALADDIN tended to detect higher nCBF values in normal GM, as well as higher perfusion portions of primary brain tumors, than did DSC perfusion MRI. We believe that the high perfusion signal on ALADDIN can be beneficial in lesion detection and characterization.
Brain Neoplasms ; Cerebrovascular Circulation ; Frontal Lobe ; Glioma ; Gray Matter ; Humans ; Magnetic Resonance Angiography ; Magnetic Resonance Imaging ; Pathology ; Perfusion ; Temporal Lobe