While multiple step saccades (MSS) are occasionally reported in the healthy population, they are more evident in patients with Parkinson's disease (PD). Therefore, MSS has been suggested as a biological marker for the diagnosis of PD. However, the lack of clarity on the neural mechanism underlying the generation of MSS largely impedes their application in the clinic. We have proposed recently that MSS are triggered by the discrepancy between desired and executed saccades. Accordingly, brain regions involved in saccadic planning and execution might play a role in the generation of MSS. To test this hypothesis, we explored the role of the prefrontal (PFC) and posterior parietal cortex (PPC) in generating MSS by conducting two experiments: electroencephalographic recording and single-pulse transcranial magnetic stimulation in the PFC or PPC of humans while participants were performing a gap saccade task. We found that the PFC and PPC are involved in the generation of MSS.
Humans ; Parietal Lobe/physiology* ; Saccades/physiology* ; Prefrontal Cortex/physiology* ; Male ; Transcranial Magnetic Stimulation ; Female ; Electroencephalography ; Adult ; Young Adult

The dorsal and ventral visual streams have been considered to play distinct roles in visual processing for action: the dorsal stream is assumed to support real-time actions, while the ventral stream facilitates memory-guided actions. However, recent evidence suggests a more integrated function of these streams. We investigated the neural dynamics and functional connectivity between them during memory-guided actions using intracranial EEG. We tracked neural activity in the inferior parietal lobule in the dorsal stream, and the ventral temporal cortex in the ventral stream as well as the hippocampus during a delayed action task involving object identity and location memory. We found increased alpha power in both streams during the delay, indicating their role in maintaining spatial visual information. In addition, we recorded increased alpha power in the hippocampus during the delay, but only when both object identity and location needed to be remembered. We also recorded an increase in theta band phase synchronization between the inferior parietal lobule and ventral temporal cortex and between the inferior parietal lobule and hippocampus during the encoding and delay. Granger causality analysis indicated dynamic and frequency-specific directional interactions among the inferior parietal lobule, ventral temporal cortex, and hippocampus that varied across task phases. Our study provides unique electrophysiological evidence for close interactions between dorsal and ventral streams, supporting an integrated processing model in which both streams contribute to memory-guided actions.
Humans ; Male ; Female ; Adult ; Young Adult ; Hippocampus/physiology* ; Memory/physiology* ; Parietal Lobe/physiology* ; Temporal Lobe/physiology* ; Visual Perception/physiology* ; Electrocorticography ; Visual Pathways/physiology* ; Electroencephalography

Recent work in decision neuroscience suggests that visual saliency can interact with reward-based choice, and the lateral intraparietal cortex (LIP) is implicated in this process. In this study, we recorded from LIP neurons while monkeys performed a two alternative choice task in which the reward and luminance associated with each offer were varied independently. We discovered that the animal's choice was dictated by the reward amount while the luminance had a marginal effect. In the LIP, neuronal activity corresponded well with the animal's choice pattern, in that a majority of reward-modulated neurons encoded the reward amount in the neuron's preferred hemifield with a positive slope. In contrast, compared to their responses to low luminance, an approximately equal proportion of luminance-sensitive neurons responded to high luminance with increased or decreased activity, leading to a much weaker population-level response. Meanwhile, in the non-preferred hemifield, the strength of encoding for reward amount and luminance was positively correlated, suggesting the integration of these two factors in the LIP. Moreover, neurons encoding reward and luminance were homogeneously distributed along the anterior-posterior axis of the LIP. Overall, our study provides further evidence supporting the neural instantiation of a priority map in the LIP in reward-based decisions.
Animals ; Macaca mulatta/physiology* ; Parietal Lobe ; Neurons/physiology* ; Saccades ; Reward ; Photic Stimulation

Animals ; Brain Mapping ; Dominance, Cerebral ; Magnetic Resonance Imaging ; Parietal Lobe ; Primates

The incidence of tinnitus is very high, which can affect the patient's attention, emotion and sleep, and even cause serious psychological distress and suicidal tendency. Currently, there is no uniform and objective method for tinnitus detection and therapy, and the mechanism of tinnitus is still unclear. In this study, we first collected the resting state electroencephalogram (EEG) data of tinnitus patients and healthy subjects. Then the power spectrum topology diagrams were compared of in the band of δ (0.5-3 Hz), θ (4-7 Hz), α (8-13 Hz), β (14-30 Hz) and γ (31-50 Hz) to explore the central mechanism of tinnitus. A total of 16 tinnitus patients and 16 healthy subjects were recruited to participate in the experiment. The results of resting state EEG experiments found that the spectrum power value of tinnitus patients was higher than that of healthy subjects in all concerned frequency bands. The
Attention ; Brain ; Electroencephalography ; Humans ; Parietal Lobe ; Tinnitus

BACKGROUND AND PURPOSE: There are three distinct subtypes of primary progressive aphasia (PPA): the nonfluent/agrammatic variant (nfvPPA), the semantic variant (svPPA), and the logopenic variant (lvPPA). We sought to characterize the pattern of [¹⁸F]-THK5351 retention across all three subtypes and determine the topography of [¹⁸F]-THK5351 retention correlated with each neurolinguistic score. METHODS: We enrolled 50 participants, comprising 13 PPA patients (3 nfvPPA, 5 svPPA, and 5 lvPPA) and 37 subjects with normal cognition (NC) who underwent 3.0-tesla magnetic resonance imaging, [¹⁸F]-THK5351 positron-emission tomography scans, and detailed neuropsychological tests. The PPA patients additionally participated in extensive neurolinguistic tests. Voxel-wise and region-of-interest-based analyses were performed to analyze [¹⁸F]-THK5351 retention. RESULTS: The nfvPPA patients exhibited higher [¹⁸F]-THK5351 retention in the the left inferior frontal and precentral gyri. In svPPA patients, [¹⁸F]-THK5351 retention was elevated in the anteroinferior and lateral temporal cortices compared to the NC group (left>right). The lvPPA patients exhibited predominant [¹⁸F]-THK5351 retention in the inferior parietal, lateral temporal, and dorsolateral prefrontal cortices, and the precuneus (left>right). [¹⁸F]-THK5351 retention in the left inferior frontal area was associated with lower fluency scores. Comprehension was correlated with [¹⁸F]-THK5351 retention in the left temporal cortices. Repetition was associated with [¹⁸F]-THK5351 retention in the left inferior parietal and posterior temporal areas, while naming difficulty was correlated with retention in the left fusiform and temporal cortices. CONCLUSIONS: The pattern of [¹⁸F]-THK5351 retention was well matched with clinical and radiological findings for each PPA subtype, in agreement with the anatomical and functional location of each language domain.
Aphasia, Primary Progressive ; Cognition ; Comprehension ; Humans ; Magnetic Resonance Imaging ; Neurofibrillary Tangles ; Neuropsychological Tests ; Parietal Lobe ; Positron-Emission Tomography ; Prefrontal Cortex ; Rabeprazole ; Semantics ; Temporal Lobe

PURPOSE: To investigate regional cerebral amyloid beta retention in cognitively normal Korean adults using F-18 florbetaben (FBB).METHODS: We prospectively analyzed F-18 FBB positron emission tomography (PET)/CT scans of 30 cognitively healthy adults (age range, 50??0 years) using automated quantification. The standardized uptake value ratios (SUVRs) of F-18 FBB were calculated for predefined regions by normalizing the regional count with cerebellar cortex.RESULTS: The distribution of amyloid beta for each brain region revealed no age-related trends (p > 0.05). From all subjects, mean SUVR of amyloid deposit was 1.30 ± 0.18. The right parietal lobe showed the highest SUVR value (1.46 ± 0.23), whereas the right frontal lobe and left precuneus showed the lowest SUVR (1.23 ± 0.25).CONCLUSIONS: We provide reference values of normative data obtained from healthy elderly Koreans and suggest its use for accurate diagnosis of patients with Alzheimer's disease.
Adult ; Aged ; Alzheimer Disease ; Amyloid ; Brain ; Cerebellar Cortex ; Diagnosis ; Frontal Lobe ; Humans ; Parietal Lobe ; Plaque, Amyloid ; Positron-Emission Tomography ; Prospective Studies ; Reference Values

The core concept for pathophysiology in panic disorder (PD) is the fear network model (FNM). The alterations in FNM might be linked with disturbances in the autonomic nervous system (ANS), which is a common phenomenon in PD. The traditional FNM included the frontal and limbic regions, which were dysregulated in the feedback mechanism for cognitive control of frontal lobe over the primitive response of limbic system. The exaggerated responses of limbic system are also associated with dysregulation in the neurotransmitter system. The neuroimaging studies also corresponded to FNM concept. However, more extended areas of FNM have been discovered in recent imaging studies, such as sensory regions of occipital, parietal cortex and temporal cortex and insula. The insula might integrate the filtered sensory information via thalamus from the visuospatial and other sensory modalities related to occipital, parietal and temporal lobes. In this review article, the traditional and advanced FNM would be discussed. I would also focus on the current evidences of insula, temporal, parietal and occipital lobes in the pathophysiology. In addition, the white matter and functional connectome studies would be reviewed to support the concept of advanced FNM. An emerging dysregulation model of fronto-limbic-insula and temporooccipito-parietal areas might be revealed according to the combined results of recent neuroimaging studies. The future delineation of advanced FNM model can be beneficial from more extensive and advanced studies focusing on the additional sensory regions of occipital, parietal and temporal cortex to confirm the role of advanced FNM in the pathophysiology of PD.
Autonomic Nervous System ; Connectome ; Frontal Lobe ; Limbic System ; Neuroimaging ; Neurotransmitter Agents ; Occipital Lobe ; Panic Disorder ; Panic ; Parietal Lobe ; Rabeprazole ; Temporal Lobe ; Thalamus ; White Matter

Transcranial direct current stimulation (tDCS) is a novel brain stimulation technique which has kindled hope in alleviating motor, language as well as cognitive deficits in neuronal injury. Current case report describes application of tDCS in two phases using two different protocols in a patient with hypoxic injury. In the first phase anodal stimulation of dorsolateral prefrontal cortex improved the language fluency. Subsequently, after 6 months second phase application of anodal stimulation over posterior parietal region targeted arithmetic and working memory deficits. Individualising the treatment protocols of brain stimulation, based on the lesion and the functional deficits, for neuro-rehabilitation is emphasised.
Brain ; Clinical Protocols ; Cognition Disorders ; Dyscalculia ; Hope ; Humans ; Hypoxia-Ischemia, Brain ; Memory, Short-Term ; Neurons ; Parietal Lobe ; Prefrontal Cortex ; Rehabilitation ; Transcranial Direct Current Stimulation

PURPOSE: We compared the activation pattern of the mirror neurons (MN) between two types of hand movement according to action observation using functional MRI. METHODS: Twelve right-handed healthy subjects (5 male and 7 female, mean age 21.92±2.02 years) participated in the experiment. During fMRI scanning, subjects underwent two different stimuli on the screen: 1) video clips showing repeated grasping and releasing of the ball via simple hand movement (SHM), and (2) video clips showing an actor performing a Purdue Pegboard test via complex hand movement (CHM). paired t-test in statistical parametric mapping (SPM) was used to compare the activation differences between the two types of hand movement. RESULTS: CHM as compared with the SHM produced a higher blood oxygen level dependent (BOLD) signal response in the right superior frontal gyrus, left inferior and superior parietal lobules, and lingual gyrus. However, no greater BOLD signal response was found by SHM compared with CHM (FWE corrected, p<0.05). CONCLUSION: Our findings provided that the activation patterns for observation of SHM and CHM are different. CHM also elicited boarder or stronger activations in the brain, including inferior parietal lobule called the MN region.
Brain ; Female ; Hand Strength ; Hand ; Healthy Volunteers ; Humans ; Magnetic Resonance Imaging ; Male ; Mirror Neurons ; Occipital Lobe ; Oxygen ; Parietal Lobe ; Prefrontal Cortex