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Sung Ho Jang - One of the best experts on this subject based on the ideXlab platform.
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neural injury of the Papez Circuit following hypoxic ischemic brain injury a case report
Medicine, 2016Co-Authors: Sung Ho Jang, Hyeok Gyu KwonAbstract:INTRODUCTION: Hypoxic-ischemic brain injury (HI-BI), a result of oxygen deprivation of the brain, is accompanied by memory impairment. In this study, we report on a patient with neural injury of the Papez Circuit following HI-BI, demonstrated by diffusion tensor tractography (DTT). CLINICAL FINDINGS/PATIENT CONCERNS: A 48-year-old male patient suffered spontaneous cardiopulmonary arrest and underwent cardiopulmonary resuscitation for approximately 20 minutes with the concomitant oxygen deprivation leading to HI-BI. The patient showed severe memory impairment at 10 weeks after onset: a Mini-Mental State Examination score of 11 (full score: 30, cut-off score < 24), and examination using the memory function test was not possible due to severe cognitive deficit. OUTCOMES: On 10-week DTT, discontinuation of the fornical column was observed in both hemispheres and thinning of the thalamocingulate tract was observed in the right hemisphere and nonreconstruction in the left hemisphere. CONCLUSION: Using DTT, neural injury of the Papez Circuit was demonstrated in a patient with memory impairment following HI-BI. These results suggest that analysis of the Papez Circuit using DTT could provide beneficial information by detecting injury of the Papez Circuit that cannot be detected on conventional brain MRI in patients with HI-BI.
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Neural injury of the Papez Circuit following hypoxic-ischemic brain injury: A case report.
Medicine, 2016Co-Authors: Sung Ho Jang, Hyeok Gyu KwonAbstract:INTRODUCTION: Hypoxic-ischemic brain injury (HI-BI), a result of oxygen deprivation of the brain, is accompanied by memory impairment. In this study, we report on a patient with neural injury of the Papez Circuit following HI-BI, demonstrated by diffusion tensor tractography (DTT). CLINICAL FINDINGS/PATIENT CONCERNS: A 48-year-old male patient suffered spontaneous cardiopulmonary arrest and underwent cardiopulmonary resuscitation for approximately 20 minutes with the concomitant oxygen deprivation leading to HI-BI. The patient showed severe memory impairment at 10 weeks after onset: a Mini-Mental State Examination score of 11 (full score: 30, cut-off score
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injury of the thalamocingulate tract in the Papez Circuit in patients with mild traumatic brain injury
American Journal of Physical Medicine & Rehabilitation, 2016Co-Authors: Dong Seok Yang, Hyeok Gyu Kwon, Sung Ho JangAbstract:: The thalamocingulate tract between the anterior thalamic nuclei and the cingulate gyrus is a part of the Papez Circuit. Using diffusion tensor tractography, injury of the thalamocingulate tract was investigated in patients with mild traumatic brain injury. Two patients (patient 1: a 58-yr-old woman and patient 2: a 49-yr-old man) with head trauma resulting from a car accident were enrolled. They were classified as mild traumatic brain injury and no specific lesion was observed on brain magnetic resonance imaging. These patients complained of memory impairment after head trauma. The entire Papez Circuits, including thalamocingulate tract, fornix, mammillothalamic tract, and cingulum, were reconstructed in both hemispheres except for the left thalamocingulate tract: patient 1, it was thinner and discontinued compared with the right thalamocingulate tract; and patient 2, it was not reconstructed. The injury of the left thalamocingulate tract appeared to be related to the memory impairment in these patients.
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Diffusion tensor tractography in a patient with memory impairment following encephalitis.
Acta Neurologica Belgica, 2016Co-Authors: Min Cheol Chang, Sung Ho JangAbstract:A 45-year-old male was admitted to the neurology department of a university hospital due to drowsiness, fever (38.5 C), and headache, which had persisted for 3 days. Cerebrospinal fluid (CSF) analysis performed on the day of admission showed 200 cells/lL, which were predominantly lymphocytic (70 %), and an increased protein level (221 mg/dL, normal range 15–45 mg/dL). CSF tests for herpes simplex virus (HSV)-polymerase chain reaction (PCR), HSV immunoglobulin-M, tuberculosis-PCR, acidfast bacillus stain, cryptococcus antigen, and cultures for bacteria and fungus were all negative. Brain MRI [T2 Fluid attenuated inversion recovery (FLAIR)] performed on the day of admission showed increased signal intensity (diffusion restrictive) in the left temporal lobe and insula, however, this increased signal intensity had disappeared on follow-up MRI performed 1-week after admission. Sleep electroencephalography (EEG) showed continuous theta waves on the left temporal lobe. After intravenous administration of acyclovir (2160 mg/day) for 2 weeks, the patient’s symptoms had almost disappeared. Although the causative organism could not be identified, a tentative diagnosis of herpes encephalitis was made based on the clinical manifestations and the results of CSF analysis, EEG, and brain MRI. Since the onset of encephalitis, the patient complained of memory impairment. Results of the neuropsychological test performed 3 months after onset showed verbal memory impairment on the Memory Assessment Scale [68 (2 %)]. The patient’s total score on the Memory Assessment Scale [84 (14 %)] was relatively low compared with his total intelligence quotient on the Wechsler Adult Intelligence Scale [123 (94 %)]. On conventional brain MRI at 3 months after onset no sequellary macroscopic brain damage (Fig. 1b). Diffusion tensor images were acquired at 3 months after onset using a sensitivity encoding head coil on a 1.5-T. Each neural tract (the thalamocingulate tract, fornix, cingulum, and mammillothalamic tract) of the Papez Circuit was determined by selection of fibers passing through seed and target regions of interest (ROI), as in previous studies [1–4]. The various neural tracts of the Papez Circuit (fornix, cingulum, mamillothalamic tract, and thalamocingulate tract) were reconstructed in both hemispheres and a disruption in the right thalamocingulate tract was observed (Fig. 1c). Encephalitis, a diffuse or focal inflammatory process of the brain parenchyma, is often followed by various neurological sequelae, including memory impairment [5, 6]. Memory impairment following encephalitis is the result of damage to the frontal lobe, temporal lobe, or the Papez Circuit of the limbic system [6]. However, the pathogenic mechanism of memory impairment has not been clearly elucidated so far. The Papez Circuit plays important roles in control of episodic memory and emotion. Partial reconstruction of the neural tracts of the Papez Circuit in three dimensions has & Sung Ho Jang strokerehab@hanmail.net
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Is thalamocortical tract injury responsible for memory impairment in a patient with putaminal hemorrhage
Neural Regeneration Research, 2015Co-Authors: Hyeok Gyu Kwon, Chul Hoon Chang, Sung Ho JangAbstract:Prior to development of diffusion tensor imaging (DTI), there were many difficulties in visualization and estimation of the Papez Circuit in the live human brain (Papez, 1995). Diffusion tensor tractography (DTT), derived from DTI, allows for identification and visualization of neural tracts in the Papez Circuit (Concha et al., 2005; Kwon et al., 2010; Granziera et al., 2011; Jang and Yeo, 2013; Jang et al., 2014a). In the current study, using DTT, we report on a patient who showed injured thalamocortical tract between the anterior thalamic nuclei and the cingulate gyrus following a putaminal hemorrhage. A 55-year-old male patient received conservative management for a putaminal hemorrhage in the left hemisphere (Figure 1A). He showed cognitive dysfunction since the onset of putaminal hemorrhage. Results of evaluation at 5 weeks after onset using the Memory Assessment Scale (MAS) which is a comprehensive standardized memory assessment battery that consists of four memory subsets: global memory, short-term memory, verbal memory, and visual memory indicate severe memory impairment (global memory: 71 (3%ile), short term memory: 75 (5%ile), verbal memory: 64 (1%ile), and visual memory: 94 (35%ile)) although Wechsler Adult Intelligence Scale (IQ) was within normal range as 94 (Williams, 1991). Figure 1 Brain CT, T2-weighted MR images, and diffusion tensor tractography (DTT) images of a 55-year-old male patient with a putaminal hemorrhage in the left hemisphere exhibiting cognitive dysfunction. DTI data was acquired at 5 weeks after onset using a 6-channel head coil on a 1.5 T Philips Gyroscan Intera (Philips, Ltd., Best, the Netherlands) with single-shot echo-planar imaging. For each of the 32 non-collinear diffusion sensitizing gradients, we acquired 70 contiguous slices parallel to the anterior commissure-posterior commissure line. Imaging parameters were as follows: acquisition matrix = 96 × 96; reconstructed to matrix = 192 × 192; field of view = 240 × 240 mm2; repetition time (TR) = 10,398 ms; echo time (TE) = 72 ms; parallel imaging reduction factor (SENSE factor) = 2; echo planar imaging factor = 59; b = 1,000 s/mm2; and a slice thickness of 2.5 mm. Fiber tracking was performed using a probabilistic tractography method based, and applied in the present study utilizing tractography routines implemented in Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL; www.fmrib.ox.ac.uk/fsl). Each neural tract of the Papez Circuit was determined by selection of fibers passing through seed and target regions of interest (ROIs) (Concha et al., 2005; Kwon et al., 2010; Jang and Yeo, 2013). We manually drew the ROIs as follows: thalamocortical tract: seed ROI – the cingulate gyrus, first target ROI – anterior limb of internal capsule, second target ROI – anterior thalamic nuclei; fornix: seed ROI – mammillary body, target ROI – crus of fornix; mammillothalamic tract: seed ROI – anterior thalamic nucleus, first target ROI – portion of isolated mammillothalamic tract, second target ROI – mammillary body; cingulum: seed ROI – middle portion of the cingulum, target ROI – posterior portion of the cingulum. Out of 5,000 samples generated from a seed voxel, results were visualized at the threshold of 5 streamline through each voxel for analysis. In the right hemisphere, the whole Papez Circuit including the thalamocortical tract, cingulum, fornix, and mammillothalamic tract were reconstructed. By contrast, the thalamocortical tract was not reconstructed in the left hemisphere due to the putaminal hemorrhage. The Papez Circuit, described by James Papez in 1937, is known to play important roles in control of emotion and memory (Papez, 1995). The pathway of the Papez Circuit was reported as follows: hippocampal formation – fornix – mammillary bodies – anterior thalamic nuclei – cingulate gyrus – cingulum – parahippocampal gyrus – hippocampus (Papez, 1995). Previous studies using DTT have reported on injury of a portion of the Papez Circuit including fornix, mammillothalamic tract and cingulum (Wang et al., 2008; Yeo and Jang, 2013; Jang et al., 2014a, b; Kwon et al., 2014). Regarding the thalamocortical tract between anterior thalamic nuclei and cingulate gyrus, a recent study reported on a patient who showed thinned thalamocortical tract and non-reconstruction of the mammillothalamic tract following anterior thalamic infarction (Jang et al., 2014a). In the current study, we investigated DTT findings of the neural tracts of the Papez Circuit and found injury of the left thalamocortical tract between anterior thalamic nuclei and cingulate gyrus. We think that this patient's memory impairment was mainly the result of the injury of this tract in the Papez Circuit. To the best of our knowledge, this is the first study to demonstrate neural tract injuries of the Papez Circuit following an intracerebral hemorrhage. We think that further studies involving larger numbers of patients and recovery of memory function using follow up DTT are necessary. This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, No. 2012R1A1A4A01001873.
Hyeok Gyu Kwon - One of the best experts on this subject based on the ideXlab platform.
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neural injury of the Papez Circuit following hypoxic ischemic brain injury a case report
Medicine, 2016Co-Authors: Sung Ho Jang, Hyeok Gyu KwonAbstract:INTRODUCTION: Hypoxic-ischemic brain injury (HI-BI), a result of oxygen deprivation of the brain, is accompanied by memory impairment. In this study, we report on a patient with neural injury of the Papez Circuit following HI-BI, demonstrated by diffusion tensor tractography (DTT). CLINICAL FINDINGS/PATIENT CONCERNS: A 48-year-old male patient suffered spontaneous cardiopulmonary arrest and underwent cardiopulmonary resuscitation for approximately 20 minutes with the concomitant oxygen deprivation leading to HI-BI. The patient showed severe memory impairment at 10 weeks after onset: a Mini-Mental State Examination score of 11 (full score: 30, cut-off score < 24), and examination using the memory function test was not possible due to severe cognitive deficit. OUTCOMES: On 10-week DTT, discontinuation of the fornical column was observed in both hemispheres and thinning of the thalamocingulate tract was observed in the right hemisphere and nonreconstruction in the left hemisphere. CONCLUSION: Using DTT, neural injury of the Papez Circuit was demonstrated in a patient with memory impairment following HI-BI. These results suggest that analysis of the Papez Circuit using DTT could provide beneficial information by detecting injury of the Papez Circuit that cannot be detected on conventional brain MRI in patients with HI-BI.
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Neural injury of the Papez Circuit following hypoxic-ischemic brain injury: A case report.
Medicine, 2016Co-Authors: Sung Ho Jang, Hyeok Gyu KwonAbstract:INTRODUCTION: Hypoxic-ischemic brain injury (HI-BI), a result of oxygen deprivation of the brain, is accompanied by memory impairment. In this study, we report on a patient with neural injury of the Papez Circuit following HI-BI, demonstrated by diffusion tensor tractography (DTT). CLINICAL FINDINGS/PATIENT CONCERNS: A 48-year-old male patient suffered spontaneous cardiopulmonary arrest and underwent cardiopulmonary resuscitation for approximately 20 minutes with the concomitant oxygen deprivation leading to HI-BI. The patient showed severe memory impairment at 10 weeks after onset: a Mini-Mental State Examination score of 11 (full score: 30, cut-off score
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injury of the thalamocingulate tract in the Papez Circuit in patients with mild traumatic brain injury
American Journal of Physical Medicine & Rehabilitation, 2016Co-Authors: Dong Seok Yang, Hyeok Gyu Kwon, Sung Ho JangAbstract:: The thalamocingulate tract between the anterior thalamic nuclei and the cingulate gyrus is a part of the Papez Circuit. Using diffusion tensor tractography, injury of the thalamocingulate tract was investigated in patients with mild traumatic brain injury. Two patients (patient 1: a 58-yr-old woman and patient 2: a 49-yr-old man) with head trauma resulting from a car accident were enrolled. They were classified as mild traumatic brain injury and no specific lesion was observed on brain magnetic resonance imaging. These patients complained of memory impairment after head trauma. The entire Papez Circuits, including thalamocingulate tract, fornix, mammillothalamic tract, and cingulum, were reconstructed in both hemispheres except for the left thalamocingulate tract: patient 1, it was thinner and discontinued compared with the right thalamocingulate tract; and patient 2, it was not reconstructed. The injury of the left thalamocingulate tract appeared to be related to the memory impairment in these patients.
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Is thalamocortical tract injury responsible for memory impairment in a patient with putaminal hemorrhage
Neural Regeneration Research, 2015Co-Authors: Hyeok Gyu Kwon, Chul Hoon Chang, Sung Ho JangAbstract:Prior to development of diffusion tensor imaging (DTI), there were many difficulties in visualization and estimation of the Papez Circuit in the live human brain (Papez, 1995). Diffusion tensor tractography (DTT), derived from DTI, allows for identification and visualization of neural tracts in the Papez Circuit (Concha et al., 2005; Kwon et al., 2010; Granziera et al., 2011; Jang and Yeo, 2013; Jang et al., 2014a). In the current study, using DTT, we report on a patient who showed injured thalamocortical tract between the anterior thalamic nuclei and the cingulate gyrus following a putaminal hemorrhage. A 55-year-old male patient received conservative management for a putaminal hemorrhage in the left hemisphere (Figure 1A). He showed cognitive dysfunction since the onset of putaminal hemorrhage. Results of evaluation at 5 weeks after onset using the Memory Assessment Scale (MAS) which is a comprehensive standardized memory assessment battery that consists of four memory subsets: global memory, short-term memory, verbal memory, and visual memory indicate severe memory impairment (global memory: 71 (3%ile), short term memory: 75 (5%ile), verbal memory: 64 (1%ile), and visual memory: 94 (35%ile)) although Wechsler Adult Intelligence Scale (IQ) was within normal range as 94 (Williams, 1991). Figure 1 Brain CT, T2-weighted MR images, and diffusion tensor tractography (DTT) images of a 55-year-old male patient with a putaminal hemorrhage in the left hemisphere exhibiting cognitive dysfunction. DTI data was acquired at 5 weeks after onset using a 6-channel head coil on a 1.5 T Philips Gyroscan Intera (Philips, Ltd., Best, the Netherlands) with single-shot echo-planar imaging. For each of the 32 non-collinear diffusion sensitizing gradients, we acquired 70 contiguous slices parallel to the anterior commissure-posterior commissure line. Imaging parameters were as follows: acquisition matrix = 96 × 96; reconstructed to matrix = 192 × 192; field of view = 240 × 240 mm2; repetition time (TR) = 10,398 ms; echo time (TE) = 72 ms; parallel imaging reduction factor (SENSE factor) = 2; echo planar imaging factor = 59; b = 1,000 s/mm2; and a slice thickness of 2.5 mm. Fiber tracking was performed using a probabilistic tractography method based, and applied in the present study utilizing tractography routines implemented in Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL; www.fmrib.ox.ac.uk/fsl). Each neural tract of the Papez Circuit was determined by selection of fibers passing through seed and target regions of interest (ROIs) (Concha et al., 2005; Kwon et al., 2010; Jang and Yeo, 2013). We manually drew the ROIs as follows: thalamocortical tract: seed ROI – the cingulate gyrus, first target ROI – anterior limb of internal capsule, second target ROI – anterior thalamic nuclei; fornix: seed ROI – mammillary body, target ROI – crus of fornix; mammillothalamic tract: seed ROI – anterior thalamic nucleus, first target ROI – portion of isolated mammillothalamic tract, second target ROI – mammillary body; cingulum: seed ROI – middle portion of the cingulum, target ROI – posterior portion of the cingulum. Out of 5,000 samples generated from a seed voxel, results were visualized at the threshold of 5 streamline through each voxel for analysis. In the right hemisphere, the whole Papez Circuit including the thalamocortical tract, cingulum, fornix, and mammillothalamic tract were reconstructed. By contrast, the thalamocortical tract was not reconstructed in the left hemisphere due to the putaminal hemorrhage. The Papez Circuit, described by James Papez in 1937, is known to play important roles in control of emotion and memory (Papez, 1995). The pathway of the Papez Circuit was reported as follows: hippocampal formation – fornix – mammillary bodies – anterior thalamic nuclei – cingulate gyrus – cingulum – parahippocampal gyrus – hippocampus (Papez, 1995). Previous studies using DTT have reported on injury of a portion of the Papez Circuit including fornix, mammillothalamic tract and cingulum (Wang et al., 2008; Yeo and Jang, 2013; Jang et al., 2014a, b; Kwon et al., 2014). Regarding the thalamocortical tract between anterior thalamic nuclei and cingulate gyrus, a recent study reported on a patient who showed thinned thalamocortical tract and non-reconstruction of the mammillothalamic tract following anterior thalamic infarction (Jang et al., 2014a). In the current study, we investigated DTT findings of the neural tracts of the Papez Circuit and found injury of the left thalamocortical tract between anterior thalamic nuclei and cingulate gyrus. We think that this patient's memory impairment was mainly the result of the injury of this tract in the Papez Circuit. To the best of our knowledge, this is the first study to demonstrate neural tract injuries of the Papez Circuit following an intracerebral hemorrhage. We think that further studies involving larger numbers of patients and recovery of memory function using follow up DTT are necessary. This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, No. 2012R1A1A4A01001873.
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Perspectives on the neural connectivity of the fornix in the human brain.
Neural Regeneration Research, 2014Co-Authors: Sung Ho Jang, Hyeok Gyu KwonAbstract:The fornix is involved in the transfer of information on episodic memory as a part of the Papez Circuit. Diffusion tensor imaging enables to estimate the neural connectivity of the fornix. The anterior fornical body has high connectivity with the anterior commissure, and brain areas relevant to cholinergic nuclei (septal forebrain region and brainstem) and memory function (medial temporal lobe). In the normal subjects, by contrast, the posterior fornical body has connectivity with the cerebral cortex and brainstem through the splenium of the corpus callosum. We believe that knowledge of the neural connectivity of the fornix would be helpful in investigation of the neural network associated with memory and recovery mechanisms following injury of the fornix.
Michael Hornberger - One of the best experts on this subject based on the ideXlab platform.
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Papez Circuit Gray Matter and Episodic Memory in Amyotrophic Lateral Sclerosis and Behavioural Variant Frontotemporal Dementia
Brain Imaging and Behavior, 2020Co-Authors: Ana Paula Arantes Bueno, Michael Hornberger, Walter Hugo L. Pinaya, Leonardo Cruz Souza, Antônio Lúcio Teixeira, Laura Godoy Rousseff Prado, Paulo Caramelli, João Ricardo SatoAbstract:Amyotrophic lateral sclerosis and behavioural variant frontotemporal dementia are two different diseases recognized to overlap at clinical, pathological and genetic characteristics. Both conditions are traditionally known for relative sparing of episodic memory. However, recent studies have disputed that with the report of patients presenting with marked episodic memory impairment. Besides that, structural and functional changes in temporal lobe regions responsible for episodic memory processing are often detected in neuroimaging studies of both conditions. In this study, we investigated the gray matter features associated with the Papez Circuit in amyotrophic lateral sclerosis, behavioural variant frontotemporal dementia and healthy controls to further explore similarities and differences between the two conditions. Our non-demented amyotrophic lateral sclerosis patients showed no episodic memory deficits measured by a short-term delayed recall test while no changes in gray matter of the Papez Circuit were found. Compared with the amyotrophic lateral sclerosis group, the behavioural variant frontotemporal dementia group had lower performance on the short-term delayed recall test and marked atrophy in gray matter of the Papez Circuit. Bilateral atrophy of entorhinal cortex and mammillary bodies distinguished behavioural variant frontotemporal dementia from amyotrophic lateral sclerosis patients as well as atrophy in left cingulate, left hippocampus and right parahippocampal gyrus. Taken together, our results suggest that sub-regions of the Papez Circuit could be differently affected in amyotrophic lateral sclerosis and behavioural variant frontotemporal dementia.
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Structural and functional Papez Circuit integrity in amyotrophic lateral sclerosis
Brain Imaging and Behavior, 2018Co-Authors: Ana Paula Arantes Bueno, Michael Hornberger, Walter Hugo L. Pinaya, Luciana M. Moura, Maxime Bertoux, Ratko Radakovic, Leonardo Cruz Souza, Antônio Lúcio Teixeira, Matthew C. Kiernan, João Ricardo SatoAbstract:Cognitive impairment in amyotrophic lateral sclerosis (ALS) is heterogeneous but now recognized as a feature in non-demented patients and no longer exclusively attributed to executive dysfunction. However, despite common reports of temporal lobe changes and memory deficits in ALS, episodic memory has been less explored. In the current study, we examined how the Papez Circuit—a Circuit known to participate in memory processes—is structurally and functionally affected in ALS patients (n = 20) compared with healthy controls (n = 15), and whether these changes correlated with a commonly used clinical measure of episodic memory. Our multimodal MRI approach (cortical volume, voxel-based morphometry, diffusion tensor imaging and resting state functional magnetic resonance) showed reduced gray matter in left hippocampus, left entorhinal cortex and right posterior cingulate as well as increased white matter fractional anisotropy and decreased mean diffusivity in the left cingulum bundle (hippocampal part) of ALS patients compared with controls. Interestingly, thalamus, mammillary bodies and fornix were preserved. Finally, we report a decreased functional connectivity in ALS patients in bilateral hippocampus, bilateral anterior and posterior parahippocampal gyrus and posterior cingulate. The results revealed that ALS patients showed statistically significant structural changes, but more important, widespread prominent functional connectivity abnormalities across the regions comprising the Papez Circuit. The decreased functional connectivity found in the Papez network may suggest these changes could be used to assess risk or assist early detection or development of memory symptoms in ALS patients even before structural changes are established.
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thalamic pathology and memory loss in early alzheimer s disease moving the focus from the medial temporal lobe to Papez Circuit
Brain, 2016Co-Authors: John Patrick Aggleton, Agathe Pralus, Andrew John Dudley Nelson, Michael HornbergerAbstract:It is widely assumed that incipient protein pathology in the medial temporal lobe instigates the loss of episodic memory in Alzheimer’s disease, one of the earliest cognitive deficits in this type of dementia. Within this region, the hippocampus is seen as the most vital for episodic memory. Consequently, research into the causes of memory loss in Alzheimer’s disease continues to centre on hippocampal dysfunction and how disease-modifying therapies in this region can potentially alleviate memory symptomology. The present review questions this entrenched notion by bringing together findings from post-mortem studies, non-invasive imaging (including studies of presymptomatic, at-risk cases) and genetically modified animal models. The combined evidence indicates that the loss of episodic memory in early Alzheimer’s disease reflects much wider neurodegeneration in an extended mnemonic system (Papez Circuit), which critically involves the limbic thalamus. Within this system, the anterior thalamic nuclei are prominent, both for their vital contributions to episodic memory and for how these same nuclei appear vulnerable in prodromal Alzheimer’s disease. As thalamic abnormalities occur in some of the earliest stages of the disease, the idea that such changes are merely secondary to medial temporal lobe dysfunctions is challenged. This alternate view is further strengthened by the interdependent relationship between the anterior thalamic nuclei and retrosplenial cortex, given how dysfunctions in the latter cortical area provide some of the earliest in vivo imaging evidence of prodromal Alzheimer’s disease. Appreciating the importance of the anterior thalamic nuclei for memory and attention provides a more balanced understanding of Alzheimer’s disease. Furthermore, this refocus on the limbic thalamus, as well as the rest of Papez Circuit, would have significant implications for the diagnostics, modelling, and experimental treatment of cognitive symptoms in Alzheimer’s disease.
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Thalamic pathology and memory loss in early Alzheimer’s disease: moving the focus from the medial temporal lobe to Papez Circuit
Brain, 2016Co-Authors: John Patrick Aggleton, Agathe Pralus, Andrew John Dudley Nelson, Michael HornbergerAbstract:It is widely assumed that incipient protein pathology in the medial temporal lobe instigates the loss of episodic memory in Alzheimer’s disease, one of the earliest cognitive deficits in this type of dementia. Within this region, the hippocampus is seen as the most vital for episodic memory. Consequently, research into the causes of memory loss in Alzheimer’s disease continues to centre on hippocampal dysfunction and how disease-modifying therapies in this region can potentially alleviate memory symptomology. The present review questions this entrenched notion by bringing together findings from post-mortem studies, non-invasive imaging (including studies of presymptomatic, at-risk cases) and genetically modified animal models. The combined evidence indicates that the loss of episodic memory in early Alzheimer’s disease reflects much wider neurodegeneration in an extended mnemonic system (Papez Circuit), which critically involves the limbic thalamus. Within this system, the anterior thalamic nuclei are prominent, both for their vital contributions to episodic memory and for how these same nuclei appear vulnerable in prodromal Alzheimer’s disease. As thalamic abnormalities occur in some of the earliest stages of the disease, the idea that such changes are merely secondary to medial temporal lobe dysfunctions is challenged. This alternate view is further strengthened by the interdependent relationship between the anterior thalamic nuclei and retrosplenial cortex, given how dysfunctions in the latter cortical area provide some of the earliest in vivo imaging evidence of prodromal Alzheimer’s disease. Appreciating the importance of the anterior thalamic nuclei for memory and attention provides a more balanced understanding of Alzheimer’s disease. Furthermore, this refocus on the limbic thalamus, as well as the rest of Papez Circuit, would have significant implications for the diagnostics, modelling, and experimental treatment of cognitive symptoms in Alzheimer’s disease.
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Into the future with little past: exploring mental time travel in a patient with damage to the mammillary bodies/fornix.
Clinical Neuropsychologist, 2016Co-Authors: Jacqui Tedder, Sicong Tu, Laurie A. Miller, Michael HornbergerAbstract:AbstractObjective: Remembering the past and imaging the future are both manifestations of ‘mental time travel’. These processes have been found to be impaired in patients with bilateral hippocampal lesions. Here, we examined the question of whether future thinking is affected by other Papez Circuit lesions, namely: damage to the mammillary bodies/fornix.Method: Case (SL) was a 43-year-old woman who developed dense anterograde and retrograde amnesia suddenly, as a result of Wernicke–Korsakoff’s syndrome. A region of interest volumetric Magnetic resonance imaging (MRI) analysis was performed. We assessed past and future thinking in SL and 11 control subjects of similar age and education with the adapted Autobiographical Interview (AI). Participants also completed a battery of neuropsychological tests.Results: Volumetric MRI analyses revealed severely reduced fornix and mammillary body volumes, but intact hippocampi. SL showed substantial, albeit temporally graded retrograde memory deficits on the adapted AI...
Sun Ha Paek - One of the best experts on this subject based on the ideXlab platform.
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Papez Circuit observed by in vivo human brain with 7 0t mri super resolution track density imaging and track tracing
Frontiers in Neuroanatomy, 2019Co-Authors: Sang Han Choi, Sun Ha PaekAbstract:The Papez Circuit has been considered as an important anatomical substrate involved in emotional experience. However, the Circuit remains difficult to elucidate in the human brain due to the resolution limit of current neuroimaging modalities. In this article, for the first time, we report the direct visualization of the Papez Circuit with 7-Tesla super-resolution magnetic resonance tractography. Two healthy, young male subjects (aged 30 and 35 years) were recruited as volunteers following the guidelines of the institutional review board (IRB). Track density imaging (TDI) generation with track tracing was performed using MRtrix software package. With these tools, we were able to visualize the entire Papez Circuit. We believe this is the first study to visualize the complete loop of the Papez Circuit, including the perforant path (PP), thalamocortical fibers of the anterior nucleus (AN), and mammillothalamic tract (MTT), which were hitherto difficult to visualize by conventional imaging techniques.
Sang Han Choi - One of the best experts on this subject based on the ideXlab platform.
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Papez Circuit observed by in vivo human brain with 7 0t mri super resolution track density imaging and track tracing
Frontiers in Neuroanatomy, 2019Co-Authors: Sang Han Choi, Sun Ha PaekAbstract:The Papez Circuit has been considered as an important anatomical substrate involved in emotional experience. However, the Circuit remains difficult to elucidate in the human brain due to the resolution limit of current neuroimaging modalities. In this article, for the first time, we report the direct visualization of the Papez Circuit with 7-Tesla super-resolution magnetic resonance tractography. Two healthy, young male subjects (aged 30 and 35 years) were recruited as volunteers following the guidelines of the institutional review board (IRB). Track density imaging (TDI) generation with track tracing was performed using MRtrix software package. With these tools, we were able to visualize the entire Papez Circuit. We believe this is the first study to visualize the complete loop of the Papez Circuit, including the perforant path (PP), thalamocortical fibers of the anterior nucleus (AN), and mammillothalamic tract (MTT), which were hitherto difficult to visualize by conventional imaging techniques.
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newly observed anterior thalamocortical fiber of the thalamus using 7 0 t super resolution magnetic resonance tractography and its implications for the classical Papez Circuit
Journal of Neuroradiology, 2018Co-Authors: Sang Han ChoiAbstract:Abstract Here, we have employed recently developed super-resolution tractography using 7.0 T-MRI to analyze the fine structures involved in thalamocortical connections, something that has proved difficult using conventional techniques. We detail a newly observed thalamocortical pathway connecting the anterior nucleus of the thalamus and the cingulate cortex not via the internal capsule but via the septal area. The observed pathway is believed to be a classical pathway of the Papez Circuit but had not been previously identified.
