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Riverol M, Ríos-Rivera MM, Imaz-Aguayo L, Solis-Barquero SM, Arrondo C, Montoya-Murillo G, Villino-Rodríguez R, García-Eulate R, Domínguez P, Fernández-Seara MA. Structural neuroimaging changes associated with subjective cognitive decline from a clinical sample. Neuroimage Clin 2024; 42:103615. [PMID: 38749146 PMCID: PMC11109886 DOI: 10.1016/j.nicl.2024.103615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND Alzheimer's disease (AD) is characterized by progressive deterioration of cognitive functions. Some individuals with subjective cognitive decline (SCD) are in the early phase of the disease and subsequently progress through the AD continuum. Although neuroimaging biomarkers could be used for the accurate and early diagnosis of preclinical AD, the findings in SCD samples have been heterogeneous. This study established the morphological differences in brain magnetic resonance imaging (MRI) findings between individuals with SCD and those without cognitive impairment based on a clinical sample of patients defined according to SCD-Initiative recommendations. Moreover, we investigated baseline structural changes in the brains of participants who remained stable or progressed to mild cognitive impairment or dementia. METHODS This study included 309 participants with SCD and 43 healthy controls (HCs) with high-quality brain MRI at baseline. Among the 99 subjects in the SCD group who were followed clinically, 32 progressed (SCDp) and 67 remained stable (SCDnp). A voxel-wise statistical comparison of gray and white matter (WM) volume was performed between the HC and SCD groups and between the HC, SCDp, and SCDnp groups. XTRACT ATLAS was used to define the anatomical location of WM tract damage. Region-of-interest (ROI) analyses were performed to determine brain volumetric differences. White matter lesion (WML) burden was established in each group. RESULTS Voxel-based morphometry (VBM) analysis revealed that the SCD group exhibited gray matter atrophy in the middle frontal gyri, superior orbital gyri, superior frontal gyri, right rectal gyrus, whole occipital lobule, and both thalami and precunei. Meanwhile, ROI analysis revealed decreased volume in the left rectal gyrus, bilateral medial orbital gyri, middle frontal gyri, superior frontal gyri, calcarine fissure, and left thalamus. The SCDp group exhibited greater hippocampal atrophy (p < 0.001) than the SCDnp and HC groups on ROI analyses. On VBM analysis, however, the SCDp group exhibited increased hippocampal atrophy only when compared to the SCDnp group (p < 0.001). The SCD group demonstrated lower WM volume in the uncinate fasciculus, cingulum, inferior fronto-occipital fasciculus, anterior thalamic radiation, and callosum forceps than the HC group. However, no significant differences in WML number (p = 0.345) or volume (p = 0.156) were observed between the SCD and HC groups. CONCLUSIONS The SCD group showed brain atrophy mainly in the frontal and occipital lobes. However, only the SCDp group demonstrated atrophy in the medial temporal lobe at baseline. Structural damage in the brain regions was anatomically connected, which may contribute to early memory decline.
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Affiliation(s)
- Mario Riverol
- Department of Neurology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain; Instituto de Investigación Sanitaria de Navarra, Pamplona 31008, Navarra, Spain.
| | - Mirla M Ríos-Rivera
- Department of Neurology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain; School of Medicine, Universidad Autónoma de Chiriquí, David 4001, Chiriquí, Panama
| | - Laura Imaz-Aguayo
- Department of Neurology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain
| | | | - Carlota Arrondo
- Department of Neurology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain
| | | | | | - Reyes García-Eulate
- Department of Radiology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain
| | - Pablo Domínguez
- Department of Radiology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain; Instituto de Investigación Sanitaria de Navarra, Pamplona 31008, Navarra, Spain
| | - Maria A Fernández-Seara
- Department of Radiology, Clínica Universidad de Navarra, Pamplona 31008, Navarra, Spain; Instituto de Investigación Sanitaria de Navarra, Pamplona 31008, Navarra, Spain
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Wang X, Zhou H, Yan CQ, Shi GX, Zhou P, Huo JW, Yang JW, Zhang YN, Wang L, Cao Y, Liu CZ. Cognitive and Hippocampal Changes in Older Adults With Subjective Cognitive Decline After Acupuncture Intervention. Am J Geriatr Psychiatry 2024:S1064-7481(24)00272-0. [PMID: 38521736 DOI: 10.1016/j.jagp.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/01/2024] [Accepted: 03/02/2024] [Indexed: 03/25/2024]
Abstract
OBJECTIVE Converging evidence indicates that subjective cognitive decline (SCD) could be an early indicator of dementia. The hippocampus is the earliest affected region during the progression of cognitive impairment. However, little is known about whether and how acupuncture change the hippocampal structure and function of SCD individuals. METHODS Here, we used multi-modal MRI to reveal the mechanism of acupuncture in treating SCD. Seventy-two older participants were randomized into acupuncture or sham acupuncture group and treated for 12 weeks. RESULTS At the end of the intervention, compared to sham acupuncture, participants with acupuncture treatment showed improvement in composite Z score from multi-domain neuropsychological tests, as well as increased hippocampal volume and functional connectivity. Moreover, the greater white matter integrity of the fornix, which is the major output tract of the hippocampus, was shown in the acupuncture group. CONCLUSION These findings suggest that acupuncture may improve the cognitive function of SCD individuals, and increase hippocampal volume on the regional level and enhance the structural and functional connectivity of hippocampus on the connective level.
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Affiliation(s)
- Xu Wang
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China; School of Life Sciences (XW), Beijing University of Chinese Medicine, Beijing, China
| | - Hang Zhou
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Chao-Qun Yan
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Guang-Xia Shi
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Ping Zhou
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Jian-Wei Huo
- Department of Radiology (J-WH, Y-NZ), Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Dongcheng District, Beijing, China
| | - Jing-Wen Yang
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Ya-Nan Zhang
- Department of Radiology (J-WH, Y-NZ), Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Dongcheng District, Beijing, China
| | - Lu Wang
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Yan Cao
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China
| | - Cun-Zhi Liu
- International Acupuncture and Moxibustion Innovation Institute, School of Acupuncture-Moxibustion and Tuina (XW, HZ, C-QY, G-XS, PZ, J-WY, LW, YC, C-ZL), Beijing University of Chinese Medicine, Beijing, China.
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Kilpatrick LA, Siddarth P, Krause-Sorio B, Milillo MM, Aguilar-Faustino Y, Ercoli L, Narr KL, Khalsa DS, Lavretsky H. Impact of Yoga Versus Memory Enhancement Training on Hippocampal Connectivity in Older Women at Risk for Alzheimer's Disease. J Alzheimers Dis 2023; 95:149-159. [PMID: 37482992 PMCID: PMC10578221 DOI: 10.3233/jad-221159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2023] [Indexed: 07/25/2023]
Abstract
BACKGROUND Yoga may be an ideal early intervention for those with modifiable risk factors for Alzheimer's disease (AD) development. OBJECTIVE To examine the effects of Kundalini yoga (KY) training versus memory enhancement training (MET) on the resting-state connectivity of hippocampal subregions in women with subjective memory decline and cardiovascular risk factors for AD. METHODS Participants comprised women with subjective memory decline and cardiovascular risk factors who participated in a parent randomized controlled trial (NCT03503669) of 12-weeks of KY versus MET and completed pre- and post-intervention resting-state magnetic resonance imaging scans (yoga: n = 11, age = 61.45±6.58 years; MET: n = 11, age = 64.55±6.41 years). Group differences in parcellated (Cole-anticevic atlas) hippocampal connectivity changes (post- minus pre-intervention) were evaluated by partial least squares analysis, controlling for age. Correlations between hippocampal connectivity and perceived stress and frequency of forgetting (assessed by questionnaires) were also evaluated. RESULTS A left anterior hippocampal subregion assigned to the default mode network (DMN) in the Cole-anticevic atlas showed greater increases in connectivity with largely ventral visual stream regions with KY than with MET (p < 0.001), which showed associations with lower stress (p < 0.05). Several posterior hippocampal subregions assigned to sensory-based networks in the Cole-anticevic atlas showed greater increases in connectivity with regions largely in the DMN and frontoparietal network with MET than with KY (p < 0.001), which showed associations with lower frequency of forgetting (p < 0.05). CONCLUSION KY training may better target stress-related hippocampal connectivity, whereas MET may better target hippocampal sensory-integration supporting better memory reliability, in women with subjective memory decline and cardiovascular risk factors.
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Affiliation(s)
- Lisa A. Kilpatrick
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
- G. Oppenheimer Center for Neurobiology of Stress and Resilience, University of California, Los Angeles, CA, USA
- Goodman-Luskin Microbiome Center, University of California, Los Angeles, CA, USA
| | - Prabha Siddarth
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Beatrix Krause-Sorio
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Michaela M. Milillo
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Yesenia Aguilar-Faustino
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Linda Ercoli
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
| | - Katherine L. Narr
- Department of Neurology, Brain Research Institute, University of California, Los Angeles, CA, USA
| | | | - Helen Lavretsky
- Department of Psychiatry, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA
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Qiu T, Zeng Q, Zhang Y, Luo X, Xu X, Li X, Shen Z, Li K, Wang C, Huang P, Zhang M, Dai S, Xie F. Altered functional connectivity pattern of hippocampal subfields in individuals with objectively-defined subtle cognitive decline and its association with cognition and cerebrospinal fluid biomarkers. Eur J Neurosci 2022; 56:6227-6238. [PMID: 36342704 PMCID: PMC10100315 DOI: 10.1111/ejn.15860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 10/17/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022]
Abstract
Recent studies have shown that in the preclinical phase of Alzheimer's disease (AD), subtle cognitive changes can be detected using sensitive neuropsychological measures, and have proposed the concept of objectively-defined subtle cognitive decline (Obj-SCD). We aimed to assess the functional alteration of hippocampal subfields in individuals with Obj-SCD and its association with cognition and pathological biomarkers. Forty-two participants with cognitively normal (CN), 29 with Obj-SCD, and 55 with mild cognitive impairment (MCI) were retrospectively collected from the ADNI database. Neuropsychological performance, functional MRI, and cerebrospinal fluid (CSF) data were obtained. We calculated the seed-based functional connectivity (FC) of hippocampal subfields (cornu ammonis1 [CA1], CA2/3/dentate gyrus [DG], and subiculum) with whole-brain voxels. Additionally, we analyzed the correlation between FC values of significantly altered regions and neuropsychological performance and CSF biomarkers. The Obj-SCD group showed lower FC between left CA1-CA2/3/DG and right thalamus and higher FC between right subiculum and right superior parietal gyrus (SPG) compared with the CN and MCI groups. In the Obj-SCD group, FC values between left CA2/3/DG and right thalamus were positively associated with Auditory Verbal Learning Test (AVLT) recognition (r = 0.395, p = 0.046) and CSF Aβ1-42 levels (r = 0.466, p = 0.019), and FC values between left CA1 and right thalamus were positively correlated with CSF Aβ1-42 levels (r = 0.530, p = 0.006). Taken together, dysfunction in CA1-CA2/3/DG subregions suggests subtle cognitive impairment and AD-specific pathological changes in individuals with Obj-SCD. Additionally, increased subiculum connectivity may indicate early functional compensation for subtle cognitive changes.
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Affiliation(s)
- Tiantian Qiu
- Department of RadiologyLinyi People's HospitalLinyiChina
| | - Qingze Zeng
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Yusong Zhang
- Department of RadiologyLinyi People's HospitalLinyiChina
| | - Xiao Luo
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Xiaopei Xu
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Xiaodong Li
- Department of RadiologyLinyi People's HospitalLinyiChina
| | - Zhujing Shen
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Kaicheng Li
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Chao Wang
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Peiyu Huang
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Minming Zhang
- Department of RadiologyThe Second Affiliated Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Shouping Dai
- Department of RadiologyLinyi People's HospitalLinyiChina
| | - Fei Xie
- Department of Equipment and Medical EngineeringLinyi People's HospitalLinyiChina
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Setton R, Mwilambwe-Tshilobo L, Sheldon S, Turner GR, Spreng RN. Hippocampus and temporal pole functional connectivity is associated with age and individual differences in autobiographical memory. Proc Natl Acad Sci U S A 2022; 119:e2203039119. [PMID: 36191210 PMCID: PMC9564102 DOI: 10.1073/pnas.2203039119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 08/02/2022] [Indexed: 11/18/2022] Open
Abstract
Recollection of one's personal past, or autobiographical memory (AM), varies across individuals and across the life span. This manifests in the amount of episodic content recalled during AM, which may reflect differences in associated functional brain networks. We take an individual differences approach to examine resting-state functional connectivity of temporal lobe regions known to coordinate AM content retrieval with the default network (anterior and posterior hippocampus, temporal pole) and test for associations with AM. Multiecho resting-state functional magnetic resonance imaging (fMRI) and autobiographical interviews were collected for 158 younger and 105 older healthy adults. Interviews were scored for internal (episodic) and external (semantic) details. Age group differences in connectivity profiles revealed that older adults had lower connectivity within anterior hippocampus, posterior hippocampus, and temporal pole but greater connectivity with regions across the default network compared with younger adults. This pattern was positively related to posterior hippocampal volumes in older adults, which were smaller than younger adult volumes. Connectivity associations with AM showed two significant patterns. The first dissociated connectivity related to internal vs. external AM across participants. Internal AM was related to anterior hippocampus and temporal pole connectivity with orbitofrontal cortex and connectivity within posterior hippocampus. External AM was related to temporal pole connectivity with regions across the lateral temporal cortex. In the second pattern, younger adults displayed temporal pole connectivity with regions throughout the default network associated with more detailed AMs overall. Our findings provide evidence for discrete ensembles of brain regions that scale with systematic variation in recollective styles across the healthy adult life span.
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Affiliation(s)
- Roni Setton
- Department of Psychology, Harvard University, Cambridge, MA, 02138
| | - Laetitia Mwilambwe-Tshilobo
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Signy Sheldon
- Department of Psychology, McGill University, Montreal, QC, H3A 1G1, Canada
| | - Gary R. Turner
- Department of Psychology, York University, Toronto, ON, M3J 1P3, Canada
| | - R. Nathan Spreng
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
- Department of Psychology, McGill University, Montreal, QC, H3A 1G1, Canada
- McConnell Brain Imaging Centre, McGill University, Montreal, QC, H3A 2B4, Canada
- Department of Psychiatry, McGill University, Montreal, QC, H3A 1A1, Canada
- Douglas Mental Health University Institute, Verdun, QC, H4H 1R3, Canada
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6
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Jiang Y, Liu DF, Zhang X, Liu HG, Zhang C, Zhang JG. Modulation of the rat hippocampal-cortex network and episodic-like memory performance following entorhinal cortex stimulation. CNS Neurosci Ther 2021; 28:448-457. [PMID: 34964261 PMCID: PMC8841309 DOI: 10.1111/cns.13795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/12/2021] [Accepted: 12/14/2021] [Indexed: 12/22/2022] Open
Abstract
Aims Entorhinal cortex (EC) deep brain stimulation (DBS) has shown a memory enhancement effect. However, its brain network modulation mechanisms remain unclear. The present study aimed to investigate the functional connectivity in the rat hippocampal‐cortex network and episodic‐like memory performance following EC‐DBS. Methods 7.0 T functional MRI (fMRI) scans and episodic‐like memory tests were performed 3 days and 28 days after EC‐DBS in healthy rats. The fMRI data processing was focused on the power spectra, functional connectivity, and causality relationships in the hippocampal‐cortex network. In addition, the exploration ratio for each object and the discrimination ratio of the “when” and “where” factors were calculated in the behavioral tests. Results EC‐DBS increased the power spectra and the functional connectivity in the prefrontal‐ and hippocampal‐related networks 3 days after stimulation and recovered 4 weeks later. Both networks exhibited a strengthened connection with the EC after EC‐DBS. Further seed‐based functional connectivity comparisons showed increased connectivity among the prefrontal cortex, hippocampus and EC, especially on the ipsilateral side of DBS. The dentate gyrus is a hub region closely related to both the EC and the prefrontal cortex and receives information flow from both. Moreover, acute EC‐DBS also enhanced the discrimination ratio of the “where” factor in the episodic‐like memory test on Day 3. Conclusion EC‐DBS caused a reversible modulation effect on functional connectivity in the hippocampal‐cortex network and episodic‐like memory performance.
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Affiliation(s)
- Yin Jiang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neurostimulation, Beijing, China
| | - De-Feng Liu
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xin Zhang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
| | - Huan-Guang Liu
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Chao Zhang
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jian-Guo Zhang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neurostimulation, Beijing, China.,Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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7
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Wirt RA, Crew LA, Ortiz AA, McNeela AM, Flores E, Kinney JW, Hyman JM. Altered theta rhythm and hippocampal-cortical interactions underlie working memory deficits in a hyperglycemia risk factor model of Alzheimer's disease. Commun Biol 2021; 4:1036. [PMID: 34480097 PMCID: PMC8417282 DOI: 10.1038/s42003-021-02558-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/28/2021] [Indexed: 01/04/2023] Open
Abstract
Diabetes mellitus is a metabolic disease associated with dysregulated glucose and insulin levels and an increased risk of developing Alzheimer’s disease (AD) later in life. It is thought that chronic hyperglycemia leads to neuroinflammation and tau hyperphosphorylation in the hippocampus leading to cognitive decline, but effects on hippocampal network activity are unknown. A sustained hyperglycemic state was induced in otherwise healthy animals and subjects were then tested on a spatial delayed alternation task while recording from the hippocampus and anterior cingulate cortex (ACC). Hyperglycemic animals performed worse on long delay trials and had multiple electrophysiological differences throughout the task. We found increased delta power and decreased theta power in the hippocampus, which led to altered theta/delta ratios at the end of the delay period. Cross frequency coupling was significantly higher in multiple bands and delay period hippocampus-ACC theta coherence was elevated, revealing hypersynchrony. The highest coherence values appeared long delays on error trials for STZ animals, the opposite of what was observed in controls, where lower delay period coherence was associated with errors. Consistent with previous investigations, we found increases in phosphorylated tau in STZ animals’ hippocampus and cortex, which might account for the observed oscillatory and cognitive changes. To investigate the effects of chronic hyperglycemia on hippocampal network activity Wirt et al induced sustained hyperglycemia in rats and tested them in a spatial delayed alternation task while recording from the hippocampus and anterior cingulate cortex. They demonstrated that hyperglycemia impaired task performance and altered theta rhythm as well as increasing tau phosphorylation, which suggest there is potentially a direct link between chronic hyperglycemia and Alzheimer’s disease.
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Affiliation(s)
- Ryan A Wirt
- Interdisciplinary Program in Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Lauren A Crew
- Interdisciplinary Program in Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Andrew A Ortiz
- Interdisciplinary Program in Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Adam M McNeela
- Interdisciplinary Program in Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Emmanuel Flores
- Interdisciplinary Program in Neuroscience, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Jefferson W Kinney
- Department of Brain Health, School of Integrated Health Sciences, University of Nevada, Las Vegas, NV, USA
| | - James M Hyman
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA.
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Schlichting ML, Gumus M, Zhu T, Mack ML. The structure of hippocampal circuitry relates to rapid category learning in humans. Hippocampus 2021; 31:1179-1190. [PMID: 34379847 DOI: 10.1002/hipo.23382] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 07/17/2021] [Accepted: 07/24/2021] [Indexed: 11/06/2022]
Abstract
Prior work suggests that complementary white matter pathways within the hippocampus (HPC) differentially support the learning of specific versus general information. In particular, while the trisynaptic pathway (TSP) rapidly forms memories for specific experiences, the monosynaptic pathway (MSP) slowly learns generalities. However, despite the theorized significance of such circuitry, characterizing how information flows within the HPC to support learning in humans remains a challenge. We leveraged diffusion-weighted imaging as a proxy for individual differences in white matter structure linking key regions along with TSP (HPC subfields CA3 and CA1 ) and MSP (entorhinal cortex and CA1 ) and related these differences in hippocampal structure to category learning ability. We hypothesized that learning to categorize the "exception" items that deviated from category rules would benefit from TSP-supported mnemonic specificity. Participant-level estimates of TSP- and MSP-related integrity were constructed from HPC subfield connectomes of white matter streamline density. Consistent with theories of TSP-supported learning mechanisms, we found a specific association between the integrity of CA3 -CA1 white matter connections and exception learning. These results highlight the significant role of HPC circuitry in complex human learning.
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Affiliation(s)
| | - Melisa Gumus
- Department of Psychology, University of Toronto, Toronto, Canada.,Institute of Medical Science, University of Toronto, Toronto, Canada
| | - Teresa Zhu
- Department of Psychology, University of Toronto, Toronto, Canada
| | - Michael L Mack
- Department of Psychology, University of Toronto, Toronto, Canada
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