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Sárkány B, Dávid C, Hortobágyi T, Gombás P, Somogyi P, Acsády L, Viney TJ. Early and selective localization of tau filaments to glutamatergic subcellular domains within the human anterodorsal thalamus. Acta Neuropathol 2024; 147:98. [PMID: 38861157 PMCID: PMC11166832 DOI: 10.1007/s00401-024-02749-3] [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: 01/12/2024] [Revised: 05/21/2024] [Accepted: 06/01/2024] [Indexed: 06/12/2024]
Abstract
Widespread cortical accumulation of misfolded pathological tau proteins (ptau) in the form of paired helical filaments is a major hallmark of Alzheimer's disease. Subcellular localization of ptau at various stages of disease progression is likely to be informative of the cellular mechanisms involving its spread. Here, we found that the density of ptau within several distinct rostral thalamic nuclei in post-mortem human tissue (n = 25 cases) increased with the disease stage, with the anterodorsal nucleus (ADn) consistently being the most affected. In the ADn, ptau-positive elements were present already in the pre-cortical (Braak 0) stage. Tau pathology preferentially affected the calretinin-expressing subpopulation of glutamatergic neurons in the ADn. At the subcellular level, we detected ptau immunoreactivity in ADn cell bodies, dendrites, and in a specialized type of presynaptic terminal that expresses vesicular glutamate transporter 2 (vGLUT2) and likely originates from the mammillary body. The ptau-containing terminals displayed signs of degeneration, including endosomal/lysosomal organelles. In contrast, corticothalamic axon terminals lacked ptau. The data demonstrate the involvement of a specific cell population in ADn at the onset of the disease. The presence of ptau in subcortical glutamatergic presynaptic terminals supports hypotheses about the transsynaptic spread of tau selectively affecting specialized axonal pathways.
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Affiliation(s)
- Barbara Sárkány
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
| | - Csaba Dávid
- Lendület Laboratory of Thalamus Research, Institute of Experimental Medicine, Budapest, 1083, Hungary
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, 1094, Hungary
| | - Tibor Hortobágyi
- Department of Neurology, Faculty of Medicine, University of Debrecen, Debrecen, 4032, Hungary
| | - Péter Gombás
- Department of Pathology, Szt. Borbála Hospital, Tatabánya, 2800, Hungary
| | - Peter Somogyi
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK
| | - László Acsády
- Lendület Laboratory of Thalamus Research, Institute of Experimental Medicine, Budapest, 1083, Hungary.
| | - Tim J Viney
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
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2
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Lomi E, Jeffery KJ, Mitchell AS. Convergence of location, direction, and theta in the rat anteroventral thalamic nucleus. iScience 2023; 26:106993. [PMID: 37448560 PMCID: PMC10336163 DOI: 10.1016/j.isci.2023.106993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/14/2023] [Accepted: 05/25/2023] [Indexed: 07/15/2023] Open
Abstract
The thalamus and cortex are anatomically interconnected, with the thalamus providing integral information for cortical functions. The anteroventral thalamic nucleus (AV) is reciprocally connected to retrosplenial cortex (RSC). Two distinct AV subfields, dorsomedial (AVDM) and ventrolateral (AVVL), project differentially to granular vs. dysgranular RSC, respectively. To probe if functional responses of AV neurons differ, we recorded single neurons and local field potentials from AVDM and AVVL in rats during foraging. We observed place cells (neurons modulated by spatial location) in both AVDM and AVVL. Additionally, we characterized neurons modulated by theta oscillations, heading direction, and a conjunction of these. Place cells and conjunctive Theta-by-Head direction cells were more prevalent in AVVL; more non-conjunctive theta and directional neurons were prevalent in AVDM. These findings add further evidence that there are two thalamocortical circuits connecting AV and RSC, and reveal that the signaling involves place information in addition to direction and theta.
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Affiliation(s)
- Eleonora Lomi
- Department of Experimental Psychology, University of Oxford, The Tinsley Building, Mansfield Road, OX1 3SR Oxford, UK
| | - Kate J. Jeffery
- School of Psychology & Neuroscience, College of Medical, Veterinary & Life Sciences, University of Glasgow, G12 8QB Glasgow, UK
| | - Anna S. Mitchell
- Department of Experimental Psychology, University of Oxford, The Tinsley Building, Mansfield Road, OX1 3SR Oxford, UK
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3
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Smith SM, Garcia EL, Davidson CG, Thompson JJ, Lovett SD, Ferekides N, Federico Q, Bumanglag AV, Hernandez AR, Abisambra JF, Burke SN. Paired associates learning is disrupted after unilateral parietal lobe controlled cortical impact in rats: A trial-by-trial behavioral analysis. Behav Brain Res 2023; 437:114106. [PMID: 36089100 PMCID: PMC9927580 DOI: 10.1016/j.bbr.2022.114106] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 02/01/2023]
Abstract
Approximately 60-70 million people suffer from traumatic brain injury (TBI) each year. Animal models continue to be paramount in understanding mechanisms of cellular dysfunction and testing new treatments for TBI. Enhancing the translational potential of novel interventions therefore necessitates testing pre-clinical intervention strategies with clinically relevant cognitive assays. This study used a unilateral parietal lobe controlled cortical impact (CCI) model of TBI and tested rats on a touchscreen-based Paired Associates Learning (PAL) task, which is part of the Cambridge Neuropsychological Test Automated Battery. In humans, the PAL task has been used to assess cognitive deficits in the ability to form stimulus-location associations in a multitude of disease states, including TBI. Although the use of PAL in animal models could be important for understanding the clinical severity of cognitive impairment post-injury and throughout intervention, to date, the extent to which a rat model of TBI produces deficits in PAL task performance has not yet been reported. This study details the behavioral consequences of the CCI injury model with a Trial-by-Trial analysis of PAL performance that enables behavioral strategy use to be inferred. Following behavior, the extent of the injury was quantified with histology and staining for the presence of glial fibrillary acid protein and ionized calcium-binding adapter molecule 1. Rats that received unilateral CCI were impaired on the PAL task and showed more aberrant response-driven behavior. The magnitude of PAL impairment was also correlated with Iba1 staining in the thalamus. These observations suggest that PAL could be useful for pre-clinical assessments of novel interventions for treating TBI.
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Affiliation(s)
- Samantha M Smith
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States; Graduate Program in Biomedical Sciences, Neuroscience Concentration, University of Florida, United States
| | - Elena L Garcia
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Caroline G Davidson
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - John J Thompson
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Sarah D Lovett
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Nedi Ferekides
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Quinten Federico
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Argyle V Bumanglag
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States
| | - Abbi R Hernandez
- Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jose F Abisambra
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States; Center for Translational Research in Neurodegenerative Disease, University of Florida College of Medicine, Gainesville, FL, United States
| | - Sara N Burke
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States; Institute on Aging, University of Florida, Gainesville, FL, United States.
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4
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Hamilton JJ, Dalrymple‐Alford JC. Anterior thalamic nuclei: A critical substrate for non-spatial paired-associate memory in rats. Eur J Neurosci 2022; 56:5014-5032. [PMID: 35985792 PMCID: PMC9804733 DOI: 10.1111/ejn.15802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/30/2022] [Accepted: 08/15/2022] [Indexed: 01/09/2023]
Abstract
Injury or dysfunction in the anterior thalamic nuclei (ATN) may be the key contributory factor in many instances of diencephalic amnesia. Experimental ATN lesions impair spatial memory and temporal discriminations, but there is only limited support for a more general role in non-spatial memory. To extend evidence on the effects of ATN lesions, we examined the acquisition of biconditional associations between odour and object pairings presented in a runway, either with or without a temporal gap between these items. Intact adult male rats acquired both the no-trace and 10-s trace versions of this non-spatial task. Intact rats trained in the trace version showed elevated Zif268 activation in the dorsal CA1 of the hippocampus, suggesting that the temporal component recruited additional neural processing. ATN lesions completely blocked acquisition on both versions of this association-memory task. This deficit was not due to poor inhibition to non-rewarded cues or impaired sensory processing, because rats with ATN lesions were unimpaired in the acquisition of simple odour discriminations and simple object discriminations using similar task demands in the same apparatus. This evidence challenges the view that impairments in arbitrary paired-associate learning after ATN lesions require the use of multimodal spatial stimuli. It suggests that diencephalic amnesia associated with the ATN stems from degraded attention to stimulus-stimulus associations and their representation across a distributed memory system.
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Affiliation(s)
- Jennifer J. Hamilton
- School of Psychology, Speech and HearingUniversity of CanterburyChristchurchNew Zealand,New Zealand Brain Research InstituteChristchurchNew Zealand,Brain Research New Zealand – Rangahau Roro AotearoaAucklandNew Zealand
| | - John C. Dalrymple‐Alford
- School of Psychology, Speech and HearingUniversity of CanterburyChristchurchNew Zealand,New Zealand Brain Research InstituteChristchurchNew Zealand,Brain Research New Zealand – Rangahau Roro AotearoaAucklandNew Zealand
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Aggleton JP, Nelson AJD, O'Mara SM. Time to retire the serial Papez circuit: Implications for space, memory, and attention. Neurosci Biobehav Rev 2022; 140:104813. [PMID: 35940310 PMCID: PMC10804970 DOI: 10.1016/j.neubiorev.2022.104813] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/20/2022] [Accepted: 08/01/2022] [Indexed: 11/26/2022]
Abstract
After more than 80 years, Papez serial circuit remains a hugely influential concept, initially for emotion, but in more recent decades, for memory. Here, we show how this circuit is anatomically and mechanistically naïve as well as outdated. We argue that a new conceptualisation is necessitated by recent anatomical and functional findings that emphasize the more equal, working partnerships between the anterior thalamic nuclei and the hippocampal formation, along with their neocortical interactions in supporting, episodic memory. Furthermore, despite the importance of the anterior thalamic for mnemonic processing, there is growing evidence that these nuclei support multiple aspects of cognition, only some of which are directly associated with hippocampal function. By viewing the anterior thalamic nuclei as a multifunctional hub, a clearer picture emerges of extra-hippocampal regions supporting memory. The reformulation presented here underlines the need to retire Papez serially processing circuit.
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Affiliation(s)
- John P Aggleton
- School of Psychology, Cardiff University, 70 Park Place, Cardiff CF10 3AT, Wales, UK.
| | - Andrew J D Nelson
- School of Psychology, Cardiff University, 70 Park Place, Cardiff CF10 3AT, Wales, UK
| | - Shane M O'Mara
- School of Psychology and Trinity College Institute of Neuroscience, Trinity College Dublin, The University of Dublin, Dublin D02 PN40, Ireland
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6
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McNaughton N, Vann SD. Construction of complex memories via parallel distributed cortical–subcortical iterative integration. Trends Neurosci 2022; 45:550-562. [PMID: 35599065 PMCID: PMC7612902 DOI: 10.1016/j.tins.2022.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/01/2022] [Accepted: 04/22/2022] [Indexed: 01/08/2023]
Abstract
The construction of complex engrams requires hippocampal-cortical interactions. These include both direct interactions and ones via often-overlooked subcortical loops. Here, we review the anatomical organization of a hierarchy of parallel ‘Papez’ loops through the hypothalamus that are homologous in mammals from rats to humans. These hypothalamic loops supplement direct hippocampal-cortical connections with iterative re-processing paced by theta rhythmicity. We couple existing anatomy and lesion data with theory to propose that recirculation in these loops progressively enhances desired connections, while reducing interference from competing external goals and internal associations. This increases the signal-to-noise ratio in the distributed engrams (neocortical and cerebellar) necessary for complex learning and memory. The hypothalamic nodes provide key motivational input for engram enhancement during consolidation.
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Affiliation(s)
- Neil McNaughton
- Department of Psychology and Brain Health Research Centre, University of Otago, POB56, Dunedin, New Zealand.
| | - Seralynne D Vann
- School of Psychology, Cardiff University, Park Place, Cardiff, CF10 3AT, UK.
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7
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Perry BAL, Lomi E, Mitchell AS. Thalamocortical interactions in cognition and disease: the mediodorsal and anterior thalamic nuclei. Neurosci Biobehav Rev 2021; 130:162-177. [PMID: 34216651 DOI: 10.1016/j.neubiorev.2021.05.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 04/12/2021] [Accepted: 05/17/2021] [Indexed: 01/15/2023]
Abstract
The mediodorsal thalamus (MD) and anterior thalamic nuclei (ATN) are two adjacent brain nodes that support our ability to make decisions, learn, update information, form and retrieve memories, and find our way around. The MD and PFC work in partnerships to support cognitive processes linked to successful learning and decision-making, while the ATN and extended hippocampal system together coordinate the encoding and retrieval of memories and successful spatial navigation. Yet, while these distinctions may appear to be segregated, both the MD and ATN together support our higher cognitive functions as they regulate and are influenced by interconnected fronto-temporal neural networks and subcortical inputs. Our review focuses on recent studies in animal models and in humans. This evidence is re-shaping our understanding of the importance of MD and ATN cortico-thalamocortical pathways in influencing complex cognitive functions. Given the evidence from clinical settings and neuroscience research labs, the MD and ATN should be considered targets for effective treatments in neuropsychiatric diseases and disorders and neurodegeneration.
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Affiliation(s)
- Brook A L Perry
- Department of Experimental Psychology, Oxford University, The Tinsley Building, Mansfield Road, OX1 3SR, United Kingdom
| | - Eleonora Lomi
- Department of Experimental Psychology, Oxford University, The Tinsley Building, Mansfield Road, OX1 3SR, United Kingdom
| | - Anna S Mitchell
- Department of Experimental Psychology, Oxford University, The Tinsley Building, Mansfield Road, OX1 3SR, United Kingdom.
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8
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Barnett S, Parr-Brownlie L, Perry B, Young C, Wicky H, Hughes S, McNaughton N, Dalrymple-Alford J. Anterior thalamic nuclei neurons sustain memory. CURRENT RESEARCH IN NEUROBIOLOGY 2021; 2:100022. [PMID: 36246504 PMCID: PMC9559952 DOI: 10.1016/j.crneur.2021.100022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/26/2021] [Accepted: 09/20/2021] [Indexed: 12/27/2022] Open
Abstract
A hippocampal-diencephalic-cortical network supports memory function. The anterior thalamic nuclei (ATN) form a key anatomical hub within this system. Consistent with this, injury to the mammillary body-ATN axis is associated with examples of clinical amnesia. However, there is only limited and indirect support that the output of ATN neurons actively enhances memory. Here, in rats, we first showed that mammillothalamic tract (MTT) lesions caused a persistent impairment in spatial working memory. MTT lesions also reduced rhythmic electrical activity across the memory system. Next, we introduced 8.5 Hz optogenetic theta-burst stimulation of the ATN glutamatergic neurons. The exogenously-triggered, regular pattern of stimulation produced an acute and substantial improvement of spatial working memory in rats with MTT lesions and enhanced rhythmic electrical activity. Neither behaviour nor rhythmic activity was affected by endogenous stimulation derived from the dorsal hippocampus. Analysis of immediate early gene activity, after the rats foraged for food in an open field, showed that exogenously-triggered ATN stimulation also increased Zif268 expression across memory-related structures. These findings provide clear evidence that increased ATN neuronal activity supports memory. They suggest that ATN-focused gene therapy may be feasible to counter clinical amnesia associated with dysfunction in the mammillary body-ATN axis. The mammillothalamic tract (MTT) supports neural activity in an extended memory system. Optogenetic activation of neurons in the anterior thalamus acutely improves memory after MTT lesions. Rescued memory associates with system-wide neuronal activation and enhanced EEG. Anterior thalamus actively sustains memory and is a feasible therapeutic target.
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Mathiasen ML, O'Mara SM, Aggleton JP. The anterior thalamic nuclei and nucleus reuniens: So similar but so different. Neurosci Biobehav Rev 2020; 119:268-280. [PMID: 33069688 PMCID: PMC7738755 DOI: 10.1016/j.neubiorev.2020.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/26/2020] [Accepted: 10/05/2020] [Indexed: 12/04/2022]
Abstract
Two thalamic sites are of especial significance for understanding hippocampal - diencephalic interactions: the anterior thalamic nuclei and nucleus reuniens. Both nuclei have dense, direct interconnections with the hippocampal formation, and both are directly connected with many of the same cortical and subcortical areas. These two thalamic sites also contain neurons responsive to spatial stimuli while lesions within these two same areas can disrupt spatial learning tasks that are hippocampal dependent. Despite these many similarities, closer analysis reveals important differences in the details of their connectivity and the behavioural impact of lesions in these two thalamic sites. These nuclei play qualitatively different roles that largely reflect the contrasting relative importance of their medial frontal cortex interactions (nucleus reuniens) compared with their retrosplenial, cingulate, and mammillary body interactions (anterior thalamic nuclei). While the anterior thalamic nuclei are critical for multiple aspects of hippocampal spatial encoding and performance, nucleus reuniens contributes, as required, to aid cognitive control and help select correct from competing memories.
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Affiliation(s)
- Mathias L Mathiasen
- School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK
| | - Shane M O'Mara
- School of Psychology and Institute of Neuroscience, Trinity College, Dublin, Ireland
| | - John P Aggleton
- School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK.
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10
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Deconstructing the Direct Reciprocal Hippocampal-Anterior Thalamic Pathways for Spatial Learning. J Neurosci 2020; 40:6978-6990. [PMID: 32753513 PMCID: PMC7470921 DOI: 10.1523/jneurosci.0874-20.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/14/2020] [Accepted: 07/19/2020] [Indexed: 01/13/2023] Open
Abstract
The hippocampus is essential for normal memory but does not act in isolation. The anterior thalamic nuclei may represent one vital partner. Using DREADDs, the behavioral consequences of transiently disrupting anterior thalamic function were examined, followed by inactivation of the dorsal subiculum. Next, the anterograde transport of an adeno-associated virus expressing DREADDs was paired with localized intracerebral infusions of a ligand to target specific input pathways. In this way, the direct projections from the anterior thalamic nuclei to the dorsal hippocampal formation were inhibited, followed by separate inhibition of the dorsal subiculum projections to the anterior thalamic nuclei. To assay spatial working memory, all animals performed a reinforced T-maze alternation task, then a more challenging version that nullifies intramaze cues. Across all four experiments, deficits emerged on the spatial alternation task that precluded the use of intramaze cues. Inhibiting dorsal subiculum projections to the anterior thalamic nuclei produced the severest spatial working memory deficit. This deficit revealed the key contribution of dorsal subiculum projections to the anteromedial and anteroventral thalamic nuclei for the processing of allocentric information, projections not associated with head-direction information. The overall pattern of results provides consistent causal evidence of the two-way functional significance of direct hippocampal-anterior thalamic interactions for spatial processing. At the same time, these findings are consistent with hypotheses that these same, reciprocal interactions underlie the common core symptoms of temporal lobe and diencephalic anterograde amnesia. SIGNIFICANCE STATEMENT It has long been conjectured that the anterior thalamic nuclei might be key partners with the hippocampal formation and that, respectively, they are principally responsible for diencephalic and temporal lobe amnesia. However, direct causal evidence for this functional relationship is lacking. Here, we examined the behavioral consequences of transiently silencing the direct reciprocal interconnections between these two brain regions on tests of spatial learning. Disrupting information flow from the hippocampal formation to the anterior thalamic nuclei and vice versa impaired performance on tests of spatial learning. By revealing the conjoint importance of hippocampal-anterior thalamic pathways, these findings help explain why pathology in either the medial diencephalon or the medial temporal lobes can result in profound anterograde amnesic syndromes.
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Perry BAL, Mitchell AS. Considering the Evidence for Anterior and Laterodorsal Thalamic Nuclei as Higher Order Relays to Cortex. Front Mol Neurosci 2019; 12:167. [PMID: 31333412 PMCID: PMC6616498 DOI: 10.3389/fnmol.2019.00167] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 06/17/2019] [Indexed: 12/25/2022] Open
Abstract
Our memories are essential in our daily lives. The frontal and cingulate cortices, hippocampal system and medial temporal lobes are key brain regions. In addition, severe amnesia also occurs after damage or dysfunction to the anterior thalamic nuclei; this subcortical thalamic hub is interconnected to these key cortical memory structures. Behavioral, anatomical, and physiological evidence across mammalian species has shown that interactions between the anterior thalamic nuclei, cortex and hippocampal formation are vital for spatial memory processing. Furthermore, the adjacent laterodorsal thalamic nucleus (LD), interconnected to the retrosplenial cortex (RSC) and visual system, also contributes to spatial memory in mammals. However, how these thalamic nuclei contribute to memory still remains largely unknown. Fortunately, our understanding of the importance of the thalamus in cognitive processes is being redefined, as widespread evidence challenges the established view of the thalamus as a passive relay of sensory and subcortical information to the cortex. In this review article, we examine whether the anterior thalamic nuclei and the adjacent LD are suitable candidates for "higher-order" thalamic nuclei, as defined by the Sherman and Guillery model. Rather than simply relaying information to cortex, "higher-order" thalamic nuclei have a prominent role in cognition, as they can regulate how areas of the cortex interact with one another. These considerations along with a review of the latest research will be used to suggest future studies that will clarify the contributions that the anterior and LD have in supporting cortical functions during cognitive processes.
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Affiliation(s)
- Brook A L Perry
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Anna S Mitchell
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
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12
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Gharaylou Z, Shafaghi L, Oghabian MA, Yoonessi A, Tafakhori A, Shahsavand Ananloo E, Hadjighassem M. Longitudinal Effects of Bumetanide on Neuro-Cognitive Functioning in Drug-Resistant Epilepsy. Front Neurol 2019; 10:483. [PMID: 31133976 PMCID: PMC6517515 DOI: 10.3389/fneur.2019.00483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/23/2019] [Indexed: 12/25/2022] Open
Abstract
Antiepileptic drugs (AEDs) have repeatedly shown inconsistent and almost contradictory effects on the neurocognitive system, from substantial impairments in processing speed to the noticeable improvement in working memory and executive functioning. Previous studies have provided a novel insight into the cognitive improvement by bumetanide as a potential antiepileptic drug. Through the current investigation, we evaluated the longitudinal effects of bumetanide, an NKCC1 co-transporter antagonist, on the brain microstructural organization as a probable underlying component for cognitive performance. Microstructure assessment was completed using SPM for the whole brain assay and Freesurfer/TRACULA for the automatic probabilistic tractography analysis. Primary cognitive operations including selective attention and processing speed, working memory capacity and spatial memory were evaluated in 12 patients with a confirmed diagnosis of refractory epilepsy. Participants treated with bumetanide (2 mg/ day) in two divided doses as an adjuvant therapy to their regular AEDs for 6 months, which followed by the re-assessment of their cognitive functions and microstructural organizations. Seizure frequency reduced in eight patients which accompanied by white matter reconstruction; fractional anisotropy (FA) increased in the cingulum-cingulate gyrus (CCG), anterior thalamic radiation (ATR), and temporal part of the superior longitudinal fasciculus (SLFt) in correlation with the clinical response. The voxel-based analysis in responder patients revealed increased FA in the left hippocampus, right cerebellum, and right medial temporal lobe, while mean diffusivity (MD) values reduced in the right occipital lobe and cerebellum. Microstructural changes in SLFt and ATR accompanied by a reduction in the error rate in the spatial memory test. These primary results have provided preliminary evidence for the effect of bumetanide on cognitive functioning through microstructural changes in patients with drug-resistant epilepsy.
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Affiliation(s)
- Zeinab Gharaylou
- Department of Neuroscience and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Lida Shafaghi
- Department of Neuroscience and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Oghabian
- Neuroimaging and Analysis Group, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Yoonessi
- Department of Neuroscience and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Tafakhori
- Imam Khomeini Hospital, Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mahmoudreza Hadjighassem
- Department of Neuroscience and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
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13
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Bubb EJ, Metzler-Baddeley C, Aggleton JP. The cingulum bundle: Anatomy, function, and dysfunction. Neurosci Biobehav Rev 2018; 92:104-127. [PMID: 29753752 PMCID: PMC6090091 DOI: 10.1016/j.neubiorev.2018.05.008] [Citation(s) in RCA: 401] [Impact Index Per Article: 66.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 05/01/2018] [Accepted: 05/04/2018] [Indexed: 12/16/2022]
Abstract
The cingulum bundle is a prominent white matter tract that interconnects frontal, parietal, and medial temporal sites, while also linking subcortical nuclei to the cingulate gyrus. Despite its apparent continuity, the cingulum's composition continually changes as fibres join and leave the bundle. To help understand its complex structure, this review begins with detailed, comparative descriptions of the multiple connections comprising the cingulum bundle. Next, the impact of cingulum bundle damage in rats, monkeys, and humans is analysed. Despite causing extensive anatomical disconnections, cingulum bundle lesions typically produce only mild deficits, highlighting the importance of parallel pathways and the distributed nature of its various functions. Meanwhile, non-invasive imaging implicates the cingulum bundle in executive control, emotion, pain (dorsal cingulum), and episodic memory (parahippocampal cingulum), while clinical studies reveal cingulum abnormalities in numerous conditions, including schizophrenia, depression, post-traumatic stress disorder, obsessive compulsive disorder, autism spectrum disorder, Mild Cognitive Impairment, and Alzheimer's disease. Understanding the seemingly diverse contributions of the cingulum will require better ways of isolating pathways within this highly complex tract.
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Affiliation(s)
- Emma J Bubb
- School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK
| | | | - John P Aggleton
- School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK.
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Dalrymple-Alford JC, Perry BAL. Lesions of the mammillothalamic tract and anterior thalamic nuclei: Response to Vann and Nelson (2018). Hippocampus 2018; 28:694-697. [PMID: 29742808 DOI: 10.1002/hipo.22963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/06/2018] [Accepted: 05/07/2018] [Indexed: 11/11/2022]
Affiliation(s)
- John C Dalrymple-Alford
- Department of Psychology, New Zealand Brain Research Institute, University of Canterbury and Brain Research New Zealand, Christchurch, 8041, New Zealand
| | - Brook A L Perry
- Department of Experimental Psychology, University of Oxford, Oxford, OX1 3SR, United Kingdom
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