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Wolff M, Halassa MM. The mediodorsal thalamus in executive control. Neuron 2024; 112:893-908. [PMID: 38295791 DOI: 10.1016/j.neuron.2024.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/15/2023] [Accepted: 01/03/2024] [Indexed: 03/23/2024]
Abstract
Executive control, the ability to organize thoughts and action plans in real time, is a defining feature of higher cognition. Classical theories have emphasized cortical contributions to this process, but recent studies have reinvigorated interest in the role of the thalamus. Although it is well established that local thalamic damage diminishes cognitive capacity, such observations have been difficult to inform functional models. Recent progress in experimental techniques is beginning to enrich our understanding of the anatomical, physiological, and computational substrates underlying thalamic engagement in executive control. In this review, we discuss this progress and particularly focus on the mediodorsal thalamus, which regulates the activity within and across frontal cortical areas. We end with a synthesis that highlights frontal thalamocortical interactions in cognitive computations and discusses its functional implications in normal and pathological conditions.
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Affiliation(s)
- Mathieu Wolff
- University of Bordeaux, CNRS, INCIA, UMR 5287, 33000 Bordeaux, France.
| | - Michael M Halassa
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA; Department of Psychiatry, Tufts University School of Medicine, Boston, MA, USA.
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d'Isa R, Comi G, Leocani L. The 4-Hole-Board Test for Assessment of Long-Term Spatial Memory in Mice. Curr Protoc 2021; 1:e228. [PMID: 34432376 DOI: 10.1002/cpz1.228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The hole-board test has been used in rodents since the early 60s to measure exploratory behavior, locomotor activity and cognitive function. The test is based on rodents' natural curiosity and attraction for novelty. Basically, the hole-board consists of a small square arena with an extractable platform as floor, which has a set of equally spaced circular holes on its surface. In this article, we describe the protocol of a 4-hole-board test allowing the assessment of long-term spatial memory in mice without the employment of water or food restriction, painful stimuli (as electrical shocks) or any aversive condition (as forced swimming or exposure to intense light). Four holes are present on the floor of the square arena (one for each of its four quadrants). Mice released in the arena spontaneously approach the holes and explore them by briefly inserting the snout inside, a behavior defined as nose-poking (or head-dipping). If, after 24 hr, rodents are re-exposed to the hole-board, the novelty of the holes decreases. Animals with an intact long-term memory will show a reduction of the frequency of nose-poking into the holes. The total number of nose-pokes on day 1 is an index of exploration, while the percentage of decrease in nose-poking on day 2 represents an index of long-term spatial memory. Number of quadrant crossings is scored as a control measure for locomotor activity, which with the present protocol should remain stable across the days of testing. Indeed, the 4-hole-board test represents a stress-free and animal-friendly option to evaluate long-term spatial memory. In the present paper, we provide detailed description of the hole-board apparatus and step-by-step protocol for assessment of spatial memory in mice. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Validation of the 4-hole-board Basic Protocol 2: Evaluation of long-term spatial memory through the 4-hole-board test.
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Affiliation(s)
- Raffaele d'Isa
- Experimental Neurophysiology Unit, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Milan, Italy
| | - Giancarlo Comi
- Vita-Salute San Raffaele University, Milan, Italy.,Casa di Cura del Policlinico, Milan, Italy
| | - Letizia Leocani
- Experimental Neurophysiology Unit, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, IRCCS-San Raffaele Hospital, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy
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3
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Loomis C, Peuß R, Jaggard JB, Wang Y, McKinney SA, Raftopoulos SC, Raftopoulos A, Whu D, Green M, McGaugh SE, Rohner N, Keene AC, Duboue ER. An Adult Brain Atlas Reveals Broad Neuroanatomical Changes in Independently Evolved Populations of Mexican Cavefish. Front Neuroanat 2019; 13:88. [PMID: 31636546 PMCID: PMC6788135 DOI: 10.3389/fnana.2019.00088] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 09/11/2019] [Indexed: 01/08/2023] Open
Abstract
A shift in environmental conditions impacts the evolution of complex developmental and behavioral traits. The Mexican cavefish, Astyanax mexicanus, is a powerful model for examining the evolution of development, physiology, and behavior because multiple cavefish populations can be compared to an extant, ancestral-like surface population of the same species. Many behaviors have diverged in cave populations of A. mexicanus, and previous studies have shown that cavefish have a loss of sleep, reduced stress, an absence of social behaviors, and hyperphagia. Despite these findings, surprisingly little is known about the changes in neuroanatomy that underlie these behavioral phenotypes. Here, we use serial sectioning to generate brain atlases of surface fish and three independent cavefish populations. Volumetric reconstruction of serial-sectioned brains confirms convergent evolution on reduced optic tectum volume in all cavefish populations tested. In addition, we quantified volumes of specific neuroanatomical loci within several brain regions that have previously been implicated in behavioral regulation, including the hypothalamus, thalamus, and habenula. These analyses reveal an enlargement of the hypothalamus in all cavefish populations relative to surface fish, as well as subnuclei-specific differences within the thalamus and prethalamus. Taken together, these analyses support the notion that changes in environmental conditions are accompanied by neuroanatomical changes in brain structures associated with behavior. This atlas provides a resource for comparative neuroanatomy of additional brain regions and the opportunity to associate brain anatomy with evolved changes in behavior.
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Affiliation(s)
- Cody Loomis
- Department of Biology, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter, FL, United States
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, FL, United States
| | - Robert Peuß
- Stowers Institute for Medical Research, Kansas City, MO, United States
| | - James B. Jaggard
- Department of Biology, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter, FL, United States
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, FL, United States
| | - Yongfu Wang
- Stowers Institute for Medical Research, Kansas City, MO, United States
| | - Sean A. McKinney
- Stowers Institute for Medical Research, Kansas City, MO, United States
| | - Stephan C. Raftopoulos
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL, United States
| | - Austin Raftopoulos
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL, United States
| | - Daniel Whu
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL, United States
| | - Matthew Green
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, FL, United States
| | - Suzanne E. McGaugh
- Department of Ecology, University of Minnesota, St. Paul, MN, United States
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO, United States
- Department of Molecular and Integrative Physiology, KU Medical Center, Kansas City, KS, United States
| | - Alex C. Keene
- Department of Biology, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter, FL, United States
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, FL, United States
| | - Erik R. Duboue
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, FL, United States
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL, United States
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Lin X, Itoga CA, Taha S, Li MH, Chen R, Sami K, Berton F, Francesconi W, Xu X. c-Fos mapping of brain regions activated by multi-modal and electric foot shock stress. Neurobiol Stress 2018; 8:92-102. [PMID: 29560385 PMCID: PMC5857493 DOI: 10.1016/j.ynstr.2018.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/17/2018] [Accepted: 02/01/2018] [Indexed: 12/29/2022] Open
Abstract
Real-world stressors are complex and multimodal, involving physical, psychological, and social dimensions. However, the brain networks that mediate stress responses to these stimuli need to be further studied. We used c-Fos mapping in mice to characterize brain circuits activated by exposure to a single episode of multimodal stress (MMS), and compared these to circuits activated by electric foot shocks (EFS). We focused on characterizing c-Fos activity in stress-relevant brain regions including the paraventricular nucleus (PVN) of the hypothalamus and the bed nucleus of the stria terminalis (BNST). We also assessed stress-induced activation of CRH-positive neurons in each of these structures. MMS and EFS activated an overlapping network of brain regions with a similar time course. c-Fos expression within the PVN and the BNST peaked 30–60 min after exposure to both MMS and EFS, and returned to baseline levels within 24 h. Quantification of c-Fos expression within BNST subregions revealed that while c-Fos expression peaked in all subregions 30–60 min after MMS and EFS exposure, the neuronal density of c-Fos expression was significantly higher in the dorsomedial and ventral BNST relative to the dorsolateral BNST. Our preliminary assessment indicated that a great majority of MMS or EFS-activated neurons in the PVN were CRH-positive (>87%); in contrast, about 6–35% of activated neurons in the BNST were CRH-positive. Our findings indicate that both MMS and EFS are effective at activating stress-relevant brain areas and support the use of MMS as an effective approach for studying multidimensional stress in animal models. The results also reveal that the PVN and BNST are part of a common neural circuit substrate involved in neural processing related to stress.
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Affiliation(s)
- Xiaoxiao Lin
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Christy A Itoga
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Sharif Taha
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112-5820, United States
| | - Ming H Li
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Ryan Chen
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Kirolos Sami
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States
| | - Fulvia Berton
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Walter Francesconi
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-1275, United States.,Department of Biomedical Engineering, University of California, Irvine, CA 92697-2715, United States.,Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4025, United States
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Pierard C, Dorey R, Henkous N, Mons N, Béracochéa D. Different implications of the dorsal and ventral hippocampus on contextual memory retrieval after stress. Hippocampus 2017; 27:999-1015. [PMID: 28597498 DOI: 10.1002/hipo.22748] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 05/24/2017] [Accepted: 05/26/2017] [Indexed: 12/26/2022]
Abstract
This study assessed the relative contributions of dorsal (dHPC) and ventral (vHPC) hippocampus regions in mediating the rapid effects of an acute stress on contextual memory retrieval. Indeed, we previously showed that an acute stress (3 electric footschocks; 0.9 mA each) delivered 15 min before the 24 h-test inversed the memory retrieval pattern in a contextual discrimination task. Specifically, mice learned in a four-hole board two successive discriminations (D1 and D2) varying by the color and texture of the floor. Twenty-four hours later, nonstressed animals remembered accurately D1 but not D2 whereas stressed mice showed an opposite memory retrieval pattern, D2 being more accurately remembered than D1. We showed here that, at the time of memory testing in that task, stressed animals exhibited no significant changes neither in pCREB activity nor in the time-course evolution of corticosterone into the vHPC; in contrast, a significant decrease in pCREB activity and a significant increase in corticosterone were observed in the dHPC as compared to nonstressed mice. Moreover, local infusion of the anesthetic lidocaine into the vHPC 15 min before the onset of the stressor did not modify the memory retrieval pattern in nonstress and stress conditions whereas lidocaine infusion into the dHPC induced in nonstressed mice an memory retrieval pattern similar to that observed in stressed animals. The overall set of data shows that memory retrieval in nonstress condition involved primarily the dHPC and that the inversion of memory retrieval pattern after stress is linked to a dHPC but not vHPC dysfunction.
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Affiliation(s)
- C Pierard
- IRBA, 91223 Brétigny sur Orge-Cedex, France
| | - R Dorey
- IRBA, 91223 Brétigny sur Orge-Cedex, France
| | - N Henkous
- Université de Bordeaux, CNRS UMR 5287, Pessac, 33615, France
| | - N Mons
- Université de Bordeaux, CNRS UMR 5287, Pessac, 33615, France
| | - D Béracochéa
- Université de Bordeaux, CNRS UMR 5287, Pessac, 33615, France
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Affiliation(s)
- V. Pallet
- Univ. Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
- INP, Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
| | - K. Touyarot
- Univ. Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
- INP, Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR, Bordeaux, France
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Jentsch MC, Van Buel EM, Bosker FJ, Gladkevich AV, Klein HC, Oude Voshaar RC, Ruhé HG, Eisel ULM, Schoevers RA. Biomarker approaches in major depressive disorder evaluated in the context of current hypotheses. Biomark Med 2015; 9:277-97. [DOI: 10.2217/bmm.14.114] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Major depressive disorder is a heterogeneous disorder, mostly diagnosed on the basis of symptomatic criteria alone. It would be of great help when specific biomarkers for various subtypes and symptom clusters of depression become available to assist in diagnosis and subtyping of depression, and to enable monitoring and prognosis of treatment response. However, currently known biomarkers do not reach sufficient sensitivity and specificity, and often the relation to underlying pathophysiology is unclear. In this review, we evaluate various biomarker approaches in terms of scientific merit and clinical applicability. Finally, we discuss how combined biomarker approaches in both preclinical and clinical studies can help to make the connection between the clinical manifestations of depression and the underlying pathophysiology.
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Affiliation(s)
- Mike C Jentsch
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
| | - Erin M Van Buel
- Department of Molecular Neurobiology, Behavioural & Cognitive Neuroscience, University of Groningen, Groningen, The Netherlands
| | - Fokko J Bosker
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
- Department of Nuclear Medicine & Molecular Imaging, University of Groningen, Groningen, The Netherlands
| | - Anatoliy V Gladkevich
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
| | - Hans C Klein
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
- Department of Nuclear Medicine & Molecular Imaging, University of Groningen, Groningen, The Netherlands
| | - Richard C Oude Voshaar
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
| | - Henricus G Ruhé
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
| | - Uli LM Eisel
- Department of Molecular Neurobiology, Behavioural & Cognitive Neuroscience, University of Groningen, Groningen, The Netherlands
| | - Robert A Schoevers
- University of Groningen, University Medical Centre of Groningen, University Centre of Psychiatry, Groningen, The Netherlands
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Bonhomme D, Pallet V, Dominguez G, Servant L, Henkous N, Lafenêtre P, Higueret P, Béracochéa D, Touyarot K. Retinoic acid modulates intrahippocampal levels of corticosterone in middle-aged mice: consequences on hippocampal plasticity and contextual memory. Front Aging Neurosci 2014; 6:6. [PMID: 24570662 PMCID: PMC3917121 DOI: 10.3389/fnagi.2014.00006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/10/2014] [Indexed: 12/13/2022] Open
Abstract
It is now established that vitamin A and its derivatives, retinoic acid (RA), are required for cognitive functions in adulthood. RA hyposignaling and hyperactivity of glucocorticoid (GC) pathway appear concomitantly during aging and would contribute to the deterioration of hippocampal synaptic plasticity and functions. Furthermore, recent data have evidenced counteracting effects of retinoids on GC signaling pathway. In the present study, we addressed the following issue: whether the stimulation of RA pathway could modulate intrahippocampal corticosterone (CORT) levels in middle-aged mice and thereby impact on hippocampal plasticity and cognitive functions. We firstly investigated the effects of vitamin A supplementation and RA treatment in middle-aged mice, on contextual serial discrimination task, a paradigm which allows the detection of early signs of age-related hippocampal-dependent memory dysfunction. We then measured intrahippocampal CORT concentrations by microdialysis before and after a novelty-induced stress. Our results show that both RA treatment and vitamin A supplementation improve “episodic-like” memory in middle-aged mice but RA treatment appears to be more efficient. Moreover, we show that the beneficial effect of RA on memory is associated to an increase in hippocampal PSD-95 expression. In addition, intrahippocampal CORT levels are reduced after novelty-induced stress in RA-treated animals. This effect cannot be related to a modulation of hippocampal 11β-HSD1 expression. Interestingly, RA treatment induces a modulation of RA receptors RARα and RARβ expression in middle-aged mice, a finding which has been correlated with the amplitude of intrahippocampal CORT levels after novelty-induced stress. Taken together, our results suggest that the preventive action of RA treatment on age-related memory deficits in middle-aged mice could be, at least in part, due to an inhibitory effect of retinoids on GC activity.
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Affiliation(s)
- Damien Bonhomme
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
| | - Véronique Pallet
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
| | - Gaelle Dominguez
- CNRS, Intititut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287 Talence, France ; INSERM, U-930, Université François Rabelais Tours, France
| | - Laure Servant
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
| | - Nadia Henkous
- CNRS, Intititut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287 Talence, France
| | - Pauline Lafenêtre
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
| | - Paul Higueret
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
| | - Daniel Béracochéa
- CNRS, Intititut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287 Talence, France
| | - Katia Touyarot
- INRA, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France ; Université de Bordeaux, Nutrition et Neurobiologie Intégrée (NutriNeuro), UMR 1286 Bordeaux, France
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Mitchell AS, Chakraborty S. What does the mediodorsal thalamus do? Front Syst Neurosci 2013; 7:37. [PMID: 23950738 PMCID: PMC3738868 DOI: 10.3389/fnsys.2013.00037] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 07/17/2013] [Indexed: 12/31/2022] Open
Abstract
Dense amnesia can result from damage to the medial diencephalon in humans and in animals. In humans this damage is diffuse and can include the mediodorsal nuclei of the thalamus. In animal models, lesion studies have confirmed the mediodorsal thalamus (MD) has a role in memory and other cognitive tasks, although the extent of deficits is mixed. Anatomical tracing studies confirm at least three different subgroupings of the MD: medial, central, and lateral, each differentially interconnected to the prefrontal cortex (PFC). Moreover, these subgroupings of the MD also receive differing inputs from other brain structures, including the basal ganglia thus the MD subgroupings form key nodes in interconnected frontal-striatal-thalamic neural circuits, integrating critical information within the PFC. We will provide a review of data collected from non-human primates and rodents after selective brain injury to the whole of the MD as well as these subgroupings to highlight the extent of deficits in various cognitive tasks. This research highlights the neural basis of memory and cognitive deficits associated with the subgroupings of the MD and their interconnected neural networks. The evidence shows that the MD plays a critical role in many varied cognitive processes. In addition, the MD is actively processing information and integrating it across these neural circuits for successful cognition. Having established that the MD is critical for memory and cognition, further research is required to understand how the MD specifically influences these cognitive processing carried out by the brain.
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Affiliation(s)
- Anna S. Mitchell
- Department of Experimental Psychology, Oxford UniversityOxford, UK
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do Nascimento ES, Cavalcante JS, Cavalcante JC, Costa MSMO. Retinal afferents to the thalamic mediodorsal nucleus in the rock cavy (Kerodon rupestris). Neurosci Lett 2010; 475:38-43. [PMID: 20338219 DOI: 10.1016/j.neulet.2010.03.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 03/12/2010] [Accepted: 03/14/2010] [Indexed: 11/17/2022]
Abstract
The MD has reciprocal connections with the ventromedial prefrontal cortex (PFC) and with limbic cortices and appears to participate in learning and memory-related processes. In this study, we report the identification of a hitherto not reported direct retinal projection to the MD of the rock cavy, a typical rodent species of the Northeast region of Brazil. After unilateral intravitreal injections of cholera toxin subunit B (CTb), anterogradely transported CTb-imunoreactive fibers and presumptive terminals were seen in the MD. A few labeled retinal fibers/terminals detected in the MD of the rock cavy brain show clear varicosities, suggesting terminal fields. The present work is the first to show a direct retinal projection to the MD of rodents and may contribute for elucidating the anatomical substrate of the functional involvement of this thalamic nucleus in the modulation of the visual recognition, emotional learning and object-reward association memory.
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Affiliation(s)
- Expedito Silva do Nascimento
- Department of Morphology/Laboratory of Chronobiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal-RN, Brazil.
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