1
|
Tsai SH, Tsao CY, Lee LJ. Altered White Matter and Layer VIb Neurons in Heterozygous Disc1 Mutant, a Mouse Model of Schizophrenia. Front Neuroanat 2020; 14:605029. [PMID: 33384588 PMCID: PMC7769951 DOI: 10.3389/fnana.2020.605029] [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: 09/11/2020] [Accepted: 11/24/2020] [Indexed: 11/13/2022] Open
Abstract
Increased white matter neuron density has been associated with neuropsychiatric disorders including schizophrenia. However, the pathogenic features of these neurons are still largely unknown. Subplate neurons, the earliest generated neurons in the developing cortex have also been associated with schizophrenia and autism. The link between these neurons and mental disorders is also not well established. Since cortical layer VIb neurons are believed to be the remnant of subplate neurons in the adult rodent brain, in this study, we aimed to examine the cytoarchitecture of neurons in cortical layer VIb and the underlying white matter in heterozygous Disc1 mutant (Het) mice, a mouse model of schizophrenia. In the white matter, the number of NeuN-positive neurons was quite low in the external capsule; however, the density of these cells was found increased (54%) in Het mice compared with wildtype (WT) littermates. The density of PV-positive neurons was unchanged in the mutants. In the cortical layer VIb, the density of CTGF-positive neurons increased (21.5%) in Het mice, whereas the number of Cplx3-positive cells reduced (16.1%) in these mutants, compared with WT mice. Layer VIb neurons can be classified by their morphological characters. The morphology of Type I pyramidal neurons was comparable between genotypes while the dendritic length and complexity of Type II multipolar neurons were significantly reduced in Het mice. White matter neurons and layer VIb neurons receive synaptic inputs and modulate the process of sensory information and sleep/arousal pattern. Aberrances of these neurons in Disc1 mutants implies altered brain functions in these mice.
Collapse
Affiliation(s)
- Shin-Hwa Tsai
- School of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Yu Tsao
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
| | - Li-Jen Lee
- School of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
- Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
| |
Collapse
|
2
|
Increased Thalamocortical Connectivity in Schizophrenia Correlates With Sleep Spindle Deficits: Evidence for a Common Pathophysiology. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:706-714. [PMID: 31262708 DOI: 10.1016/j.bpsc.2019.04.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/06/2019] [Accepted: 04/24/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND Converging evidence implicates abnormal thalamocortical interactions in the pathophysiology of schizophrenia. This evidence includes consistent findings of increased resting-state functional connectivity of the thalamus with somatosensory and motor cortex during wake and reduced spindle activity during sleep. We hypothesized that these abnormalities would be correlated, reflecting a common mechanism: reduced inhibition of thalamocortical neurons by the thalamic reticular nucleus (TRN). The TRN is the major inhibitory nucleus of the thalamus and is abnormal in schizophrenia. Reduced TRN inhibition would be expected to lead to increased and less filtered thalamic relay of sensory and motor information to the cortex during wake and reduced burst firing necessary for spindle initiation during sleep. METHODS Overnight polysomnography and resting-state functional connectivity magnetic resonance imaging were performed in 26 outpatients with schizophrenia and 30 demographically matched healthy individuals. We examined the relations of sleep spindle density during stage 2 non-rapid eye movement sleep with connectivity of the thalamus to the cortex during wakeful rest. RESULTS As in prior studies, patients with schizophrenia exhibited increased functional connectivity of the thalamus with bilateral somatosensory and motor cortex and reduced sleep spindle density. Spindle density inversely correlated with thalamocortical connectivity, including in somotosensory and motor cortex, regardless of diagnosis. CONCLUSIONS These findings link two biomarkers of schizophrenia-the sleep spindle density deficit and abnormally increased thalamocortical functional connectivity-and point to deficient TRN inhibition as a plausible mechanism. If TRN-mediated thalamocortical dysfunction increases risk for schizophrenia and contributes to its manifestations, understanding its mechanism could guide the development of targeted interventions.
Collapse
|
3
|
Manoach DS, Pan JQ, Purcell SM, Stickgold R. Reduced Sleep Spindles in Schizophrenia: A Treatable Endophenotype That Links Risk Genes to Impaired Cognition? Biol Psychiatry 2016; 80:599-608. [PMID: 26602589 PMCID: PMC4833702 DOI: 10.1016/j.biopsych.2015.10.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/18/2015] [Accepted: 10/05/2015] [Indexed: 11/26/2022]
Abstract
Although schizophrenia (SZ) is defined by waking phenomena, abnormal sleep is a common feature. In particular, there is accumulating evidence of a sleep spindle deficit. Sleep spindles, a defining thalamocortical oscillation of non-rapid eye movement stage 2 sleep, correlate with IQ and are thought to promote long-term potentiation and enhance memory consolidation. We review evidence that reduced spindle activity in SZ is an endophenotype that impairs sleep-dependent memory consolidation, contributes to symptoms, and is a novel treatment biomarker. Studies showing that spindles can be pharmacologically enhanced in SZ and that increasing spindles improves memory in healthy individuals suggest that treating spindle deficits in patients with SZ may improve cognition. Spindle activity is highly heritable, and recent large-scale genome-wide association studies have identified SZ risk genes that may contribute to spindle deficits and illuminate their mechanisms. For example, the SZ risk gene CACNA1I encodes a calcium channel that is abundantly expressed in the thalamic spindle generator and plays a critical role in spindle activity based on a mouse knockout. Future genetic studies of animals and humans can delineate the role of this and other genes in spindles. Such cross-disciplinary research, by forging empirical links in causal chains from risk genes to proteins and cellular functions to endophenotypes, cognitive impairments, symptoms, and diagnosis, has the potential to advance the mechanistic understanding, treatment, and prevention of SZ. This review highlights the importance of deficient sleep-dependent memory consolidation among the cognitive deficits of SZ and implicates reduced sleep spindles as a potentially treatable mechanism.
Collapse
Affiliation(s)
- Dara S. Manoach
- Department of Psychiatry and Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02215, USA,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Jen Q. Pan
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Shaun M. Purcell
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02215, USA,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA,Division of Psychiatric Genomics, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Robert Stickgold
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA,Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA 02215 Harvard Medical School, Boston, MA, 02215
| |
Collapse
|
4
|
Vukadinovic Z. Sleep spindle reductions in schizophrenia and its implications for the development of cortical body map. Schizophr Res 2015; 168:589-90. [PMID: 26285830 DOI: 10.1016/j.schres.2015.08.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 08/05/2015] [Accepted: 08/07/2015] [Indexed: 11/29/2022]
|
5
|
Vukadinovic Z. Elevated striatal dopamine attenuates nigrothalamic inputs and impairs transthalamic cortico-cortical communication in schizophrenia: A hypothesis. Med Hypotheses 2015; 84:47-52. [DOI: 10.1016/j.mehy.2014.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 10/28/2014] [Accepted: 11/11/2014] [Indexed: 12/12/2022]
|
6
|
Vukadinovic Z. NMDA receptor hypofunction and the thalamus in schizophrenia. Physiol Behav 2014; 131:156-9. [PMID: 24792662 DOI: 10.1016/j.physbeh.2014.04.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 04/10/2014] [Accepted: 04/24/2014] [Indexed: 12/16/2022]
Abstract
The thalamus can be subdivided into two kinds of nuclei, the higher order (HO) and the first order (FO) relays, which are distinguished based on the origin of their main or driver inputs. The driver inputs to the HO nuclei arrive from the cortex, and the messages they deliver are then relayed to other cortical areas. As the origin of these inputs is the cortical layer V, whose axons branch and innervate lower motor centers in the CNS, the messages are copies of motor instructions issued to those lower motor centers. These copies are thus an integral part of perceptual processes. In schizophrenia, the HO nuclei are shrunken suggesting that a reduced ability to integrate copies of ongoing motor commands in perceptual processes may be one part of the underlying pathophysiology. The driver inputs in the thalamus utilize ionotropic glutamate receptors such as the NMDAR. NMDAR antagonists may exert their pro-psychotic effects by impairing the function of the HO nuclei. Here, we argue that such agents (or the proposed NMDAR hypofunction in schizophrenia) weaken the driver inputs in the HO nuclei, thereby producing a cortico-thalamo-cortical disconnection and impairing sensorimotor integration.
Collapse
Affiliation(s)
- Zoran Vukadinovic
- University of New Mexico School of Medicine, Department of Psychiatry, United States.
| |
Collapse
|
7
|
Astori S, Wimmer RD, Lüthi A. Manipulating sleep spindles – expanding views on sleep, memory, and disease. Trends Neurosci 2013; 36:738-48. [DOI: 10.1016/j.tins.2013.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 12/12/2022]
|