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A gamma wave or gamma rhythm is a pattern of neural oscillation in humans with a frequency between 25 and 140 Hz, the 40 Hz point being of particular interest. Gamma rhythms are correlated with large-scale brain network activity and cognitive phenomena such as working memory, attention, and perceptual grouping, and can be increased in amplitude via meditation or neurostimulation. Altered gamma activity has been observed in many mood and cognitive disorders such as Alzheimer's disease, epilepsy, and schizophrenia.
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Transcranial direct current stimulation (tDCS) is a form of neuromodulation that uses constant, low direct current delivered via electrodes on the head. It was originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder. It can be contrasted with cranial electrotherapy stimulation, which generally uses alternating current the same way, as well as transcranial magnetic stimulation.
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Kynurenic acid is a product of the normal metabolism of amino acid L-tryptophan. It has been shown that kynurenic acid possesses neuroactive activity. It acts as an antiexcitotoxic and anticonvulsant, most likely through acting as an antagonist at excitatory amino acid receptors. Because of this activity, it may influence important neurophysiological and neuropathological processes. As a result, kynurenic acid has been considered for use in therapy in certain neurobiological disorders. Conversely, increased levels of kynurenic acid have also been linked to certain pathological conditions.
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Kalirin, also known as Huntingtin-associated protein-interacting protein (HAPIP), protein duo (DUO), or serine/threonine-protein kinase with Dbl- and pleckstrin homology domain, is a protein that in humans is encoded by the KALRN gene. Kalirin was first identified in 1997 as a protein interacting with huntingtin-associated protein 1. Is also known to play an important role in nerve growth and axonal development.
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The Abelson helper integration site 1 (AHI1) is a protein coding gene that is known for the critical role it plays in brain development. Proper cerebellar and cortical development in the human brain depends heavily on AHI1. The AHI1 gene is prominently expressed in the embryonic hindbrain and forebrain. AHI1 specifically encodes the Jouberin protein and mutations in the expression of the gene is known to cause specific forms of Joubert syndrome. Joubert syndrome is autosomal recessive and is characterized by the brain malformations and mental retardation that AHI1 mutations have the potential to induce. AHI1 has also been associated with schizophrenia and autism due to the role it plays in brain development. An AHI1 heterozygous knockout mouse model was studied by Bernard Lerer and his group at Hadassah Medical Center in Jerusalem to elucidate the correlation between alterations in AHI1 expression and the pathogenesis of neuropsychiatric disorders. The core temperatures and corticosterone secretions of the heterozygous knockout mice after exposure to environmental and visceral stress exhibited extreme repression of autonomic nervous system and hypothalamic-pituitary-adrenal responses. The knockout mice demonstrated an increased resilience to different types of stress and these results lead to a correlation between emotional regulation and neuropsychiatric disorders.
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Scientific studies have found that different brain areas show altered activity in humans with major depressive disorder (MDD), and this has encouraged advocates of various theories that seek to identify a biochemical origin of the disease, as opposed to theories that emphasize psychological or situational causes. Factors spanning these causative groups include nutritional deficiencies in magnesium, vitamin D, and tryptophan with situational origin but biological impact. Several theories concerning the biologically based cause of depression have been suggested over the years, including theories revolving around monoamine neurotransmitters, neuroplasticity, neurogenesis, inflammation and the circadian rhythm. Physical illnesses, including hypothyroidism and mitochondrial disease, can also trigger depressive symptoms.
Magnetic seizure therapy (MST) is a proposed form of electrotherapy and electrical brain stimulation. It is currently being investigated for the treatment of major depressive disorder, treatment-resistant depression (TRD), bipolar depression, schizophrenia and obsessive-compulsive disorder. MST is stated to work by inducing seizures via magnetic fields, in contrast to ECT which does so using alternating electric currents. Additionally, MST works in a more concentrated fashion than ECT, thus able to create a seizure with less of a total electric charge. In contrast to (r)TMS, the stimulation rates are higher resulting in more energy transfer. Currently it is thought that MST works in patients with major depressive disorder by activating the connection between the subgenual anterior cingulate cortex and the parietal cortex.
Resting state fMRI is a method of functional magnetic resonance imaging (fMRI) that is used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an explicit task is not being performed. A number of resting-state brain networks have been identified, one of which is the default mode network. These brain networks are observed through changes in blood flow in the brain which creates what is referred to as a blood-oxygen-level dependent (BOLD) signal that can be measured using fMRI.
Heather Clare Whalley is a Scottish scientist. She is a senior research fellow in neuroimaging at the Centre for Clinical Brain Sciences, University of Edinburgh, and is an affiliate member of the Centre for Genomic and Experimental Medicine at the University of Edinburgh. Her main focus of research is on the mechanisms underlying the development of major psychiatric disorders using the latest genomic and neuroimaging approaches.
Network neuroscience is an approach to understanding the structure and function of the human brain through an approach of network science, through the paradigm of graph theory. A network is a connection of many brain regions that interact with each other to give rise to a particular function. Network Neuroscience is a broad field that studies the brain in an integrative way by recording, analyzing, and mapping the brain in various ways. The field studies the brain at multiple scales of analysis to ultimately explain brain systems, behavior, and dysfunction of behavior in psychiatric and neurological diseases. Network neuroscience provides an important theoretical base for understanding neurobiological systems at multiple scales of analysis.
References
- ↑ Mancuso L, Costa T, Nani A, Manuello J, Liloia D, Gelmini G, et al. (March 2019). "The homotopic connectivity of the functional brain: a meta-analytic approach". Scientific Reports. 9 (1): 3346. Bibcode:2019NatSR...9.3346M. doi:10.1038/s41598-019-40188-3. PMC 6399443 . PMID 30833662.
- ↑ Shan X, Cui X, Liu F, Li H, Huang R, Tang Y, et al. (May 2021). "Shared and distinct homotopic connectivity changes in melancholic and non-melancholic depression". Journal of Affective Disorders. 287: 268–275. doi:10.1016/j.jad.2021.03.038. PMID 33799047. S2CID 232775109.
- ↑ Hermesdorf M, Sundermann B, Feder S, Schwindt W, Minnerup J, Arolt V, et al. (March 2016). "Major depressive disorder: Findings of reduced homotopic connectivity and investigation of underlying structural mechanisms". Human Brain Mapping. 37 (3): 1209–1217. doi:10.1002/hbm.23097. PMC 6867499 . PMID 26704348.
- ↑ Li HJ, Xu Y, Zhang KR, Hoptman MJ, Zuo XN (April 2015). "Homotopic connectivity in drug-naïve, first-episode, early-onset schizophrenia". Journal of Child Psychology and Psychiatry, and Allied Disciplines. 56 (4): 432–443. doi:10.1111/jcpp.12307. PMC 4333112 . PMID 25130214.
- ↑ Rossi LF, Wykes RC, Kullmann DM, Carandini M (August 2017). "Focal cortical seizures start as standing waves and propagate respecting homotopic connectivity". Nature Communications. 8 (1): 217. Bibcode:2017NatCo...8..217R. doi:10.1038/s41467-017-00159-6. PMC 5550430 . PMID 28794407.
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