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- 1. Presenter: Dr. Amrindar JeetKour JR 2 Psychiatry AFMC, Pune Moderator: Col V S Chauhan Prof (Psychiatry) AFMC, Pune Functional Neural Networks
- 2. Overview • Introduction • History •Functional neural networks • Implication in Psychiatric disorders 2 • Other networks • Therapeutic implication • Future aspects • Summary • Take home message
- 3. Introduction Human brain • 100billion (1011 ) neurons • 100 trillion (1014 ) synapses Brain functions are determined • Not only by a single neuron or a single brain region independently • Also by Clusters of neurons Neural circuits within a function block Group of interactions between brain regions 3 F. A. C. Azevedo, L. R. B. Carvalho, L. T. Grinberg et al., “Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain,” Journal of Comparative Neurology,vol.513, p532,2009.
- 4. Introduction Specific regions ofbrain are specialized for different functions Role of particular brain region in production of specific behaviors cannot be viewed in isolation Speech a complex faculty Role to be considered within context of neural circuits connecting neurons with other brain regions 4 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 5. History 1943 ,Warren Mcculloch and Walter Pitts describe how neurons in the brain work Modeled a simple neural network using electrical circuits 1949, Donald Hebb wrote The Organization of Behavior Neural pathways are strengthened each time they are used 1950's, simulation of hypothetical neural network by Nathanial Rochester 5
- 6.
- 7. 7 Functional neural networks GordonEM, Laumann TO, Adeyemo B, Huckins JF, Kelley WM, Petersen SE. Generation and evaluation of a cortical area parcellation from resting-state correlations. Cereb Cortex. 2016;26(1):288–303
- 8. Default mode network 8 McCormick,E.M., Telzer, E.H. Contributions of default mode network stability and deactivation to adolescent task engagement. Sci Rep 8, 18049 (2018).
- 9.
- 10. Default Mode Network:Functions Neurological basis for the self: • Autobiographical information: Memories of collection of events and facts about one's self • Self-reference: Referring to traits and descriptions of one's self Remembering the past and thinking about the future: • Remembering the past: Recalling events that happened in the past • Imagining the future: Envisioning events that might happen in the future 10 Andrews-Hanna JR. The brain’s default network and its adaptive role in internal mentation. The Neuroscientist. 2012 Jun;18(3):251- 70.
- 11. Default Mode Network:Functions Thinking about others: Theory of mind: Thinking about the thoughts of others and what they might or might not know Emotions of other: Understanding the emotions of other people and empathizing with their feelings Moral reasoning: Determining just and unjust result of an action Social evaluations: Good-bad attitude judgments about social concepts 11 Andrews-Hanna JR. The brain’s default network and its adaptive role in internal mentation. The Neuroscientist. 2012 Jun;18(3):251-70.
- 12. Default mode Network:Task related behavior Down-regulated in order to perform goal-directed behaviours. Default Mode Network shows marked suppression during task engagement visual attention or cognitive tasks Thus network labelled as task negative network Activation in DMN regions : inverse relationship with “task-active” regions 12 Andrews-Hanna JR. The brain’s default network and its adaptive role in internal mentation. The Neuroscientist. 2012 Jun;18(3):251-70.
- 13. Central Executive Network:Anatomy Network gets activated during functional MRI tasks Term equivalent to the frontoparietal network 13 • Dorsolateral prefrontal cortex • Posterior parietal cortex Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 14. Executive functions Tasks whichneed cognitive control and working memory Target-directed activities Control of intellectual activities Active during task condition Exhibits anticorrelated network during resting condition 14 Central Executive Network: Function Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 15. Salience network Anatomy Dorsal anteriorcingulate cortex Bilateral insula Presupplementary motor area 15 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 16. Salience network: Functions Switchingbetween other large-scale networks to facilitate access to attention and working memory resources when a salient event occurs Strong functional coupling with Anterior Cingulate cortex to facilitate rapid access to motor system 16 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 17. Switching in Functionalnetworks 17 Bressler SL, Menon V. Large-scale brain networks in cognition: emerging methods and principles. Trends in cognitive sciences. 2018 Jun 1;14(6):277-90.
- 18.
- 19. Substance use disorder 19 ZhangR, Volkow ND. Brain defaultmode network dysfunction in addiction. Neuroimage. 2019 Oct 15;200:313-31. Substance use disorder Aberrant patterns of brain functional connectivity in Default Mode Network Resting State Functional Connectivity anterior region decreased posterior region increased Associated with craving and relapse Prominence decreased during intoxication phases Disruption of the Default Mode Network in addiction reflects in changes in dopaminergic, glutamatergic and others Neuro transmitters
- 20. Schizophrenia Significant hypoconnectivities wereobserved between seed regions and Areas in auditory network (left insula) Core network (right superior temporal cortex) Default mode network Self-referential network (right superior temporal cortex) Somatomotor network (right precentral gyrus) 20 Lewis DA, Curley AA, Glausier JR, Volk DW. Cortical parvalbumin interneurons and cognitive dysfunction in schizophrenia. Trends Neurosci. 2012;35;57–67
- 21. Obsessive Compulsive Disorder Intrinsicfunctional connectivity in Salience Network Decreased intrinsic functional connectivity strength within Salience Network subregions Decreased intrinsic functional connectivity strength between left thalamus and left cerebellum Between left insula and right thalamus Between right cerebellum and bilateral insula, and right Ant Cingulate Cortex 21 Yun JY, Boedhoe PS, Vriend C, Jahanshad N, Abe Y, Ameis SH, Anticevic A, Arnold PD, Batistuzzo MC, Benedetti F, Beucke JC. Brain structural covariance networks in obsessive-compulsive disorder: a graph analysis from the ENIGMA Consortium. Brain. 2020 Feb 1;143(2):684-700.
- 22. Obsessive Compulsive Disorder FunctionalConnectivity Between the SN and Other Networks Exhibited decreased intrinsic Functional Connectivity strength between the Salience Network and Default Mode Network Intrinsic Functional Connectivity strength between Salience Network and Central Executive Network was significantly decreased in patients with OCD Specifically between Salience Network subregions (left insula) and ventral lateral prefrontal cortex (VLPFC) 22 Yun JY, Boedhoe PS, Vriend C, Jahanshad N, Abe Y, Ameis SH, Anticevic A, Arnold PD, Batistuzzo MC, Benedetti F, Beucke JC. Brain structural covariance networks in obsessive-compulsive disorder: a graph analysis from the ENIGMA Consortium. Brain. 2020 Feb 1;143(2):684-700.
- 23. 23 Depression Rive MM, vanRooijen G, Veltman DJ, Phillips ML, Schene AH, Ruhé HG. Neural correlates of dysfunctional emotion regulation in major depressive disorder. A systematic review of neuroimaging studies. Neuroscience & Biobehavioral Reviews. 2013 Dec 1;37(10):2529-53 Amygdala connectivity and emotion regulation Positive functional connectivity with amygdala Hippocampus Ventro Medial Pre Frontal Cortex Anterior temporal poles Negative functional connectivity with amygdala DorsoLateral Prefrontal Cortex Parietal regions Dorsal Anterior Cingulate • Also seen in early life stress, or at risk for depression (eg, family history)
- 24. 24 Depression Rive MM, vanRooijen G, Veltman DJ, Phillips ML, Schene AH, Ruhé HG. Neural correlates of dysfunctional emotion regulation in major depressive disorder. A systematic review of neuroimaging studies. Neuroscience & Biobehavioral Reviews. 2013 Dec 1;37(10):2529-53. Default Mode Network connectivity and rumination Increase in Default Mode Network connectivity (Intra-network) Preoccupation with negative mood, negative self-evaluation and rumination Increased connectivity of Default Mode Network with salience network Dominance of Default Mode Network over Salience Network Negative evaluation bias to salient information in environment Degree of hyperconnectivity between sub genual Prefrontal Cortex and Default Mode Network predicts the level of rumination
- 25. Stroke Damage to theattention network and symptoms of spatial neglect Functional connectivity correlates with severity of symptoms Alterations in default-mode network associated with post stroke depression and episodic memory dysfunction 25 Ovadia-Caro S, Margulies DS, Villringer A. The value of resting-state functional magnetic resonance imaging in stroke. Stroke. 2014 Sep;45(9):2818-24.
- 26. Autism spectrum disorder SalienceNetwork is decisive for identifying salient stimuli Builds central interface between sensory information processing, attention, motor function and cognition Alterations in social cognition is characteristic Alterations in the Salience Network is characteristically seen 26 Neufeld J, Kuja-Halkola R, Mevel K, Cauvet É, Fransson P, Bölte S. Alterations in resting state connectivity along the autism trait continuum: a twin study. Molecular psychiatry. 2018 Jul;23(7):1659-65.
- 27. Autism spectrum disorder Earlyhyperconnectivity followed by decreased connectivity in adulthood Negative within-pair correlation between autistic traits and connectivity between rt Ant Insula and ventromedial Prefrontal Cortex only in adults Default Mode Network under-active owing to dysfunctional regulatory mechanisms depending on other networks Reduced connectivity of Default Mode Network at different ages 27 Neufeld J, Kuja-Halkola R, Mevel K, Cauvet É, Fransson P, Bölte S. Alterations in resting state connectivity along the autism trait continuum: a twin study. Molecular psychiatry. 2018 Jul;23(7):1659-65.
- 28. Attention Deficit HyperactivityDisorder Higher local efficiency and decreased global efficiency Indicating a developmental delay of whole-brain functional networks Medial prefrontal, temporal, and occipital cortices Regional loss of efficiency Inferior frontal gyrus Increased nodal efficiency Default mode network connectivity Delayed maturation Decreased anterior-posterior connectivity 28
- 29. Stress Impact of earlylife stress associated Decreased default network connectivity Changes in structure and function in medial prefrontal cortex Increases in connectivity between amygdala and medial prefrontal cortex 29 Philip NS, Sweet LH, Tyrka AR, Price LH, Bloom RF, Carpenter LL. Decreased default network connectivity is associated with early life stress in medication-free healthy adults. European Neuropsychopharmacology. 2013 Jan 1;23(1):24-32.
- 30.
- 31. Dorsal and VentralAttention Networks 24 Vossel S, Geng JJ, Fink GR. Dorsal and ventral attention systems: distinct neural circuits but collaborative roles. The Neuroscientist. 2014 Apr;20(2):150-9.
- 32. Dorsal and VentralAttention Networks: Function Top-down, goal-driven attention Orienting after symbolic predictive cues Visual search Visual short-term maintenance Stimulus-driven attention to salient behaviorally relevant events Orienting to exogenous cues Reorienting to unexpected events Response to contextual cues 32 Vossel S, Geng JJ, Fink GR. Dorsal and ventral attention systems: distinct neural circuits but collaborative roles. The Neuroscientist. 2014 Apr;20(2):150-9.
- 33. Post Traumatic StressDisorder Greater cross-network connectivity involving Salience Network (dorsal Ant Cingulate Cortex) and default mode network (ventromedial Prefrontal cortex) associated with impairments in disengagement and orienting of attention, processes Both attentional orienting processes and balance observed to be disrupted in veterans with Post Traumatic Stress Disorder Interventions that utilize attention training, such as mindfulness might be useful for alleviating attentional impairments in Post Traumatic Stress Disorder 33 Block SR, King AP, Sripada RK, Weissman DH, Welsh R, Liberzon I. Behavioral and neural correlates of disrupted orienting attention in posttraumatic stress disorder. Cognitive, Affective, & Behavioral Neuroscience. 2017 Apr;17(2):422-36.
- 34. Cingulo-Opercular Network: Function Functionhas been particularly difficult to characterize Network's pervasive activity Frequent co-activation with other control-related networks Functions Sustaining alertness Cognitive control functions 34 Coste CP, Kleinschmidt A. Cingulo-opercular network activity maintains alertness. Neuroimage. 2016 Mar 1;128:264-72.
- 35. Precuneus network Core ofdefault mode network High metabolic rate compared to other networks Part of superior Parietal lobule Located in front of Cuneus Functions Autobiographical memory retrieval, Emotional stimulus processing Reward outcome monitoring Assists behavioral function 35 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 36. Visual Network: Anatomy& Function Primary visual areas Lateral occipital gyrus Superior occipital gyrus Function Perception of visual stimuli 36 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 37. Visuo-spatial Network: Anatomy& Function Posterior parietal cortex of the occipitoparietal junction Midline of the precuneus Posterior cingulate cortex Frontal pole 37 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17. Functions Spatial attention Orienting to salient visuospatial cues
- 38. Language Network: Anatomy 38 Broca’sareas Wernicke’s areas Additional regions Prefrontal Temporo-parietal Subcortical regions Wernick area Broca s area Auditory cortex Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17.
- 39. Language Network: Function 39 Speech Comprehension Reading Interpreting Mimicking
- 40. Sensorimotor Network: Anatomy& Functions 40 Smitha KA, Akhil Raja K, Arun KM, Rajesh PG, Thomas B, Kapilamoorthy TR, Kesavadas C. Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks. The neuroradiology journal. 2017 Aug;30(4):305-17. Primary motor cortex Pre-central gyrus Somatosensory motor cortex Post-central gyrus Function Performing and co-ordinating motor tasks
- 41.
- 42. Therapeutic Implications • Mindfulness •Repetitive Trans cranial Magnetic Stimulation • Transcranial Direct Current Stimulation 42
- 43. Mindfulness Associated with brainactivity in areas overlapping with default mode, salience, and central executive networks (DMN, SN, CEN) Four different mental states during meditation Focus on the present experience was most strongly related to dorso-lateral prefrontal cortex activation of central executive network (CEN) Mind wandering was associated with default mode network (DMN), Awareness of mind wandering linked with activation salience network (SN) Shift of attention back towards focus on the present experience was again linked with of central executive network (CEN) 43 Doll A, Hölzel BK, Boucard CC, Wohlschläger AM, Sorg C. Mindfulness is associated with intrinsic functional connectivity between default mode and salience networks. Frontiers in human neuroscience. 2015 Aug 25;9:461.
- 44. Mindfulness Mindfulness is correlatedwith inter-intrinsic Functional Connectivity of subnetworks of Default Mode network Show decreased correlation between anterior and posterior-dorsal Default Mode Network Stronger negative correlation between the insula Salience Network and posterior ventral Default Mode Network 44
- 45.
- 46. Repetitive Trans cranialMagnetic Stimulation Applied over left dorso-lateral prefrontal cortex (DLPFC) Treatment response mechanism based on modulations in functional networks, particularly the meso-cortico-limbic reward circuit. Stimulation of left Dorsol-ateral Prefrontal Cortex modulates anterior cingulate cortex connectivity in one specific meso-cortico-limbic network 46 Tik M, Hoffmann A, Sladky R, Tomova L, Hummer A, de Lara LN, Bukowski H, Pripfl J, Biswal B, Lamm C, Windischberger C. Towards understanding rTMS mechanism of action: stimulation of the DLPFC causes network-specific increase in functional connectivity. N euroimage. 2017 Nov 15;162:289-96.
- 47. Transcranial Direct CurrentStimulation • Psychiatric disorders demonstrate disrupted functional and structural neural networks, • tDCS application modulate functional connectivity and induce synchronization changes • Active tDCS enhanced functional connectivity in frontal and fronto-parietal regions regions known to play important underlying role in depression • tDCS results in increase in cortical excitability within DLPFC leads to a subsequent disturbance of the integrity of DMN • tDCS-induced deactivations of Default Mode N facilitate reallocation of cerebral resources to support task performance 47 Baeken C, Brunelin J, Duprat R, Vanderhasselt MA. The application of tDCS in psychiatric disorders: a brain imaging view. Socioaffective neuroscience & psychology. 2016 Jan 1;6(1):29588.
- 48. Future Aspects Recent advancesshould focus on persistent needs to identify neural networks involved in biologic process of psychiatric illness and aid in drug discovery process Non invasive Interventions targeting various networks can be utilized for benefits in whom drugs are not indicated Networks can act as potential biomarker for predicting clinical outcomes and intervention at appropriate time 48
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- 50.
Editor's Notes
- #3 Same
- #4 Regions of the brain are specialized for different functions. . However, speech is a complex faculty that depends not only on the integrity of Broca area but also on the distributed processing of information across numerous brain regions through various interconnections. Thus, the role of any particular brain region or group of neurons in the production of specific behaviors or in the pathophysiology of a given neuropsychiatric disorder cannot be viewed in isolation, but must be considered within the context of the neural circuits connecting the neurons with other brain regions.
- #5 History of neural
- #6 1957, 58,59, 97
- #7 Over the last 20 years neuroimaging studies have vastly expanded our knowledge of corticocortical connectivity in humans. However, it is important to note that most of these neuroimaging studies have identified functional connectivity (i.e., brain areas that are coactivated during a specific task) and not physical connections between regions. Evidence of direct anatomical corticocortical connections in the human brain is sparse, although newer imaging techniques such as Diffusion Tensor Imaging do provide some structural detail. Large-scale cortical networks linking distributed areas that subserve particular functions, such as attention or memory, have long been suggested and are now more readily studied with the neuroimaging techniques. Numerous networks DMN VIS, FRP,CING OPER,Dorsal attention, ventral attention have been described, but three particular networks have received the greatest focus. They are dmn cen sn
- #8 Regions of the DMN include posterior cingulate or precuneus ,angular gyrus medial-prefrontal, hippocampal, and lateral temporal areas Regions showing strong functional connectivity with the posterior cingulate during rest
- #10 The default mode network is active during passive rest and mind-wandering[4] which usually involves thinking about others, thinking about one's self, remembering the past, and envisioning the future rather than the task being performed Functional hubs:[32] Information regarding the self Posterior cingulate cortex (PCC) & precuneus: Combines bottom-up (not controlled) attention with information from memory and perception. The ventral (lower) part of PCC activates in all tasks which involve the DMN including those related to the self, related to others, remembering the past, thinking about future, Medial prefrontal cortex (mPFC): Decisions about self processing such as personal information, autobiographical memories, future goals and events, and decision making regarding those personally very close such as family
- #12 Additionally, during attention demanding tasks, sufficient deactivation of the default mode network at the time of memory encoding has been shown to result in more successful long-term memory consolidation. In particular, the DMN shows marked suppression during task engagement, and need to be down-regulated in order to perform goal-directed behaviors such as visual attention or cognitive tasks thus this network labelled as the task-negative network.[6]
- #13 Network which gets activated during Fmri tasks involving executive functions he term central executive network (CEN) is generally equivalent to the frontoparietal network in literature,[ It constitutes
- #14 CEN nodes that show strong intrinsic functional coupling also show strong coactivation during cognitively challenging tasks. In particular, the CEN is critical for actively maintaining and manipulating information in working memory, and for judgment and decision making in the context of goal-directed behavior
- #15 Salience network (red) (b) Salience sub-divisions as defined showing ventral anterior insula network (red), dorsal anterior insula network (blue) and the overlap between the two (purple)The salience network constitutes the dorsal anterior cingulate cortex, bilateral insula and presupplementary motor area. The dysfunction of the network will disrupt the functioning of other networks, because it has a key role in regulating the dynamic changes in other networks. Moreover, the network is indispensable during the rapid change of behaviour. That is, what to do next or not to do is decided by the appropriate functioning of the network. For these reasons the salient network’s proper functioning is inevitable for the commencement of control of cognition processes
- #16 It is involved in detecting and filtering salient stimuli, as well as in recruiting relevant functional networks.[3][4] Together with its interconnected brain networks, the SN contributes to a variety of complex functions, including communication, social behavior, and self-awareness through the integration of sensory, emotional, and cognitive information.[5] Switching between other large-scale networks to facilitate access to attention and working memory resources when a salient event occurs Interaction of the anterior and posterior insula to modulate autonomic reactivity to salient stimuli Strong functional coupling with the ACC to facilitate rapid access to the motor system Key role in regulating dynamic changes in other networks Network indispensable in rapid change of behavior Commencement of control of cognition processes
- #19 ant dmn self-referential mental thought and post dmn engages in episodic memory retrieval and scene construction Imbalance between anterior and posteriorDMN caused by altered DA-related reward function inaddiction. During the binge-intoxication stage, the rewarding effects of drug (red) are mediated by acti-vation of the DA reward system projecting from theVTA into the VS (and to a lesser extent the DS) and the PFC including regions from the anterior DMN and regionsfrom the ECN while suppressing the function of pos-terior DMN shifting attention to external stimuli. Chronic drug use however decreases the activity ofthe brain DA reward system (grey) of addicted in-dividuals resulting in opposite effects than during acute drug intoxication. Reduced emotional control(mediated by anterior DMN) and increased self-referential processing (mediated by posterior DMN)can enhance ruminatory behaviors and negative affect(mediated by amygdala and habenula and decreased dopaminergic signaling in VS) during withdrawal and contribute to negative reinforcement of drug use. Lower baseline activity of anterior DMN exaggerates the reactivity to drug cues. Along with compromised cognitive control (mediated by ECN), it facilitates craving and relapsing behavior in the preoccupation stage of the addiction cycle.
- #20 Default mode network (right medial prefrontal cortex, and left precuneus and anterior cingulate cortex ) No hyperconnectivity between seed regions and any other areas within the networks was detected in patients Altered Default Mode Connectivity Altered perceptual experiences that individuals with schizophrenia reflect enhanced attention to internal thoughts, feelings, and experiences, Failure to suppress default mode network activity during cognitive task performance leading to disrupted cognitive function Presence of auditory verbal hallucinations tends to be associated with reduced connectivity among these default mode structures.
- #22 Functional Connectivity Between the SN and Other Networks Exhibited decreased intrinsic Functional Connectivity strength between the Salience Network and Default Mode Network mainly found in Salience Network subregions (left insula) and the MCC Patients with OCD exhibited decreased iFC strength between the SN and the DMN compared to the HCs, which mainly foun
- #25 Damage to the attention network and corresponding symptoms of spatial neglect have been associated with decreased interhemispheric connectivity in structurally intact areas that are part of the attention network.Importantly, functional connectivity correlates with the severity of symptoms.24 rs-fMRI has also bee Another network that has been explored after stroke is the default-mode network. The default-mode network is a network of regions including the posterior cingulate and precuneus, the temporoparietal junction, and the medial prefrontal cortex. It has been widely implicated in various neurological and mental disorders and has been linked to tasks such as autobiographical memory retrieval and theory of mind functions.26 After stroke, alterations in default-mode network functional connectivity have been associated with poststroke depression27 and episodic memory dysfunction
- #26 1Alterations in social cognition is characteristic of ASD 2SN has been hypothesized to be decisive for identifying salient stimuli, building a central interface between bottom-up sensory information processing, attention guidance, emotion processing, motor function and cognition It has been suggested that might be related to alterations in the SN since these functions depend on the perception of what is salient.56 In line with this notion, a meta-analysis found consistently reduced activation of the insula in ASD compared to typically developing individuals during social processing.57 Altered salience processing might further be related to sensory issues such as sensory hyper- or hypo-sensitivity56 as well as enhanced attention to detail characteristic of ASD.58
- #27 connectivity between these networks in adults with higher autistic traits could indicate that this modulatory function is weaker. In line with this notion, it has been hypothesized that the DMN might be under-active in ASD owing to dysfunctional regulatory mechanisms depending on other networks.11 Current developmental models of ASD suggest early hyperconnectivity followed by decreased connectivity in adulthood.10,55, Reduced connectivity of DMN in ASD at different ages Early hyperconnectivity followed by decreased connectivity in adulthood Negative within-pair correlation between autistic traits and connectivity between rAI and vmPFC only in adults Reduced RS connectivity between networks in adults with higher autistic traits indicate weak modulatory function DMN under-active in ASD owing to dysfunctional regulatory mechanisms depending on other networks
- #28 Weaker interconnectivity in the DMN, dorsal attention network, and cerebellum Stronger short-range connectivity within reward network
- #29 In the paper entitled ‘‘Decreased Default Network Connectivity is Associated with Early Life Stress in Medication-Free Healthy Adults’’ by Philip et al. (in this issue) the impact of early life stress was associated with changes in structure and function in the medial prefrontal cortex, as part of the default network. Early life stress was associated with decreased default network connectivity and trend-level increases in connectivity between the amygdala and the medial prefrontal cortex, suggesting an altered resting state connectivity is a correlate of stress exposure, rather than a product of medication or psychiatric morbidity. In the paper
- #31 .IT HAS BEEN proposed tht neither of the two networks controls attentional processes in isolation and that the flexible interaction between both systems enables the dynamic control of attention in relation to top-down goals and bottom-up sensory stimulation The dorsal network (Fig. 1, blue) is supposed to be organized bilaterally and comprises the intraparietal sulcus (IPS) and the frontal eye fields (FEF) of each hemisphere. These areas are active when attention is overtly or covertly oriented in space The ventral network comprises the temporoparietal junction (TPJ) and the ventral frontal cortex (VFC) (Fig. 1, orange) and typically responds when behaviorally relevant stimuli occur unexpectedly (e.g., when they appear outside the cued focus of spatial attention). I
- #33 PTSD group exhibited greater rsFC between the salience network and (a) the default mode network, (b) the dorsal attention network, and (c) the ventral attention network. Moreover, problems with disengaging spatial attention increased the rsFC between the networks above in the control group, but not in the PTSD group. The present findings link PTSD to both altered orienting of spatial attention and altered relationships between spatial orienting and functional connectivity involving the salience network. Interventions that target orienting and disengaging spatial attention may be a new avenue for PTSD research. ePTSD group exhibited greater resting-state functional connectivity between the SN (dACC) and the default mode network (vmPFC) independent of attentional performance (Supplementary materials), replicating our previous findings (Sripada et al. 2012a). The control group did not exhibit greater rsFC than the PTSD group between the SN and any other regions.
- #37 Ghazi-Saidi L. Visuospatial and Executive Deficits in Parkinson’s Disease: A Review. Acta Scientific Neurology (ISSN: 2582-1121). 2020 Apr;3(4). Visuospatial perception permits the recognition and interpretation of information regarding many aspects of the visual world and is distinct from visuospatial attention, which is specific to directing attention to a particular location in space. Visuospatial deficit has been associated with dysfunction of several brain regions including occipital lobe, parietal lobe, frontal lobe, thalamus, and the superior longitudinal fasciculus Application Studies of visuospatial function in PD have largely focused on visual hallucination, perception, attention, and neglect given the common occurrence of related symptoms in the disease
- #39 Speech Comprehension Reading Interpreting Mimicking Broca’s area is the location of mirror neurons Observing similar movements of others Imitate motor activities
- #40 neuroscience, the sensorimotor network (SMN) is a large-scale brain network . The SMN includes somatosensory (post-central gyrus) and motor (pre-central gyrus) regions and extends to the supplementary motor areas.[1] Studies have shown that this network is activated during motor tasks such as finger tapping[2] indicating that these regions may involve a pre-mediated state that ready the brain when performing and coordinating a motor task.[1] Dysfunction in the SMN has been implicated in various neuropsychiatric disorders. Pathophysiology[edit] Bipolar Disorder: The psychomotor disturbances that characterize the depressive and manic phases of bipolar disorder may be related to dysfunction in the sensorimotor network (SMN) and its balance with other large-scale networks such as the default mode network.[3][4] Amyotrophic Lateral Sclerosis: Altered functional connectivity patterns in the SMN may contribute to various symptoms in the neurodegenerative disease .[
- #42 Needless to say, the hand is the principal instrument for writing and writing is one of the most fundamental things we do with the hand. It is therefore worthwhile to consider in some detail the hand in a book dealing with several aspects of writing. In this chapter I do not claim to present a complete and detailed review of the functions of the hand, but I will try to describe some fundamental sensory and motor mechanisms in an attempt to construct an overview of hand functioning. The hand is both a sensory and a motor organ, so that the sensory functions cannot be completely separated from the motor ones. When we explore the world with our hands, the tactile information arriving at our brain plays an essential role in the ongoing motor behavior. This continuous sensory inflow and motor outflow represents what has been called “active touch” (Gibson, 1962) or “haptics” (Revesz, 1950; Kennedy, 1978). Thus these terms mean the combined action of skin, joints and muscles for acquiring information from the external world. On the other hand, the movement
- #43 Mindfulness is attention to present moment experience without judgment. Mindfulness practice is associated with brain activity in areas overlapping with the default mode, salience, and central executive networks (DMN, SN, CEN). Intrinsic functional connectivity (iFC; i.e., synchronized ongoing activity) across these networks is associated with mindfulness scores. four different mental states during meditation with each state being preferentially related to activity in different intrinsic brain networks: focus on the present experience was most strongly related to dorso-lateral prefrontal cortex activation of the central executive network (CEN), mind wandering was associated with the default mode network (DMN), awareness of mind wandering was linked with activation in the salience network (SN), shift of attention back towards focus on the present experience was again linked with the right dorsolateral prefrontal cortex (DLPFC) and right posterior parietal cortex with both regions being part of the CEN. . These networks are believed to subserve specific cognitive functions like attentional control or core affect (Fox and Raichle, 2007) as their patterns of coherent ongoing activity overlap and reflect the activation patterns observed during goal directed . These networks are believed to subserve specific cognitive functions like attentional control or core affect as their patterns of coherent ongoing activity overlap and reflect the activation patterns observed during goal directed
- #44 A decreased connectivity of the aDMN and pDMN might indicate that more mindful individuals interpret the affective relevance of a given stimulus as less self-related. This is also supported by the association of the MAAS questionnaire with this connectivity. The MAAS focuses on measuring the ability to consciously perceive the present moment (Brown and Ryan, 2003). This present moment experience has been associated with a deactivation of the PCC/Precuneus (Garrison et al., 2013) area and with activations in dorso medial (Hölzel et al., 2007; Dickenson et al., 2013) and lateral prefrontal regions (Brefczynski-Lewis et al., 2007). Thus, this would speak for a reduced synchrony of the antDMN and the pDMN regions during this experience, which could transition into a stronger decoupling of these parts of the DMN network in more mindful individuals during rest. Instead, these regions may be coupled more strongly to either lateral parietal or DLPFC in expert meditators. e.g., Brewer et al. (2011) found increased connectivity between the PCC, dorsal ACC and DLPFC in participants with more meditation experience both during rest and during different kinds of meditation. The authors interpreted these results as an at baseline increased connectivity and activity of task positive control regions together with reduced activation of the DMN in experienced meditators regardless of condition. Other authors have argued for a coactivation of the aDMN together with inferior parietal regions during rest, which might reduce distractibility by mind wandering in experienced meditators (Hasenkamp and Barsalou, 2012). Our data are more in accordance with the model by Hasenkamp and Barsalou (2012), which suggests a critical interplay between medial DMN and lateral CEN for engaging attention on present experience. Instead of being engaged in mind-wandering which results in activation of the anterior and posterior DMN (Mason et al., 2007), regions in the dmPFC might be responsible for focusing attention back to present experience likely reflected by stronger anti-correlated coupling between CEN and DMN. Future studies will have to further clarify the directionality of connectivity between the anterior DMN, posterior DMN, and attention-relevant regions of frontal and parietal CEN and how this is related to meditation experience
- #45 Abbreviations: aDMN, anterior default mode network; pvDMN, posterior ventral default mode network; pdDMN, posterior dorsal default mode network; accSN, cingular salience network; insSN, insula salience network; lCEN, left central executive network; rCEN, right central executive network.
- #46 Transcranial magnetic stimulation (TMS) is a powerful non-invasive technique for the modulation of brain activity. While the precise mechanism of action is still unknown, TMS is applied in cognitive neuroscience to establish causal relationships between stimulation and subsequent changes in cerebral function and behavioral outcome. In addition, TMS is an FDA-approved therapeutic agent in psychiatric disorders, especially major depression. Successful repetitive TMS in such disorders is usually applied over the left dorso-lateral prefrontal cortex (DLPFC) and treatment response mechanism was therefore supposed to be based on modulations in functional networks, particularly the meso-cortico-limbic reward circuit. However, mechanistic evidence for the direct effects of rTMS over DLPFC is sparse. Here we show the specificity and temporal evolution of rTMS effects by comparing connectivity changes within 20 common independent components in a sham-controlled study. Using an unbiased whole-brain resting-state network (RSN) approach, we successfully demonstrate that stimulation of left DLPFC modulates anterior cingulate cortex (ACC) connectivity in one specific meso-cortico-limbic network, while all other networks are neither influenced by rTMS nor by sham treatment. The results of this study show that the neural correlates of TMS treatment response are also traceable in DLPFC stimulation of healthy brains and therefore represent direct effects of the stimulation procedure.
- #47 ranscranial 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.Active tDCS enhanced functional connectivity in the frontal and fronto-parietal regions (Keeser et al., 2011), regions that are known to play an important underlying role in depression ( tDCS-induced deactivations of the DMN facilitate reallocation of cerebral resources to support task performance, and thereby beneficially influence the regulation of corticosubcortical network activity.
- #48 Findings are starting to reveal DMN RSFC as a potential biomarker for predicting clinical outcomes in SUD apotential biomarker for predicting clinical outcomes nd identify the DMN as a promising target for the treatment of addiction Impairments present at the start of illness, or even before and more prominent among those individuals who go on to develop full blown psychosis Promising avenue for future biomarker and intervention work