3 results
Understanding the mechanisms underlying cognitive control in psychosis
- R. Maitra, I. L. J. Lemmers-Jansen, M. Vooren, Lucy Vanes, Timea Szentgyorgyi, Charlotte Crisp, Elias Mouchlianitis, S. S. Shergill
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- Journal:
- Psychological Medicine , First View
- Published online by Cambridge University Press:
- 23 May 2024, pp. 1-10
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Background
Cognitive control (CC) involves a top–down mechanism to flexibly respond to complex stimuli and is impaired in schizophrenia.
MethodsThis study investigated the impact of increasing complexity of CC processing in 140 subjects with psychosis and 39 healthy adults, with assessments of behavioral performance, neural regions of interest and symptom severity.
ResultsThe lowest level of CC (Stroop task) was impaired in all patients; the intermediate level of CC (Faces task) with explicit emotional information was most impaired in patients with first episode psychosis. Patients showed activation of distinct neural CC and reward networks, but iterative learning based on the higher-order of CC during the trust game, was most impaired in chronic schizophrenia. Subjects with first episode psychosis, and patients with lower symptom load, demonstrate flexibility of the CC network to facilitate learning, which appeared compromised in the more chronic stages of schizophrenia.
ConclusionThese data suggest optimal windows for opportunities to introduce therapeutic interventions to improve CC.
TMS-EEG in the Investigation of Excitation-Inhibition Imbalance in Psychosis and Cognition
- Panayiota G Michalopoulou, Rachel TS Chow, Nimra Farooq, Timea Szentgyorgyi, Maryam Mohammed-Akram, Lorenzo Rocchi, Sukhi S Shergill
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- Journal:
- BJPsych Open / Volume 9 / Issue S1 / July 2023
- Published online by Cambridge University Press:
- 07 July 2023, pp. S62-S63
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Aims
Transcranial Magnetic Stimulation (TMS) is an in-vivo, non-invasive, and safe method that probes neurophysiological properties associated with cortical glutamatergic (excitatory) and GABAergic (inhibitory) neurotransmission. The combination of TMS with Electroencephalography (EEG) allows us to measure TMS-evoked cortical responses directly from brain activity and it is uniquely placed to elucidate in-vivo cortical Excitatory/Inhibitory processes. Schizophrenia has been associated with Excitation/Inhibition (E/I) imbalance. Cognitive impairment, which is almost ubiquitous in schizophrenia, has been linked with the E/I abnormalities observed in schizophrenia. Among the TMS-EEG evoked potentials (TEPs), the N100 is thought to reflect activation of inhibitory GABA-B cortical circuits and has been associated with attentional processes in healthy individuals, attention deficit hyperactivity disorder (ADHD) and depression. Our aim was to investigate the cortical processes related to the generation of N100 after motor cortex stimulation and its association with attention measures in patients with schizophrenia and healthy controls.
MethodsTEPs were recorded following application of 150 TMS pulses at 90% of resting motor threshold on two brain sites, i.e., left primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC) in stable patients with schizophrenia (n = 9) and healthy controls (n = 9). Region of Interest (ROI) analysis was performed to calculate the regional average of the N100 peak amplitude in M1 and DLPFC based on previous literature. Attention was assessed with a Continuous Performance Task (CPT).
ResultsWe found a significant negative correlation between the amplitude of N100 from M1 and CPT score in the patient group (rho = -0.73, p = 0.026). The N100 component from DLPFC in patients did not correlate with the CPT score (rho = -0.034, p = 0.93), which may suggest regional specificity of M1 inhibitory processes in attention in patients with schizophrenia.
ConclusionN100 is considered to be related to cortical inhibitory processes influenced by cortico–striato–thalamo–cortical loops, with greater cortical inhibitory activity producing a larger N100 amplitude. Our preliminary results suggest association of the GABA-B-ergic TEP N100 with attentional processes in M1 and may represent cortical inhibition beyond motor inhibition in patients with schizophrenia. Overall, TMS-EEG offers the potential to investigate the state and dynamics of E/I imbalance in schizophrenia and cognition.
Virtual reality cognitive & functional assessment in psychosis
- Sukhwinder Shergill, Lilla Porffy, Gabriella Whomersley, Timea Szentgyorgyi, Elias Mouchlianitis, Joel Patchitt
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- Journal:
- BJPsych Open / Volume 7 / Issue S1 / June 2021
- Published online by Cambridge University Press:
- 18 June 2021, pp. S289-S290
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Aims
To compare the MATRICS Consensus Cognitive Battery (MCCB) and a novel Virtual Reality (VR) task, called VStore, in assessing cognition and functional capacity (FC) in schizophrenia. We hypothesise that VStore reliably discriminates between patients and controls, correlates with the MCCB, and is well-tolerated. Additionally, VStore is expected to strongly correlate with FC measures.
BackgroundCognitive and functional deficits in schizophrenia have a major impact on everyday functioning of patients. The gold-standard cognitive assessment is the MCCB, while the USCD Performance-Based Skills Assessment (UPSA) is used to assess FC in this patient group. Neither of which are without limitations. For example, both take a long time to administer, and the MCCB alone cannot give clear indications of FC. We propose the use of a novel VR task to simultaneously measure cognition and FC in a single assessment. VStore is a shopping task, which involves a verbal learning task followed by buying items from a predetermined shopping list in a virtual minimarket.
MethodTen patients with schizophrenia or schizoaffective disorder and ten age/gender-matched healthy controls recruited from South London, completed the following assessments: VStore, MCCB, UPSA & Global Assessment of Functioning (GAF), and VR-Symptom Questionnaire (VRSQ); while controls only completed the VR task. To test whether VStore can differentiate between patients and controls we employed unpaired t-test. To explore associations between VStore Total Time, MCCB composite score and FC measures Pearson's r was used. Finally, mean differences between pre/post-VR symptoms scores were tested using paired t-test.
ResultThere was a significant difference between patients and controls on the verbal learning task (t16.38=−4.67,p < .001), and total time spent completing the VR task (t11.41 = 2.67, p = .023). In addition, VStore had a strong association with MCCB composite score (r=−.80,p = .010). While both VStore (r=−.82, p < 001) and MCCB (r = .77,p = .010) had significant correlation with the UPSA, only VStore had a significant association with the GAF (r=−.68,p = .030). Finally, VStore appears to be well-tolerated, causing no measurable side effects in the VRSQ (Pre-VR Mean =12.1[SD = 13.5], Post-VR Mean = 9.6[SD = 11.5],t9 = 0.49,p > .05).
ConclusionResults suggest that VStore can discriminate between schizophrenia patients and healthy controls. In addition, VStore and MCCB seem to be strongly associated, suggesting that they tap into identical cognitive domains. VStore seems to be strongly correlated with FC, more so than the MCCB, and cause no measurable side effects. Taken together, this suggests that this novel VR task has the potential to reliably measure cognition and FC simultaneously.