Biology subjects

Roach, B.

Publications and source records attributed to Roach, B..

5 recordsLinked to original sources

bioRxiv2021

Alpha Event-related Desynchronization During Reward Processing in Schizophrenia

BackgroundDeficits in the way the brain processes rewards may contribute to negative symptoms in schizophrenia. Synchronization of alpha band neural oscillations is a dominant EEG signal when people are awake, but at rest. In contrast, alpha desynchronization to salient events is thought to direct allocation of information processing resources away from the internal state, to process salient stimuli in the external environment. Here, we hypothesize that alpha event-related desynchronization (ERD) during reward processing is altered in schizophrenia, leading to less difference in alpha ERD magnitude between winning and losing outcomes. MethodsEEG was recorded while participants (patients with schizophrenia (SZ)=54; healthy controls (HC) = 54) completed a casino-style slot machine gambling task. Total power, a measure of neural oscillation magnitude was measured in the alpha frequency range (8-14 Hz), time-locked to reward delivery, extracted via principal components analysis, and then compared between groups and equiprobable win and near miss loss reward outcomes. Associations between alpha power and negative symptoms and trait rumination were examined. ResultsA significant Group X Reward Outcome interaction (p=.018) was explained by differences within the HC group, driven by significant posterior-occipital alpha desynchronization to wins, relative to near miss losses (p<.001). In contrast, SZ did not modulate alpha power to wins vs. near miss losses (p>.1), nor did alpha power relate to negative symptoms (p>.1). However, across all participants, less alpha ERD to reward outcomes was related to more trait rumination, for both wins (p=.005) and near-miss losses (p=.002), with no group differences observed in the slopes of these relationships. ConclusionThese findings suggest that event-related modulation of alpha power is altered in schizophrenia during reward outcome processing, even when reward attainment places minimal demands on higher-order cognitive processes during slot machine play. In addition, high trait rumination is associated with less event-related desynchronization to reward feedback, suggesting that rumination covaries with less external attentional allocation to reward processing, regardless of reward outcome valence and group membership.

neuroscience↗

bioRxiv2021

Aperiodic measures of neural excitability are associated with anticorrelated hemodynamic networks at rest: a combined EEG-fMRI study

The hallmark of resting EEG spectra are distinct rhythms emerging from a broadband, aperiodic background. This aperiodic neural signature accounts for most of total EEG power, although its significance and relation to functional neuroanatomy remains obscure. We hypothesized that aperiodic EEG reflects a significant metabolic expenditure and therefore might be associated with the default mode network while at rest. During eyes-open, resting-state recordings of simultaneous EEG-fMRI, we find that aperiodic and periodic components of EEG power are only minimally associated with activity in the default mode network. However, a whole-brain analysis identifies increases in aperiodic power correlated with hemodynamic activity in an auditory-salience-cerebellar network, and decreases in aperiodic power are correlated with hemodynamic activity in prefrontal regions. Desynchronization in residual alpha and beta power is associated with visual and sensorimotor hemodynamic activity, respectively. These findings suggest that resting-state EEG signals acquired in an fMRI scanner reflect a balance of top-down and bottom-up stimulus processing, even in the absence of an explicit task. HIGHLIGHTSO_LIPeriodic and aperiodic EEG parameters associated with distinct resting-state networks C_LIO_LIIncreases in aperiodic power associated with an auditory-salience-cerebellar network C_LIO_LIDecreases in aperiodic power associated with prefrontal regions C_LIO_LIGlobal neural excitability may reflect stimulus processing or arousal attributable to the uniqueness of the resting-state MR-scanner environment C_LI

neuroscience↗

bioRxiv2020

Reward processing electrophysiology in schizophrenia: Effects of age and illness phase

BackgroundReward processing abnormalities may underlie characteristic pleasure and motivational impairments in schizophrenia. Some neural measures of reward processing show strong age-related modulation, highlighting the importance of considering age effects on reward sensitivity. We compared event-related potentials (ERPs) reflecting reward anticipation (stimulus-preceding negativity, SPN) and evaluation (reward positivity, RewP; late-positive potential, LPP) across individuals with schizophrenia (SZ) and healthy controls (HC), with an emphasis on examining effects of chronological age, brain age (i.e., predicted age based on neurobiological measures), and illness phase. MethodsSubjects underwent EEG while completing a slot-machine task for which rewards were not dependent on performance accuracy, speed, or other preparatory demands. Slot-machine task EEG responses were compared between 54 SZ and 54 HC individuals, ages 19 to 65. Reward-related ERPs were analyzed with respect to chronological age, categorically-defined illness phase (early; ESZ versus chronic schizophrenia; CSZ), and were used to model brain age relative to chronological age. ResultsIllness phase-focused analyses indicated there were no group differences in average SPN or RewP amplitudes. However, a group x reward outcome interaction revealed that ESZ differed from HC in later outcome processing, reflected by greater LPP responses following loss versus reward (a reversal of the HC pattern). While brain age estimates did not differ among groups, depressive symptoms in SZ were associated with older brain age estimates while controlling for negative symptoms. ConclusionsESZ and CSZ did not differ from HC in reward anticipation or early outcome processing during a cognitively undemanding reward task, highlighting areas of preserved functioning. However, ESZ showed altered later reward outcome evaluation, pointing to selective reward deficits during the early illness phase of schizophrenia. Further, an association between ERP-derived brain age and depressive symptoms in SZ extends prior findings linking depression with reward-related ERP blunting. Taken together, both illness phase and age may impact reward processing in SZ, and brain aging may offer a promising, novel marker of reward dysfunction that warrants further study.

neuroscience↗

bioRxiv2019

Reliability of Mismatch Negativity Event-Related Potentials in a Multisite, Traveling Subjects Study

ObjectiveMismatch negativity (MMN) is an auditory event-related potential (ERP) used to study schizophrenia and psychosis risk. MMN reliability from a multisite, traveling subjects study was compared using different ERP referencing, averaging, and scoring techniques.\n\nMethodsReliability of frequency, duration, and double (frequency+duration) MMN was determined from eight traveling subjects, tested on two occasions at eight EEG laboratory sites. Deviant-specific variance components were estimated for MMN peak amplitude and latency measures using different ERP processing methods. Generalizability (G) coefficients were calculated using two-facet (site, occasion), fully-crossed models and single-facet (occasion) models within each laboratory to assess MMN reliability.\n\nResultsG-coefficients calculated from two-facet models indicated fair (0.4 0.5). Reliability of MMN amplitude was greater than latency, and reliability with mastoid referencing significantly outperformed nose-referencing.\n\nConclusionsEEG preprocessing methods have a significant impact on the reliability of MMN amplitude. Within site MMN reliability can be excellent, consistent with prior single site studies.\n\nSignificanceWith standardized data collection and ERP processing, MMN can be reliably obtained in multisite studies, providing larger samples sizes within rare patient groups.

neuroscience↗

bioRxiv2018

Dynamin-2 facilitates Atg9 recycling from nascent autophagosomes

Autophagy involves rapid growth of phagophores through membrane addition. Newly added membranes are derived from other organelles through vesicles carrying the Atg9 protein. Membrane is delivered by fusing these vesicles with the phagophores. Atg9 is, nevertheless, not incorporated in autophagosomes. We now show that this protein is retrieved from phagophores by fission utilizing Dynamin-2 (Dnm2) as the membrane scission protein. Blocking Atg9 recycling by interfering with Dnm2 helps retain Atg9 in autophagosomes and degrades this protein by autophagy. Dnm2 colocalizes with the BAR domain protein Endophilin-B1 (EndoB1/Bif-1) when autophagy is induced, consistent with transient interactions during Atg9 retrieval. EndoB1 and Dnm2 also control the downstream fusion of phagophores to late endosomes, thus ensuring the completion of phagophores before proceeding to the next stage in the autophagy process. These data provide novel insights into the roles of membrane scission proteins during autophagy.

cell biology↗