scholarly journals Drifting codes within a stable coding scheme for working memory

2019 ◽  
Author(s):  
M. J. Wolff ◽  
J. Jochim ◽  
E. G. Akyürek ◽  
T. J. Buschman ◽  
M. G. Stokes
Keyword(s):  
Working Memory ◽  
Brain Activity ◽  
Memory Performance ◽  
Specific Impulse ◽  
Mental States ◽  
Dynamic Component ◽  
Coding Scheme ◽  
Stable Maintenance ◽  
Low Dimensional ◽  
Time Specific

AbstractWorking memory (WM) is important to maintain information over short time periods to provide some stability in a constantly changing environment. However, brain activity is inherently dynamic, raising a challenge for maintaining stable mental states. To investigate the relationship between WM stability and neural dynamics, we used electroencephalography to measure the neural response to impulse stimuli during a WM delay. Multivariate pattern analysis revealed representations were both stable and dynamic: there was a clear difference in neural states between time-specific impulse responses, reflecting dynamic changes, yet the coding scheme for memorized orientations was stable. This suggests that a stable subcomponent in WM enables stable maintenance within a dynamic system. A stable coding scheme simplifies readout for WM-guided behaviour, whereas the low-dimensional dynamic component could provide additional temporal information. Despite having a stable subspace, WM is clearly not perfect – memory performance still degrades over time. Indeed, we find that even within the stable coding scheme, memories drift during maintenance. When averaged across trials, such drift contributes to the width of the error distribution.

scholarly journals Focal neural perturbations reshape low-dimensional trajectories of brain activity supporting cognitive performance

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Kartik K. Iyer ◽  
Kai Hwang ◽  
Luke J. Hearne ◽  
Eli Muller ◽  
Mark D’Esposito ◽  
...  
Keyword(s):  
Working Memory ◽  
Neural Activity ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Memory Performance ◽  
Functional Link ◽  
Low Dimensional Topology ◽  
Brain Functions ◽  
Human Participants ◽  
Low Dimensional

AbstractThe emergence of distributed patterns of neural activity supporting brain functions and behavior can be understood by study of the brain’s low-dimensional topology. Functional neuroimaging demonstrates that brain activity linked to adaptive behavior is constrained to low-dimensional manifolds. In human participants, we tested whether these low-dimensional constraints preserve working memory performance following local neuronal perturbations. We combined multi-session functional magnetic resonance imaging, non-invasive transcranial magnetic stimulation (TMS), and methods translated from the fields of complex systems and computational biology to assess the functional link between changes in local neural activity and the reshaping of task-related low dimensional trajectories of brain activity. We show that specific reconfigurations of low-dimensional trajectories of brain activity sustain effective working memory performance following TMS manipulation of local activity on, but not off, the space traversed by these trajectories. We highlight an association between the multi-scale changes in brain activity underpinning cognitive function.

scholarly journals Resting‐State EEG Microstates Parallel Age‐Related Differences in Allocentric Spatial Working Memory Performance

2021 ◽  
Author(s):  
Adeline Jabès ◽  
Giuliana Klencklen ◽  
Paolo Ruggeri ◽  
Christoph M. Michel ◽  
Pamela Banta Lavenex ◽  
...  
Keyword(s):  
Older Adults ◽  
Working Memory ◽  
Resting State ◽  
Cognitive Aging ◽  
Temporal Dynamics ◽  
Spatial Working Memory ◽  
Brain Activity ◽  
Memory Performance ◽  
Brain Regions ◽  
Age Related

AbstractAlterations of resting-state EEG microstates have been associated with various neurological disorders and behavioral states. Interestingly, age-related differences in EEG microstate organization have also been reported, and it has been suggested that resting-state EEG activity may predict cognitive capacities in healthy individuals across the lifespan. In this exploratory study, we performed a microstate analysis of resting-state brain activity and tested allocentric spatial working memory performance in healthy adult individuals: twenty 25–30-year-olds and twenty-five 64–75-year-olds. We found a lower spatial working memory performance in older adults, as well as age-related differences in the five EEG microstate maps A, B, C, C′ and D, but especially in microstate maps C and C′. These two maps have been linked to neuronal activity in the frontal and parietal brain regions which are associated with working memory and attention, cognitive functions that have been shown to be sensitive to aging. Older adults exhibited lower global explained variance and occurrence of maps C and C′. Moreover, although there was a higher probability to transition from any map towards maps C, C′ and D in young and older adults, this probability was lower in older adults. Finally, although age-related differences in resting-state EEG microstates paralleled differences in allocentric spatial working memory performance, we found no evidence that any individual or combination of resting-state EEG microstate parameter(s) could reliably predict individual spatial working memory performance. Whether the temporal dynamics of EEG microstates may be used to assess healthy cognitive aging from resting-state brain activity requires further investigation.

scholarly journals Urinary tetrahydrocannabinol is associated with poorer working memory performance and alterations in associated brain activity

2018 ◽  
Vol 44 (3) ◽  
pp. 613-619 ◽  
Author(s):  
Max M. Owens ◽  
Shannon McNally ◽  
Tashia Petker ◽  
Michael T. Amlung ◽  
Iris M. Balodis ◽  
...  
Keyword(s):  
Working Memory ◽  
Brain Activity ◽  
Memory Performance

scholarly journals Age-Related Differences in Resting-State EEG and Allocentric Spatial Working Memory Performance

2021 ◽  
Vol 13 ◽  
Author(s):  
Adeline Jabès ◽  
Giuliana Klencklen ◽  
Paolo Ruggeri ◽  
Jean-Philippe Antonietti ◽  
Pamela Banta Lavenex ◽  
...  
Keyword(s):  
Older Adults ◽  
Working Memory ◽  
Resting State ◽  
Spatial Working Memory ◽  
Brain Activity ◽  
Memory Performance ◽  
Group Differences ◽  
Age Group ◽  
Eeg Activity ◽  
Recording Conditions

During normal aging resting-state brain activity changes and working memory performance declines as compared to young adulthood. Interestingly, previous studies reported that different electroencephalographic (EEG) measures of resting-state brain activity may correlate with working memory performance at different ages. Here, we recorded resting-state EEG activity and tested allocentric spatial working memory in healthy young (20–30 years) and older (65–75 years) adults. We adapted standard EEG methods to record brain activity in mobile participants in a non-shielded environment, in both eyes closed and eyes open conditions. Our study revealed some age-group differences in resting-state brain activity that were consistent with previous results obtained in different recording conditions. We confirmed that age-group differences in resting-state EEG activity depend on the recording conditions and the specific parameters considered. Nevertheless, lower theta-band and alpha-band frequencies and absolute powers, and higher beta-band and gamma-band relative powers were overall observed in healthy older adults, as compared to healthy young adults. In addition, using principal component and regression analyses, we found that the first extracted EEG component, which represented mainly theta, alpha and beta powers, correlated with spatial working memory performance in older adults, but not in young adults. These findings are consistent with the theory that the neurobiological bases of working memory performance may differ between young and older adults. However, individual measures of resting-state EEG activity could not be used as reliable biomarkers to predict individual allocentric spatial working memory performance in young or older adults.

scholarly journals The Dynamic-Processing Model of Working Memory

2020 ◽  
Vol 29 (4) ◽  
pp. 378-387
Author(s):  
Nathan S. Rose
Keyword(s):  
Working Memory ◽  
Brain Activity ◽  
Memory Performance ◽  
Short Term ◽  
Dynamic Activity ◽  
Mind And Brain ◽  
Latent Representations ◽  
Dynamic Processing ◽  
Conventional Models ◽  
The Mind

Recent shifts in the understanding of how the mind and brain retain information in working memory (WM) call for revision to traditional theories. Evidence of dynamic, “activity-silent,” short-term retention processes diverges from conventional models positing that information is always retained in WM by sustained neural activity in buffers. Such evidence comes from machine-learning methods that can decode patterns of brain activity and the simultaneous administration of transcranial magnetic stimulation (TMS) to causally manipulate brain activity in specific areas and time points. TMS can “ping” brain areas to both reactivate latent representations retained in WM and affect memory performance. On the basis of these findings, I argue for a supplement to sustained retention mechanisms. Brain-decoding methods also reveal that dynamic levels of representational codes are retained in WM, and these vary according to task context, from perceptual (sensory) codes in posterior areas to abstract, recoded representations distributed across frontoparietal regions. A dynamic-processing model of WM is advanced to account for the overall pattern of results.

scholarly journals Balance between Transmitter Availability and Dopamine D2 Receptors in Prefrontal Cortex Influences Memory Functioning

2019 ◽  
Vol 30 (3) ◽  
pp. 989-1000 ◽  
Author(s):  
Goran Papenberg ◽  
Nina Karalija ◽  
Alireza Salami ◽  
Anna Rieckmann ◽  
Micael Andersson ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Brain Activity ◽  
Memory Performance ◽  
D2 Receptors ◽  
Imaging Data ◽  
Magnetic Resonance Imaging Data ◽  
Memory Functioning ◽  
Dorsolateral Prefrontal ◽  
Dopaminergic Tone

Abstract Insufficient or excessive dopaminergic tone impairs cognitive performance. We examine whether the balance between transmitter availability and dopamine (DA) D2 receptors (D2DRs) is important for successful memory performance in a large sample of adults (n = 175, 64–68 years). The Catechol-O-Methyltransferase polymorphism served as genetic proxy for endogenous prefrontal DA availability, and D2DRs in dorsolateral prefrontal cortex (dlPFC) were measured with [11C]raclopride-PET. Individuals for whom D2DR status matched DA availability showed higher levels of episodic and working-memory performance than individuals with insufficient or excessive DA availability relative to the number of receptors. A similar pattern restricted to episodic memory was observed for D2DRs in caudate. Functional magnetic resonance imaging data acquired during working-memory performance confirmed the importance of a balanced DA system for load-dependent brain activity in dlPFC. Our data suggest that the inverted-U–shaped function relating DA signaling to cognition is modulated by a dynamic association between DA availability and receptor status.

scholarly journals Nimodipine improves cortical efficiency during working memory in healthy subjects

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Caroline F. Zink ◽  
Mellissa Giegerich ◽  
Greer E. Prettyman ◽  
Kayla E. Carta ◽  
Marcus van Ginkel ◽  
...  
Keyword(s):  
Working Memory ◽  
Calcium Channel ◽  
Calcium Channel Blockers ◽  
Brain Activity ◽  
Memory Performance ◽  
Cortical Activity ◽  
Cortical Activation ◽  
Channel Blockers ◽  
Double Blind ◽  
Emotional Processes

Abstract The L-type calcium channel gene, CACNA1C, is a validated risk gene for schizophrenia and the target of calcium channel blockers. Carriers of the risk-associated genotype (rs1006737 A allele) have increased frontal cortical activity during working memory and higher CACNA1C mRNA expression in the prefrontal cortex. The aim of this study was to determine how the brain-penetrant calcium channel blocker, nimodipine, changes brain activity during working memory and other cognitive and emotional processes. We conducted a double-blind randomized cross-over pharmacoMRI study of a single 60 mg dose of oral nimodipine solution and matching placebo in healthy men, prospectively genotyped for rs1006737. With performance unchanged, nimodipine significantly decreased frontal cortical activity by 39.1% and parietal cortical activity by 42.8% during the N-back task (2-back > 0-back contrast; PFWE < 0.05; n = 28). Higher peripheral nimodipine concentrations were correlated with a greater decrease in activation in the frontal cortex. Carriers of the risk-associated allele, A (n = 14), had a greater decrease in frontal cortical activation during working memory compared to non-risk allele carriers. No differences in brain activation were found between nimodipine and placebo for other tasks. Future studies should be conducted to test if the decreased cortical brain activity after nimodipine is associated with improved working memory performance in patients with schizophrenia, particularly those who carry the risk-associated genotype. Furthermore, changes in cortical activity during working memory may be a useful biomarker in future trials of L-type calcium channel blockers.

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