scholarly journals The Neurocognitive Cost of Enhancing Cognition with Methylphenidate: Improved Distractor Resistance but Impaired Updating

2017 ◽  
Vol 29 (4) ◽  
pp. 652-663 ◽  
Author(s):  
Sean James Fallon ◽  
Marieke E. van der Schaaf ◽  
Niels ter Huurne ◽  
Roshan Cools
Keyword(s):  
Working Memory ◽  
Cognitive Flexibility ◽  
Dependent Manner ◽  
Neural Signal ◽  
Specific Effects ◽  
Cognitive Stability ◽  
Paradoxical Effects ◽  
Memory Representations ◽  
The Stability ◽  
And Task

A balance has to be struck between supporting distractor-resistant representations in working memory and allowing those representations to be updated. Catecholamine, particularly dopamine, transmission has been proposed to modulate the balance between the stability and flexibility of working memory representations. However, it is unclear whether drugs that increase catecholamine transmission, such as methylphenidate, optimize this balance in a task-dependent manner or bias the system toward stability at the expense of flexibility (or vice versa). Here we demonstrate, using pharmacological fMRI, that methylphenidate improves the ability to resist distraction (cognitive stability) but impairs the ability to flexibly update items currently held in working memory (cognitive flexibility). These behavioral effects were accompanied by task-general effects in the striatum and opposite and task-specific effects on neural signal in the pFC. This suggests that methylphenidate exerts its cognitive enhancing and impairing effects through acting on the pFC, an effect likely associated with methylphenidate's action on the striatum. These findings highlight that methylphenidate acts as a double-edged sword, improving one cognitive function at the expense of another, while also elucidating the neurocognitive mechanisms underlying these paradoxical effects.

scholarly journals Reward Acts on the pFC to Enhance Distractor Resistance of Working Memory Representations

2014 ◽  
Vol 26 (12) ◽  
pp. 2812-2826 ◽  
Author(s):  
Sean James Fallon ◽  
Roshan Cools
Keyword(s):  
Working Memory ◽  
Ventral Striatum ◽  
Reward Processing ◽  
Functional Coupling ◽  
Dependent Manner ◽  
Cognitive Stability ◽  
Memory Representations ◽  
Types Of Information ◽  
Differential Coupling ◽  
Dependent Interaction

Working memory and reward processing are often thought to be separate, unrelated processes. However, most daily activities involve integrating these two types of information, and the two processes rarely, if ever, occur in isolation. Here, we show that working memory and reward interact in a task-dependent manner and that this task-dependent interaction involves modulation of the pFC by the ventral striatum. Specifically, BOLD signal during gains relative to losses in the ventral striatum and pFC was associated not only with enhanced distractor resistance but also with impairment in the ability to update working memory representations. Furthermore, the effect of reward on working memory was accompanied by differential coupling between the ventral striatum and ignore-related regions in the pFC. Together, these data demonstrate that reward-related signals modulate the balance between cognitive stability and cognitive flexibility by altering functional coupling between the ventral striatum and the pFC.

scholarly journals Quantifying the cost of cognitive stability and flexibility

2019 ◽  
Author(s):  
Danae Papadopetraki ◽  
Monja I. Froböse ◽  
Andrew Westbrook ◽  
Bram B. Zandbelt ◽  
Roshan Cools
Keyword(s):  
Working Memory ◽  
Cognitive Control ◽  
Cognitive Flexibility ◽  
Strong Evidence ◽  
Cognitive Effort ◽  
Delayed Response ◽  
Cognitive Stability ◽  
Effort Discounting ◽  
Memory Representations ◽  
The Cost

AbstractExerting cognitive control is well known to be accompanied by a subjective effort cost and people are generally biased to avoid it. However, the nature of cognitive control costs is currently unclear. Recent theorizing suggests that the cost of cognitive effort serves as a motivational signal to bias the system away from excessive focusing (i.e. cognitive stability) and towards more cognitive flexibility. We asked whether the effort cost of cognitive stability is higher than that of cognitive flexibility. Specifically, we tested this prediction in the domain of working memory by using (i) a delayed response paradigm that allows us to manipulate demands for stability (distractor resistance) and flexibility (flexible updating) of working memory representations, as well as (ii) a subsequent cognitive effort discounting paradigm that allows us to quantify the subjective effort costs assigned to performing the delayed response paradigm. We show strong evidence, in two different samples (28 and 62 participants respectively) that subjective cost increases as a function of demand. Moreover, we demonstrate that the subjective cost of performing a task requiring cognitive stability (distractor resistance) is higher than that requiring flexible updating, supporting the hypothesis that the subjective effort cost of cognitive stability is higher than that of flexibility.

scholarly journals Intraparietal sulcus maintains working memory representations of somatosensory categories in an adaptive, context-dependent manner

NeuroImage ◽  
2020 ◽  
Vol 221 ◽  
pp. 117146 ◽  
Author(s):  
Lisa Alexandria Velenosi ◽  
Yuan-Hao Wu ◽  
Timo Torsten Schmidt ◽  
Felix Blankenburg
Keyword(s):  
Working Memory ◽  
Dependent Manner ◽  
Intraparietal Sulcus ◽  
Memory Representations ◽  
Context Dependent

The Nature of Task Set Representations in Working Memory

2017 ◽  
Vol 29 (11) ◽  
pp. 1950-1961 ◽  
Author(s):  
Atsushi Kikumoto ◽  
Ulrich Mayr
Keyword(s):  
Working Memory ◽  
Executive Control ◽  
Long Term Memory ◽  
Dependent Manner ◽  
Stimulus Response ◽  
Set Size ◽  
Memory Representations ◽  
Task Sets ◽  
Limited Process

Selection and preparation of action plans (task sets) is often assumed to occur in working memory (WM). Yet, the absence of consistent evidence that WM capacity and task selection efficiency is correlated raises questions about the functional relationship between these two aspects of executive control. We used the EEG-derived contralateral delay activity (CDA) to index the WM load of task sets. In Experiment 1, we found a CDA set size effect (2 vs. 4 stimulus–response [S-R] rules) for high-WM, but not for low-WM, individuals when S-R sets were novel. In contrast, when only four task sets were presented throughout the experiment, we observed a sustained yet set size-independent use of WM for high-WM participants. Moreover, Experiment 2 showed an increase of the CDA in situations with task conflict, and this effect was larger the more that participants experienced RT conflict effects. Combined, these results indicate that even highly familiar S-R settings are maintained in WM, albeit in a compressed manner, presumably through cues to long-term memory representations. Finally, participants with low-WM capacity represented even familiar tasks in a load-dependent manner, suggesting that the establishment of effective retrieval structures itself is a capacity-limited process.

scholarly journals On How to Be Flexible (or Not): Modulation of the Stability-Flexibility Balance

2018 ◽  
Vol 28 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Gesine Dreisbach ◽  
Kerstin Fröber
Keyword(s):  
Working Memory ◽  
Dynamic Balance ◽  
Cognitive Mechanisms ◽  
Task Context ◽  
Context Sensitive ◽  
New Information ◽  
The Stability ◽  
The One ◽  
Goal Directed Behavior ◽  
And Task

Goal-directed behavior in a constantly changing environment requires a dynamic balance between two antagonistic modes of control: On the one hand, goals need to be maintained and shielded from distraction (stability), and on the other hand, goals need to be relaxed and flexibly updated whenever significant changes occur (flexibility). A dysregulation of this stability-flexibility balance can result in overly rigid or overly distractible behavior, and it is therefore important to understand how this balance is regulated in a context-sensitive, adaptive manner. In the present article, we review recent evidence on how positive affect, reward prospect, and task context modulate the stability-flexibility balance. Two distinct underlying cognitive mechanisms will be discussed: Flexibility may result either from lowering the updating threshold in working memory or from keeping multiple tasks active in working memory. Critically, these two mechanisms allow different (testable) predictions: Whereas lowering the updating threshold should ease the access of new information in working memory and thereby increase flexibility in general, concurrent task activation should only increase flexibility between the respective tasks.

scholarly journals Selective control of working memory in prefrontal, parietal, and visual cortex

2020 ◽  
Author(s):  
Matthew F. Panichello ◽  
Timothy J. Buschman
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Visual Cortex ◽  
Primary Role ◽  
Dependent Manner ◽  
Sensory Stimuli ◽  
Neural Recordings ◽  
Memory And Attention ◽  
Memory Representations ◽  
Selection Of

AbstractCognitive control guides behavior by controlling what, where, and how information is represented in the brain. Previous work has shown parietal and prefrontal cortex direct attention, which controls the representation of external sensory stimuli1,2. However, the neural mechanisms controlling the selection of representations held ‘in mind’, in working memory, are unknown. To address this, we trained two monkeys to switch between two tasks, requiring them to either select an item from a set of items held in working memory or attend to one stimulus from a set of visual stimuli. Simultaneous neural recordings in prefrontal, parietal, and visual cortex found prefrontal cortex played a primary role in selecting an item from working memory, representing selection before parietal and visual cortex. Surprisingly, a common population representation in prefrontal cortex encoded selection of an item in working memory and attention to an external stimulus, suggesting prefrontal cortex may act as a domain-general controller. Selection acted on memory representations in two ways. First, selection improved the accuracy of memory reports by enhancing the selected item’s representation in prefrontal and parietal cortex. Second, selection transformed memory representations in a task-dependent manner. Before selection, when both items were relevant to the task, the identity of each item was represented in an independent subspace of neural activity. After selection, the representation of only the selected item was transformed into a new subspace that was used to guide the animal’s behavioral report. Together, our results provide insight into how prefrontal cortex controls working memory representations, selectively enhancing and transforming them to support behavior.

scholarly journals Brain state stability during working memory is explained by network control theory, modulated by dopamine D1/D2 receptor function, and diminished in schizophrenia

2019 ◽  
Author(s):  
Urs Braun ◽  
Anais Harneit ◽  
Giulio Pergola ◽  
Tommaso Menara ◽  
Axel Schaefer ◽  
...  
Keyword(s):  
Working Memory ◽  
Receptor Gene ◽  
D2 Receptor ◽  
Network Control ◽  
D1 Receptor ◽  
Receptor Expression ◽  
State Transitions ◽  
Brain State ◽  
Memory Representations ◽  
The Stability

Dynamical brain state transitions are critical for flexible working memory but the network mechanisms are incompletely understood. Here, we show that working memory entails brain-wide switching between activity states. The stability of states relates to dopamine D1 receptor gene expression while state transitions are influenced by D2 receptor expression and pharmacological modulation. Schizophrenia patients show altered network control properties, including a more diverse energy landscape and decreased stability of working memory representations.

scholarly journals Prefrontal Cortical Mechanisms Underlying Individual Differences in Cognitive Flexibility and Stability

2012 ◽  
Vol 24 (12) ◽  
pp. 2385-2399 ◽  
Author(s):  
Diana J. N. Armbruster ◽  
Kai Ueltzhöffer ◽  
Ulrike Basten ◽  
Christian J. Fiebach
Keyword(s):  
Working Memory ◽  
Individual Differences ◽  
Cognitive Flexibility ◽  
Task Switching ◽  
Functional Coupling ◽  
Switching Rate ◽  
Distractor Inhibition ◽  
Cognitive Stability ◽  
The Individual ◽  
Inferior Frontal Junction

The pFC is critical for cognitive flexibility (i.e., our ability to flexibly adjust behavior to changing environmental demands), but also for cognitive stability (i.e., our ability to follow behavioral plans in the face of distraction). Behavioral research suggests that individuals differ in their cognitive flexibility and stability, and neurocomputational theories of working memory relate this variability to the concept of attractor stability in recurrently connected neural networks. We introduce a novel task paradigm to simultaneously assess flexible switching between task rules (cognitive flexibility) and task performance in the presence of irrelevant distractors (cognitive stability) and to furthermore assess the individual “spontaneous switching rate” in response to ambiguous stimuli to quantify the individual dispositional cognitive flexibility in a theoretically motivated way (i.e., as a proxy for attractor stability). Using fMRI in healthy human participants, a common network consisting of parietal and frontal areas was found for task switching and distractor inhibition. More flexible persons showed reduced activation and reduced functional coupling in frontal areas, including the inferior frontal junction, during task switching. Most importantly, the individual spontaneous switching rate antagonistically affected the functional coupling between inferior frontal junction and the superior frontal gyrus during task switching and distractor inhibition, respectively, indicating that individual differences in cognitive flexibility and stability are indeed related to a common prefrontal neural mechanism. We suggest that the concept of attractor stability of prefrontal working memory networks is a meaningful model for individual differences in cognitive stability versus flexibility.

scholarly journals How Sequentially Changing Reward Prospect Modulates Meta-control: Increasing Reward Prospect Promotes Cognitive Flexibility

2020 ◽  
Author(s):  
Kerstin Fröber ◽  
Gesine Dreisbach
Keyword(s):  
Working Memory ◽  
Cognitive Flexibility ◽  
Task Switching ◽  
Control Signal ◽  
The Other ◽  
Switch Costs ◽  
Cognitive Stability ◽  
High Reward ◽  
Nonsignificant Difference ◽  
Switch Rate

Abstract Meta-control is necessary to regulate the balance between cognitive stability and flexibility. Evidence from (voluntary) task switching studies suggests performance-contingent reward as one modulating factor. Depending on the immediate reward history, reward prospect seems to promote either cognitive stability or flexibility: Increasing reward prospect reduced switch costs and increased the voluntary switch rate, suggesting increased cognitive flexibility. In contrast, remaining high reward prospect increased switch costs and reduced the voluntary switch rate, suggesting increased cognitive stability. Recently we suggested that increasing reward prospect serves as a meta-control signal toward cognitive flexibility by lowering the updating threshold in working memory. However, in task switching paradigms with two tasks only, this could alternatively be explained by facilitated switching to the other of two tasks. To address this issue, a series of task switching experiments with uncued task switching between three univalent tasks was conducted. Results showed a reduction in reaction time (RT) switch costs to a nonsignificant difference and a high voluntary switch rate when reward prospect increased, whereas repetition RTs were faster, switch RTs slower, and voluntary switch rate was reduced when reward prospect remained high. That is, increasing reward prospect put participants in a state of equal readiness to respond to any target stimulus—be it a task repetition or a switch to one of the other two tasks. The study thus provides further evidence for the assumption that increasing reward prospect serves as a meta-control signal to increase cognitive flexibility, presumably by lowering the updating threshold in working memory.

Transient Working Memory Representations That Govern Intentional S-R Translation

2007 ◽  
Author(s):  
Nachshon Meiran ◽  
Yoav Kessler ◽  
Oshrit Cohen-Kdoshai ◽  
Ravid Elenbogen
Keyword(s):  
Working Memory ◽  
Memory Representations
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