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Why do we divide ('chunk') long tasks into a series of shorter subtasks? A popular view is that limits in working memory (WM) prevent us from simultaneously maintaining all task relevant information in mind. We therefore chunk the task into smaller units so that we only maintain information in WM that is relevant to the current unit. In contrast to this view, we show that long tasks that are not constrained by WM limits are nonetheless chunked into smaller units. Participants executed long sequences of standalone but demanding trials that were not linked to any WM representation and whose execution was not constrained by how much information could be simultaneously held in WM. Using signs well-known to reflect beginning of new task units, we show that such trial sequences were not executed as a single task unit but were spontaneously chunked and executed as series smaller units. We also found that sequences made of easier trials were executed as longer task units and vice-versa, further suggesting that the length of task executed as one unit may be constrained by cognitive limits other than WM. Cognitive limits are typically seen to constrain how many things can be done simultaneously e.g., how many events can be maintained in WM or attended at the same time. We show a new aspect of these limits that constrains the length of behaviour that can be executed sequentially as a single task-unit.

Patients with glioblastoma face abysmal overall survival, cognitive deficits, poor quality of life and limitations to social participation; partly attributable to surgery. Emotion recognition deficits mediated by pathophysiological mechanisms in the right inferior fronto-occipital fasciculus and right inferior longitudinal fasciculus have been demonstrated in traumatic brain injury and dementia, with negative associations for social participation. We hypothesize similar mechanisms occur in patients undergoing resection surgery for glioblastoma. Here, we apply tract-based spatial statistics using a combination of automated image registration methods alongside cognitive testing before and after surgery. In this prospective, longitudinal, observational study of 15 patients, surgery is associated with an increase in emotion recognition deficits (P = 0.009) and this is correlated with decreases in fractional anisotropy in the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, anterior thalamic radiation and uncinate fasciculus; all in the right hemisphere (P = 0.014). Methodologically, the combination of registration steps used demonstrate that tract-based spatial statistics can be applied in the context of large, scan distorting lesions such as glioblastoma. These results can inform clinical consultations with patients undergoing surgery, support consideration for social cognition rehabilitation and are consistent with theoretical mechanisms that implicate these tracts in emotion recognition deficits across different diseases., Sinha et al. report that glioblastoma surgery is associated with emotion recognition deficits. Using automated image registrations for large lesion distortion and tract-based spatial statistics, this deficit is shown to be associated with changes in the same right hemisphere white matter tracts as seen in other diseases., Graphical Abstract Graphical Abstract

Background Acquired brain injury (ABI) affects approximately 79.3 million individuals annually and is linked with elevated rates of depression and low mood. Existing methods for treating depression in ABI have shown mixed efficacy. Behavioural activation (BA) is a potentially promising intervention. Its premise is that individuals with low mood avoid planning and engaging in activities due to low expectations of a positive outcome. Consequently, their exposure to positive reinforcement is reduced, exacerbating low mood. BA aims to break this cycle by encouraging activity planning and engagement. It is unknown whether cognitive demands of traditional BA may undermine efficacy in ABI. Here, we assess the feasibility and acceptability of two groups designed to increase activity engagement. In the activity planning group (traditional BA), the importance of meaningful and positive activity will be discussed and participants encouraged to plan/engage in activities in everyday life. The activity engagement group (experiential BA) instead focuses on engagement in positive experiences (crafts, games, discussion) within the group. The primary aims are to evaluate the feasibility and acceptability of the two groups in ABI. A secondary aim is to explore relative efficacy of the groups compared to an equivalent period of waitlist controls. Method This study outlines a parallel-arm pilot feasibility trial for individuals with low mood and ABI that compares a traditional vs experiential BA group vs waitlist controls. Adults (≥ 18 years) will be recruited from local ABI services and randomised to condition. Feasibility and acceptability will be assessed via recruitment, retention, attendance and participant feedback. Groups will be compared (pre- and post-intervention and 1 month follow-up) by assessing self-reported activity engagement. Secondary outcomes include self-report measures of depression, anxiety, post-traumatic distress related to the ABI, motivation, participation and sense of control over one’s life. Ethics and dissemination The trial has been approved by the Health Research Authority of the NHS in the UK (East of England—Cambridge Central, REF 18/EE/0305). Results will inform future research on interventions for mood in ABI and be disseminated broadly via peer-reviewed journals, conference presentations and social media. Trial registration ClinicalTrials.gov, NCT03874650 pre-results. Protocol version 2.1, March 5, 2019

OBJECTIVE: To investigate effects of cognitive rehabilitation with mobile technology and social support on veterans with traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). PARTICIPANTS: There were 112 dyads, comprised by a veteran and a family member or friend (224 participants in total). DESIGN: Dyads were randomized to the following: (1) a novel intervention, Cognitive Applications for Life Management (CALM), involving goal management training plus mobile devices for cueing and training attentional control; or (2) Brain Health Training, involving psychoeducation plus mobile devices to train visual memory. MAIN MEASURES: Executive dysfunction (disinhibition, impulsivity) and emotional dysregulation (anger, maladaptive interpersonal behaviors) collected prior to randomization and following intervention completion at 6 months. RESULTS: The clinical trial yielded negative findings regarding executive dysfunction but positive findings on measures of emotion dysregulation. Veterans randomized to CALM reported a 25% decrease in anger over 6 months compared with 8% reduction in the control (B = -5.27, P = .008). Family/friends reported that veterans randomized to CALM engaged in 26% fewer maladaptive interpersonal behaviors (eg, aggression) over 6 months compared with 6% reduction in the control (B = -2.08, P = .016). An unanticipated result was clinically meaningful change in reduced PTSD symptoms among veterans randomized to CALM (P < .001). CONCLUSION: This preliminary study demonstrated effectiveness of CALM for reducing emotional dysregulation in veterans with TBI and PTSD.

We select and execute extended task episodes (‘make tea’) as one entity and not individually execute their very many components (find kettle, boil water, etc.). Such hierarchical execution is thought to occur in familiar task situations with pre-existing task episode-related scripts that once selected, control the identity and sequence of component steps. Here, in contrast, we show hierarchical execution of extended behavior in situations, where the identity and sequence of component steps were unknown and a predetermined script could not have existed. Participants performed a rule-switching task in which the rule to be applied on each trial could not be predicted. Crucially, they were biased into construing a recurring instance of three or five trials as a single task episode. Behavioral signs of hierarchical execution, identical to those seen during memorized task-sequence executions, were present. These included longer reaction time on the first trial of each episode that was proportionate to the length of that episode, and absence of rule switch costs only between those consecutive trials that crossed episode boundaries. Hierarchical execution thus occurs every time the to-be-executed behavior is construed as one task episode, and is not limited to predictable sequences. We suggest that hierarchical execution occurs because task episodes are controlled and executed through goal-related entities assembled at the beginning of execution that subsume the execution and instantiate purposive control across time until the goal is complete.

Objectives Depression, which is common following acquired brain injury (ABI), has been shown to predict cognitive impairment, rehabilitation outcome, and quality of life. Whilst many studies have examined links between depression and cognitive-affective processing in the non-ABI population, their applicability to this important clinical group, where cognitive difficulties can be marked, remains unknown. Here, we investigated biases in prospective cognition, which is known to be disrupted in (non-ABI) depression yet important for well-being. Design Cross-sectional design with three groups (depressed ABI, non-depressed ABI, and non-ABI control participants). Continuous data were additionally analysed in correlation analyses. Methods Individuals with ABI varying in extent of self-reported depression and matched non-ABI control participants completed assessments of mood and prospective cognition (anticipating and imagining future events), alongside background tests of executive function and fluid intelligence. Results Relative to non-depressed ABI and control participants, depressed ABI individuals demonstrated a reduced positive bias in prospective cognition: whereas non-depressed ABI and control participants generated more examples of likely or possible positive versus negative future events, there was no evidence for such a positive bias in depressed ABI participants. Non-depressed ABI and control participants also reported more vivid mental imagery for positive versus negative future scenarios, whereas such a pattern was not evident in depressed ABI participants. This pattern emerged despite background impairments in fluid intelligence and executive function associated with ABI. Conclusions These findings (1) elucidate depression-linked cognitive-affective processes following ABI, where cognitive difficulties are common, and (2) highlight psychological processes associated with depression that are common to ABI and non-ABI populations. Practitioner points Clinical implications A relative negative bias in future-directed cognition is associated with depressed mood in individuals with chronic ABI. Such processes may contribute to the onset and maintenance of depression following ABI. These findings suggest it may be important to consider a role for prospective cognition in psychological interventions for depression following ABI. Limitations of the study The extent to which depressed mood following ABI is associated with biases in other cognitive domains remains unclear. Whether similar patterns would be observed in acute patients with more profound cognitive difficulties requires further investigation. Despite large effect sizes, our sample size is modest; these effects thus require replication in larger groups.

We recently demonstrated that drowsiness, indexed using EEG, was associated with left-inattention in a group of 26 healthy right-handers. This has been linked to alertness-related modulation of spatial bias in left neglect patients and the greater persistence of left, compared with right, neglect following injury. Despite handedness being among the most overt aspects of human lateralization, studies of this healthy analogue of left neglect have only been conducted with predominantly or exclusively right-handed individuals. Here, with a group of 26 healthy non-right-handers we demonstrate that, unlike right-handers who showed a rightward shift in attention with drowsiness, non-right-handers showed the opposite pattern on an auditory spatial localization task. The current results are the first indication that factors linked to handedness can affect the development and extremity of spatial biases, potentially conferring resilience to clinical symptoms in non-right-handers and, given that 90% of us are right-handed, why left neglect is disproportionately persistent.

The well-known deactivation of the Default Mode Network (DMN) during external tasks is usually thought to reflect the suppression of internally directed mental activity during external attention. In 3 experiments with human participants we organized sequences of task events identical in their attentional and control demands into larger task episodes. We found that DMN deactivation across such sequential events was never constant, but was maximum at the beginning of the episode, then decreased gradually across the episode, reaching baseline towards episode completion, with the final event of the episode eliciting an activation. Crucially, this pattern of activity was not limited to a fixed set of DMN regions but, across experiments, was shown by a variable set of regions expected to be uninvolved in processing the ongoing task. This change in deactivation across sequential but identical events showed that the deactivation cannot be related to attentional/control demands which were constant across the episode, instead it has to be related to some episode related load that was maximal at the beginning and then decreased gradually as parts of the episode got executed. We argue that this load resulted from cognitive programs through which the entire episode was hierarchically executed as one unit. At the beginning of task episodes, programs related to their entire duration is assembled, causing maximal deactivation. As execution proceeds, elements within the program related to the completed parts of the episode dismantle, thereby decreasing the program load and causing a decrease in deactivation.Significance StatementWe prepare breakfasts and write emails, and not individually execute their many component acts. The current study suggests that cognitive entities that enable such hierarchical execution of goal-directed behavior may cause the ubiquitously seen deactivation during external task execution. Further, while this deactivation has previously been associated with a defined set of the so called default mode regions, current study demonstrates that deactivation is shown by any region not currently involved in task execution, and in certain task episodes can even include attention related fronto-parietal regions as well as primary sensory and motor regions.

BackgroundGoal neglect refers to a dissociation between intended and actual action. Although commonly associated with frontal brain damage, this phenomenon is also characteristic of clinical depression. To date, tests of goal neglect typically require individuals to switch between subtasks populated with neutral stimuli. This study examined the impact of affective and personally salient stimulus contexts on goal neglect in clinical depression.MethodsParticipants were randomly allocated to either positively or negatively-valenced versions of the Affective Six Elements Test (A-SET). We hypothesised that depressed individuals (n= 30) would exhibit an overall impairment in A-SET performance by neglecting entire subtasks and allocating suboptimal time to each task, relative to never-depressed peers (n= 30), with effects being strongest for the negatively-valenced version.ResultsFindings showed that depressed individuals exhibited specific deficits, relative to controls on these measures in the negative A-SET only, with a magnitude comparable to that found in brain injured patients.ConclusionsIndividuals with depression are impaired in their ability to monitor performance and implement strategies that are optimal for the purpose of pursuing an overarching goal when the task context is negatively-valenced. Potential mechanisms are discussed.

PUBLISHED, Action errors can occur when routine responses are triggered inappropriately by familiar cues. Here, EEG was recorded as volunteers performed a ?go/no-go? task of long duration that occasionally and unexpectedly required them to withhold a frequent, routine response. EEG components locked to the onset of relevant go trials were sorted according to whether participants erroneously responded to immediately subsequent no-go trials or correctly withheld their responses. Errors were associated with a significant relative reduction in the amplitude of the preceding P300, that is, a judgement could be made bout whether a responseinhibition error was likely before it had actually occurred. Furthermore, fluctuations in P300 amplitude across the task formed a reliable associate of individual error propensity, supporting its use as a marker of sustained control over action., MRC, NIH

Facilitating engagement in rewarding activities is a key treatment target in depression. Mental imagery can increase engagement in planned behaviours, potentially due to its special role in representing emotionally salient experiences. The present study tested the hypothesis that mental imagery promotes motivation and engagement when planning pleasant and rewarding activities. Participants were recruited from a community volunteer panel (N = 72). They self-nominated six activities to complete over the following week, and were randomized to either: a) a single-session Motivational Imagery condition (N = 24); b) an Activity Reminder control condition (N = 24); or c) a No-Reminder control condition (N = 24). As predicted, relative to control groups, the Motivational Imagery group reported higher levels of motivation, anticipated pleasure, and anticipated reward for the planned activities. The Motivational Imagery group also completed significantly more activities than the Activity Reminder group, but not more than the No-Reminder group. Relevance of results to behavioural activation approaches for depression are discussed., Highlights • Mental imagery of planned activities increases motivation to engage in them. • Higher imagery vividness is associated with higher anticipated reward. • Mental imagery of planned activities is associated with higher activity completion.