Visual Attention-Related Processing: Perspectives from Ageing, Cognitive Decline and Dementia

Visual attention is essential for environmental interactions, but our ability to respond to stimuli gradually declines across the lifespan, and such deficits are even more pronounced in various states of cognitive impairment. Examining the integrity of related components, from elements of attention capture to executive control, will improve our understanding of related declines by helping to explain behavioural and neural effects, which will ultimately contribute towards our knowledge of the extent of dysfunctional attention processes and their impact upon everyday life. Accordingly, this Special Issue represents a body of literature that fundamentally advances insights into visual attention processing, featuring studies spanning healthy ageing, mild cognitive impairment, and dementi

Function and dysfunction of the prefrontal cortex: effects of distraction on active maintenance in healthy controls and individuals with schizophrenia

The prefrontal cortex (PFC) is thought to be critical for the active maintenance of goal-related information in the face of distraction. Previous studies have demonstrated that schizophrenia is associated with changes in the function of the PFC, and is characterized by difficulties in the active maintenance of information in working memory and in the ability to resist distraction. Two functional neuroimaging experiments were conducted with healthy control participants that examined the effects of distracter demand on working memory by manipulating both voluntary attention to distracters ("executive") and involuntary capture of attention by emotional distracters. Two additional behavioral experiments were conducted to assess how processing of these types of distracters would be affected in individuals with schizophrenia. It was expected that specific prefrontal subregions would be differentially recruited under conditions of increased distracter demand, and that the group with schizophrenia would be disproportionately affected by executive, but not emotional distraction. The results largely supported the hypotheses, and indicated that the ventrolateral PFC was specifically recruited during both executive and emotional distraction. The dorsolateral PFC was activated during both active maintenance and executive distraction processes, but its activity was significantly disrupted during emotional distraction. The group with schizophrenia also showed specific impairments in the allocation of attention to executive distracters, but showed similar patterns to controls during emotional distraction. The findings suggest that prefrontal subregions may take on specific roles in resolving interference, and that dysfunction in these regions may underlie changes in distracter processing in schizophrenia

Human brain networks of auditory attention and working memory

This thesis examines brain networks involved in auditory attention and auditory working memory using measures of task performance, brain activity, and neuroanatomical connectivity. Auditory orienting and maintenance of attention were compared with visual orienting and maintenance of attention, and top-down controlled attention was compared to bottom-up triggered attention in audition. Moreover, the effects of cognitive load on performance and brain activity were studied using an auditory working memory task. Corbetta and Shulman s (2002) model of visual attention suggests that what is known as the dorsal attention system (intraparietal sulcus/superior parietal lobule, IPS/SPL and frontal eye field, FEF) is involved in the control of top-down controlled attention, whereas what is known as the ventral attention system (temporo-parietal junction, TPJ and areas of the inferior/middle frontal gyrus, IFG/MFG) is involved in bottom-up triggered attention. The present results show that top-down controlled auditory attention also activates IPS/SPL and FEF. Furthermore, in audition, TPJ and IFG/MFG were activated not only by bottom-up triggered attention, but also by top-down controlled attention. In addition, the posterior cerebellum and thalamus were activated by top-down controlled attention shifts and the ventromedial prefrontal cortex (VMPFC) was activated by to-be-ignored, but attention-catching salient changes in auditory input streams. VMPFC may be involved in the evaluation of environmental events causing the bottom-up triggered engagement of attention. Auditory working memory activated a brain network that largely overlapped with the one activated by top-down controlled attention. The present results also provide further evidence of the role of the cerebellum in cognitive processing: During auditory working memory tasks, both activity in the posterior cerebellum (the crus I/II) and reaction speed increased when the cognitive load increased. Based on the present results and earlier theories on the role of the cerebellum in cognitive processing, the function of the posterior cerebellum in cognitive tasks may be related to the optimization of response speed.Tässä väitöskirjatutkimuksessa tutkittiin kuulotarkkaavaisuuteen ja kuulonvaraiseen työmuistiin liittyviä aivoverkostoja mittaamalla tehtäväsuoriutumista, aivojen aktivaatiota ja aivoalueiden välisiä anatomisia yhteyksiä. Ääniin kohdistuvan tarkkaavaisuuden suuntaamista ja ylläpitoa verrattiin kuviin kohdistuvan tarkkaavaisuuden suuntaamiseen ja ylläpitoon, sekä ääniin tavoitteellisesti kohdistettua tarkkaavaisuutta verrattiin niihin tahattomasti kohdistuvaan tarkkaavaisuuteen. Lisäksi tutkittiin kognitiivisen kuormituksen vaikutuksia tehtäväsuoriutumiseen ja aivojen aktivaatioon kuulonvaraisessa työmuistitehtävässä. Corbettan ja Shulmanin (2002) mallin mukaan niin sanottu dorsaalinen tarkkaavaisuusjärjestelmä (päälaen- ja otsalohkon yläosien taaemmat alueet) säätelee tavoitteellista, ylhäältä alaspäin kontrolloitua näkötarkkaavaisuutta, kun taas niin sanottu ventraalinen tarkkaavaisuusjärjestelmä (päälaenlohkon alaosan ja etuotsalohkon sivun alaosan taaemmat alueet) osallistuu näkökohteiden alhaalta ylöspäin käynnistämään tarkkaavaisuuteen. Osoitimme, että myös tavoitteellinen kuulotarkkaavaisuuden suuntaaminen aktivoi samoja päälaenlohkon ja etuotsalohkon yläosien taaempia alueita kun näkötarkkaavaisuuden suuntaaminen. Kuulojärjestelmässä päälaenlohkon alaosan ja etuotsalohkon sivun taaempien alaosan alueiden aktivaation kasvu ei sen sijaan liittynyt vain äänten käynnistämään tahattomaan tarkkaavaisuuteen, vaan myös tavoitteelliseen kuulotarkkaavaisuuden suuntaamiseen. Lisäksi tavoitteelliseen tarkkaavaisuuden suuntaamiseen liittyi myös pikkuaivojen takaosan ja talamuksen aktivaation kasvu, ja etuotsalohkon sisäpinnan alaosa puolestaan aktivoitui ei-tarkkailtavien äänten joukossa esiintyneiden muita hieman voimakkaampien äänten vaikutuksesta. Tämä etuotsalohkojen sisäpinnan alue saattaa osallistua tarkkaavaisuuden puoleensa vetävien äänien merkityksen arviointiin. Tulokset osoittivat myös, että kuulonvaraisen työmuistitehtävä aktivoi pääosin samoja aivoalueita kuin tavoitteellinen tarkkaavaisuuden suuntaaminen. Kun työmuistitehtävän aikana esiintyvä pikkuaivojen taka-osan aktivaatio kasvoi, koehenkilöiden reaktioajat lyhenivät. Näiden tulosten ja aiempien teorioiden perusteella tämä pikkuaivojen alue saattaa osallistua reaktionopeuden optimointiin kognitiivisessa tehtävässä

Effects of cognitive tasks on car drivers’ behaviors and physiological responses

The effects of drivers’ engagement in cognitive tasks (i.e., non-visual, cognitively loading activities unrelated to the task of driving) are debated and unclear. Numerous experiments show impaired driver behaviors, yet naturalistic studies typically do not find an increased crash risk. In the future, autonomous driving (AD) is expected to improve traffic safety while allowing safe engagement in cognitive (and other) tasks. Having the opportunity to perform non-driving related tasks while traveling may then motivate drivers to use AD, provided they can actually engage in the tasks. Unfortunately, research on drivers’ engagement in cognitive tasks suffers severe methodological limitations since reliable and unintrusive measures of cognitive load are lacking.The aim of this thesis is therefore to advance the understanding of task-induced cognitive load in the context of traffic safety. This aim is split into two objectives: A) to better understand how drivers’ involvement in cognitive tasks can affect safety-relevant driver behaviors and decisions and B) to provide methodological guidance about assessing cognitive load in drivers using physiological measures.To accomplish Objective A, effects of cognitive tasks on driver behaviors were studied during routine driving and in a safety-critical event in a driving simulator. Also, drivers’ ability to engage in a non-driving related task while using AD in real traffic was explored. In line with the cognitive control hypothesis (Engstr\uf6m et al., 2017), it was found that cognitive tasks negatively affected driver behaviors in situations where cognitive control was needed, for example in intersections—but not in a lead vehicle braking scenario where responses were triggered automatically by visual looming. It was also found that although the number of off-path glances decreased during cognitive load, the timing of the remaining glances was unaffected. Clearly, cognitive load has different effects on different mechanisms. When using AD, drivers were indeed capable of engaging in a non-driving related task—suggesting that AD will be able to fulfill drivers’ desire to perform such tasks while traveling, which may motivate AD usage and thus improve traffic safety (given that AD is truly safer than manual driving). Finally, a simulator study addressing Objective B showed that the measurability of cognitive load was greatly improved by recognizing that multiple coexisting mental responses give rise to different physiological responses. This approach can provide less context-dependent measurements and allows for a better, more detailed understanding of the effects of cognitive tasks.These findings can help improve traffic safety—both by being used in system development, and as part of the systems themselves

The two-component model of memory development, and its potential implications for educational settings

We recently introduced a two-component model of the mechanisms underlying age differences in memory functioning across the lifespan. According to this model, memory performance is based on associative and strategic components. The associative component is relatively mature by middle childhood, whereas the strategic component shows a maturational lag and continues to develop until young adulthood. Focusing on work from our own lab, we review studies from the domains of episodic and working memory informed by this model, and discuss their potential implications for educational settings. The episodic memory studies uncover the latent potential of the associative component in childhood by documenting children's ability to greatly improve their memory performance following mnemonic instruction and training. The studies on working memory also point to an immature strategic component in children whose operation is enhanced under supportive conditions. Educational settings may aim at fostering the interplay between associative and strategic components. We explore possible routes towards this goal by linking our findings to recent trends in research on instructional design

Working Memory Maintenance of Visual and Auditory Spatial Information Relies on Supramodal Neural Codes in the Dorsal Frontoparietal Cortex

The frontoparietal attention network plays a pivotal role during working memory (WM) maintenance, especially under high-load conditions. Nevertheless, there is ongoing debate regarding whether this network relies on supramodal or modality-specific neural signatures. In this study, we used multi-voxel pattern analysis (MVPA) to evaluate the neural representation of visual versus auditory information during WM maintenance. During fMRI scanning, participants maintained small or large spatial configurations (low- or high-load trials) of either colour shades or sound pitches in WM for later retrieval. Participants were less accurate in retrieving high- vs. low-load trials, demonstrating an effective manipulation of WM load, irrespective of the sensory modality. The frontoparietal regions involved in maintaining high- vs. low-load spatial maps in either sensory modality were highlighted using a conjunction analysis. Widespread activity was found across the dorsal frontoparietal network, peaking on the frontal eye fields and the superior parietal lobule, bilaterally. Within these regions, MVPAs were performed to quantify the pattern of distinctness of visual vs. auditory neural codes during WM maintenance. These analyses failed to reveal distinguishable patterns in the dorsal frontoparietal regions, thus providing support for a common, supramodal neural code associated with the retention of either visual or auditory spatial configurations.</p

Dynamic and strategic aspects of executive processing

Abstract Executive cognitive functions have been postulated to include both dynamic behavioral selection and strategic goal-setting or response preparation. To investigate the relation between these aspects of executive processing, we embedded an event-related oddball paradigm within a blocked design. Subjects responded to infrequent targets presented within a series of standard stimuli that required no response; this task alternated with a visually similar nontask condition. Using functional magnetic resonance imaging (fMRI), we found that a set of brain regions including dorsolateral prefrontal cortex (dlPFC), insular cortex, cingular cortex, and the basal ganglia demonstrated transient activation both to target stimuli and to the onset of task blocks. Within the parietal cortex, there was a dissociation such that the supramarginal gyrus exhibited greater activity to the target stimuli than to block onsets, while the converse pattern was observed in the intraparietal sulcus. Sustained positive activity during task blocks was present in the caudate and supplementary motor area, while sustained negative activity was present in the precuneus and medial parietal cortex. We conclude that dlPFC and related brain regions mediate both dynamic and strategic processing, through the preparation and selection of rules for behavior.

Prefrontal inhibition of threat processing reduces working memory interference

Bottom-up processes can interrupt ongoing cognitive processing in order to adaptively respond to emotional stimuli of high potential significance, such as those that threaten wellbeing. However it is vital that this interference can be modulated in certain contexts to focus on current tasks. Deficits in the ability to maintain the appropriate balance between cognitive and emotional demands can severely impact on day-to-day activities. This fMRI study examined this interaction between threat processing and cognition; 18 adult participants performed a visuospatial working memory (WM) task with two load conditions, in the presence and absence of anxiety induction by threat of electric shock. Threat of shock interfered with performance in the low cognitive load condition; however interference was eradicated under high load, consistent with engagement of emotion regulation mechanisms. Under low load the amygdala showed significant activation to threat of shock that was modulated by high cognitive load. A directed top-down control contrast identified two regions associated with top-down control; ventrolateral PFC and dorsal ACC. Dynamic causal modeling provided further evidence that under high cognitive load, top-down inhibition is exerted on the amygdala and its outputs to prefrontal regions. Additionally, we hypothesized that individual differences in a separate, non-emotional top-down control task would predict the recruitment of dorsal ACC and ventrolateral PFC during top-down control of threat. Consistent with this, performance on a separate dichotic listening task predicted dorsal ACC and ventrolateral PFC activation during high WM load under threat of shock, though activation in these regions did not directly correlate with WM performance. Together, the findings suggest that under high cognitive load and threat, top-down control is exerted by dACC and vlPFC to inhibit threat processing, thus enabling WM performance without threat-related interference