Doctoral School of Psychology (Cognitive Science)  

Cognitive Psychology Research Group, Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences

Supervisor: Dr. Gaál Zsófia Anna

Psychophysiological investigation of the modulatory factors in cognitive aging

Introducing the research area

In our research, we investigate the age-related cognitive changes; mainly impaired cognitive control processes and how these changes affect the task-related performance and the measured psychophysiological correlates in different experimental paradigms. In our already published studies, we examined the effect of task-irrelevant stimuli on task performance and the extent to which these irrelevant stimuli were processed in younger and older adults.

In our future studies (one of them is under review and another one is a finalized manuscript) we are interested in other factors like creativity, cognitive training, and contextual cueing, which could modify and affect cognitive control processes and neural processing differently in younger and older age-groups.

 

Brief introduction of the research place

The Cognitive Psychology Research Group (RCNS ICNP) led by Dr. Zsófia Anna Gaál has been investigating the psychophysiological correlates of visual processing and different cognitive functions and their changes in distinct populations with different EEG (electroencephalography) signal processing methods. Main research topics: cognitive aging, automatic visual processing, creativity.

http://www.ttk.hu/kpi/en/cognitive-psychology/

https://www.youtube.com/channel/UCf2_DX7EYDU-WLbys2j-RdQ/featured

 

History and context of the research

As life expectancy and with that retirement age and active working years has been increasing in modern societies, it has become even more important to keep our efficient daily and working performance as well as physical and mental health to the best level possible. To achieve that, it is crucial to investigate the biological, sociological, neurobiological, and cognitive processes behind healthy aging. Our research group explores the latter two fields and uses specific experimental designs and paradigms to examine different cognitive functions and the changes in performance and psychophysiology between younger and older adults. Earlier research has revealed the age-related decline in different cognitive processes and domains, like stimulus-processing, attention, memory, planning and decision-making which could be observed in laboratory and everyday environments as well. Multiple cognitive and neurobiological theories try to explain the cognitive changes accompanying healthy aging. Of them, probably the most established and examined one is the inhibitory deficit hypothesis of healthy aging (Hasher & Zacks, 1988). This suggests that impaired inhibitory functions cause the general age-related cognitive decline through stimulus selection associated with less efficient task, thus more task-irrelevant stimuli are processed and maintained in the working memory load which could interfere with the task-relevant stimuli processing. Our experiments are based on this hypothesis.

 

The research goals, open questions

One of our main research goals is to study the difference in cognitive control processes in younger and older adults, mainly in those paradigms where the information content of the presented stimuli can activate opposite behavior and responses which causes cognitive conflict. Based on the inhibitory deficit hypothesis of aging it is also crucial to investigate the age-related difference in task-irrelevant stimulus processing and its effect on performance and different task processing steps like target detection and categorization, processing of cognitive conflict which can be contained in the task-relevant or irrelevant stimulus, motor response organization and execution (Cespón et al., 2013; Van der Lubbe & Verleger, 2002). Older adults presumably could not suppress and inhibit task-irrelevant information effectively, thus these could interfere with target processing and task-related behavior.

Additionally, our other important goal is to find ways for benefitting from the suggested increased task-irrelevant stimulus processing and turning it into a supporting mechanism in older adults. In connection with this question, we are interested if this processed irrelevant information could be effectively consolidated and retrieved through memory processes in older adults and if they could have access to them later (Biss et al., 2013; Weeks & Hasher, 2018).

Our results in connection with these research questions have been already published in peer reviewed international journals. I am the first author of one of them (Nagy et al., 2020, PLoS ONE, impact factor: 2.74, Q1 journal) and the corresponding author of another (Gaál et al., 2020, Frontier in Human Neuroscience, impact factor: 2.67, Q1 journal).

 

 

Methods

In our experiments we analyzed the recorded EEG signals with the event-related potential (ERP) method, which is suitable for detecting and measuring the neural responses evoked by different stimuli and responses. To achieve that, we need to average the recorded voltage values timepoint-by-timepoint from the same trial conditions. We use many repetitions from every stimulus and response condition to increase the signal-to-noise ratio. With this method we can examine the neural processes and the temporal resolution of different stimulus processing and cognitive functions as well as their age-related changes. To learn more on how these EEG measures take place in the lab and how we process the recorded EEG data, please watch our research group’s video (in Hungarian).

Kutatók Éjszakája 2020 - Eseményhez kötött potenciálok - Mi történik az agyban, amikor gondolkodunk?

 

To examine the effect of task-irrelevant stimulus on task-related cognitive conflict processing, we applied a modified Simon task. In this task the laterality of the given response based on an attribute of the target stimulus (in this case right hand response for letter J, left hand response for letter B) interferes with the laterality of the target stimulus presentation (left or right side of the screen). If the presentation and the response are on the same side (e.g., letter J presented on the right side) no cognitive conflict emerges during the target processing (congruent Simon condition), but if they differ (e.g., letter J presented on the left side) cognitive conflict occurs (incongruent Simon condition). Meanwhile, a task-irrelevant face stimulus was shown in the center of the screen and its gaze could look at the target letter (congruent gaze condition) or look away from it (incongruent gaze condition) (Figure 1). We chose face stimuli because of their great importance and ecological validity in human behavior, and the attentional orientation effect of gaze-direction happens nearly automatically (Frischen et al., 2007). With this experimental paradigm, we could detect the cognitive conflict caused by the target or the task-irrelevant stimulus and their interaction in younger and older age-groups. Additionally, at the end of our experiment, we presented an unexpected old/new face recognition test to our participants to study the retrieval performance of the task-irrelevant information.

 

Figure 1: Experimental design of the modified Simon task

 

 

Results

The most important result of the modified Simon task is that the task-irrelevant gaze modified the older but not the younger age-group’s task-performance and cognitive conflict resolution. Older adults’ performance was worse when the gaze looked at the incongruent Simon target compared to the situation when it looked away from it. This effect could be recognized by the increased reaction time and error rate (Figure 2) as well as increased early wrong response activation (Figure 3) when the attention was oriented by the irrelevant gaze to the incongruent Simon target containing cognitive conflict. The latter effect was indicated by the s-LRP component’s early positive dip (Figure 3; s-LRP – stimulus-locked lateralized readiness potential – is a negative going ERP component which is evoked over the motor cortex, and it is connected to motor response organization and selection). However, the task-irrelevant gaze did not modify (support) the performance when it was looking at congruent Simon stimuli.

 

Figure 2: Reaction times (ms) and error rates (%) in different conditions of the modified Simon task in young (blue) and old (red) adults (mean ± SD). Asterisk – significant difference, CG – congruent gaze, ICG – incongruent gaze

 

 

Figure 3: Target-locked s-LRP component (difference of C3-C4 electrodes over the motor cortex) evoked in the modified Simon task in young and old adults. Waveforms: red – congruent Simon, congruent gaze (CS-CG); black – incongruent Simon, congruent gaze (ICS-CG); blue – congruent Simon, incongruent gaze (CS-ICG); green – incongruent Simon, incongruent gaze (ICS-ICG)

 

 

Additionally, we revealed that the irrelevant gaze-orientation did not have any effect on the target categorization measured with the P3b component (centro-parietally distributed positive going ERP component) or the motor response execution which is measured by the r-LRP component (response-locked lateralized readiness potential, which is a negative going difference component evoked over the motor cortex) (Figure 4). The analysis of these two ERP components showed age and cognitive load effects, which are established in the literature. In detail, the effectiveness of stimulus-categorization and the activated motor program execution is decreased with age, which was revealed by the smaller amplitude and later latency in the P3b and earlier latency and larger amplitude in the r-LRP components in older adults compared to younger ones. (The earlier latency and larger amplitude in r-LRP shows less effective processes due to the larger and longer activation, thus higher activation threshold is needed from the motor cortex in order to execute the motor response). Moreover, later latency and smaller amplitude in the P3b component was evoked in the incongruent Simon conditions compared to the congruent Simon conditions, which suggests less effective stimulus-categorization when the cognitive capacity is more loaded.

 

Figure 4: Target-locked P3b (measured at Pz electrode, left figure) and response-locked r-LRP components (difference of C3-C4 electrodes over motor cortex, right figure) evoked in the modified Simon task in young and old adults. Waveforms: red – congruent Simon, congruent gaze (CS-CG); black – incongruent Simon, congruent gaze (ICS-CG); blue – congruent Simon, incongruent gaze (CS-ICG); green – incongruent Simon, incongruent gaze (ICS-ICG)

 

 

Therefore, elderly people processed the task-irrelevant stimulus to a greater extent, which could be supported by the larger N170 amplitude in this age-group (negative going ERP component, which is connected to face-specific early visual processing and evoked at parieto-occipital visual areas) for the irrelevant faces compared to younger adults (Figure 5). Even though both age-groups performed better than chance in the old/new face recognition test (the discrimination index was significantly larger than 0 in young and old adults as well) but younger adults performed better than older ones. On top of that, the LPC component (late parietal component; positive going ERP component) which is related to recollection and recognition processes was only observed in the younger age-group but not in the old one (however, it was larger for new faces compared to old ones, which is in contrast with the previous literature). So eventually, the older age-group could not consolidate and retrieve the task-irrelevant information effectively.

In conclusion, we could detect only the negative effect of the task-irrelevant information on the cognitive load and cognitive conflict resolution in the older age group, but we found no evidence in this paradigm for the supporting role of the increased task-irrelevant stimuli processing.

Our main research questions and results are presented in the following video as well (in Hungarian):

Kutatók Éjszakája 2020 - A figyelmen innen és túl - Segíthető-e az idősek cél-vezérelt viselkedése?

 

 

Figure 5: Top – irrelevant face-locked N170 component and the evoked early visual face-processing in the modified Simon task (measured at PO7 and PO8 in the parieto-occipital visual areas). Waveforms: red – young adults, blue – old adults

Bottom – target face-locked LPC component (recollection effect measured at Pz electrode) in the old/new face recognition test, which could be detected just in young adults. Waveforms: red – right response for new faces (new); black – right response for old faces (old); blue - wrong response to new faces (old); green – wrong response to old faces (new)

 

 

 

Expected impact and further research

Our current state of research suggests that the age-related impairment in cognitive control processes have a great effect on the task-related behavior and performance mainly when a task-irrelevant stimulus is introduced, and its information content can interfere with target- and task-processing. These results can have the potential of supporting new approaches for organizing our environment and creating task-oriented and execution strategies that could help not only the older population but the whole society in selecting and inhibiting stimuli from our overly stimuli-rich environment. In line with these goals, our current studies focus on further factors like creativity, cognitive training and contextual cueing that may influence the effectiveness of cognitive control functions and their age-related changes.

 

Publications, references, links

List of corresponding own publications:

●       Nagy, B., Czigler, I., File, D., & Gaál, Zs. A. (2020). Can irrelevant but salient visual cues compensate for the age-related decline in cognitive conflict resolution? – An ERP study. PLoS one, 15(5), e0233496. https://doi.org/10.1371/journal.pone.0233496

●       Gaál, Zs. A., Nagy, B., File, D., & Czigler, I. (2020). Older adults encode task-irrelevant stimuli, but can this side-effect be useful to them? Frontiers in Human Neuroscience, 14, 446. https://doi.org/10.3389/fnhum.2020.569614

●       Nagy, B., Czigler, I., File, D., Csizmadia, P., Fáy, N., & Gaál, Zs. A. (submitted in May 2021, under review). Do age-related changes in cognitive control affect creative performance in older compared to younger adults? – An ERP study of task-switching. Biological Psychology

●       Nagy, B., Protzner, B. A., Wang, H., van der Wijk, G., Cortese, F., Czigler, I., & Gaál, Zs. A (manuscript in progress). Can Cognitive Training Modulate Resting-State Neural Network Dynamics? – An Age-Related Multiscale Entropy and Spectral Power Density Study on Task-Switching

 

List of references:

●       Biss, R. K., Ngo, K. J., Hasher, L., Campbell, K. L., & Rowe, G. (2013). Distraction can reduce age-related forgetting. Psychological Science, 24, 448–455. doi: 10.1177/0956797612457386

●       Cespón, J., Galdo-Álvarez, S., & Díaz, F. (2013) Age-related changes in ERP correlates of visuospatial and motor processes. Psychophysiology. 50(8), 743–57. doi:10.1111/psyp.12063

●       Frischen, A., Bayliss, A. P., & Tipper, S. P. (2007). Gaze cueing of attention: visual attention, social cognition, and individual differences. Psychological bulletin, 133(4), 694.

●       Hasher, L., & Zacks, R. T. (1988). Working memory, comprehension, and aging: A review and a new view. The psychology of learning and motivation, 22, 193–225. doi: 10.1016/S0079-7421(08)60041-9

●       Van der Lubbe, R. H, & Verleger, R. (2002) Aging and the Simon task. Psychophysiology, 39(1): 100–110. doi: 10.1017/S0048577202001221

●        Weeks, J. C., & Hasher, L. (2018). Older adults encode more, not less: evidence for age-related attentional broadening. Aging, Neuropsychology, and Cognition, 25, 576–587, doi: 10.1080/13825585.2017.1353678