Paper on assessment of conscious states

How can we tell whether an immobiised patient is conscious or not? This was the starting point for the master thesis of three clinical psychology students that I supervised. The students reviewed and provided a synthesis of the recent scientific literature on the subject. After the thesis work was over and the students had left the university for clinical positions, I collaborated with them to rewrite the work into a article intended for Norwegian clinicians.

Table 1:

STATE OF  CONSCIOUSNESS	WAKEFULLNESS	AWARENESS	INTENTIONAL BEHAVIOUR
Normal awake state	Yes	Yes	Yes
unresponsive wakefulness syndrome	Yes	No	No
Minimally conscious state	Yes	Occasionally	Some
Locked-in-syndrome	Yes	Yes	Very limited motor capacity
Coma	No	No	No

The paper gives a definition of consciousness and outlines the clinical disorders of consciousness (see table 1 above). We then categorise four different types of assessment of consciousness: behaviour checklists, electrophysiology, imaging of activation and imaging of networks. We discuss each approach's standing, merits and disadvantages (table 2). Finally we discuss to which extent the assessment approaches reflect the theoretical definition.

Table 2:

APPROACH	TYPE	EXAMPLES	PRINCIPLE	ADVANTAGES	DISADVATAGES
Behaviour checklist	Active or passive	GCS-R, SMART, etc., see Seel et al. (2010) for review	Checklist for whether actions occur, spontaneously or on instruction	Has clinical standard	Unable to capture consciousness that does not appear in the behavior
Electro-physiology	Active or passive	EEG, ERP	Electrodes measure simultaneous fireing of groups of neurons	Equipment readily available can be used on all patients, also at bedside	Hard to say where the signal comes from, hard to say which processing the response involves
Imaging of brain activity	Active	fMRI, PET	Imaging of the metabolism from activity in different parts of the brain	Good localization of the signal, can determine whether a task activates the same areas as in healthy people	Expensive and scarce equipment, cannot be applied to all patients. Measures the capacity for consciousness, but this capacity is not necessarily in use
Imaging of networks	Passive	Default mode network, DTI	Measures which parts of the brain that are connected, or that are activated simultaneously	As above, but does not require active participation from the patient	As above, but in addition it is unclear how the networks should be interpreted

As we wanted to inform Norwegian clinicians working in adjacent fields and next-of-kin to patients with consciousness afflictions, we wanted the paper to be easily accessible. We published in a peer-reviewed Norwegian online open-access journal (abstract in English)

Link to the publication in psykologisk.no (Scandinavian Psychologist).

The "updating" component of WM is differently involved in various noise conditions

Several years ago Patrik Sörqvist and I collected fMRI recordings of participants performing a working memory (WM) task, where WM content updating could be compared to WM maintenance. Soon thereafter we published a paper on the data from the pilot sample of eight participants performing the task in silence.

In addition to examining WM mechanisms, we also wanted to study how the WM functions in different auditory noise conditions. Therefore the majority of the participants performed the task while different noise conditions were played in the background. However, this was not part of our initial publication, and both Patrik and I got involved in other projects, preventing us from publishing on this aspect of the study until this year.

We found that the larger data set (from 18 participants) confirmed the main finding of the pilot study: that updating WM content activates areas mainly in dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes (shown in red in the animation below, t-values 7-16), while rejecting the input and not updating WM content activates the anterior medial frontal cortex (shown in blue). Comparing this to the similar contrast in our previous publication shows a very similar pattern, indicating a replication of the finding.

In order to address our second research question of how noise affects WM function, all participants performed the study in three different conditions: In silence, in aircraft noise and in speech noise. We wanted to see whether updating WM content in speech noise activated different cortical areas than updating in aircraft noise. As shown in the animation below (t-values 4-9), the prefrontal cortex is involved to a greater extent when updating in speech noise (shown in gold) than when updating in aircraft noise (shown in silver). This could indicate that speech noise is more intrusive on e.g. phonological loop processes, and requires deliberate processing to counteract.

The publication is currently in press at Scandinavian Journal of Psychology. You can find a pdf of the pre-print version of the paper here. The publication is currently in press at Scandinavian Journal of Psychology. You can find a pdf of the pre-print version of the paper here.

Presentation of field study for applied network (HFC forum)

I was invited to hold a presentation on my research at one of the meeting for Human Factors in Control, a national network for researchers, industry and consultants that are working with human factors. The presentation is fairly similar to the one I held at HFES in 2012, but somewhat updated and with some added details.

ERP paper on sequential effects of selective attention (Primed DL)

During my ambitious young PhD years in cognitive neuroscience I collected more data than I had time to publish on. For example, I equipped participants with 61 scalp electrodes and let them perform the "primed dichotic listening" experiment that I had developed. My previous studies had established a priming effect, and fMRI neuroimaging had indicated that cognitive control and inhibition may be involved in producing the effect. As ERP has a finer temporal resolution, this could be used to examine the time course of such an effect. Unfortunately, I didn't have time to analyse the data during my PhD time, so the data was left unused for several years. I later got in touch with René Huster whom I went to graduate school with, and we analysed the data together during a research visit to his research group in Oldenburg.

As before, in each trial of the experiment a single syllable was played followed by a dichotic syllable pair, and in some cases one of the syllables in the pair repeated the prime syllable. The trials were categorized based on whether the repeated syllable was selected or not, as shown in the figure below.

A strong behavioural effect was seen as in the previous studies. The ERP analysis was optimized to identify differences in the early attention processing (i.e. the N200s) between the different response categories. ERPs were extracted for three midline electrodes from four relevant time-windows and compared between the conditions using repeated measures ANOVA. Significant effects were seen in both the prime-related (left in the figure below) and in the dichotic target-related activity (right in the figure below). 

Trials where the participant reported the non-primed syllable (prime ignored trials) showed more negative ERPs at prime presentation, which may indicate inhibition of the prime representation. Trials where the participant reported the primed syllable (prime reported trials) showed more negative ERPs at target presentation, which may indicate cognitive conflict and effortful response selection. In reference to the theoretical framework presented previously, the data suggest that the interplay of a proactive inhibition bias (during prime presentation) and a reactive potential for conflict (during target presentation) is involved in causing the primed dichotic listening effect.

Sætrevik, Huster & Herrmann (2013) Proactive and reactive sequential effects on selective attention - Brain and Cognition

There is also a second data set, with EEG recorded from a larger data set doing a sequence of dichotic listening trials which we will hopefully go on to publish some day.

Theory of science lectures

During my post-doc years, I lectured in the topic of Theory of science (Norwegian: vitenskapsteori) for the first semester of psychology (spring and fall). This took the form of three two-hour lectures based on the textbook "How to think straight about psychology" by Keith E. Stanovich. In the presentation materials for the lectures, I proposed a mind map that the students were invited to structure their understanding around. Branches specific for the science of psychology were structured to the left, while less topic specific branches were on the right. the students appeared to respond well to the presentation materials.

Suggesting a context-general survey for situation awareness

One of the aims of my post-doc was to develop a measurement approach for situation awareness (SA) that could be applied across different settings, and can be used in large data collections. Endsley's theoretical model suggests that SA consists of three levels - perception, understanding and prediction, and should be measured with instruments adapted to the setting in question.

Based on a theoretical review, I developed and piloted an inventory of 13 items, which were then tested on a larger sample of 166 sailors. To test whether the inventory supported the theoretical model for SA, two different confirmatory factor analyses were run, one where all items were associated with a single factor, and one where the items were associated with three factors.  The three factor model showed a good fit with the response patterns.

Thus the approach appears psychometrically valid, although it remains to see whether it has any predictive value. Further, some researchers may be reluctant to measure SA in the same way across contexts. The article was published in a special issue of International Maritime Health.

Link to paper: Sætrevik, B. (2013). Developing a context-general self-report approach to measuring three-level situation awareness. 

Poster on emergency preparedness center teams for stakeholder seminar

In September 2012, the research group I was part of arranged a stakeholder conference for our industry partners and other stakeholders in the maritime and offshore business. Formal organizer of the conference was the marine insurance company Norwegian Hull Group, and the overall theme for the conference was "safety climate".

Our research collaborators Jarle Eid, Rhona Flin and Fred Luthans had oral presentations at the conference. I presented a poster on the shared situation awareness in teams field study described in previous posts. The poster is available here: Emergency preparedness center poster

To zoom around the different sections of the poster, use the Prezi below: