The study investigated brain activity changes during performance of a verbal working memory task in a population of adolescents with narcolepsy. Seventeen narcolepsy patients and twenty healthy controls performed a verbal working memory task during simultaneous fMRI and EEG acquisition. All subjects also underwent MRS to measure GABA and Glutamate concentrations in the medial prefrontal cortex. Activation levels in the default mode network and left middle frontal gyrus were examined to investigate whether narcolepsy is characterized by an imbalance in cognitive resources. Significantly increased deactivation within the default mode network during task performance was observed for the narcolepsy patients for both the encoding and recognition phases of the task. No evidence for task performance deficits or reduced activation within the left middle frontal gyrus was noted for the narcolepsy patients. Correlation analyses between the spectroscopy and fMRI data indicated that deactivation of the anterior aspect of the default mode in narcolepsy patients correlated more with increased concentrations of Glutamate and decreased concentrations of GABA. In contrast, deactivation in the default mode was correlated with increased concentrations of GABA and decreased concentrations of Glutamate in controls. The results suggested that narcolepsy is not characterized by a deficit in working memory but rather an imbalance of cognitive resources in favor of monitoring and maintaining attention over actual task performance. This points towards dysregulation within the sustained attention system being the origin behind self-reported cognitive difficulties in narcolepsy.

Whether cognitive load and other aspects of task difficulty increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information which decreases distractibility as a side effect of the increased activity in a focused-attention network.

This study investigates the relation between individual language ability and neural semantic processing abilities. Our aim was to explore whether high-level language ability would correlate to decreased activation in language-specific regions or rather increased activation in supporting language regions during processing of sentences. Moreover, we were interested if observed neural activation patterns are modulated by semantic incongruency similarly to previously observed changes upon syntactic congruency modulation. We investigated 27 healthy adults with a sentence reading task which tapped language comprehension and inference, and modulated sentence congruency employing functional magnetic resonance imaging (fMRI). We assessed the relation between neural activation, congruency modulation, and test performance on a high-level language ability assessment with multiple regression analysis. Our results showed increased activation in the left-hemispheric angular gyrus extending to the temporal lobe related to high language ability. This effect was independent of semantic congruency, and no significant relation between language ability and incongruency modulation was observed. Furthermore, there was a significant increase of activation in the inferior frontal gyrus (IFG) bilaterally when the sentences were incongruent, indicating that processing incongruent sentences was more demanding than processing congruent sentences and required increased activation in language regions. The correlation of high-level language ability with increased rather than decreased activation in the left angular gyrus, a region specific for language processing, is opposed to what the neural efficiency hypothesis would predict. We can conclude that no evidence is found for an interaction between semantic congruency related brain activation and highlevel language performance, even though the semantic incongruent condition shows to be more demanding and evoking more neural activation.

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest.

The ability to perform effortful tasks is a topic that has received considerable interest in the research of higher functions of the human brain. Neuroimaging studies show that the anterior insular and the anterior cingulate cortices are involved in a multitude of cognitive tasks that require mental effort. In this study, we investigated brain responses to effort using cognitive tasks with task-difficulty modulations and functional magnetic resonance imaging (fMRI). We hypothesized that effortful performance involves modulation of activation in the anterior insular and the anterior cingulate cortices, and that the modulation correlates with individual performance levels. Healthy participants performed tasks probing verbal working memory capacity using the reading span task, and visual perception speed using the inspection time task. In the fMRI analysis, we focused on identifying effort-related brain activation. The results showed that working memory and inspection time performances were directly related. The bilateral anterior insular and anterior cingulate cortices showed significantly increased activation during each task with common portions that were active across both tasks. We observed increased brain activation in the right anterior insula and the anterior cingulate cortex in participants with low working memory performance. In line with the reported results, we suggest that activation in the anterior insular and cingulate cortices is consistent with the neural efficiency hypothesis (Neubauer).

Dagens arbetsliv ställer allt större krav på kognitiva förmågor. Vi arbetar alltmer med information inte bara i traditionellt intellektuella yrken, utan även inom industri, hantverk och sjukvård. Informationsteknologi i form av datorer, avancerad teknisk utrustning och andra komplexa system blir allt viktigare att kunna hantera. Detta ställer nya krav på arbetsmiljöarbetet, något som gäller för alla arbetstagare, men särskilt för de av oss som har en kognitiv funktionsnedsättning.

I denna rapport sammanfattar vi arbetsmiljörelaterade hinder förknippade med nedsatt funktion inom nio kognitiva områden: språk, exekutiva funktioner, minnesfunktioner, visuospatiala funktioner, snabbhet, uppmärksamhet, emotion/social kognition, mental trötthet samt global kognitiv förmåga/intelligens. Vi uppmärksammar även mental trötthet (”fatigue”) som ett viktigt problemområde i  sammanhanget.

Den första delen av rapporten ger en bakgrund till området. Avsnittet ger en kort översikt över neuropsykologi och kognitiv neurovetenskap.

Den andra delen sammanfattar kunskap om omfattningen av problemet: hur vanliga är kognitiva funktionsnedsättningar i arbetslivet? En stor del av de människor som är i yrkesverksam ålder antingen har, eller kommer någon gång under yrkeslivet att drabbas av kognitiva funktionsproblem. Vi uppskattar att detta berör en femtedel till en tredjedel av de yrkesverksamma. Eftersom kognitiv funktionsnivå långt ifrån enbart beror på individens begränsningar till följd av sjukdom eller annan funktionsnedsättning, utan även på miljön och dess krav på individen, är problemen och lösningar på dessa både giltiga och viktiga för alla.

Rapportens andra del visar att kognitiv nedsättning inte begränsas till ett enstaka funktionellt område, exempelvis minnesbesvär, utan kan innefatta flera av de funktionella områden som berörs. Det finns alltså ingen enkel koppling mellan en sjukdom och vilka kognitiva funktionsproblem den medför för den enskilde arbetstagaren. Problemen måste ses i ljuset av både de erfarenheter och begränsningar den enskilde personen har och den aktuella arbetsuppgiften.

Rapportens tredje del diskuterar mer ingående arbetsmiljörelaterade konsekvenser av kognitiva funktionsnedsättningar. Den börjar med att sammanfatta en modell för att analysera funktionsnedsättningar som en produkt av fyra samverkande faktorer: individen (till exempel kognitiva funktionsbegränsningar efter en sjukdom), individens förhållningssätt (till exempel motivation), arbetsuppgiften och miljön. En kognitiv funktionsproblematik finns aldrig enbart i en av dessa faktorer utan i skärningspunkten mellan dessa faktorer. Av detta skäl är kunskap om arbetsmiljömässiga aspekter av kognitiva funktionsnedsättningar giltig för alla. Även de som inte har nedsatt kognitiv funktion hamnar i situationer där faktorer kopplade till miljön eller arbetsuppgiften (eller vår inställning till uppgiften) resulterar i att kognitiva förmågor belastas!

Vidare identifierar och sammanfattar rapportens tredje del praktiska lösningar som stödjer arbetsförmåga vid nedsättning av funktioner inom de nio områden som rapporten omfattar: språk, exekutiva funktioner, minnesfunktioner, visuospatiala funktioner, snabbhet, uppmärksamhet, emotion/social kognition, mental trötthet samt global kognitiv förmåga/intelligens. Särskilt betonas att det idag finns många tillgängliga men sannolikt mindre ofta utnyttjade åtgärder som kan utnyttjas för att mildra eller eliminera arbetsmiljöproblem relaterade till kognitiva funktionsnedsättningar. Rapporten redovisar sju sådana övergripande åtgärder. Därtill diskuteras kognitiva funktionsnedsättningar i samband med arbetstagare som är över 65 år och arbetsgivarens roll. Avslutningsvis identifieras kunskapsbehov för fortsatt arbete inom området.

This work aims at reviewing the present state of the art when it comes to understanding the pathophysiology of narcolepsy and the Kleine–Levin syndrome (KLS) from a neuroimaging point of view. This work also aims at discussing future perspectives of functional neuroimaging in these sleep disorders. We focus on functional magnetic resonance imaging (fMRI), which is a technique for in vivo measurements of brain activation in neuronal circuitries under healthy and pathological conditions. fMRI has significantly increased the knowledge on the affected neuronal circuitries in narcolepsy and the Kleine–Levin syndrome. It has been shown that narcolepsy is accompanied with disturbances of the emotional and the closely related reward systems. In the Kleine Levin syndrome, fMRI has identified hyperactivation of the thalamus as a potential biomarker that could be used in the diagnostic procedure. The fMRI findings in both narcolepsy and the Kleine–Levin syndrome are in line with previous structural and functional imaging studies. We conclude that fMRI in combination with multi-modal imaging can reveal important details about the pathophysiology in narcolepsy and the Kleine–Levin syndrome. In the future, fMRI possibly gives opportunities for diagnostic support and prediction of treatment response in individual patients.

BACKGROUND:

Mild traumatic brain injury (TBI) or concussion is common in many sports. Today, neuropsychological evaluation is recommended in the monitoring of a concussion and in return-to-play considerations. To investigate the sensitivity of neuropsychological assessment, we tested amateur boxers post bout and compared with controls. Further the relationship between neuropsychological test results and brain injury biomarkers in the cerebrospinal fluid (CSF) were investigated.

METHOD:

Thirty amateur boxers on high elite level with a minimum of 45 bouts and 25 non-boxing matched controls were included. Memory tests (Rey Osterrieth Complex Figure, Listening Span, Digit Span, Controlled Word Association Test, and computerized testing of episodic memory), tests of processing speed and executive functions (Trail Making, Reaction Time, and Finger Tapping) were performed and related to previously published CSF biomarker results for the axonal injury marker neurofilament light (NFL).

RESULTS:

The neurological assessment showed no significant differences between boxers and controls, although elevated CSF NFL, as a sign of axonal injury, was detected in about 80% of the boxers 1-6 days post bout. The investigation of the relationship between neuropsychological evaluation and CSF NFL concentrations revealed that boxers with persisting NFL concentration elevation after at least 14 days resting time post bout, had a significantly poorer performance on Trail Making A (p = 0.041) and Simple Reaction Time (p = 0.042) compared to other boxers.

CONCLUSION:

This is the first study showing traumatic axonal brain injury can be present without measureable cognitive impairment. The repetitive, subconcussive head trauma in amateur boxing causes axonal injury that can be detected with analysis of CSF NFL, but is not sufficient to produce impairment in memory tests, tests of processing speed, or executive functions. The association of prolonged CSF NFL increase in boxers with impairment of processing speed is an interesting observation, which needs to be verified in larger studies.

The Kleine–Levin syndrome (KLS) is a rare sleep disorder, characterized by exceptionally long sleep episodes. The neuropathology of the syndrome is unknown and treatment is often inadequate. The aim of the study was to improve understanding of the underlying neuropathology, related to cerebral networks, in KLS during sleep episodes. One patient with KLS and congenital nystagmus was investigated by resting state functional magnetic resonance imaging during both asymptomatic and hypersomnic periods. Fourteen healthy subjects were also investigated as control samples. Functional connectivity was assessed from seed regions of interest in the thalamus and the dorsal pons. Thalamic connectivity was normal in the asymptomatic patient whereas the connectivity between the brain stem, including dorsal pons, and the thalamus was diminished during hypersomnia. These results suggest that the patient’s nystagmus and hypersomnia might have their pathological origin in adjacent dorsal pontine regions. This finding provides additional knowledge of the cerebral networks involved in the neuropathology of this disabling disorder. Furthermore, these findings regarding a rare syndrome have broad implications, and results could be of interest to researchers and clinicians in the whole field of sleep medicine.

Background: leukocyte telomere length (TL) is considered a marker of biological aging. Several studies have investigated the link between leukocyte TL and aging-associated functional attributes of the brain, but no prior study has investigated whether TL can be linked to brain atrophy and white matter hyperintensities (WMHs); two prominent structural manifestations of brain aging.

Methods: we investigated whether leukocyte TL was related to brain atrophy and WMHs in a sample of 102 non-demented individuals aged 64–75 years.

Results: shorter TL was related to greater degree of subcortical atrophy (β = −0.217, P = 0.034), but not to cortical atrophy. Furthermore, TL was 371 bp shorter (P = 0.041) in participants exhibiting subcortical WMHs, and 552 bp shorter (P = 0.009) in older participants exhibiting periventricular WMHs.

Conclusion: this study provides the first evidence of leukocyte TL being associated with cerebral subcortical atrophy and WMHs, lending further support to the concept of TL as a marker of biological aging, and in particular that of the aging brain.