Jonas K. Olofsson

Affective picture processing: An integrative review of ERP findings

The review summarizes and integrates findings from 40 years of event-related potential (ERP) studies using pictures that differ in valence (unpleasant-to-pleasant) and arousal (low-to-high) and that are used to elicit emotional processing. Affective stimulus factors primarily modulate ERP component amplitude, with little change in peak latency observed. Arousal effects are consistently obtained, and generally occur at longer latencies. Valence effects are inconsistently reported at several latency ranges, including very early components. Some affective ERP modulations vary with recording methodology, stimulus factors, as well as task-relevance and emotional state. Affective ERPs have been linked theoretically to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced stimulus processing has been associated with memory encoding for arousing pictures of assumed intrinsic motivational relevance, with task-induced differences contributing to emotional reactivity at later components (>300 ms). Theoretical issues, stimulus factors, task demands, and individual differences are discussed.

Affective visual event-related potentials : arousal, repetition, and time-on-task

Affective stimulus pictures that differed in valence (unpleasant, neutral, and pleasant) were repeated as targets in an oddball task to elicit event-related potentials (ERPs) in young female adults. Each picture target was repeated consecutively four times, with picture order counterbalanced and time-on-task influences assessed across subjects. Response time decreased from the first to second stimulus presentation and remained stable. Stimulus repetition was associated with voltage increases for N1, P2, N2, and P3, from initial to subsequent presentations. Arousal effects did not interact with stimulus repetition at any latency range. Time-on-task was associated with decreased voltages for the N2 and P3 potentials but was unaffected by stimulus valence. The findings suggest affective arousal, stimulus repetition, and time-on-task independently modulate ERP outcomes at overlapping time ranges. Theoretical implications are discussed.

The muted sense: neurocognitive limitations of olfactory language

Most people find it profoundly difficult to name familiar smells. This difficulty persists even when perceptual odor processing and visual object naming are unimpaired, implying deficient sensory-specific interactions with the language system. Here we synthesize recent behavioral and neuroimaging data to develop a biologically informed framework for olfactory lexical processing in the human brain. Our central premise is that the difficulty in naming common objects through olfactory (compared with visual) stimulation is the end result of cumulative effects occurring at three successive stages of the olfactory language pathway: object perception, lexical-semantic integration, and verbalization. Understanding the neurocognitive mechanisms by which the language network interacts with olfaction can yield unique insights into the elusive nature of olfactory naming.

Odor identification impairment in carriers of ApoE-ɛ4 is independent of clinical dementia

The ApoE gene is expressed in olfactory brain structures and is believed to play a role in neuronal regenerative processes as well as in development of Alzheimers disease (AD), the most common form of dementia. The varepsilon4 allele has been reported to be associated with compromised odor identification ability in the elderly, and this deficit has been interpreted as a sign of pre-diagnostic AD. However, because it has not been demonstrated that the relationship between the varepsilon4 allele and odor identification is mediated by dementia, it is possible that the varepsilon4 allele may have an effect on odor identification over and above any effects of dementia. The present study investigated effects of ApoE-status on odor identification in a large, population-based sample (n=1236) of adults (45-80 years), who were assessed for dementia at time of testing and 5 years later. The results showed that the varepsilon4 allele was associated with an odor identification deficit among elderly participants (75-80). Critically, this effect remained after current and pre-diagnostic dementia, vocabulary, global cognitive status and health variables were partialled out. The present results suggest that the ApoE gene plays a role in olfactory functioning that is independent of dementia conversion within 5 years.

Affected by Smells? Environmental Chemical Responsivity Predicts Odor Perception

Strong negative reactions, physical symptoms, and behavioral disruptions due to environmental odors are common in the adult population. We investigated relationships among such environmental chemosensory responsivity (CR), personality traits, affective states, and odor perception. Study 1 showed that CR and neuroticism were positively correlated in a sample of young adults (n = 101), suggesting that persons high in neuroticism respond more negatively to environmental odors. Study 2 explored the relationships among CR, noise responsivity (NR), neuroticism, and odor perception (i.e., pleasantness and intensity) in a subset of participants (n = 40). High CR was associated with high NR. Regression analyses indicated that high CR predicted higher odor intensity ratings and low olfactory threshold (high sensitivity) predicted lower pleasantness ratings. However, neuroticism was not directly associated with odor ratings or thresholds. Overall, the results suggest that CR and odor thresholds predict perceptual ratings of odors and that high CR is associated with nonchemosensory affective traits.

A Time-Based Account of the Perception of Odor Objects and Valences

Is human odor perception guided by memory or emotion? Object-centered accounts predict that recognition of unique odor qualities precedes valence decoding. Valence-centered accounts predict the opposite: that stimulus-driven valence responses precede and guide identification. In a speeded response time study, participants smelled paired odors, presented sequentially, and indicated whether the second odor in each pair belonged to the same category as the first (object evaluation task) or whether the second odor was more pleasant than the first (valence evaluation task). Object evaluation was faster and more accurate than valence evaluation. In a complementary experiment, participants performed an identification task, in which they indicated whether an odor matched the previously presented word label. Responses were quicker for odors preceded by semantically matching, rather than nonmatching, word labels, but results showed no evidence of interference from valence on nonmatching trials. These results are in accordance with object-centered accounts of odor perception.

A Designated Odor–Language Integration System in the Human Brain

Odors are surprisingly difficult to name, but the mechanism underlying this phenomenon is poorly understood. In experiments using event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), we investigated the physiological basis of odor naming with a paradigm where olfactory and visual object cues were followed by target words that either matched or mismatched the cue. We hypothesized that word processing would not only be affected by its semantic congruency with the preceding cue, but would also depend on the cue modality (olfactory or visual). Performance was slower and less precise when linking a word to its corresponding odor than to its picture. The ERP index of semantic incongruity (N400), reflected in the comparison of nonmatching versus matching target words, was more constrained to posterior electrode sites and lasted longer on odor-cue (vs picture-cue) trials. In parallel, fMRI cross-adaptation in the right orbitofrontal cortex (OFC) and the left anterior temporal lobe (ATL) was observed in response to words when preceded by matching olfactory cues, but not by matching visual cues. Time-series plots demonstrated increased fMRI activity in OFC and ATL at the onset of the odor cue itself, followed by response habituation after processing of a matching (vs nonmatching) target word, suggesting that predictive perceptual representations in these regions are already established before delivery and deliberation of the target word. Together, our findings underscore the modality-specific anatomy and physiology of object identification in the human brain.

Guarded transitions? Youth trajectories and school-to-work transition policies in Sweden

In Sweden as in most other OECD countries, school-to-work transitions have become extended and uncertain endeavours. School dropout and youth unemployment rates are comparatively high, and the so-called yo–yo transitions are common. Although traditionally characterised as a prominent example of a social democratic welfare regime, Sweden has recently incorporated numerous neo-liberal ideas into its educational and youth policies. The responsibility for managing and implementing these policies has been extensively devolved to the countrys 290 municipalities. Moreover, young people are increasingly expected to take exclusive responsibility for forging their own careers, and to be self-governing, enterprising and proactive, both within the educational quasi-market and beyond. The aim of this article was to critically analyse current Swedish national school-to-work transition policies as well as the ways in which local strategies and measures are implemented and developed within individual municipalities given the relatively broad latitude available to them, and to provide some tentative explanations for Swedens problems with school dropout rates and youth unemployment.

Time to smell: a cascade model of human olfactory perception based on response-time (RT) measurement.

The timing of olfactory behavioral decisions may provide an important source of information about how the human olfactory-perceptual system is organized. This review integrates results from olfactory response-time (RT) measurements from a perspective of mental chronometry. Based on these findings, a new cascade model of human olfaction is presented. Results show that main perceptual decisions are executed with high accuracy within about 1~s of sniff onset. The cascade model proposes the existence of distinct processing stages within this brief time-window. According to the cascade model, different perceptual features become accessible to the perceiver at different time-points, and the output of earlier processing stages provides the input for later processing stages. The olfactory cascade starts with detecting the odor, which is followed by establishing an odor object. The odor object, in turn, triggers systems for determining odor valence and edibility. Evidence for the cascade model comes from studies showing that RTs for odor valence and edibility assessment are predicted by the shorter RTs needed to establish the odor object. Challenges for future research include innovative task designs for olfactory RT experiments and the integration of the behavioral processing sequence into the underlying cortical processes using complementary RT measures and neuroimaging methods.

Olfactory and chemosomatosensory function in pregnant women assessed with event-related potentials

The purpose of the study was to better understand past findings of nasal chemosensory hypersensitivity in pregnant women by recording chemosensory event-related potentials (CSERPs) for information about cortical neuronal allocation (amplitudes) and temporal processing (latencies) of three concentrations of pyridine ranging from predominantly olfactory to trigeminal in activation in 15 pregnant and 15 non-pregnant women. CSERP components of primarily sensory (N1 and P2) and cognitive (P3) origin were evaluated. The results displayed no group differences in either N1 or P2 amplitudes or latencies, but tendencies of larger amplitudes and shorter latencies for P3 in pregnant women. This implies that pregnant womens hypersensitivity may more likely be referred to cognitive than sensory processing.