Ignition’s glow: Ultra-fast spread of global cortical activity accompanying local “ignitions” in visual cortex during conscious visual perception

Despite extensive research, the spatiotemporal span of neuronal activations associated with the emergence of a conscious percept is still debated. The debate can be formulated in the context of local vs. global models, emphasizing local activity in visual cortex vs. a global fronto-parietal “workspace” as the key mechanisms of conscious visual perception. These alternative models lead to differential predictions with regard to the precise magnitude, timing and anatomical spread of neuronal activity during conscious perception. Here we aimed to test a specific aspect of these predictions in which local and global models appear to differ – namely the extent to which fronto-parietal regions modulate their activity during task performance under similar perceptual states. So far the main experimental results relevant to this debate have been obtained from non-invasive methods and led to conflicting interpretations. Here we examined these alternative predictions through large-scale intracranial measurements (Electrocorticogram – ECoG) in 43 patients and 4445 recording sites. Both ERP and broadband high frequency (50–150 Hz – BHF) responses were examined through the entire cortex during a simple 1-back visual recognition memory task. Our results reveal short latency intense visual responses, localized first in early visual cortex followed (at ∼200 ms) by higher order visual areas, but failed to show significant delayed (300 ms) visual activations. By contrast, oddball image repeat events, linked to overt motor responses, were associated with a significant increase in a delayed (300 ms) peak of BHF power in fronto-parietal cortex. Comparing BHF responses with ERP revealed an additional peak in the ERP response – having a similar latency to the well-studied P3 scalp EEG response. Posterior and temporal regions demonstrated robust visual category selectivity. An unexpected observation was that high-order visual cortex responses were essentially concurrent (at ∼200 ms) with an ultra-fast spread of signals of lower magnitude that invaded selected sites throughout fronto-parietal cortical areas. Our results are compatible with local models in demonstrating a clear task-dependence of the 300 ms fronto-parietal activation. However, they also reveal a more global component of low-magnitude and poor content selectivity that rapidly spreads into fronto-parietal sites. The precise functional role of this global “glow” remains to be elucidated.     

Efficacy of neurostimulation to treat symptoms of Mal de Debarquement Syndrome. A preliminary study using repetitive transcranial magnetic stimulation

Mal de debarquement syndrome (MdDS) is a rare and poorly understood condition of perceived continual motion. Using a multiple‐case design (n = 13; 8 f; 63.5 ± 12.6 years), this study investigated the efficacy of eight 20‐min sessions, over 4 weeks, of repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral pre‐frontal cortex. Compared to sham, rTMS demonstrated improvement in balance and confidence in daily living activities. rTMS shows promise for the treatment of MdDS. However, larger trials with longer intervention periods are required.     

The Emergence of Creativity

Creativity is one of the central dimensions of human achievement and social development and has always fascinated scientists and non-scientists alike. But what is the essential nature of creativity? And what is the role of consciousness in the emergence of creativity? If it is true that it has been explored in many aspects in the cognitive and neurobiological field, it is also true that the lore chest—from which the conscious mind through unconscious mechanisms extracts the rough material that is then brought to the surface—has been less investigated. The purpose of this article is to give an account of how the multiplicity of levels of awareness is made possible by a spontaneous order that has nothing to do with a monolithic view of creativity.     

Prediction and unconscious attention operate synergistically to facilitate stimulus processing: An fMRI study

There is considerable evidence that prediction and attention aid perception. However, little is known about the possible neural mechanisms underlying the impact of prediction and unconscious attention on perception, probably due to the relative neglect of unconscious attention in scholarly literature. Here, we addressed this issue using functional magnetic resonance imaging (fMRI). We adopted a variant of the double-cue paradigm, in which prediction and attention were factorially manipulated by two separate cues (prediction and attention cues). To manipulate consciousness, the attention cues were presented subliminally and supraliminally. Behaviorally, we reported an unconscious-attended effect in the predictable trials and a conscious-attended effect in the unpredictable trials. On the neural level, it was shown that prediction and unconscious attention interacted in the left dorsolateral prefrontal cortex (dlPFC). More specifically, there was a significantly decreased activation in dlPFC for predictable relative to unpredictable stimuli in the unconscious-attended trials, but not in the unconscious-unattended trials. This result suggests that prediction and unconscious attention operate synergistically to facilitate stimulus processing. This is further corroborated by the subsequent functional connectivity analysis, which revealed increased functional connectivity between the left dlPFC and the premotor cortex for predictable versus unpredictable stimuli in the unconscious-attended trials.     

Mindfulness meditation and consciousness: An integrative neuroscientific perspective

Although mindfulness meditation has been practiced in the East for more than two millennia, Western scientific research and healthcare programs have only recently drawn their attention to it. Basically, the concept of mindfulness hinges on focusing on one’s own awareness at the present moment. In this review we analyze different hypotheses about the functioning and the cerebral correlates of mindfulness meditation. Since mindfulness is strictly associated with a particular state of consciousness, we also examine some of the most relevant theories that have been proposed as accounts of consciousness. Finally, we suggest that consciousness and mindfulness meditation can be integrated within a neuroscientific perspective, by identifying the brain areas which seem to play an essential role in both, namely the anterior cingulate cortex, posterior cingulate cortex, insula and thalamus.     

Can we distinguish an “I” and “ME” during listening?—an event-related EEG study on the processing of first and second person personal and possessive pronouns

Theoretically, stimuli can be related to the self as subject (“I”) or object (“ME”) of experience. This event-related brain potential (ERP) study investigated whether listening to personal and possessive pronouns elicits different modes of self-processing regarding time-course and neural sources. Going beyond previous research, first (1PP) and second person (2PP) pronouns were included to determine the specificity of self-processing. Participants listened passively to German pronouns while the electroencephalogram was recorded. Modulation of ERPs revealed a processing advantage for the 2PP personal pronoun “du” (“you”) already in early time windows. Regarding possessive pronouns, N1 amplitudes indicated increased attention orientation to the 1PP pronoun “mein” (“my”), whereas during later time windows, processing of 1PP and 2PP possessive pronouns did not differ but differed from the third person pronoun “sein” (“his”). ERP source imaging suggests that primary sensory brain regions (auditory cortex), the insula and cortical midline structures are differentially involved into these two processing modes. The results support the idea of distinct self-processing modes (“I” and “ME”) and confirm their dynamic nature. Moreover, they demonstrate that on a neural level neither “I” or “ME” are invariantly tied to the first person, in line with the hypothesis that self-processing is relational and context-dependent.     

A Voxel-based lesion study on facial emotion recognition after circumscribed prefrontal cortex damage

Previous studies have shown inconsistent findings regarding the contribution of the different prefrontal regions in emotion recognition. Moreover, the hemispheric lateralization hypothesis posits that the right hemisphere is dominant for processing all emotions regardless of affective valence, whereas the valence specificity hypothesis posits that the left hemisphere is specialized for processing positive emotions while the right hemisphere is specialized for negative emotions. However, recent findings suggest that the evidence for such lateralization has been less consistent. In this study, we investigated emotion recognition of fear, surprise, happiness, sadness, disgust, and anger in 30 patients with focal prefrontal cortex lesions and 30 control subjects. We also examined the impact of lesion laterality on recognition of the six basic emotions. The results showed that compared to control subjects, the frontal subgroups were impaired in recognition of three negative basic emotions of fear, sadness, and anger – regardless of the lesion laterality. Therefore, our findings did not establish that each hemisphere is specialized for processing specific emotions. Moreover, the voxel-based lesion symptom mapping analysis showed that recognition of fear, sadness, and anger draws on a partially common bilaterally distributed prefrontal network.     

Sulcal morphology and volume of Broca's area linked to handedness and sex

We investigated the effect of handedness and sex on: (i) sulcal contours defining PO and PTR and (ii) volume estimates of PO and PTR subfields in 40 left- and 42 right-handers. Results show an effect of handedness on discontinuity of the inferior frontal sulcus (IFS: P < 0.01). Discontinuity of IFS was observed in: 43% left- and 62% right hemispheres in right-handers and in 65% left- and 48% right-hemispheres in left-handers. PO volume asymmetry was rightward in left-handed males (P = 0.007) and females (P = 0.02), showed a leftward trend in right-handed males (P = 0.06), and was non-asymmetrical in right-handed females (P = 0.96, i.e. left- and right-hemisphere PO volumes did not differ significantly). PO volume asymmetry in males differed significantly between handedness groups (P = 0.001). Findings indicate a high degree of variability in the sulcal contours of PO and PTR and volume asymmetry of PO: the factors sex and handedness can explain some of this variability.     

Parametric effects of syntactic-semantic conflict in Broca's area during sentence processing

The hypothesized role of Broca’s area in sentence processing ranges from domain-general executive function to domain-specific computation that is specific to certain syntactic structures. We examined this issue by manipulating syntactic structure and conflict between syntactic and semantic cues in a sentence processing task. Functional neuroimaging revealed that activation within several Broca’s area regions of interest reflected the parametric variation in syntactic-semantic conflict. These results suggest that Broca’s area supports sentence processing by mediating between multiple incompatible constraints on sentence interpretation, consistent with this area’s well-known role in conflict resolution in other linguistic and non-linguistic tasks.