The Lack of Self-Consciousness in Right Brain-Damaged Patients Can Be due to a Disconnection From the Left Interpreter: The DiLeI Theory

Is There a Causal Link between the Left Lateralization of Language and Other Brain Asymmetries? A Review of Data Gathered in Patients with Focal Brain Lesions

This review evaluated if the hypothesis of a causal link between the left lateralization of language and other brain asymmetries could be supported by a careful review of data gathered in patients with unilateral brain lesions. In a short introduction a distinction was made between brain activities that could: (a) benefit from the shaping influences of language (such as the capacity to solve non-verbal cognitive tasks and the increased levels of consciousness and of intentionality); (b) be incompatible with the properties and the shaping activities of language (e.g., the relations between language and the automatic orienting of visual-spatial attention or between cognition and emotion) and (c) be more represented on the right hemisphere due to competition for cortical space. The correspondence between predictions based on the theoretical impact of language on other brain functions and data obtained in patients with lesions of the right and left hemisphere was then assessed. The reviewed data suggest that different kinds of hemispheric asymmetries observed in patients with unilateral brain lesions could be subsumed by common mechanisms, more or less directly linked to the left lateralization of language.

Delayed access to conscious processing in multiple sclerosis: Reduced cortical activation and impaired structural connectivity

Although multiple sclerosis (MS) is frequently accompanied by visuo‐cognitive impairment, especially functional brain mechanisms underlying this impairment are still not well understood. Consequently, we used a functional MRI (fMRI) backward masking task to study visual information processing stratifying unconscious and conscious in MS. Specifically, 30 persons with MS (pwMS) and 34 healthy controls (HC) were shown target stimuli followed by a mask presented 8–150 ms later and had to compare the target to a reference stimulus. Retinal integrity (via optical coherence tomography), optic tract integrity (visual evoked potential; VEP) and whole brain structural connectivity (probabilistic tractography) were assessed as complementary structural brain integrity markers. On a psychophysical level, pwMS reached conscious access later than HC (50 vs. 16 ms, p < .001). The delay increased with disease duration (p < .001, β = .37) and disability (p < .001, β = .24), but did not correlate with conscious information processing speed (Symbol digit modality test, β = .07, p = .817). No association was found for VEP and retinal integrity markers. Moreover, pwMS were characterized by decreased brain activation during unconscious processing compared with HC. No group differences were found during conscious processing. Finally, a complementary structural brain integrity analysis showed that a reduced fractional anisotropy in corpus callosum and an impaired connection between right insula and primary visual areas was related to delayed conscious access in pwMS. Our study revealed slowed conscious access to visual stimulus material in MS and a complex pattern of functional and structural alterations coupled to unconscious processing of/delayed conscious access to visual stimulus material in MS.

Exploring neurophysiological markers of visual perspective taking: Methodological considerations

RATIONALE

For visual perspective taking (VPT) using the avatar task, examinations of neural processes using event related potentials (ERP) indicate a distinction between an early posterior perspective calculation process (P3) and a later frontal process (LFSW) managing perspective conflict. While it is unknown if these neural processes are affected in clinical populations, it is unclear if the avatar task can be applied to this group, due to the long duration and sensitivity to data loss. Thus, we performed a methodological study of the avatar task, testing the feasibility of a shortened experimental paradigm.

OBJECTIVE

To investigate whether previously reported behavioural and ERP effects in the avatar task can also be seen if analysing all trials (matching/non-matching) jointly, and whether they remain robust if only a subset of the data is analysed.

METHOD

Healthy individuals (n = 20) completed the avatar task with ERP measurement. ERP components (P3, LFSW) and behavioural data were investigated by A) comparing use of only matching trials (n = 384) versus all trials (n = 768), and B) examining if reduced duration of assessment, by analysing only a subset of the data, impacts ERP findings.

RESULTS

We observed minimal differences when analysing data from only matching trial types compared to all trial types. Further, ERP amplitudes and latency findings were replicated when analysing only a subset of the data.

CONCLUSIONS

The duration of the avatar task can be reduced to avoid long testing times, thus making it better suited for use in clinical populations.

Effects of mindfulness on psychological and psychophysiological responses during self-paced walking

The aim of the present study was to investigate the effects of an audio-guided mindfulness (MF) single session on psychological and psychophysiological responses during an outdoor walking task. Twenty-four participants (12 females and 12 males; M_age  = 23.6, SD = 3.9 years) were required to walk 200 m at a pace of their choosing. Two experimental conditions (mindfulness meditation and mindlessness [ML] meditation) and a control condition (CO) were administered. Electrical activity in the brain was measured by the use of a portable electroencephalography (EEG) system during walking. Fast Fourier Transform was used to decompose the EEG samples into theta (5-7 Hz), alpha (8-14 Hz), and beta (15-29 Hz) frequencies. Brain connectivity analysis between frontal and temporo-parietal electrode sites was conducted to explore functional interactions through the use of spectral coherence. Affective and perceptual responses were measured by the use of single-item scales and questionnaires. The present findings indicate that MF was sufficiently potent to reallocate attention toward task-related thoughts, downregulate perceived activation, and enhance affective responses to a greater degree than the other two conditions. Conversely, ML was sufficient to increase the use of dissociative thoughts, make participants less aware of their physical sensations and emotions, induce a more negative affective state, and upregulate perceived activation to a greater extent than MF and CO. The brain mechanisms that underlie the effects of MF on exercise appear to be associated with the enhanced inter-hemispheric connectivity of high-frequency waves between right frontal and left temporo-parietal areas of the cortex.