Neuropsychologia
October 1, 2020
Łucja Doradzińska, Michał J Wójcik, Marta Paź et al.
The P3b brain wave component, long debated as either a marker of conscious perception or of cognitive processes like working memory, can be modulated by a person's own name even when that name is presented subliminally—outside of awareness. In two experiments, participants' own names evoked a larger P3b than other names when consciously seen. Subliminally, the own-name effect on P3b appeared only when participants performed a forced-choice identification task, not during a subjective rating task. This shows that a highly salient stimulus can influence P3b without conscious awareness, but the effect depends on the task and top-down attention. The findings argue against interpreting P3b as a direct correlate of consciousness and challenge the Global Workspace Theory.
Neuropsychologia
April 30, 2020
Amnon Dafni-Merom, S. Arzy
Endel Tulving's concept of autonoetic consciousness—self-knowing awareness that enables mental time travel—links episodic memory with the ability to remember past events and simulate future ones. This review traces how Tulving's ideas have expanded into related theories including episodic memory, mental time travel, episodic simulation, scene construction, and self-projection. The authors examine the cognitive operations involved in traveling or projecting across temporal, spatial, and social domains. A meta-analysis of functional neuroimaging studies shows overlapping brain activations in medial prefrontal cortex, precuneus, retrosplenial cortex, temporoparietal junction, and medial temporal lobe, supporting the interconnectedness of these theories and their roots in Tulving's original framework.
Neuropsychologia
August 1, 2019
Umberto León-Domínguez, José León-Carrión
The prefrontal cortex (PFC) is a key brain region for consciousness, involved in both awareness and manipulating conscious content. While its role in cortico-cortical networks is agreed upon, its function in thalamocortical networks and forming conscious content is debated. This review proposes that the PFC, via connections with nonspecific thalamic nuclei, integrates sensory perceptions into a unified conscious experience. A cortico-thalamocortical loop organizes temporal and spatial information to maintain a subjective stream of consciousness. Attentional top-down mechanisms between the PFC and the reticular thalamic nucleus may influence conscious content by regulating thalamic activity. The PFC acts as a dynamic hub that recalibrates neural dynamics and regulates brain processes associated with consciousness.
Neuropsychologia
June 1, 2019
Itsaso Colás, Ana B Chica, Estrella Ródenas et al.
Damage to the right dorsolateral prefrontal cortex and reduced integrity of the ventral branch of the right superior longitudinal fasciculus (SLF III) are causally linked to conscious perception of near-threshold stimuli. Patients with right prefrontal damage required greater perceptual contrast to detect near-threshold targets compared to matched healthy controls, supporting a causal role of the prefrontal lobe in conscious processing.
Neuropsychologia
June 1, 2019
Anh-Thu Mai, Tijl Grootswagers, Thomas A. Carlson
Visual information can be processed by the brain without reaching consciousness. Using multivariate pattern analysis and magnetoencephalography, brain activity was recorded while participants viewed stimuli at threshold contrast in a backward masking paradigm. Both conscious and non-conscious trials contained stimulus information, but the information was enhanced in conscious trials. Visual consciousness is characterized by enhanced neural activity representing the visual stimulus, an effect arising as early as 180 ms post-stimulus onset.
Neuropsychologia
May 1, 2019
Chiara Mazzi, Silvia Savazzi, Juha Silvanto
A lesion to primary visual cortex (V1) abolishes all phenomenal awareness while unconscious visual functions can remain, leading to the view that V1 is crucial for generating visual consciousness. However, since the early 20th century, controversial reports have described phenomenal awareness in patients with V1 lesions, including selective sparing of motion awareness, hemianopic completion, and visual aftereffects. Recent successful attempts to induce visual qualia with noninvasive brain stimulation are also reviewed. This critical review discusses the implications of these findings for theoretical understanding of phenomenal awareness.
Neuropsychologia
August 31, 2017
Haakon Engen, B. Bernhardt, Leon Skottnik et al.
Long-term meditation practitioners who had spent an average of 40,000 hours cultivating loving-kindness and compassion showed increased cortical thickness in fronto-insular brain regions compared to meditation-naïve controls. Functional MRI during a loving-kindness meditation session revealed increased brain activity in multiple prefrontal and insular areas, with partial overlap in the left ventrolateral prefrontal cortex and anterior insula, suggesting these regions are central to generating emotional states relevant to the practice. These cross-sectional findings motivate future longitudinal research on brain plasticity from training aimed at enhancing altruism and prosocial motivation.
Neuropsychologia
June 1, 2016
J. Speth, C. Speth
Applying anodal transcranial direct current stimulation (tDCS) over the motor cortex (C3) during REM sleep increases both the quantity and quality of spontaneous motor imagery, including athletic motor imagery, compared to cathodal or sham stimulation. A randomized triple-blinded design combined neurophysiological techniques with quantitative analysis of mentation reports. The findings suggest that electrophysiological manipulation of motor imagery in REM sleep could eventually support rehabilitative tDCS protocols for temporarily immobile patients, such as those with dementia, infants with motor disorders, or coma patients, who cannot perform specific motor imagery tasks.
Neuropsychologia
March 25, 2007
Todd A. Girard, Désirée L M A Martius, J Allan Cheyne
Hallucinations experienced during sleep paralysis—both sensory and motor—tend to be projected toward the lower-left and especially the upper-right region of external space, a pattern that exceeds what would be expected from simply adding separate left-right and up-down biases. This oblique bias suggests a systematic link between hemispheric brain organization and ventral/dorsal cerebral pathways, adding to evidence that spatial preferences are multidimensional and not merely additive. The findings come from analyzing the three-dimensional distribution of hypnagogic and hypnopompic hallucinations, offering a window into internal spatial representation free from typical task-related influences.
Neuropsychologia
October 1, 1998
M C Corballis
Sperry's empirical work on split-brain patients reinforced a materialist view of mind-brain relations, but his concept of emergent consciousness that can causally influence neural function echoes Cartesian dualism, potentially allowing for free will, individual responsibility, and a synthesis of science with moral and religious values. Sperry insisted his view was entirely materialistic, distinguishing not between non-material mind and material brain but between holism and reductionism. He associated this distinction with right- versus left-brain modes of thought and hoped for unification of holistic and reductionist approaches, believing these modes are fundamentally unified in the normal brain.