Neuroscience and Biobehavioral Reviews
October 1, 2022
Saampras Ganesan, Emillie Beyer, Bradford A. Moffat et al.
Focused attention meditation consistently engages three key functional brain networks: the Default-mode, Salience, and Executive Control networks. A quantitative meta-analysis of 10 functional MRI studies (200 participants) showed that meditation expertise, mindfulness levels, and attentional skills influence the magnitude, but not the regional extent, of activation and functional connectivity in these networks. A unified neurocognitive brain-network model of focused attention meditation is proposed.
Neuroscience and Biobehavioral Reviews
September 1, 2022
Jeremy I Skipper
Language, especially inner speech, is hypothesized to generate and sustain higher-order self-awareness. A 'HOLISTIC' model proposes a core set of inner speech production regions that initiate the experience of feeling and hearing words, which acquire affective qualities through activation of associated sensory, motor, and emotional representations in a largely unconscious dynamic periphery distributed throughout the brain. Responding to these words sustains network activity involving default mode activation and prefrontal and thalamic/brainstem selection of contextually relevant responses. The model offers a more parsimonious account of the neural correlates of consciousness and has implications for mental health and wellbeing.
Neuroscience and Biobehavioral Reviews
September 21, 2021
Susanna Feruglio, Alessio Matiz, G. Pagnoni et al.
A systematic review of 24 studies examined how Mindfulness Meditation (MM) affects mind wandering (MW). Most pre-post intervention studies showed that at least two weeks of MM practice reduced MW and limited its negative effects on cognitive tasks. Cross-sectional studies found that expert meditators reported less MW and showed decreased Default Mode Network activity during meditation and at rest compared to non-meditators. The reviewed studies varied widely in design, outcome measures, and interventions. The authors call for further research to replicate findings and explore how meditation influences the qualitative characteristics of MW.
Neuroscience and Biobehavioral Reviews
August 9, 2020
G. Northoff, V. Lamme
Various theories of the neural basis of consciousness propose diverse neural signs and mechanisms. This review asks whether that diversity is real or whether theories share basic ideas that could converge. It compares neural signs, measures, and mechanisms across theories, showing that different theories focus on distinct aspects of neural activity—stimulus-related, prestimulus, and resting state—and on distinct features of consciousness. The mechanisms may partly complement each other. The authors conclude that the different theories concern distinct aspects of neural activity and consciousness that may be integrated and nested within the brain's overall temporo-spatial dynamics.
Neuroscience and Biobehavioral Reviews
January 26, 2020
P. Frewen, M. Schroeter, G. Riva et al.
A review of neuroimaging research on self-referential processing (SRP) distinguishes between verbal and non-verbal forms, each occurring in controlled, top-down tasks (introspection and interoception) and in spontaneous, bottom-up states (mind wandering and body wandering during rest). The authors propose a conceptual and methodological framework for future SRP research, which they apply to understanding psychological and neurological disorders linked to abnormal SRP. The discussion draws on William James' writings on the consciousness of self.
Neuroscience and Biobehavioral Reviews
September 1, 2019
B. Hutchinson
A review of neuroscientific studies using inattentional blindness—where people fail to see an unexpected object because their attention is elsewhere—finds clear evidence that visual processing up to intermediate stages (such as visual features and orthographic processing) occurs even when people are unaware of a stimulus. The most common brain activity markers linked to awareness are the visual awareness negativity and post-stimulus alpha suppression, while key brain regions involved include the lateral occipital cortex, temporoparietal junction, and intraparietal sulcus. The authors address limitations of this literature and recommend how future inattentional blindness research can advance neuroscientific theories of consciousness.
Neuroscience and Biobehavioral Reviews
August 1, 2019
Sylvie Tordjman, Macarena-Paz Celume, L. Denis et al.
Self-consciousness disorders in schizophrenia and autism spectrum disorder (ASD) are linked to impairments in body self, which disrupt self-other differentiation, theory of mind, and empathy, leading to social communication difficulties. A proposed model suggests that altered or absent intermodal sensory integration—especially visual-kinesthetic-tactile integration—underlies these bodily self-consciousness disorders. This disruption causes problems distinguishing self from others, which in turn contributes to deficits in theory of mind and empathy and impairs social communication. The model offers new avenues for understanding and developing therapeutic strategies for these conditions.
Neuroscience and Biobehavioral Reviews
April 1, 2019
Federico Turkheimer, Peter J. Hellyer, Angie A. Kehagia et al.
Emergence describes how complex systems exhibit properties not easily explained by their individual parts, seen in ant colonies, bird flocks, or brain function. This paper clarifies the concept, distinguishing strong emergence (where properties are irreducible to lower-level mechanisms) from weak emergence (where properties arise from but are explainable by lower-level interactions). It argues that models based on strong emergence, such as the free energy principle and integrated information theory, risk metaphysical implausibility and overdetermination, making them only one of many possible explanations. In contrast, weakly emergent computational models like oscillatory networks, which start from biologically plausible elementary units, are ontologically sound and offer a powerful approach for future neuroscientific research.
Neuroscience and Biobehavioral Reviews
October 1, 2017
Bernhard Hommel, Lorenza S. Colzato
People often face trade-offs between sticking with a strategy (persistence) and switching to a new one (flexibility), a dilemma requiring metacontrol—the regulation of which cognitive-control policy to use. Individual differences in metacontrol biases toward persistence or flexibility show up in specially designed tasks and correlate with genetic variations in dopamine systems and with whether a person comes from an individualistic or collectivistic culture. Yet mood and meditation also shift these biases: negative mood and focused-attention meditation favor persistence, while positive mood and open-monitoring meditation favor flexibility. Thus genetic and cultural factors do not fully determine metacontrol; a proposed framework explains how they set defaults that situational factors can override.
Neuroscience and Biobehavioral Reviews
June 1, 2017
Kristine Rømer Thomsen, M. B. Callesen, S. W. F. Ewing
A commentary argues that most research on cannabis has treated it as a single substance, obscuring the opposing cognitive effects of THC and CBD. The authors contend that rising cannabis potency over the past two decades limits the generalizability of older studies to current public health. They urge future research to separately examine THC and CBD and to measure potency to better understand cannabis's impact on cognition and health.
Neuroscience and Biobehavioral Reviews
February 4, 2017
D. Terhune, Axel Cleeremans, Amir Raz et al.
Hypnosis is a top-down regulatory process in which verbal suggestions produce pronounced changes in psychological phenomena. It serves both as a technique for studying consciousness and as a therapeutic method for symptoms. This review synthesizes current knowledge on the characteristics and neurocognitive mechanisms of hypnosis, drawing on evidence from cognitive neuroscience, experimental psychopathology, and clinical psychology. It discusses hypnosis as an experimental method for modulating consciousness, a model for studying healthy and pathological cognition, and a therapeutic tool. The review also relates hypnosis to broader suggestion and suggestibility, identifies challenges in the cognitive neuroscience of hypnosis, and outlines future research directions.
Neuroscience and Biobehavioral Reviews
March 21, 2016
K. Fox, Matthew L. Dixon, Savannah Nijeboer et al.
Different styles of meditation produce distinct patterns of brain activity and deactivation, according to a systematic review and meta-analysis of 78 functional neuroimaging studies. Four common styles—focused attention, mantra recitation, open monitoring, and compassion/loving-kindness—showed reliably dissociable activation patterns consistent with their psychological aims. Some brain areas, such as the insula and dorsal anterior cingulate cortex, were recruited across multiple techniques, but convergence was the exception. A preliminary effect-size analysis found medium effects for both activations and deactivations, suggesting potential practical significance. The review also raised methodological concerns and suggested avenues for future research.
Neuroscience and Biobehavioral Reviews
May 1, 2013
Zoran Vukadinovic, Merrill S Herman, Ivana Rosenzweig
Cannabis use is a strong environmental risk factor for schizophrenia, but the mechanism is unknown. This theoretical paper argues that exogenous cannabinoids may directly affect T-type calcium channels in the thalamus. These channels are critical for amplifying corticothalamic inputs and generating neuronal burst firing, which is important for trans-thalamic cortico-cortical interactions. Interference with burst firing could impair these interactions, leading to a relative disconnection between cortical areas, reduced ability to recognize re-afferent sensory inputs, and psychosis. Δ(9)THC may be more detrimental than cannabidiol because it increases thalamic neuron excitability through its direct effect on T-type calcium channels.
Neuroscience and Biobehavioral Reviews
July 1, 2008
Vĕra Bubeníková‐valešová, Jiří Horáček, Monika Vrajová et al.
Research using non-competitive NMDA receptor antagonists—phencyclidine, ketamine, and dizocilpine—produces behavioral changes in humans and rats that resemble schizophrenia symptoms. Acute and chronic administration models show phenomenological validity and help test potential antipsychotic drugs. However, schizophrenia's pathophysiology remains unexplained. The neurodevelopmental model suggests that early-life NMDA receptor antagonism increases apoptosis or alters glutamatergic receptor function during central nervous system development, leading to psychosis that often emerges only in adulthood. Chronic antagonist administration triggers adaptation mechanisms that match findings in schizophrenia patients, making this model useful for studying the disease's pathophysiology.
Neuroscience and Biobehavioral Reviews
January 1, 1998
F Sams-Dodd
Phencyclidine (PCP) can induce a model psychosis in humans that mimics both positive and negative symptoms of schizophrenia. In the social interaction test, PCP causes stereotyped behavior and social isolation in rats, which can be inhibited by antipsychotic drugs. To further evaluate this model's predictive validity, drugs without antipsychotic activity—diazepam (0.02–17.5 µmol/kg), citalopram (0.62–19.8 µmol/kg), methadone (0.36–5.8 µmol/kg), and naloxone (0.34–22.0 µmol/kg)—were tested. None specifically inhibited PCP-induced behaviors, suggesting that only antipsychotic drugs can do so.