The neural basis of human memory is incredibly complex. We argue that the diversity of neural sys... more The neural basis of human memory is incredibly complex. We argue that the diversity of neural systems underlying various forms of memory suggests that any discussion of enhancing 'memory' per se is too broad, thus obfuscating the biopolitical debate about human enhancement. Memory can be differentiated into at least four major (and several minor) systems with largely dissociable (i.e., non-overlapping) neural sub-strates. We outline each system, and discuss both the practical and the ethical implications of these diverse neural substrates. In practice, distinct neural bases imply the possibility, and likely the necessity, of specific approaches for the safe and effective enhancement of various memory systems. In the debate over the ethical and social implications of enhancement technologies, this fine-grained perspective clarifies—and may partially mitigate—certain common concerns in enhancement debates, including issues related to safety, fairness, coercion, and authenticity. While many researchers certainly appreciate the neurobiological complexity of memory, the political debate tends to revolve around a monolithic one-size-fits-all conception. The overall project—exploring how human enhancement technologies affect society – stands to benefit from a deeper appreciation of memory's neurobiological diversity.
Meditation and hypnosis both aim to facilitate cognitive-emotional flexibility, i.e., the “de-aut... more Meditation and hypnosis both aim to facilitate cognitive-emotional flexibility, i.e., the “de-automatization” of thought and behavior. However, little research or theory has addressed how internal thought patterns might change after such interventions, even though alterations in the internal flow of consciousness may precede externally observable changes in behavior. This chapter outlines three mechanisms by which meditation or hypnosis might alter or reduce automatic associations and elaborations of spontaneous thought: by an overall reduction of the chaining of thoughts into an associative stream; by de-automatizing and diversifying the content of thought chains (i.e., increasing thought flexibility or variety); and, finally, by re-automatizing chains of thought along desired or valued paths (i.e., forming new, voluntarily chosen mental habits). The authors discuss behavioral and cognitive neuroscientific evidence demonstrating the influence of hypnosis and meditation on internal cognition and highlight the putative neurobiological basis, as well as potential benefits, of these forms of de-automatization.
Thoughts arise spontaneously in our minds with remarkable frequency, but tracking the brain syste... more Thoughts arise spontaneously in our minds with remarkable frequency, but tracking the brain systems associated 17 withtheearlyinceptionofathoughthasprovedchallenging.Hereweaddressedthisissuebytakingadvantageof 18 theheightenedintrospectiveabilityofexperiencedmindfulnesspractitionerstodetecttheonsetoftheirsponta- 19 neously arising thoughts. We observed subtle differences in timing among the many regions typically recruited 20 byspontaneousthought.Onlyinsomeoftheseregionsdidneuralactivationpeakpriortothespontaneousaris- 21 ingofathought—mostnotablyinthemedialtemporallobeandinferiorparietallobule.Incontrast,activationin 22 themedialprefrontal,temporopolar,mid-insular,lateralprefrontal,anddorsalanteriorcingulatecorticespeaked 23 together with or immediately following the arising of spontaneous thought. We propose that brain regions that 24 show antecedent recruitment may be preferentially involved in the initial inception of spontaneous thoughts, 25 while those that show later recruitment may be preferentially involved in the subsequent elaboration and 26 metacognitive processing of spontaneous thoughts. Our findings highlight the temporal dynamics of neural re- 27 cruitment surrounding the emergence of spontaneous thoughts and may help account for some of spontaneous 28 thought's peculiar qualities, including its wild diversity of content and its links to memory and attention.
Mind wandering (MW) and metacognition may give the impression of 7 lying at the opposite poles of... more Mind wandering (MW) and metacognition may give the impression of 7 lying at the opposite poles of the spectrum of human cognition. MW involves 8 undirected, spontaneous thought processes that often occur without our volition 9 and sometimes despite our intentions. Metacognition, by contrast, involves the 10 conscious, often intentional monitoring and evaluation of our own mental pro-11 cesses and behaviors. The neural correlates of MW and metacognition may also 12 appear strictly distinct at first, considering the almost exclusive focus on default 13 network regions' involvement in MW, in contrast to the emphasis on higher order 14 prefrontal regions' role in metacognitive processing. In this chapter, we will argue 15 that despite the apparent gulf between MW and metacognition, some of the most 16 intriguing mental phenomena we humans are capable of experiencing involve an 17 intimate, dynamic interplay between MW and metacognition. According to the 18 standard view of their interaction, metacognition serves to correct the wandering 19 mind, suppressing spontaneous thoughts and bringing attention back to more 20 ''worthwhile'' tasks. In this chapter, we argue that this ''negative'' or suppressant 21 view of their interactions represents only a part of the whole picture. Instead, we 22 outline and discuss three examples of positive, facilitative interactions: creative 23
This article argues that the default network, augmented by secondary visual and sensorimotor cort... more This article argues that the default network, augmented by secondary visual and sensorimotor cortices, is the likely neural correlate of dreaming. This hypothesis is based on a synthesis of work on dream content, the findings on the contents and neural correlates of mind-wandering, and the results from EEG and neuroimaging studies of REM sleep. Relying on studies in the 1970s that serendipitously discovered episodes of dreaming during waking mind-wandering, this article presents the seemingly counterintuitive hypothesis that the neural correlates for dreaming could be further specified in the process of carrying out EEG/fMRI studies of mind-wandering and default network activity. This hypothesis could be tested by asking participants for experiential reports during moments of differentially high levels of default network activation, as indicated by mixed EEG/fMRI criteria. Evidence from earlier EEG/fMRI studies of mind-wandering and from laboratory studies of dreaming during the sle...
The functional organization of brain areas supporting goal-directed behavior is debated. Some acc... more The functional organization of brain areas supporting goal-directed behavior is debated. Some accounts suggest a rostro-caudal organization, while others suggest a broad recruitment as part of a multiple demand network. We used fMRI and an anatomical region of interest (ROI) approach to test which account better characterizes the organization of key brain areas related to goal-directed behavior: the lateral prefrontal cortex (LPFC), medial prefrontal cortex (MPFC), cingulate cortex, and insula. Subjects performed a cognitive control task with distinct trial events corresponding to rule representation, rule maintenance, action execution, and monitoring progress towards an overarching motivational goal. The use of ROIs allowed us to look for evidence of rostro-caudal gradients during each event separately. Our results provide strong evidence for rostro-caudal gradients in all regions. During the action execution period, activation was robust in caudal ROIs and decreased linearly movin...
Please cite this article as: Fox, K.C.R., et al., The wandering brain: Meta-analysis of functiona... more Please cite this article as: Fox, K.C.R., et al., The wandering brain: Meta-analysis of functional neuroimaging studies of mind-wandering and related spontaneous thought processes, NeuroImage (2015), http://dx.Restricting analyses to DMN regions is problematic for at least two 123 other reasons. For one, the subjective variety of spontaneous thought 124 modes (which can include memory recall, planning for the future, hypo-125 thetical imaginings, mentalizing, and so on) suggest correspondingly 126 complex and variegated neural correlates (Andrews-Hanna et al., 127 2013; Dixon et al., 2014; Fox and Christoff, 2014; Fox et al., 2013); a sim-128 ple DMN-mind-wandering mapping is unlikely to fulfill this criterion. 129 Moreover, despite its involvement in spontaneous thought, the DMN 130 is implicated in many cognitive processes that may not be spontaneous, 131 such as famous face recognition (Spreng et al., 2014). It therefore seems 132 likely that other brain areas and/or networks play a role in spontaneous 133 thought.
Isolated reports have long suggested a similarity in content and thought processes across mind wa... more Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both "daydreaming" and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous functional neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an "intensified" version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.
The accuracy of subjective reports, especially those involving introspection of one's own interna... more The accuracy of subjective reports, especially those involving introspection of one's own internal processes, remains unclear, and research has demonstrated large individual differences in introspective accuracy. It has been hypothesized that introspective accuracy may be heightened in persons who engage in meditation practices, due to the highly introspective nature of such practices. We undertook a preliminary exploration of this hypothesis, examining introspective accuracy in a cross-section of meditation practitioners (1-15,000 hrs experience). Introspective accuracy was assessed by comparing subjective reports of tactile sensitivity for each of 20 body regions during a 'body-scanning' meditation with averaged, objective measures of tactile sensitivity (mean size of body representation area in primary somatosensory cortex; two-point discrimination threshold) as reported in prior research. Expert meditators showed significantly better introspective accuracy than novices; overall meditation experience also significantly predicted individual introspective accuracy. These results suggest that long-term meditators provide more accurate introspective reports than novices.
Numerous studies have begun to address how the brain's gray and white matter may be shaped by med... more Numerous studies have begun to address how the brain's gray and white matter may be shaped by meditation. This research is yet to be integrated, however, and two fundamental questions remain: Is meditation associated with altered brain structure? If so, what is the magnitude of these differences? To address these questions, we reviewed and meta-analyzed 123 brain morphology differences from 21 neuroimaging studies examining ∼300 meditation practitioners. Anatomical likelihood estimation (ALE) meta-analysis found eight brain regions consistently altered in meditators, including areas key to meta-awareness (frontopolar cortex/BA 10), exteroceptive and interoceptive body awareness (sensory cortices and insula), memory consolidation and reconsolidation (hippocampus), self and emotion regulation (anterior and mid cingulate; orbitofrontal cortex), and intra-and interhemispheric communication (superior longitudinal fasciculus; corpus callosum). Effect size meta-analysis (calculating 132 effect sizes from 16 studies) suggests a global 'medium' effect size (Cohen'sd = 0.46;r = .19). Publication bias and methodological limitations are strong concerns, however. Further research using rigorous methods is required to definitively link meditation practice to altered brain morphology.
1. Existing data show that the surface area to volume ratio ( Λ ) of leaves generally decreases a... more 1. Existing data show that the surface area to volume ratio ( Λ ) of leaves generally decreases along both aridity and altitudinal gradients. That results in the relations: Λ decreases as it gets drier and hotter, as well as wetter and colder. Thus variations in rainfall and temperature do not explain the gross trends in Λ in a consistent manner. We hypothesized that Λ should vary in a regular manner with variations in light, water, nutrients and CO 2 , because recent work has shown regular relationships between Λ and the carbon, nitrogen and water contents of leaves. To test the hypothesis we used existing measurements of leaves from various eucalypt species along aridity, altitudinal and fertility gradients in south-east Australia. The measurements were converted from a dry mass to a volumetric basis using an empirical leaf model known as the RSBS-model leaf. 3. Variation in leaf composition and morphology generally followed that predicted by the RSBS-model leaf. 4. We found that Λ increased with site fertility. Analysis of data from the literature showed that increasing the supply rate of nitrogen also results in an increase in Λ . We conclude that increases in site fertility are associated with increases in Λ . 5. Leaf thickness increased (hence Λ decreased) with light along the aridity and altitudinal gradients, in agreement with theoretical predictions. The increase in light along the aridity gradient is attributed to a decrease in cloud cover, while the increase in light with altitude is due to a decline in the optical thickness of the atmosphere. 6. Along the altitudinal gradient, the soils became increasingly boggy and anoxic with elevation, leading to increased soil acidity and a consequent decline in oxygen and nutrient availability. In contrast, along the aridity gradient decreases in nutrient availability were related to dry soil. 7. Both an excess and shortage of soil water can lead to reductions in the availability of oxygen and/or nutrients. When that relationship was considered, we found that a consistent framework linking Λ with the availability of light, water, nutrients and CO 2 /O 2 could be established. In that framework, leaf area is controlled jointly by the availability of water and nutrients, while leaf thickness is controlled by the avail - ability of carbon (i.e. light, CO 2 ). Λ is the result of interactions between those two factors. The resulting framework should be useful in the development of models linking vegetation with environmental conditions. 8. A method for extending these results to the modelling of vegetation communities is proposed.
International Journal of Dream Research, Apr 27, 2012
NREM stage 1 sleep, known as a brief interval of transition from wake to sleep, is characterized ... more NREM stage 1 sleep, known as a brief interval of transition from wake to sleep, is characterized by neurophysiological events and subjective sensory experiences that suggest the stage may be involved in memory processing. To examine this possibility, we conducted multiple awakenings with a trained participant during short bursts of theta activity defining the 5 th sub stage of NREM stage 1 sleep (NREM1Ф). Awakenings provided frequent reports of vivid dreaming containing coherent scenes—as opposed to isolated ...
Meditation is a family of mental practices that encompasses a wide array of techniques employing ... more Meditation is a family of mental practices that encompasses a wide array of techniques employing distinctive mental strategies. We systematically reviewed 78 functional neuroimaging (fMRI and PET) studies of meditation, and used activation likelihood estimation to meta-analyze 257 peak foci from 31 experiments involving 527 participants. We found reliably dissociable patterns of brain activation and deactivation for four common styles of meditation (focused attention, mantra recitation, open monitoring , and compassion/loving-kindness), and suggestive differences for three others (visualization, sense-withdrawal, and non-dual awareness practices). Overall, dissociable activation patterns are congruent with the psychological and behavioral aims of each practice. Some brain areas are recruited consistently across multiple techniques—including insula, pre/supplementary motor cortices, dorsal anterior cingulate cortex, and frontopolar cortex—but convergence is the exception rather than the rule. A preliminary effect-size meta-analysis found medium effects for both activations (d = 0.59) and deactivations (d = −0.74), suggesting potential practical significance. Our meta-analysis supports the neu-rophysiological dissociability of meditation practices, but also raises many methodological concerns and suggests avenues for future research.
Humans have employed an incredible variety of plant-derived substances over the millennia in orde... more Humans have employed an incredible variety of plant-derived substances over the millennia in order to alter consciousness and perception. Among the innumerable narcotics, analgesics, 'ordeal' drugs, and other psychoactive substances discovered and used in ritualistic contexts by cultures around the world, one class in particular stands out not only for its radical psychological effects, but also for the highly charged political and legal atmosphere that has surrounded it since its widespread adoption about 50 years ago: so-called psychedelic substances. We review functional neuroimaging investigations of the neural correlates of the psychedelic experience, and highlight relationships with the psychological and neural bases of creativity, daydreaming, and dreaming.
The neural basis of human memory is incredibly complex. We argue that the diversity of neural sys... more The neural basis of human memory is incredibly complex. We argue that the diversity of neural systems underlying various forms of memory suggests that any discussion of enhancing 'memory' per se is too broad, thus obfuscating the biopolitical debate about human enhancement. Memory can be differentiated into at least four major (and several minor) systems with largely dissociable (i.e., non-overlapping) neural sub-strates. We outline each system, and discuss both the practical and the ethical implications of these diverse neural substrates. In practice, distinct neural bases imply the possibility, and likely the necessity, of specific approaches for the safe and effective enhancement of various memory systems. In the debate over the ethical and social implications of enhancement technologies, this fine-grained perspective clarifies—and may partially mitigate—certain common concerns in enhancement debates, including issues related to safety, fairness, coercion, and authenticity. While many researchers certainly appreciate the neurobiological complexity of memory, the political debate tends to revolve around a monolithic one-size-fits-all conception. The overall project—exploring how human enhancement technologies affect society – stands to benefit from a deeper appreciation of memory's neurobiological diversity.
Meditation and hypnosis both aim to facilitate cognitive-emotional flexibility, i.e., the “de-aut... more Meditation and hypnosis both aim to facilitate cognitive-emotional flexibility, i.e., the “de-automatization” of thought and behavior. However, little research or theory has addressed how internal thought patterns might change after such interventions, even though alterations in the internal flow of consciousness may precede externally observable changes in behavior. This chapter outlines three mechanisms by which meditation or hypnosis might alter or reduce automatic associations and elaborations of spontaneous thought: by an overall reduction of the chaining of thoughts into an associative stream; by de-automatizing and diversifying the content of thought chains (i.e., increasing thought flexibility or variety); and, finally, by re-automatizing chains of thought along desired or valued paths (i.e., forming new, voluntarily chosen mental habits). The authors discuss behavioral and cognitive neuroscientific evidence demonstrating the influence of hypnosis and meditation on internal cognition and highlight the putative neurobiological basis, as well as potential benefits, of these forms of de-automatization.
Thoughts arise spontaneously in our minds with remarkable frequency, but tracking the brain syste... more Thoughts arise spontaneously in our minds with remarkable frequency, but tracking the brain systems associated 17 withtheearlyinceptionofathoughthasprovedchallenging.Hereweaddressedthisissuebytakingadvantageof 18 theheightenedintrospectiveabilityofexperiencedmindfulnesspractitionerstodetecttheonsetoftheirsponta- 19 neously arising thoughts. We observed subtle differences in timing among the many regions typically recruited 20 byspontaneousthought.Onlyinsomeoftheseregionsdidneuralactivationpeakpriortothespontaneousaris- 21 ingofathought—mostnotablyinthemedialtemporallobeandinferiorparietallobule.Incontrast,activationin 22 themedialprefrontal,temporopolar,mid-insular,lateralprefrontal,anddorsalanteriorcingulatecorticespeaked 23 together with or immediately following the arising of spontaneous thought. We propose that brain regions that 24 show antecedent recruitment may be preferentially involved in the initial inception of spontaneous thoughts, 25 while those that show later recruitment may be preferentially involved in the subsequent elaboration and 26 metacognitive processing of spontaneous thoughts. Our findings highlight the temporal dynamics of neural re- 27 cruitment surrounding the emergence of spontaneous thoughts and may help account for some of spontaneous 28 thought's peculiar qualities, including its wild diversity of content and its links to memory and attention.
Mind wandering (MW) and metacognition may give the impression of 7 lying at the opposite poles of... more Mind wandering (MW) and metacognition may give the impression of 7 lying at the opposite poles of the spectrum of human cognition. MW involves 8 undirected, spontaneous thought processes that often occur without our volition 9 and sometimes despite our intentions. Metacognition, by contrast, involves the 10 conscious, often intentional monitoring and evaluation of our own mental pro-11 cesses and behaviors. The neural correlates of MW and metacognition may also 12 appear strictly distinct at first, considering the almost exclusive focus on default 13 network regions' involvement in MW, in contrast to the emphasis on higher order 14 prefrontal regions' role in metacognitive processing. In this chapter, we will argue 15 that despite the apparent gulf between MW and metacognition, some of the most 16 intriguing mental phenomena we humans are capable of experiencing involve an 17 intimate, dynamic interplay between MW and metacognition. According to the 18 standard view of their interaction, metacognition serves to correct the wandering 19 mind, suppressing spontaneous thoughts and bringing attention back to more 20 ''worthwhile'' tasks. In this chapter, we argue that this ''negative'' or suppressant 21 view of their interactions represents only a part of the whole picture. Instead, we 22 outline and discuss three examples of positive, facilitative interactions: creative 23
This article argues that the default network, augmented by secondary visual and sensorimotor cort... more This article argues that the default network, augmented by secondary visual and sensorimotor cortices, is the likely neural correlate of dreaming. This hypothesis is based on a synthesis of work on dream content, the findings on the contents and neural correlates of mind-wandering, and the results from EEG and neuroimaging studies of REM sleep. Relying on studies in the 1970s that serendipitously discovered episodes of dreaming during waking mind-wandering, this article presents the seemingly counterintuitive hypothesis that the neural correlates for dreaming could be further specified in the process of carrying out EEG/fMRI studies of mind-wandering and default network activity. This hypothesis could be tested by asking participants for experiential reports during moments of differentially high levels of default network activation, as indicated by mixed EEG/fMRI criteria. Evidence from earlier EEG/fMRI studies of mind-wandering and from laboratory studies of dreaming during the sle...
The functional organization of brain areas supporting goal-directed behavior is debated. Some acc... more The functional organization of brain areas supporting goal-directed behavior is debated. Some accounts suggest a rostro-caudal organization, while others suggest a broad recruitment as part of a multiple demand network. We used fMRI and an anatomical region of interest (ROI) approach to test which account better characterizes the organization of key brain areas related to goal-directed behavior: the lateral prefrontal cortex (LPFC), medial prefrontal cortex (MPFC), cingulate cortex, and insula. Subjects performed a cognitive control task with distinct trial events corresponding to rule representation, rule maintenance, action execution, and monitoring progress towards an overarching motivational goal. The use of ROIs allowed us to look for evidence of rostro-caudal gradients during each event separately. Our results provide strong evidence for rostro-caudal gradients in all regions. During the action execution period, activation was robust in caudal ROIs and decreased linearly movin...
Please cite this article as: Fox, K.C.R., et al., The wandering brain: Meta-analysis of functiona... more Please cite this article as: Fox, K.C.R., et al., The wandering brain: Meta-analysis of functional neuroimaging studies of mind-wandering and related spontaneous thought processes, NeuroImage (2015), http://dx.Restricting analyses to DMN regions is problematic for at least two 123 other reasons. For one, the subjective variety of spontaneous thought 124 modes (which can include memory recall, planning for the future, hypo-125 thetical imaginings, mentalizing, and so on) suggest correspondingly 126 complex and variegated neural correlates (Andrews-Hanna et al., 127 2013; Dixon et al., 2014; Fox and Christoff, 2014; Fox et al., 2013); a sim-128 ple DMN-mind-wandering mapping is unlikely to fulfill this criterion. 129 Moreover, despite its involvement in spontaneous thought, the DMN 130 is implicated in many cognitive processes that may not be spontaneous, 131 such as famous face recognition (Spreng et al., 2014). It therefore seems 132 likely that other brain areas and/or networks play a role in spontaneous 133 thought.
Isolated reports have long suggested a similarity in content and thought processes across mind wa... more Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both "daydreaming" and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous functional neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an "intensified" version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.
The accuracy of subjective reports, especially those involving introspection of one's own interna... more The accuracy of subjective reports, especially those involving introspection of one's own internal processes, remains unclear, and research has demonstrated large individual differences in introspective accuracy. It has been hypothesized that introspective accuracy may be heightened in persons who engage in meditation practices, due to the highly introspective nature of such practices. We undertook a preliminary exploration of this hypothesis, examining introspective accuracy in a cross-section of meditation practitioners (1-15,000 hrs experience). Introspective accuracy was assessed by comparing subjective reports of tactile sensitivity for each of 20 body regions during a 'body-scanning' meditation with averaged, objective measures of tactile sensitivity (mean size of body representation area in primary somatosensory cortex; two-point discrimination threshold) as reported in prior research. Expert meditators showed significantly better introspective accuracy than novices; overall meditation experience also significantly predicted individual introspective accuracy. These results suggest that long-term meditators provide more accurate introspective reports than novices.
Numerous studies have begun to address how the brain's gray and white matter may be shaped by med... more Numerous studies have begun to address how the brain's gray and white matter may be shaped by meditation. This research is yet to be integrated, however, and two fundamental questions remain: Is meditation associated with altered brain structure? If so, what is the magnitude of these differences? To address these questions, we reviewed and meta-analyzed 123 brain morphology differences from 21 neuroimaging studies examining ∼300 meditation practitioners. Anatomical likelihood estimation (ALE) meta-analysis found eight brain regions consistently altered in meditators, including areas key to meta-awareness (frontopolar cortex/BA 10), exteroceptive and interoceptive body awareness (sensory cortices and insula), memory consolidation and reconsolidation (hippocampus), self and emotion regulation (anterior and mid cingulate; orbitofrontal cortex), and intra-and interhemispheric communication (superior longitudinal fasciculus; corpus callosum). Effect size meta-analysis (calculating 132 effect sizes from 16 studies) suggests a global 'medium' effect size (Cohen'sd = 0.46;r = .19). Publication bias and methodological limitations are strong concerns, however. Further research using rigorous methods is required to definitively link meditation practice to altered brain morphology.
1. Existing data show that the surface area to volume ratio ( Λ ) of leaves generally decreases a... more 1. Existing data show that the surface area to volume ratio ( Λ ) of leaves generally decreases along both aridity and altitudinal gradients. That results in the relations: Λ decreases as it gets drier and hotter, as well as wetter and colder. Thus variations in rainfall and temperature do not explain the gross trends in Λ in a consistent manner. We hypothesized that Λ should vary in a regular manner with variations in light, water, nutrients and CO 2 , because recent work has shown regular relationships between Λ and the carbon, nitrogen and water contents of leaves. To test the hypothesis we used existing measurements of leaves from various eucalypt species along aridity, altitudinal and fertility gradients in south-east Australia. The measurements were converted from a dry mass to a volumetric basis using an empirical leaf model known as the RSBS-model leaf. 3. Variation in leaf composition and morphology generally followed that predicted by the RSBS-model leaf. 4. We found that Λ increased with site fertility. Analysis of data from the literature showed that increasing the supply rate of nitrogen also results in an increase in Λ . We conclude that increases in site fertility are associated with increases in Λ . 5. Leaf thickness increased (hence Λ decreased) with light along the aridity and altitudinal gradients, in agreement with theoretical predictions. The increase in light along the aridity gradient is attributed to a decrease in cloud cover, while the increase in light with altitude is due to a decline in the optical thickness of the atmosphere. 6. Along the altitudinal gradient, the soils became increasingly boggy and anoxic with elevation, leading to increased soil acidity and a consequent decline in oxygen and nutrient availability. In contrast, along the aridity gradient decreases in nutrient availability were related to dry soil. 7. Both an excess and shortage of soil water can lead to reductions in the availability of oxygen and/or nutrients. When that relationship was considered, we found that a consistent framework linking Λ with the availability of light, water, nutrients and CO 2 /O 2 could be established. In that framework, leaf area is controlled jointly by the availability of water and nutrients, while leaf thickness is controlled by the avail - ability of carbon (i.e. light, CO 2 ). Λ is the result of interactions between those two factors. The resulting framework should be useful in the development of models linking vegetation with environmental conditions. 8. A method for extending these results to the modelling of vegetation communities is proposed.
International Journal of Dream Research, Apr 27, 2012
NREM stage 1 sleep, known as a brief interval of transition from wake to sleep, is characterized ... more NREM stage 1 sleep, known as a brief interval of transition from wake to sleep, is characterized by neurophysiological events and subjective sensory experiences that suggest the stage may be involved in memory processing. To examine this possibility, we conducted multiple awakenings with a trained participant during short bursts of theta activity defining the 5 th sub stage of NREM stage 1 sleep (NREM1Ф). Awakenings provided frequent reports of vivid dreaming containing coherent scenes—as opposed to isolated ...
Meditation is a family of mental practices that encompasses a wide array of techniques employing ... more Meditation is a family of mental practices that encompasses a wide array of techniques employing distinctive mental strategies. We systematically reviewed 78 functional neuroimaging (fMRI and PET) studies of meditation, and used activation likelihood estimation to meta-analyze 257 peak foci from 31 experiments involving 527 participants. We found reliably dissociable patterns of brain activation and deactivation for four common styles of meditation (focused attention, mantra recitation, open monitoring , and compassion/loving-kindness), and suggestive differences for three others (visualization, sense-withdrawal, and non-dual awareness practices). Overall, dissociable activation patterns are congruent with the psychological and behavioral aims of each practice. Some brain areas are recruited consistently across multiple techniques—including insula, pre/supplementary motor cortices, dorsal anterior cingulate cortex, and frontopolar cortex—but convergence is the exception rather than the rule. A preliminary effect-size meta-analysis found medium effects for both activations (d = 0.59) and deactivations (d = −0.74), suggesting potential practical significance. Our meta-analysis supports the neu-rophysiological dissociability of meditation practices, but also raises many methodological concerns and suggests avenues for future research.
Humans have employed an incredible variety of plant-derived substances over the millennia in orde... more Humans have employed an incredible variety of plant-derived substances over the millennia in order to alter consciousness and perception. Among the innumerable narcotics, analgesics, 'ordeal' drugs, and other psychoactive substances discovered and used in ritualistic contexts by cultures around the world, one class in particular stands out not only for its radical psychological effects, but also for the highly charged political and legal atmosphere that has surrounded it since its widespread adoption about 50 years ago: so-called psychedelic substances. We review functional neuroimaging investigations of the neural correlates of the psychedelic experience, and highlight relationships with the psychological and neural bases of creativity, daydreaming, and dreaming.
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Papers by Kieran Fox
flow of consciousness may precede externally observable changes in
behavior. This chapter outlines three mechanisms by which meditation or hypnosis might alter or reduce automatic associations and elaborations of spontaneous thought: by an overall reduction of the chaining of thoughts
into an associative stream; by de-automatizing and diversifying the content of thought chains (i.e., increasing thought flexibility or variety); and, finally, by re-automatizing chains of thought along desired or valued paths (i.e., forming new, voluntarily chosen mental habits). The authors discuss behavioral and cognitive neuroscientific evidence demonstrating the influence of hypnosis and meditation on internal cognition and highlight the putative neurobiological basis, as well as potential benefits, of these forms of de-automatization.
Drafts by Kieran Fox
flow of consciousness may precede externally observable changes in
behavior. This chapter outlines three mechanisms by which meditation or hypnosis might alter or reduce automatic associations and elaborations of spontaneous thought: by an overall reduction of the chaining of thoughts
into an associative stream; by de-automatizing and diversifying the content of thought chains (i.e., increasing thought flexibility or variety); and, finally, by re-automatizing chains of thought along desired or valued paths (i.e., forming new, voluntarily chosen mental habits). The authors discuss behavioral and cognitive neuroscientific evidence demonstrating the influence of hypnosis and meditation on internal cognition and highlight the putative neurobiological basis, as well as potential benefits, of these forms of de-automatization.