Increasing propensity to mind-wander with transcranial direct current stimulation

Significance Mind wandering is a spontaneous and self-generated behavior believed to be important for many mental functions, including creativity and future planning. Can the propensity to mind-wander be modulated externally? If so, this observation would mean that directly modifying spontaneous neural activity can change internally directed thought. To answer this question, we used noninvasive transcranial direct current stimulation (tDCS) to stimulate the prefrontal cortex. Our results showed, for the first time to our knowledge, that mind wandering, probably the most omnipresent internal cognitive function, can be enhanced by external stimulation. In addition, we showed that the frontal lobes play a causal role in mind wandering. We furthermore suggest that the executive control system, and specifically the dorsolateral prefrontal cortex, might play an important role in mind-wandering behavior. Humans mind-wander quite intensely. Mind wandering is markedly different from other cognitive behaviors because it is spontaneous, self-generated, and inwardly directed (inner thoughts). However, can such an internal and intimate mental function also be modulated externally by means of brain stimulation? Addressing this question could also help identify the neural correlates of mind wandering in a causal manner, in contrast to the correlational methods used previously (primarily functional MRI). In our study, participants performed a monotonous task while we periodically sampled their thoughts to assess mind wandering. Concurrently, we applied transcranial direct current stimulation (tDCS). We found that stimulation of the frontal lobes [anode electrode at the left dorsolateral prefrontal cortex (DLPFC), cathode electrode at the right supraorbital area], but not of the occipital cortex or sham stimulation, increased the propensity to mind-wander. These results demonstrate for the first time, to our knowledge, that mind wandering can be enhanced externally using brain stimulation, and that the frontal lobes play a causal role in mind-wandering behavior. These results also suggest that the executive control network associated with the DLPFC might be an integral part of mind-wandering neural machinery.

[1]  D. Gilbert,et al.  A Wandering Mind Is an Unhappy Mind , 2010, Science.

[2]  J. Mattingley,et al.  Applications of transcranial direct current stimulation for understanding brain function , 2014, Trends in Neurosciences.

[3]  Steve Majerus,et al.  Mind-wandering: phenomenology and function as assessed with a novel experience sampling method. , 2011, Acta psychologica.

[4]  Brandon M. Turner,et al.  When the Brain Takes a Break: A Model-Based Analysis of Mind Wandering , 2014, The Journal of Neuroscience.

[5]  Sergio P. Rigonatti,et al.  Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory , 2005, Experimental Brain Research.

[6]  M. Kane,et al.  Conducting the train of thought: working memory capacity, goal neglect, and mind wandering in an executive-control task. , 2009, Journal of experimental psychology. Learning, memory, and cognition.

[7]  C. Miniussi,et al.  The Role of Timing in the Induction of Neuromodulation in Perceptual Learning by Transcranial Electric Stimulation , 2013, Brain Stimulation.

[8]  M. Nitsche,et al.  Transcranial direct current stimulation of the prefrontal cortex: a means to modulate fear memories , 2013, Neuroreport.

[9]  K. Christoff,et al.  Experience sampling during fMRI reveals default network and executive system contributions to mind wandering , 2009, Proceedings of the National Academy of Sciences.

[10]  A. Brunoni,et al.  Working memory improvement with non-invasive brain stimulation of the dorsolateral prefrontal cortex: A systematic review and meta-analysis , 2014, Brain and Cognition.

[11]  R. de Raedt,et al.  tDCS over the Left Prefrontal Cortex Enhances Cognitive Control for Positive Affective Stimuli , 2013, PloS one.

[12]  J. Smallwood,et al.  Inspired by Distraction : Mind Wandering Facilitates Creative Incubation , 2012 .

[13]  H. Möller,et al.  Prefrontal Transcranial Direct Current Stimulation Changes Connectivity of Resting-State Networks during fMRI , 2011, The Journal of Neuroscience.

[14]  Melissa J. Green,et al.  Use of transcranial direct current stimulation (tDCS) to enhance cognitive training: effect of timing of stimulation , 2014, Experimental Brain Research.

[15]  Erik D. Reichle,et al.  Meta-awareness, perceptual decoupling and the wandering mind , 2011, Trends in Cognitive Sciences.

[16]  Moshe Bar,et al.  The proactive brain: memory for predictions , 2009, Philosophical Transactions of the Royal Society B: Biological Sciences.

[17]  Á. Pascual-Leone,et al.  Modulation of large-scale brain networks by transcranial direct current stimulation evidenced by resting-state functional MRI , 2012, Brain Stimulation.

[18]  Ethan R. Buch,et al.  Noninvasive cortical stimulation enhances motor skill acquisition over multiple days through an effect on consolidation , 2009, Proceedings of the National Academy of Sciences.

[19]  M. Nitsche,et al.  Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation , 2000, The Journal of physiology.

[20]  B. Hommel,et al.  Evidence for a Role of the Right Dorsolateral Prefrontal Cortex in Controlling Stimulus-response Integration: A Transcranial Direct Current Stimulation (tDCS) Study , 2014, Brain Stimulation.

[21]  I. Robertson,et al.  `Oops!': Performance correlates of everyday attentional failures in traumatic brain injured and normal subjects , 1997, Neuropsychologia.

[22]  M. Nitsche,et al.  Physiological Basis of Transcranial Direct Current Stimulation , 2011, The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry.

[23]  J. Smallwood,et al.  Segmenting the stream of consciousness: The psychological correlates of temporal structures in the time series data of a continuous performance task , 2008, Brain and Cognition.

[24]  Matthew L. Dixon,et al.  A framework for understanding the relationship between externally and internally directed cognition , 2014, Neuropsychologia.

[25]  M. Nitsche,et al.  Shaping the effects of transcranial direct current stimulation of the human motor cortex. , 2007, Journal of neurophysiology.

[26]  J. Smallwood,et al.  Letting go of the present: Mind-wandering is associated with reduced delay discounting , 2013, Consciousness and Cognition.

[27]  Á. Pascual-Leone,et al.  Treatment of depression with transcranial direct current stimulation (tDCS): A Review , 2009, Experimental Neurology.

[28]  Benjamin W. Mooneyham,et al.  The costs and benefits of mind-wandering: a review. , 2013, Canadian journal of experimental psychology = Revue canadienne de psychologie experimentale.

[29]  K. Davis,et al.  Mind wandering away from pain dynamically engages antinociceptive and default mode brain networks , 2013, Proceedings of the National Academy of Sciences.

[30]  Scott T. Grafton,et al.  Wandering Minds: The Default Network and Stimulus-Independent Thought , 2007, Science.

[31]  M. Bar,et al.  The units of thought , 2007, Hippocampus.

[32]  A. Baddeley,et al.  Stimulus-independent thought depends on central executive resources , 1995, Memory & cognition.

[33]  Robert Lindenberg,et al.  Transcranial direct current stimulation and simultaneous functional magnetic resonance imaging. , 2014, Journal of visualized experiments : JoVE.

[34]  P. Matthews,et al.  Polarity and timing-dependent effects of transcranial direct current stimulation in explicit motor learning , 2011, Neuropsychologia.

[35]  Jonathan Smallwood,et al.  The balanced mind: the variability of task-unrelated thoughts predicts error monitoring , 2013, Front. Hum. Neurosci..

[36]  D H Brainard,et al.  The Psychophysics Toolbox. , 1997, Spatial vision.

[37]  V. Walsh,et al.  Modulating Neuronal Activity Produces Specific and Long-Lasting Changes in Numerical Competence , 2010, Current Biology.

[38]  M. Kane,et al.  Does mind wandering reflect executive function or executive failure? Comment on Smallwood and Schooler (2006) and Watkins (2008). , 2010, Psychological bulletin.

[39]  E. Miller,et al.  An integrative theory of prefrontal cortex function. , 2001, Annual review of neuroscience.

[40]  J. Smallwood,et al.  The restless mind. , 2006, Psychological bulletin.

[41]  Steve Majerus,et al.  Neural Correlates of Ongoing Conscious Experience: Both Task-Unrelatedness and Stimulus-Independence Are Related to Default Network Activity , 2011, PloS one.

[42]  C. Miniussi,et al.  The timing of cognitive plasticity in physiological aging: a tDCS study of naming , 2014, Front. Aging Neurosci..

[43]  D. Stegeman,et al.  Investigation of tDCS volume conduction effects in a highly realistic head model , 2014, Journal of neural engineering.

[44]  R. N. Spreng,et al.  The default network and self‐generated thought: component processes, dynamic control, and clinical relevance , 2014, Annals of the New York Academy of Sciences.

[45]  L. Cohen,et al.  Transcranial direct current stimulation: State of the art 2008 , 2008, Brain Stimulation.

[46]  J. Gabrieli,et al.  The frontopolar cortex and human cognition: Evidence for a rostrocaudal hierarchical organization within the human prefrontal cortex , 2000, Psychobiology.

[47]  C. Frith,et al.  Recruitment of lateral rostral prefrontal cortex in spontaneous and task-related thoughts , 2010, Quarterly journal of experimental psychology.