Brain Imaging of Hypnosis

Whether hypnosis is an altered state of consciousness has been debated for nearly 200 years. Today, brain imaging studies seem to confirm that hypnosis is an altered state. Numerous studies using electroencephalography (EEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI) show distinct changes in the brain during hypnosis and in response to suggestion.

Brain imaging studies observing the general effect of the hypnotic state (as opposed to the effects of specific suggestions) have found that hypnosis causes observable changes in the brain areas and systems involved in:

• Consciousness and sense of self.[1]
• Attentional absorption and spontaneous conceptual thought.[2]
• Concentration, attentional control and executive function (reasoning, problem solving, planning, self-control, and cognitive flexibility).[3]
• Higher cortical functions.[4]
• Awareness and control of internal bodily processes and emotions.[11]
• Emotional evaluation and worrying. [11]


Studies observing the effects of hypnotic suggestions have most frequently centered on the neurophysiological response to suggestions for pain, motor function and limb paralysis, mental imagery, and memory. These studies demonstrate not only that changes occur in brain physiology, but also that these changes explain the phenomena and behaviors observed in hypnosis. Hypnotic suggestion has been shown to affect the brain areas and systems involved in:

• Consciousness, sleep, and alertness.[5]
• Motor control.[6]
• Autonomic functions, emotion, motivation, impulse control, reward anticipation, and decision-making.[7]
• Color perception.[8]
• Reasoning and decision making.[9]
• Imagery, self-awareness, and motor control.[10]



Neural activity in hypnosis


Hypnosis causes changes in brain activity and connectivity consistent with decreased self-consciousness, increased control of internal sensations and emotion, and less worry.

A study by researchers at Stanford University in July 2016 considered what takes place in the brain in general during hypnosis. Functional magnetic resonance imaging (fMRI) was used to observe brain activity in 57 subjects in hypnosis. Changes were observed in three specific areas of the brain:[11]

1. Reduced connectivity between the dorsolateral prefrontal cortex (part of the executive control network involved in planning and decision making) and the posterior cingulate cortex (the part of the default mode network active during self-related thinking). This reduced connection between planning of actions and self-awareness may account for the immediacy of action that takes place during hypnosis. In hypnosis, as in states of deep absorption in a task or performance, one acts spontaneously, without reflecting upon actions.

2. Increased connectivity between the dorsolateral prefrontal cortex (part of the executive control network involved in planning and decision making) and the insula (the part of the salience network involved in sensing and regulating internal bodily processes). This may be responsible for the increased control over bodily and emotional processes in hypnosis.

3. Reduced activity in the dorsal anterior cingulate cortex (part of the salience network involved in the emotional evaluation of errors and worrying). The dorsal ACC is also active during effortful performance. This reduced activity may explain why, in hypnosis and states of deep absorption, actions and performance take place effortlessly and with less worry.




The Brain is Not the Mind

While brain imaging studies are exciting, changes in electrical activity in the brain do little to explain the subjective experience and intentionality of consciousness.
There are two basic ways of looking at the relationship between the brain and the mind:

The physicalist viewpoint argues that electrical impulses in the brain create the subjective experience we call the “mind,” and that consciousness is a product of the continuous activity of the brain.

Others believe that mind is a property of nature (like electrical charge, spin, or mass) which exists independent of the brain, and that the mind interacts with the brain as a device that it uses and directs. Dr. Wilder Penfield (1891-1976), the renowned father of modern neurosurgery, reached the conclusion that the mind has a reality of its own, far more than being a product of the brain. In Mystery of the Mind: A Critical Study of Consciousness and the Human Brain he wrote:

“The mind seems to act independently of the brain in the same sense that a programmer acts independently of his computer, however much he may depend upon the action of that computer for certain purposes…

“To expect the highest brain-mechanism or any set of reflexes, however complicated, to carry out what the mind does, and thus perform all the functions of the mind, is quite absurd..

“It seems to me certain that it will always be quite impossible to explain the mind on the basis of neuronal action within the brain…
Reduced activity in parts of the brain's default mode network (DMN) increases attentional absorption.

The DMN is a network of interacting brain regions that is active when a person is not involved in a task, and when thinking, remembering, and daydreaming. The DMN is not active when a person is involved in a goal-oriented task or has their attention completely absorbed by something.

Hypnosis reduces the activity of the DMN.[2] Reduced activation of the DMN is also observed in long-term practitioners of meditation. The fact that the brain under hypnosis shows reduced DMN activity supports the definition of hypnosis as a state of attentional absorption, rather than a state where one loses consciousness. Hypnosis shows neural responses similar to spontaneous conceptual thought. Perhaps this is why hypnosis can spark creativity and insight.

The Default Mode Network (DMN).

Increased activity in the prefrontal attentional systems increases executive function.

The frontal areas of the brain govern a person’s ability to concentrate, known as attentional control. Attentional control is closely related to executive functions such as reasoning, problem solving, planning, self-control, and cognitive flexibility (the ability to think about multiple concepts at the same time). Hypnosis increases the activity of the systems involved in these functions, and which are impaired in addiction and ADHD.[2]

The prefrontal cortex.

Hypnosis modulates activity in the brain areas involved in the regulation of consciousness.

PET scans of cerebral blood flow in hypnosis show the involvement of the anterior cingulate cortex (ACC), the thalamus, and the ponto-mesencephalic brainstem. Hypnosis increases blood flow in the occipital region, which is consistent with the theory that hypnosis decreases cortical arousal (i.e., cortical inhibition theory). Increases in mental absorption during hypnosis were associated with increased blood flow in the brain's attentional system.[4]

The anterior cingulate cortex (ACC).


Sources:

[1] Rainville, P., & Price, D. D. (2003). Hypnosis Phenomenology and the Neurobiology of Consciousness. International Journal of Clinical and Experimental Hypnosis, 51(2), 105-129.

[2] Deeley, Q., Oakley, D. A., Toone, B., Giampietro, V., Brammer, M. J., Williams, S. C., & Halligan, P. W. (2012). Modulating the Default Mode Network Using Hypnosis. International Journal of Clinical and Experimental Hypnosis, 60(2), 206-228.

[3] Ibid.

[4] Rainville, P., Hofbauer, R. K., Bushnell, M. C., Duncan, G. H., & Price, D. D. (2002). Hypnosis Modulates Activity in Brain Structures Involved in the Regulation of Consciousness. Journal of Cognitive Neuroscience, 14(6), 887-901.

[5] Müller, K., Bacht, K., Prochnow, D., Schramm, S., & Seitz, R. J. (2013). Activation of thalamus in motor imagery results from gating by hypnosis. NeuroImage, 66, 361-367.

[6] Ibid.

[7] Vanhaudenhuyse, A., Boly, M., Balteau, E., Schnakers, C., Moonen, G., Luxen, A., . . . Faymonville, M. (2009). Pain and non-pain processing during hypnosis: A thulium-YAG event-related fMRI study. NeuroImage, 47(3), 1047-1054.

[8] Kosslyn, S. M., Thompson, W. L., Costantini-Ferrando, M. F., Alpert, N. M., & Spiegel, D. (2000). Hypnotic Visual Illusion Alters Color Processing in the Brain. American Journal of Psychiatry AJP, 157(8), 1279-1284.

[9] Raij, T. T., Numminen, J., Närvänen, S., Hiltunen, J., & Hari, R. (2009). Strength of prefrontal activation predicts intensity of suggestion-induced pain. Human Brain Mapping Hum. Brain Mapp., 30(9), 2890-2897.

[10] Cojan, Y., Waber, L., Schwartz, S., Rossier, L., Forster, A., & Vuilleumier, P. (2009). The Brain under Self-Control: Modulation of Inhibitory and Monitoring Cortical Networks during Hypnotic Paralysis. Neuron, 62(6), 862-875.

[11] Jiang, H., White, M. P., Greicius, M. D., Waelde, L. C., & Spiegel, D. (2016). Brain Activity and Functional Connectivity Associated with Hypnosis. Cerebral Cortex.