How do contents get into a dream?
Rapid eye movement (REM) sleep cancels wakefulness and blocks external afference. How do contents get into the conscious field? Morsella et al. argue that consciousness arises from configurations of unconscious afference to content generators. Afference is not only “bottom-up,” but also may include “top-down processes from knowledge systems and from frontal control regions” (sect. 4.1, para. 1). I shall argue that although (pre)frontal control regions are quiescent in REM, and afference is necessarily intrinsic, dream content is generated in the same way that Morsella et al.'s wakeful content is generated.
I have argued (Porte Reference Porte2013) that REM afference implicates acetylcholinergic cell groups Ch1-Ch8 (characterized, for example, by Schaffer et al. Reference Schaffer, Eiden and Weihe1998), and that REM afference, like retinal waves, is at once probabilistic and structured (for a review of retinal waves, see Wong Reference Wong1999). Excitation evolves stochastically: afference to REM content generators is neither bottom-up nor top-down, but distributed on the neural axis.
What is consciousness in a dream like?
In the conscious field in REM as in wakefulness, the liaison between action and consciousness is fundamental. The wakeful field is for skeletomotor action. In REM, action is in the field. Afference to skeletomotor neurons is real. Dreamers walk, run, swim, and fly. They rotate, accelerate, and run backward. They lie still only because REM, while allowing the eyes to move and the dreamer to breathe, paralyzes the skeletal muscles.
Grillner et al. (Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008) state that “in all vertebrates, networks coordinating the basic propulsive movement synergy are located at the spinal level, whether in fish swimming, bird flight or mammalian locomotion” (p. 3). If when awakened from a dream Morsella et al.'s creature in the cave were to say, “I am walking down the street,” most of us would agree that this conscious content might originate in a ‘low-level’ reticulospinal mechanism. Even frenzied dream action might exceed “I am walking” only in regard to level of excitation:
Hilary-Ashby and others walk, or walk-float rapidly in front of us – i.e., walk without effort or apparent stepping. Separately, we intone “hello,” in rich sustained notes … This catches on, and everyone … begins to sing “hello.” I sing out above the other voices, and begin to leap off the floor vertically – as if lifted, or “beaming up” – as I sing and bellow “hello” in an increasingly high (and difficult for me) register. I spring (again, as if floating or flying up rapidly, vertically) so high that I nearly reach the extraordinarily high ceiling … I feel queasy and afraid, briefly, but close my eyes and decide there is nothing to do but wait for the fall back to earth. (Anonymous dream report, 1984. Laboratory of J. Allan Hobson, Harvard Medical School.)
If “the command regions for locomotion are evolutionarily conserved and stimulation of these regions gives rise to walking, trotting or galloping in tetrapods like cats, depending on stimulation strengths [and if] stimulation of the same region in a bird gives rise to walking and at higher strengths flapping movements of the wings” (Grillner et al. Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008, p. 3), then this dream's “hellos” become mere, albeit calamitously aroused, vestibular incantation.
If configurations of afference that deliver content to the conscious field are action-related, then dream action should approximate wakeful action. Indeed, as Morsella et al. remark, “few would argue about the isomorphism among the conscious contents experienced while acting (e.g., saying ‘hello’) dreaming (e.g., saying ‘hello’ in a dream), or observing the action of another (e.g., hearing ‘hello’)” (sect. 3.1, para. 3). Likewise, the dreamer's point of view should be egocentric (sect.4.2, para. 3). The “hello” dream is very much in the (locomotor-vestibular) first person. To the creature in the cave, “I am walking” will afford a sense of self, in REM as in wakefulness.
The entrance into consciousness in REM is automatic. As Morsella et al. argue for wakefulness, content is “just there.” Often, action is ongoing as a dream report begins. Or action “just starts,” as if the unconscious induction of locomotion coincides with the emergence of conscious content. “Reflex-like” entrance of action into consciousness in REM accords with the operation of skeletomotor neural networks: “In most cases these networks are silent at rest and need to be activated from the brainstem command centres … which via reticulospinal neurons regulate the activity level of the spinal [pattern generators]” (Grillner et al. Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008, p. 3).
Conscious contents in REM, like those in wakefulness, are encapsulated. Assume that the “hello” dream report describes the contents of the dreamer's conscious field completely. Can skeletomotor afference account completely for those contents? Someone will say, “The ‘hello’ dream is not an action dream. It is an ‘Icarus’ dream.” But no metaphor is present in the conscious field, and neither is Icarus. “The field itself,” as Morsella et al. say of wakefulness, “has no memory and performs no symbol manipulation” (sect. 6, para. 2). If Icarus is to be found anywhere, it is in unconscious afference from a system that knows about Icarus. Encapsulated, the conscious (vestibular) content does not. To paraphrase T. S. Eliot: The dreamer has the experience, but misses the meaning (Eliot Reference Eliot1943).
By homing in on consciousness, Morsella et al. have established a new vocabulary for homing in on consciousness in sleep. Thus, we can say that in REM sleep the conscious field is not “for” adaptive skeletomotor action, although unconscious configurations of afference may be. We realize that in dreams that are not lucid, “framing” is explicitly absent. We see that the conscious field in REM and the wakeful conscious field share formal characteristics.
Whether consciousness in REM is for anything remains uncertain. But Morsella et al. help us see that the liaison between action and consciousness often verges on identity in REM – that at some level (“lower” than wakefulness?), skeletomotor action is consciousness.
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To the creature in the cave, consciousness is for adaptive “voluntary” action. What is consciousness in a dream for?
How do contents get into a dream?
Rapid eye movement (REM) sleep cancels wakefulness and blocks external afference. How do contents get into the conscious field? Morsella et al. argue that consciousness arises from configurations of unconscious afference to content generators. Afference is not only “bottom-up,” but also may include “top-down processes from knowledge systems and from frontal control regions” (sect. 4.1, para. 1). I shall argue that although (pre)frontal control regions are quiescent in REM, and afference is necessarily intrinsic, dream content is generated in the same way that Morsella et al.'s wakeful content is generated.
I have argued (Porte Reference Porte2013) that REM afference implicates acetylcholinergic cell groups Ch1-Ch8 (characterized, for example, by Schaffer et al. Reference Schaffer, Eiden and Weihe1998), and that REM afference, like retinal waves, is at once probabilistic and structured (for a review of retinal waves, see Wong Reference Wong1999). Excitation evolves stochastically: afference to REM content generators is neither bottom-up nor top-down, but distributed on the neural axis.
What is consciousness in a dream like?
In the conscious field in REM as in wakefulness, the liaison between action and consciousness is fundamental. The wakeful field is for skeletomotor action. In REM, action is in the field. Afference to skeletomotor neurons is real. Dreamers walk, run, swim, and fly. They rotate, accelerate, and run backward. They lie still only because REM, while allowing the eyes to move and the dreamer to breathe, paralyzes the skeletal muscles.
Grillner et al. (Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008) state that “in all vertebrates, networks coordinating the basic propulsive movement synergy are located at the spinal level, whether in fish swimming, bird flight or mammalian locomotion” (p. 3). If when awakened from a dream Morsella et al.'s creature in the cave were to say, “I am walking down the street,” most of us would agree that this conscious content might originate in a ‘low-level’ reticulospinal mechanism. Even frenzied dream action might exceed “I am walking” only in regard to level of excitation:
Hilary-Ashby and others walk, or walk-float rapidly in front of us – i.e., walk without effort or apparent stepping. Separately, we intone “hello,” in rich sustained notes … This catches on, and everyone … begins to sing “hello.” I sing out above the other voices, and begin to leap off the floor vertically – as if lifted, or “beaming up” – as I sing and bellow “hello” in an increasingly high (and difficult for me) register. I spring (again, as if floating or flying up rapidly, vertically) so high that I nearly reach the extraordinarily high ceiling … I feel queasy and afraid, briefly, but close my eyes and decide there is nothing to do but wait for the fall back to earth. (Anonymous dream report, 1984. Laboratory of J. Allan Hobson, Harvard Medical School.)
If “the command regions for locomotion are evolutionarily conserved and stimulation of these regions gives rise to walking, trotting or galloping in tetrapods like cats, depending on stimulation strengths [and if] stimulation of the same region in a bird gives rise to walking and at higher strengths flapping movements of the wings” (Grillner et al. Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008, p. 3), then this dream's “hellos” become mere, albeit calamitously aroused, vestibular incantation.
If configurations of afference that deliver content to the conscious field are action-related, then dream action should approximate wakeful action. Indeed, as Morsella et al. remark, “few would argue about the isomorphism among the conscious contents experienced while acting (e.g., saying ‘hello’) dreaming (e.g., saying ‘hello’ in a dream), or observing the action of another (e.g., hearing ‘hello’)” (sect. 3.1, para. 3). Likewise, the dreamer's point of view should be egocentric (sect.4.2, para. 3). The “hello” dream is very much in the (locomotor-vestibular) first person. To the creature in the cave, “I am walking” will afford a sense of self, in REM as in wakefulness.
The entrance into consciousness in REM is automatic. As Morsella et al. argue for wakefulness, content is “just there.” Often, action is ongoing as a dream report begins. Or action “just starts,” as if the unconscious induction of locomotion coincides with the emergence of conscious content. “Reflex-like” entrance of action into consciousness in REM accords with the operation of skeletomotor neural networks: “In most cases these networks are silent at rest and need to be activated from the brainstem command centres … which via reticulospinal neurons regulate the activity level of the spinal [pattern generators]” (Grillner et al. Reference Grillner, Wallen, Saitoh, Kozlov and Robertson2008, p. 3).
Conscious contents in REM, like those in wakefulness, are encapsulated. Assume that the “hello” dream report describes the contents of the dreamer's conscious field completely. Can skeletomotor afference account completely for those contents? Someone will say, “The ‘hello’ dream is not an action dream. It is an ‘Icarus’ dream.” But no metaphor is present in the conscious field, and neither is Icarus. “The field itself,” as Morsella et al. say of wakefulness, “has no memory and performs no symbol manipulation” (sect. 6, para. 2). If Icarus is to be found anywhere, it is in unconscious afference from a system that knows about Icarus. Encapsulated, the conscious (vestibular) content does not. To paraphrase T. S. Eliot: The dreamer has the experience, but misses the meaning (Eliot Reference Eliot1943).
By homing in on consciousness, Morsella et al. have established a new vocabulary for homing in on consciousness in sleep. Thus, we can say that in REM sleep the conscious field is not “for” adaptive skeletomotor action, although unconscious configurations of afference may be. We realize that in dreams that are not lucid, “framing” is explicitly absent. We see that the conscious field in REM and the wakeful conscious field share formal characteristics.
Whether consciousness in REM is for anything remains uncertain. But Morsella et al. help us see that the liaison between action and consciousness often verges on identity in REM – that at some level (“lower” than wakefulness?), skeletomotor action is consciousness.