Hockenbury Discovering Psychology 5th txtbk

152 CHAPTER 4 Consciousness and Its VariationsMany different kinds of studies refute Freudian dream theory on every point where ithas proved to be testable. Beyond the general idea that the brain becomes “activated”or “aroused” during dreaming, an idea that is now accepted by all theorists, there isnothing else to salvage from Freudian dream theory. It is time to abandon Freud’s theoryand use [contemporary] findings in the development of a new theory of dreams.Dream Researcher J. Allan HobsonNeuroscientist J. Allan Hobson developedthe activation–synthesis model of dreamingwith his colleague Robert McCarley.Although Hobson believes that dreams arethe by-products of physiological processes inthe brain, he does not believe that dreamsare meaningless. Hobson (1999) observed,“Dreaming may be our most creative consciousstate, one in which the chaotic, spontaneousrecombination of cognitive elementsproduces novel configurations of information:new ideas. While many or even mostof these ideas may be nonsensical, if even afew of its fanciful products are truly useful,our dream time will not have been wasted.”The Activation–Synthesis Model ofDreamingResearchers J. Allan Hobson and RobertMcCarley first proposed a new model of dreamingin 1977. Called the activation–synthesismodel of dreaming, this model maintains thatdreaming is our subjective awareness of thebrain’s internally generated signals during sleep.Since it was first proposed, the model hasevolved as new findings have been reported (seeMcCarley, 2007; Pace-Schott, 2005).Specifically, the activation–synthesis modelmaintains that the experience of dreamingsleep is due to the automatic activation ofbrainstem circuits at the base of the brain (see Figure 4.5). These circuits arousemore sophisticated brain areas, including visual, auditory, and motor pathways. Asnoted earlier in the Focus on Neuroscience box “The Dreaming Brain,” limbic systemstructures involved in emotion, such as the amygdala and hippocampus, are activatedduring REM sleep. When we’re awake, these brain structures and pathwaysare involved in registering stimuli from the external world. But rather than respondingto stimulation from the external environment, the dreaming brain is respondingto its own internally generated signals (Hobson, 2005).Figure 4.5 The Activation–SynthesisModel of Dreaming According to the activation–synthesismodel of dreaming,dreaming is our subjective awareness of thebrain’s internally generated signals duringsleep. Dreaming is initiated when brainstemcircuits arouse brain areas involved inemotions, memories, movements, and sensations.These activated brain areas, shownin green, give rise to dreaming consciousnessand the dream imaginations of sensations,perceptions, movements, and feelings.The activated brain synthesizes, orcombines, these elements, drawing on previousexperiences and memories to imposea personal meaning on the dream story(Hobson, 2005; McCarley, 2007).Other brain areas, highlighted in purple,are deactivated or blocked during dreaming.Outgoing motor signals and incomingsensory signals are blocked, keeping thedreamer from acting out the dream orresponding to external stimuli (Pace-Schott,2005). The logical, rational, and planningfunctions of the prefrontal cortex are suspended.Hence, dream stories can evolve inways that seem disjointed or illogical. Andbecause the prefrontal cortex is involved inprocessing memories, most nightly dreamproductions evaporate with no lingeringmemories of having had these experiences(Muzur & others, 2002).Sources: Adapted from Hobson (2005); Pace-Schott (2005).Activated areasDeactivated areasBlocked: Incomingsensory signalsBlocked: Outgoingmotor signals