September 12, 2013
Even People With Auto-Activation Disorder Can Still Dream
Brett Smith for redOrbit.com - Your Universe Online
In a new study involving people with Auto-Activation Deficit (AAD), French researchers revealed that the brainstem initiates dreaming and appears to set the stage for complex or bizarre events to take place in such dreams. The study appears in a new paper published in the journal Brain.
The study subjects provided a unique window into dreaming because AAD, caused by bilateral damage to the basal ganglia, is marked by a lack of natural activation of thought and an absence of self-driven behavior. Patients with AAD must be roused by their caregivers to take part in everyday tasks like standing up or eating. AAD patients are essentially characterized as having a ‘blank mind.’
Through their research, the study scientists, from the Pierre-and-Marie-Curie University in Paris, said they hoped to prove either the top-down or bottom-up theory of dreaming. The top-down theory posits that dreaming starts in higher cortex memory structures and then progresses backwards as imagination develops during wakefulness. The bottom-up theory says that the brainstem structures evoke rapid eye movements and cortex activation during REM sleep, resulting in the emotional and sensory aspects of dreaming.
In the study, 13 participants with AAD recorded their dreams in diaries during the week preceding the primary evaluation. The dreaming behavior of this group was compared with 13 non-medicated, healthy control subjects. All 26 participants were monitored for two consecutive nights.
During the first night, participants’ sleep duration, structure, and dream architecture were all recorded. During the second night, the researchers woke the subjects just as they started a second non-REM sleep cycle, and again after 10 minutes of established REM sleep during the following sleep cycle. Both times the participants were asked what they were dreaming about before being woken up. The dream reports were then analyzed based on the reported dream’s complexity, bizarreness, and elaboration.
After being awakened from REM sleep, 4 of the 13 patients with AAD said they had been dreaming – even though they have issues generating spontaneous thoughts during the daytime – compared to 12 out of 13 of the control patients. The AAD patients' dreams were noticeably without any complex, bizarre, or emotional elements.
The research team said these simple yet spontaneous dreams during the REM sleep of individuals with AAD, supports the bottom-up theory that basic dream imagery is spurred by the brainstem and passed along to the sensory cortex. The lack of intricacy in the dreams of the AAD patients, compared to the convoluted natures of some of the control patients' dreams, showed that the full dreaming process means that these sensations must be interpreted by a higher-order cortical area, the researchers said.
The scientists also noted the interestingly, banal tasks that the AAD patients dreamt about. While one patient dreamed of shaving, an activity he never self-initiated during the daytime, another patient dreamed about writing – although he never wrote in the daytime without being invited to by his caregivers.
The study team also found little to no difference in sleep measures between the AAD patients and the control patients – except that 46 percent of the AAD patients didn’t exhibit the standard burst of oscillatory brain activity seen on an EEG that occurs during stage 2 sleep.