THE PHYSIOLOGICAL BASIS OF DREAMING: What happens in your brain when you dream

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                Many researches has focus on dream and the interpretation of dream from the perspective of the belief system and the psychoanalytic perspective that stress that dream is a result of unconscious processes and neglect the important function of sensory information and perceptual processing in our conscious and unconscious experience.

                Many of us have been puzzle with the question how come we dream? Or rather why do we dream?  Or what is responsible for we dreaming. well before I go into this in details I would like to clear a notion that this article is not in any way aim at any religious belief about dream neither is this article exploring the interpretation of dream but rather this article is directed towards shedding light to a possible cause of dream that is far less explore to be responsible for dreaming.

               

Torsten Wiesel and David Hubel won the Nobel Prize in 1981 for their groundbreaking work exploring the function of individual cells in the visual system. Hubel and Wiesel, through recordings from individual nerve cells was able to show to us that human possesses what they called features detector- neurons in the brain or retina that respond to specific attribute of the stimulus, such as movement, orientation, and so on.

Neurons in the optic nerve or the brain all have a preferred target, a certain type of stimulus that’s especially effective in causing that cell to fire. They said “we can think of the cells therefore as “detectors.” These investigators confirmed that each cells in the visual cortex  responds to stimuli in only a limited region of space – this region defines the receptive field; the pattern of retinal stimulation that most effectively causes the cell to fire.

It is the firing of this feature detectors that is responsible for us seeing and perceiving objects and complex forms. For instance when an input reaches our retina and it triggers horizontal line detector and a vertical line detector. When these two detectors fire at the same time, this event might trigger a response of a right angle detector. The combination of activities in the detectors might eventually lead to the one saying I see my psychopathology textbook.

Hence I put forward that this features detectors might therefore be responsible for dreaming as the features detectors might be firing while we are asleep which causes us the experience of dreaming. And don’t forget that Johannes Muller opined that for us to have a perceptual experience it lies in the nerve that is being stimulated. Stimulation of optic nerve (whether from light or some other source) causes the sense of seeing; this is why strong pressure on the eyeballs lead us to see rings or stars. Similarly, stimulation of the auditory nerves – whether from a sound or something else causes the sense of hearing. This is why people sometimes experience “ringing in their ears” in the absence of any environmental sound – some illness or injury is causes stimulation of the auditory nerve.

Therefore the firing of the features detectors causes us to experience all kind of sensation that in turn forms our dream. This sensation includes virtually all the sensation that we are aware of in our conscious experience.
The question now is that where do this so called features detectors get their stimulation from since the  individual is in a state of sleep? The answer to this question lies in the fact that the biological nature of man can not do without stimulation if the individual must function properly, as such, when the brain is subjected to a resting potential due to sleep, after sometime the brain will no longer be able to tolerate the state of being deprived of stimulation. This state of stimuli deprivation will trigger the Recticular Activating System(RAS) of the brain to start creating neural impulses for the brain. The RAS is able to do this because of its connectivity to the part of the brain responsible for memory and all the sensory system except smell. This stimulation generated by the RAS lead to cortical arousal that is called dream, which occur during sleep. 

Dreams mostly occur in the stage 4 of sleep that is characterized with rapid eye movement (REM), at this stage of sleep the brain is active but the body is immobile. The cortex is energized but the skeletal muscles are completely in active. The EEG (Electroencephalogram) shows a high frequency wave that is associated with wakefulness. There is increase in the heart rate and respiration rate that is similar to that of a person awake and exercising (Jouvet, 1967).

During the REM sleep the brain been active suggest that there might be an activity in the features detectors  and other brain areas concern with sensory processing  while the skeletal motor system seem to be inactive, this also suggest why people in a horrible dreams seems not to be able to run away from impending danger in their dream .

In conclusion this article therefore does not in any form attempt to dispute other explanation that has been giving to the cause of dreaming but rather this article tries to look into the physiological event that may be responsible for dreaming and also advocate for research into the activity of the features detectors in the brain during the various stages of sleep.

Author: Awujoola Olaoluwa Emmanuel.

photo credit: wikipedia

REFRENCE:

Henry Gleitman, James Gross, Daniel Reisberg (2011). Psychology Eight Edition. New York: W.W. Norton & Company 

Jouvet, M. Mechanisms of the states of sleep: a neuropharmacological approach. Res. Publ. Ass. nerv. ment. Dis. 1967;45:86–126.

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