The reticular system appears randomly organized, but there is some order in its neural tangles. It contains many different networks, each with its own set of functions. Its processing patterns are highly fluid, but they are patterns, determined by the interactions of its many interwoven networks.
So the reticular system has various functions. Its best-known function is control of sleeping, dreaming, and waking. Many networks, located in various parts of the core, participate in this global regulation of consciousness. Some of them activate the brain, generating waking awareness and arousal. They determine background activation levels, from drowsy and lethargic to fully alert and active. Scientists are still mapping the tangled reticular networks, still learning how they interact to produce these states of consciousness. Because of their complexity, our picture is still sketchy.
The reticular system also controls the selective spotlight of attention. Some generate and direct the focus. One thing we do know is that anything new triggers reticular attention. All vertebrates, from fish to humans, respond selectively to novel stimuli. This immediate interest in anything new is one of our oldest brain programs, part of the reticular program for controlling attention. Scientists have identified some of the networks involved. The reticular system is also central to body regulation.
More than any other brain region, the reticular system is essential for life. People can live after damage for example, from strokes or trauma in most brain regions, but usually not after damage to the vital core. The reticular system also plays a central role in motor movement control functions. Motor programs in other systems control specific movement patterns, from simple reflexes to complex skills, but core networks activate them all.
They are the central source of drive, motivation, and will. Finally, the reticular system is central to pleasure and pain processing. Again, our maps are incomplete and our knowledge is limited. And multiple networks may be so interconnected that clear distinctions among them and their functions are impossible.
Core networks have many different functions, but all are mixed and merged. Compared to other brain systems, reticular processing patterns are diffuse, undifferentiated, and highly fluid. Signals flow through the core in streams and waves, their currents in constant flux. At the time this was a radical idea. The traditional dogma was that older brain regions are not conscious. Consciousness occurs only in the cerebral cortex, and probably just the human cortex.
But over the years this attitude has softened considerably. Brainstem creatures, like lizards and fish, probably have simple sensory awareness. There is no clear end point, and many even suspect that consciousness extends beyond brains, perhaps as part of a universal life force. It goes like this:. Reticular processing is largely undifferentiated, and so presumably is its associated awareness. In this emerging view, reticular awareness may take various related forms.
We experience it as a sense of newness , as intuition , as existential awareness, and as spiritual awareness. Each of these involves at least a spark sometimes much more of that simple consciousness-without-content or pure awareness. So the sense of newness , as noted earlier, is programmed in reticular networks, part of the reticular program for controlling attention. When something new catches your attention, you feel a spark of awareness, a split-second sense of its newness. This immediate interest in anything new is programmed in your core.
Intuition builds on that sense of newness. It refers to hunches, insights, and inspirations, each accompanied by a spark or flash of intuitive awareness. Here is an undifferentiated sense of existence, or simple being. Spiritual awareness is experienced most fully in deep prayer and meditation.
These take you to your core, to a sense of the infinite, to your sense of a soul. The notion of a spiritual center , at a deepest psychological level, is a major theme in most religions. So every person has a spiritual core, an inner sanctum of the soul. The kingdom of heaven is indeed within. Again, this theme of reticular consciousness is still speculative, and many who believe it does exist may not endorse its spiritual aspects. But the basic concept is rapidly gaining support, as we learn more about our brains and about ourselves.
The following sections take a closer look —. Penfield was a neuroscience pioneer who challenged the conventional view that consciousness is limited to the cerebral cortex. Penfield was widely respected, and for a few years his view of the centrencephalic system was influential. But it was also scientific heresy. Again, the orthodox view was that older brain regions are not conscious. The resulting controversy continues, to some degree, even today. It was replaced by a more conservative and circumspect view of the reticular system. In particular, consciousness was not attributed to the core itself.
For decades, despite intense scientific interest in reticular activation of consciousness in the cerebral cortex, there was almost no discussion of possible core consciousness. But some independent thinkers still wondered about that. And despite the effective blackout, their speculations did occasionally make it into the scientific literature. In , psychiatrist Donald Rinsley reviewed psychoanalytic ideas about the ego or self. But all are rooted in the core.
The sense of self is built on this existential foundation.
Consciousness - Wikipedia
Most of the time, Rinsley said, such core awareness is barely conscious, just a subliminal backdrop to the usual stream of sensations, feelings, and thoughts. But in certain situations, for example the twilight state experienced just before falling asleep, core awareness may predominate.
Awareness becomes more or less centered in the core itself. Rinsley suggested that core networks mediate such experiences. He said. In the mids, scientific research on meditation was just beginning. An emerging view then and much stronger today is that during deep meditation core networks are activated, while other brain systems are deactivated. These scientists and philosophers were among the first to write about possible core consciousness. They faced strong skepticism, even censure, as everyone knew that only the cerebral cortex was conscious.
Many researchers are now mapping the reticular networks and untangling their various functions, including their likely roles in core awareness. One of the most prominent is neurologist Antonio Damasio. Core consciousness is generated primarily in the reticular system. Extended consciousness includes all the newer, more complex forms of consciousness — specific sensations, feelings, and thoughts processed elsewhere in the brain.
And of course, extended consciousness is most highly developed in the human cerebral cortex. Our remarkable memory, and our ability to plan for the future, bring a sense of past and future to the eternal present of core consciousness. As Damasio says,. The here and now is still there, but it is flanked by the past…and just as importantly, it is flanked by the anticipated future. The scope of extended consciousness, at its zenith, may span the entire life of an individual, from the cradle to the future, and it can place the world beside it.
As noted earlier, most of those patients do not survive. But some do, with various subtle or dramatic disturbances of consciousness.
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Many other neuroscientists, also studying similar patients, have reached similar conclusions. Another group of patients also shed light on the subject. They are children born without a cerebral cortex. These children often die in infancy, but in some cases may live several years, always with extreme psychological limitations, and usually with other medical problems.
And of course, as in other humans, this consciousness is generated in the reticular system. Until recently brain imaging techniques did not yield clear views of the reticular system, so in some ways our knowledge of it has lagged behind other brain regions. Fortunately, newer PET scans are now shedding better light on reticular functions. For example, several recent studies scanned humans waking up from anesthesia and from normal sleep. In both situations, the first regions to become activated are in the reticular core. This reticular activation corresponds with a subjective sense of waking up.
Some of its networks project diffusely throughout the cortex. Most researchers emphasize two-way re-entrant loops of electrical activity interconnecting the reticular core and cerebral cortex. It cannot be dissected out of the consciousness loop. Again, these reverberating bioelectric circuits, millions of them, always active and in constant flux, are the basis of human intelligence.
The reticular system is the core of that intelligence. A sharp distinction is made between the property C and the contents of consciousness. The idea was that deep meditation activates the reticular core and deactivates other brain systems. More recent research supports and refines that notion. For example, we now know some of the key networks involved. During meditation certain inhibitory networks dampen activity in the cerebral cortex.
And we now know that reticular networks generate the characteristic EEG brainwave patterns of meditation. During deep meditation, the entire brain resonates with rhythmic electrical patterns primarily alpha and theta rhythms , which are generated in certain core networks.
These core brain rhythms spread throughout the brain and can be recorded outside the skull by an EEG. And with that, it has also gained popularity among non-scientists. An Internet search illustrates that —. Brain researchers are mostly conservative in their published comments. Some is too far-out, and easily dismissed, while some is more insightful and intriguing. Similarly, a mother may sleep through all kinds of noise, but wakes when her infant in another room barely whimpers. On a deepest level, they say, paying attention to good things brings good things to you.
Finally, we can program the core ourselves, by training ourselves to focus on things that enhance our lives. For example, the most effective ads trigger both positive and negative emotions e. Other websites view core awareness from other spiritual perspectives. But he does have some interesting things to say about the reticular system —.
The reason for life is to locate that center. The purpose is to adore, accentuate and enhance that center. Chakras are traditional spiritual energy centers, usually associated with various body organs. The Alta Major Chakra is particularly involved in cosmic consciousness and enlightenment. Eugene Shea views the brain from a systems analytic perspective. Shea is also a devout Catholic, and views the brain from that perspective as well.
For such broad themes this book is rather short. Trimble gives only a cursory overview of everything, and his use of language falls flat.
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- Music and the brain: the neuroscience of music and musical appreciation.
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I found myself re-reading many paragraphs because of their Michael R. Appendix 2 Some Notable Religious Poets.
Other Neurological Conditions.