Late morning. You are at Pine Hill Lakes Park, facing east
by the earth dam while Carol takes her walk this rather brisk partly cloudy
day. Jill is house cleaning while you’re out. – Amorella
1120
hours. It is a rather quiet morning; however, as we drove in we saw Tim K.
taking one of his “Words in the Wild” (juniors and seniors) classes up along
the larger lake. He gets paid for doing what he loves. You can’t beat that.
You think that since nothing worthwhile
is going on in your head, that is, nothing entertaining; you might as well work
continue working on that first chapter. – Amorella
1125
hours. That’s rather blunt, Amorella, but I cannot deny the thought.
This, that I can read your thoughts, does
not appear to bother you. – Amorella
1128
hours. I have learned to accept myself, thoughts and all, as I am. It is
somewhat disconcerting (the bluntness) sometimes, but what you come up with is
true enough. I just haven’t expressed openly in words.
So, exactly how are your thoughts expressed
when and/or before they are not in words? – Amorella
1132
hours. This is a good question. This particular one above on nothing
entertaining was certainly not based on emotion as I appeared to be somewhat
bored at the time. I must have been at least semi-conscious of the thought. I
don’t know if semi-conscious is the same as being a part of the subconscious or
not. I always need to define things before I tackle them.
This appears to be the case most of the time.
A read through the blog will show this to be true. – Amorella
1138
hours. This blog is more than seven years old. I can hardly believe it.
You don’t need to believe it; you can’t
‘believe’ it because it is a true statement. – Amorella
1150 hours. I
found “Internal Monologue” on Wikipedia. I could not find semi-consciousness.
** **
Internal
monologue,
also known as inner voice, internal speech, or verbal stream
of consciousness is thinking in words. It also refers to the semi-constant
internal monologue some people have with themselves at a conscious or
semi-conscious level (see Default mode network). Much of what people
consciously report "thinking about" may be thought of as an internal
monologue, a conversation with oneself. Some of this can be considered as
speech rehearsal.
- When
reading, some people's internal monologue moves their muscles slightly as
if they were speaking; this is called subvocalization.
- In
some medical or mental conditions, there is uncertainty about the source
of internal sentences. Attribution for an internal monologue may lead to
concerns over schizophrenia, hallucinations, or hearing voices. This
internal monologue is stimulated by the sensory parts of the brain,
activating both auditory and visual receptors.
- Contemplation
"attempts to calm the internal voice" by various means.
- In the philosophical field of languate there is much research about internal speech in correlation with the building and usage of phrases in one's own idiom and thus the importance of language in the process of thinking.
In
neuroscience, the default mode network (DMN), (also default network,
or default state network), is a network of interacting brain regions
known to have activity highly correlated with each other and distinct from
other networks in the brain.
The
default mode network is most commonly shown to be active when a person is not
focused on the outside world and the brain is at wakeful rest, such as during
daydreaming and mind-wandering. But it is also active when the individual is
thinking about others, thinking about themselves, remembering the past, and
planning for the future. The network activates "by default" when a
person is not involved in a task. Though the DMN was originally noticed to be
deactivated in certain goal-oriented tasks and is sometimes referred to as the
task-negative network, it can be active in other goal-oriented tasks such as
social working memory or autobiographical tasks. The DMN has been shown to be
negatively correlated with other networks in the brain such as attention
networks. Thinking about others also could include guessing their thoughts,
emotions, and psychological motivations.
Evidence
has pointed to disruptions in the DMN with people with Alzheimer’s and autism
spectrum disorder.
Function
The
default mode network is known to be involved in many seemingly different
functions:
Information
regarding the self
- Autobiographical
information: Memories of collection of
events and facts about one’s self
- Self-reference:
Referring to traits and descriptions of one’s self
- Emotion
of one’s self: Reflecting about one’s own
emotional state
Thinking
about others:
- Theory
of Mind: Thinking about the thoughts of
others and what they might or might not know
- Emotions
of other: Understanding the emotions of
other people and empathizing with their feelings
- Moral
reasoning: Determining just and unjust
result of an action
- Social
evaluations: Good-bad attitude judgments
about social concepts
- Social
categories: Reflecting on important social
characteristics and status of a group
Remembering
the past and thinking about the future:
- Remembering
the past: Recalling events that happened
in the past
- Imagining
the future: Envisioning events that might
happen in the future
- Episodic
memory: Detailed memory related to
specific events in time
- Story
comprehension: Understanding and remembering
a narrative
The
default mode network is active during passive rest and mind-wandering. Mind-wandering
usually involves thinking about others, thinking about one’s self, remembering
the past, and envisioning the future. Electrocorticography studies (which
involve placing electrodes on the surface of epileptic patient’s brains) have
shown the default mode network becomes activated within an order of a fraction
of a second after participants finish a task.
Studies
have shown that when people watch a movie, listen to a story, or read a story,
their DMNs are highly correlated with each other. DMNs are not correlated if
the stories are scrambled or are in a language the person does not understand,
suggesting that the network is highly involved in the comprehension and the
subsequent memory formation of that story. The DMN is shown to even be
correlated if the same story is presented to different people in different
languages, further suggesting the DMN is truly involved in the comprehension
aspect of the story and not the auditory or language aspect.
The
default mode network has shown to deactivate during external goal-oriented
tasks such as visual attention or cognitive working memory tasks, thus leading
some researchers to label the network as the task-negative network. However,
when the tasks are external goal-oriented tasks that are known to be a role of
the DMN, such as social working memory or an autobiographical task, the DMN is
positively activated with the task and correlates with other networks such as
the network involved in executive function.
Anatomy
Graphs of the dynamic development of
correlations between brain networks. (A) In children the regions are largely
local and are organized by their physical location; the frontal regions are
highlighted in light blue. (B) In adults the networks become highly correlated
despite their physical distance; the default network is highlighted in light
red.
The
default mode network is an interconnected and anatomically defined set of brain
regions. The network can be separated into hubs and subsections:
Functional
hubs: Information regarding the self
1
Posterior cingulate cortex
(PCC) & precuneus: Combines bottom-up (not controlled) attention with information
from memory and perception. The ventral (lower) part of PCC activates in all
tasks which involve the DMN including those related to the self, related to
others, remembering the past, thinking about future, and processing concepts
plus spatial navigation. The dorsal (upper) part of PCC involves involuntary
awareness and arousal. The precuneus is involved in visual, sensorimotor, and
attentional information.
2
Medial prefrontal cortex (mPFC): Decisions about self-processing
such as personal information, autobiographical memories, future goals and
events, and decision making regarding those personally very close such as
family. The ventral (lower) part is involved in positive emotional information and
internally valued reward.
3
Angular gyrus Connects perception, attention, spatial cognition, and action
and helps with parts of recall of episodic memories
Dorsal
medial subsystem: Thinking about others
•
Functional hubs: PCC, mPFC, and
angular gyrus
•
Dorsal medial
prefrontal cortex (dmPFC): Involved in social
directed thought such as determining or inferring the purpose of others'
actions
•
Temporoparietal junction (TPJ): Reflects on beliefs about
others, also known as theory of mind
•
Lateral temporal cortex: Retrieval of social semantic and conceptual knowledge
•
Anterior temporal pole: Abstract conceptual information particularly social in nature
•
Medial
temporal subsystem: Autobiographical memory and future simulations
•
Functional hubs: PCC, mPFC, and
angular gyrus
•
Hippocampus (HF+): Formation of new
memories as well as remembering the past and imagining the future
•
Parahippocampus (PHC): Spatial and scene recognition and
simulation
Retrosplenial cortex
(RSC): Spatial
navigation
•
Posterior inferior parietal lobe (pIPL): Junction of auditory, visual, and somatosensory
information and attention
•
The
default mode network is most commonly defined with resting state data by
putting a seed in the posterior cingulate cortex and examining which other
brain areas most correlate with this area. The DMN can also be defined by the
areas deactivated during external directed tasks compared to rest.
It
has been shown that the default mode network exhibits the highest overlap in
its structural and functional connectivity, which suggests that the structural
architecture of the brain may be built in such a way that this particular
network is activated by default. In the infant brain, there is limited evidence
of the default network, but default network connectivity is more consistent in
children aged 9–12 years, suggesting that the default network undergoes
developmental change.
Function
connectivity analysis in monkeys shows a similar network of regions to the
default mode network seen in humans. The PCC is also a key hub in monkeys;
however, the mPFC is smaller and less well connected to other brain regions,
largely because human’s mPFC is much larger and well developed.
Diffusion
MRI imaging shows white matter tracks connecting different areas of the DMN
together. The structural connections found from diffusion MRI imaging and the
functional correlations from resting state fMRI r
show the highest level of overlap and agreement within the DMN areas. This
provides evidence that neurons in the DMN regions are linked to each other
through large tracks of axons and this causes activity in these areas to be
correlated with one another.
Pathophysiology
The
default mode network has been hypothesized to be relevant to disorders including
Alzheimer’s disease, autism, schizophrenia, depression, chronic pain and
others.
People
with Alzheimer’s disease show a reduction in glucose (energy use) within the
areas of the default mode network. These reductions start off as slight
decreases in mild patients and continue to large reductions in severe patients.
Surprisingly, disruptions in the DMN begin even before individuals show signs
of Alzheimer’s disease. Plots of amyloid-beta, which is thought to cause
Alzheimer’s disease, show the buildup of the protein is within the DMN. This
prompted Randy Buckner and colleagues to propose the high metabolic rate from
continuous activation of DMN causes more amyloid-beta protein to accumulate in
these DMN areas. These amyloid-beta proteins disrupt the DMN and because the
DMN is heavily involved in memory formation and retrieval, this disruption
leads to the symptoms of Alzheimer’s disease.
DMN
is thought to be disrupted in individuals with autism spectrum disorder. These
individual are impaired in social interaction and communication which are tasks
central to this network. Studies have shown worse connections between areas of
the DMN in individuals with autism, especially between the mPFC (involved in
thinking about the self and others) and the PCC (the central core of the DMN). The more severe the autism, the
less connected these areas are to each other. It is not clear if this is a
cause or a result of autism.
Lower
connectivity was found across the default network in people who have
experienced long term trauma, such as childhood abuse. Among people
experiencing posttraumatic stress disorder, lower activation was found in the
posterior cingulate gyrus compared to controls. Hyperconnectivity of the
default network has been linked to rumination in depression and chronic pain.
Modulation
The
default mode network (DMN) may be modulated by the following interventions and
processes:
•
Acupuncture – Deactivation of the
limbic brain areas and the DMN. It has been suggested that this is due to the
pain response.
•
•
Meditation – Structural changes
in areas of the DMN such as the temporoparietal junction, posterior cingulate
cortex, and precuneus have been found in meditation practitioners. There is
reduced activation and reduced functional connectivity of the DMN in long-term
practitioners. Various forms of nondirective meditation, including
Transcendental Meditation and Acem Meditation have been found to activate the
DMN.
•
•
Sleeping and resting
wakefulness
•
Resting wakefulness – Functional connectivity between nodes of the DMN is strong.
Onset of sleep – Decrease in connectivity between the DMN and the task-positive
network.
Stage N2 of NREM sleep – Decrease in connectivity between the posterior cingulate
cortex and medial prefrontal cortex.
Stage N3 of NREM sleep – Further decrease in connectivity between the PCC and MPFC.
REM sleep – Possible increase in connectivity between nodes of the DMN.
•
Sleep deprivation – Functional
connectivity between nodes of the DMN in their resting-state is usually strong,
but sleep deprivation results in a decrease in connectivity within the DMN. Recent studies suggest a
decrease in connectivity between the DMN and the task-positive network as a
result of sleep loss.
•
•
Psychedelic drugs – Reduced blood
flow to the PCC and mPFC was observed under the administration of psilocybin.
These two areas are considered to be the main nodes of the DMN. One study on
the effects of LSD demonstrated that the drug desynchronizes brain activity
within the DMN; the activity of the brain regions that constitute the DMN
becomes less correlated.
•
History
Hans
Berger, the inventor of the electroencephalogram, was the first to propose the
idea that the brain is constantly busy. In a series of papers published in 1929
he showed that the electrical oscillations detected by his device do not cease
even when the subject is at rest. However, his ideas were not taken seriously,
and a general perception formed among neurologists that only when a focused
activity is performed does the brain (or a part of the brain) become active. In
the 1950s, to the surprise of the researchers, Louis Sokoloff and his
colleagues noticed metabolism in the brain stayed the same when a person went
from a resting state to performing effortful math problems suggesting active
metabolism in the brain must also be happening during rest. In the 1970s,
Ingvar and colleagues observed blood flow in the front part of the brain became
the highest when a person is at rest. Around the same time, intrinsic
oscillatory behavior in vertebrate neurons was observed in cerebellar Purkinje
cells, inferior olivary nucleus and thalamus.
In
the 1990s, with the advent of positron emission tomography (PET) scans,
researchers began to notice that when a person is involved in perception,
language, and attention tasks the same brain areas become less active compared
to passive rest, and labeled these areas as becoming “deactivated”. Later,
experiments by neurologist Marcus E. Raicle’s lab at Washington University
School of Medicine and other groups showed that the brain's energy consumption
is increased by less than 5% of its baseline energy consumption while
performing a focused mental task. These experiments showed that the brain is
constantly active with a high level of activity even when the person is not
engaged in focused mental work. Research thereafter focused on finding the
regions responsible for this constant background activity level.
Raichle
coined the term "default mode" in 2001 to describe resting state
brain function; the concept rapidly became a central theme in neuroscience.
Around this time the idea was implanted that this network of brain areas is
involved in internally directed thoughts and is suspended during specific
goal-directed behaviors. In 2003, Greicius and colleagues examined resting
state fMRI scans and looked at how correlated different sections in the brain
are to each other and found the correlation maps showed the same areas Raichle
found active during rest and that others found to deactivated. It was important
because it demonstrated a convergence of methods all lead to the same areas
being involved in the DMN. Since then other resting state networks (RSNs) have
been found, such as visual, auditory, and attention networks, some of them are
often anti-correlated with the default mode network.
The number of publication per year with
"default mode network" or "default network" in the title.
Searches were done in Google Scholar.
In the beginning to mid 2000s,
researches labeled the default mode network as the task negative network
because it was deactivated when participants had to perform tasks. DMN was
thought to only be active during passive rest and then turned off during
externally focused goal-directed tasks. However, studies have demonstrated the
DMN to be active in external goal-directed tasks which is known to involve the
DMN such as social working memory or autobiographical tasks.
Around 2007, the number of papers
referencing the default mode network have skyrocketed. All years prior to 2007,
there were 12 papers published that referenced “default mode network” or
“default network” in the title, however, between 2007 and 2014 there were 1384
papers published. One reason for the increase in papers is a result of the
robust effect of finding the DMN with resting state scans. Another reason is
the DMN can be measured with a short and effortless resting state scans meaning
they can be performed on any population including young children, clinical
populations, and nonhuman primates. A third reason is role of the DMN has been
expanded to more than just a passive brain network.
Criticism
Some have argued the brain areas in the
default mode network only show up together because of the vascular coupling of
large arteries and veins in the brain near these areas, not because these areas
are actually functionally connected to each other. Support for this argument
comes from studies that show changing in breathing alters oxygen levels in the
blood which in turn affects DMN the most. These studies however do not explain
why the DMN can also be identified using PET scans by measuring glucose
metabolism which is independent of vascular coupling or in electrocorticography
studies measuring electrical activity on the surface the brain.
The idea
of a "default network" is not universally accepted. In 2007 the concept
of the default mode was criticized as not being useful for understanding brain
function, on the grounds that a simpler hypothesis is that a resting brain
actually does more processing than a brain doing certain "demanding"
tasks, and that there is no special significance to the intrinsic activity of
the resting brain.
From
Wikipedia – default mode network
** **
Afternoon. You had lunch at Potbelly’s after
reading at the cemetery, then you stopped at Kroger’s. Jill had left by the
time you arrived home. – Amorella
1447
hours. I have been reading some research on language and thinking and it
appears to, that following my earlier observations above the Wiki quotes – I was
thinking without language. The research argues on whether language influences
thought more or whether thought influences language more. This is a copy of
what I wrote earlier:
**
So, exactly how are your thoughts expressed
when and/or before they are not in words? – Amorella
1132
hours. This is a good question. This particular one above on nothing
entertaining was certainly not based on emotion as I appeared to be somewhat
bored at the time. I must have been at least semi-conscious of the thought. I
don’t know if semi-conscious is the same as being a part of the subconscious or
not. I always need to define things before I tackle them.
(copied from above before the Wikipedia)
**
1459
hours. It appears that the thought was on my mind but language didn’t display
itself until you made your observation. Is it possible that somewhere in the unconscious
mind thought exists without the verbal language to express it? Presently and intuitively
I say, Yes, it is possible that the unconscious mind thinks without verbal
language needed to express it. Actually,
it’s a given. Lower animals ‘think through problems’ without the verbal
language. Problem solving can be demonstrated by body language and then
resolved, for example.
Carol forgot yogurt so you have returned
to Kroger. Such is life, eh, boy? – Amorella
1618
hours. When retired and time is more readily available such little problems are
easily resolved without emotions playing much of a part. You forget something
(we all forget), you back and get it or wait until tomorrow. Letters appearing
on the screen is a calming effect – I am conscious and alive enough to put my
fingers to the keyboard when appropriate. It is still interesting to wonder how
it is that unconscious thought can be transposed without consciousness not
picking it up? Non-religious people could pray every day without knowing it. This
is strikingly funny.
Later. Dusk. You are home. This is the reason,
you see, that in the books, the Dead spend ‘time’ having to think things out.
Socrates was talking about the Living when he said, “Know Thyself” but in here,
it works for the Dead too. Psychologists talk about how people suppress things
and that some of this comes out in symbolic form through dreams and nightmares.
Symbolic form because words are not needed to communicate between the so called
consciousness and unconsciousness. In here when you are physically dead
unconsciousness and consciousness are one in the same – the personality and the
heartansoulanmind of the individual is one and the same. This takes some
getting used to, but then ‘the truth’ is like that, it takes a while, so to
speak, to get used to. What do you think? – Amorella
1712
hours. You sound reasonable, in fact, you haven’t really varied from this
concept. Is this a theme in Soki’s Choice?
Yes. It is strange that you wouldn’t trust yourself
enough to just accept these revolving themes. – Amorella
1722
hours. I take nothing for granted, Amorella. This comes from my believing you
were God when we first met. I was on a walk in the neighborhood, long ago, in
the early eighties. It was dark and I was on another street heading back to 800
Majken Place where we lived. A voice said, “Who are you?” to me and I replied
to myself half-heartedly, “And who are you?” You know, I don’t think you
actually replied, but I got goosebumps and assumed you were God. However, I
immediately and ever after had my doubts. If you had responded, “I am God,” I
would have been confused, at least momentarily, about who the pronoun was
referring to and I would have immediately questioned my sanity because I would
have known it wasn’t me. Basic orndorff momentary confusion. (1734)
This is an example of learning what you may
have known but then you didn’t know how to listen. – Amorella
1736
hours. I need to stop and let this settle in.
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