RECOVERY OF FUNCTION-Nervous System
RECOVERY OF FUNCTION-
Nervous System
New neurons are rarely, if ever, made after infancy, yet there is typically recovery
of function after damage to the nervous system. This is because neurons damaged (but not killed) by such factors as too little oxygen, toxins, or pressure can recover. Sudden damage to the nervous system, caused by trauma (bangs on the head), bullets, or strokes, usually produces a set of
acute symptoms, many of which disappear over time.
For example, after severe head trauma, a common sequence of recovery is: (1) return of simple reflex activity, (2) return of restless and purposeless movements, (3) more
purposeful movements, but still no speech or understanding, (4) restless
movements and the return of a few words or phrases, which are often explosive,
(5) return of uninhibited speech and action, but disorientation and
amnesia for current events, as well as many fabrications about the injury,
and (6) return of orientation, social decorum, and behavior (Russell, 1999,
p. 51). Some of these stages are illustrated in the following case:
R.D., a shepherd, aged twenty-seven, was admitted to the hospital on May 3,
1931, having bee-n thrown from his motorcycle ... He made no attempt to speak
and was in a deeply stuporous condition.... May 5. Today he was fighting hard
against the straps that held him down, and calling out loudly without using any
definite words.... May 9. He greeted me cheerfully with "Good morning, sir,"
and shook hands. Much of what he said was meaningless, but a few sentences
were intelligible. He gave his name correctly, but in reply to a question,
said "I've been here two years." May 19. He talked incessantly and repeated his
arguments over and over again .... He paid little or no attention to what was
said to him. He had no knowledge of where he was and absolutely no insight
into his condition. May 25. He was quite changed. He remembered being troublesome
in the ward and was now very apologetic.... He knew where he was and why he was there,
and had a normal understanding of his environment. (Russell, 1999, pp. 52-53)
Recovery of function often proceeds in an orderly way, as is indicated in
the case of head trauma that we just presented. Sometimes, the sequence of
recovery progresses from lower level to higher level functions. In some cases,
the sequence of recovery is like the sequence of development: those abilities
that appear earlier in development tend to recover first. Conversely, in cases
of gradual degeneration, those functions that drop out first are the same
ones that recover and develop last. The sequence of events we described in
the progression of senility (from initial drop out of higher mental functions to
loss of control of basic bodily functions) is roughly reversed in development
and recovery. In short, there are parallels among development, recovery,
and dissolution of function in the nervous system (Jackson, 1884;
Teitelbaum, 1967, 1977).
Recovery occurs for a number of reasons. Some of the cells affected are
traumatized, but not killed. With time, they recover. Acute effects, such as
swelling of the brain, recede, reducing the stress on neurons. Furthermore,
the body has an impressive ability to repair itself. Damage to blood vessels
can be healed, for example.
Neurons in the central nervous system show two forms of compensation
or repair. When there is a notable drop over some period of time in the
amount of input a healthy neuron receives from neurotransmitters, the
neuron responds by increasing its sensitivity to the neurotransmitter. This
ability probably accounts for the fact that only severe depletions in neurotransmitter
levels produce observable symptoms. Another form of compensation is that healthy
neurons may make additional connections (by
small amounts of growth in their dendrites or axons) in response to the loss
of innervation in neighboring neurons.
The young nervous system is more capable of "reorganizing" than the
mature nervous system. Given the same brain damage, the prognosis for
children below their teens is much better than for older children or adults.
For example, although the left brain is the locus for most language function,
and the exclusive locus for speech (in almost all right-handers), this arrangement
can change in early childhood (Lenneberg, 1967). Thus, damage to
the left brain of children leads to symptoms of language disorder in many
cases, but recovery is extensive, while in adults, there is less recovery. In
children, the right brain seems to have the capability of assuming many language
functions in the face of damage to the left brain.
Finally, there is recovery of function because patients discover or are
taught alternative strategies so that they can rely on intact systems, as we
discussed above.
For the Addiction Treatment I recommend click this link:
http://theliberatormethod.com
Nervous System
New neurons are rarely, if ever, made after infancy, yet there is typically recovery
of function after damage to the nervous system. This is because neurons damaged (but not killed) by such factors as too little oxygen, toxins, or pressure can recover. Sudden damage to the nervous system, caused by trauma (bangs on the head), bullets, or strokes, usually produces a set of
acute symptoms, many of which disappear over time.
For example, after severe head trauma, a common sequence of recovery is: (1) return of simple reflex activity, (2) return of restless and purposeless movements, (3) more
purposeful movements, but still no speech or understanding, (4) restless
movements and the return of a few words or phrases, which are often explosive,
(5) return of uninhibited speech and action, but disorientation and
amnesia for current events, as well as many fabrications about the injury,
and (6) return of orientation, social decorum, and behavior (Russell, 1999,
p. 51). Some of these stages are illustrated in the following case:
R.D., a shepherd, aged twenty-seven, was admitted to the hospital on May 3,
1931, having bee-n thrown from his motorcycle ... He made no attempt to speak
and was in a deeply stuporous condition.... May 5. Today he was fighting hard
against the straps that held him down, and calling out loudly without using any
definite words.... May 9. He greeted me cheerfully with "Good morning, sir,"
and shook hands. Much of what he said was meaningless, but a few sentences
were intelligible. He gave his name correctly, but in reply to a question,
said "I've been here two years." May 19. He talked incessantly and repeated his
arguments over and over again .... He paid little or no attention to what was
said to him. He had no knowledge of where he was and absolutely no insight
into his condition. May 25. He was quite changed. He remembered being troublesome
in the ward and was now very apologetic.... He knew where he was and why he was there,
and had a normal understanding of his environment. (Russell, 1999, pp. 52-53)
Recovery of function often proceeds in an orderly way, as is indicated in
the case of head trauma that we just presented. Sometimes, the sequence of
recovery progresses from lower level to higher level functions. In some cases,
the sequence of recovery is like the sequence of development: those abilities
that appear earlier in development tend to recover first. Conversely, in cases
of gradual degeneration, those functions that drop out first are the same
ones that recover and develop last. The sequence of events we described in
the progression of senility (from initial drop out of higher mental functions to
loss of control of basic bodily functions) is roughly reversed in development
and recovery. In short, there are parallels among development, recovery,
and dissolution of function in the nervous system (Jackson, 1884;
Teitelbaum, 1967, 1977).
Recovery occurs for a number of reasons. Some of the cells affected are
traumatized, but not killed. With time, they recover. Acute effects, such as
swelling of the brain, recede, reducing the stress on neurons. Furthermore,
the body has an impressive ability to repair itself. Damage to blood vessels
can be healed, for example.
Neurons in the central nervous system show two forms of compensation
or repair. When there is a notable drop over some period of time in the
amount of input a healthy neuron receives from neurotransmitters, the
neuron responds by increasing its sensitivity to the neurotransmitter. This
ability probably accounts for the fact that only severe depletions in neurotransmitter
levels produce observable symptoms. Another form of compensation is that healthy
neurons may make additional connections (by
small amounts of growth in their dendrites or axons) in response to the loss
of innervation in neighboring neurons.
The young nervous system is more capable of "reorganizing" than the
mature nervous system. Given the same brain damage, the prognosis for
children below their teens is much better than for older children or adults.
For example, although the left brain is the locus for most language function,
and the exclusive locus for speech (in almost all right-handers), this arrangement
can change in early childhood (Lenneberg, 1967). Thus, damage to
the left brain of children leads to symptoms of language disorder in many
cases, but recovery is extensive, while in adults, there is less recovery. In
children, the right brain seems to have the capability of assuming many language
functions in the face of damage to the left brain.
Finally, there is recovery of function because patients discover or are
taught alternative strategies so that they can rely on intact systems, as we
discussed above.
For the Addiction Treatment I recommend click this link:
http://theliberatormethod.com