- Frontal
Cortex Hemoencephalography (HEG); Brain
oxygenation proportionally improves Variables of
Attention,
- Hershel
Toomim
- Abstract:
-
In HEG a non-invasive
spectrophotometer measures brain reflected and refracted light from a
pair of selected wavelengths incident on the brain through the scalp.
A display derived from a metric proportional to capillary blood
oxygenation is provided for control by an observer.
-
Frontal cortex is widely recognized
as part of the executive functioning of the brain. Important in this
function is attention, accuracy, speed and stability of response time
to a visual stimulus.
- Speed and accuracy of
decision-making are accepted components of Intelligence testing. (Wechsler…)
- Deficits in frontal cortex
blood flow have been found in studies of deficits of frontal cortex
functioning.
- The Test of Variables of
Attention (TOVA) is a standardized test to assess Omission,
Impulsivity, Response Time, and Response Time Variability to
approximately 690 targets and non-targets randomly displayed at 2
second intervals.
- Toomim (2001), in a
literature study has found all publications of neurofeedback training
for Attention Deficit Disorder that utilized TOVA as the before and
after assessing test showed a direct proportionality between TOVA
point gain and the number of exposures to this training.
- HEG training described
below examined the effect of training time for intentional increase of
cerebral oxygenation on the gain in TOVA measurements.
-
- Objective:
- The study investigated the hypothesis that the speed
and accuracy of the frontal cortex component of decision making as
measured with TOVA improves with HEG training duration.
-
- Method:
- Fifty three self-selected age and initial TOVA
matched memory deficit adults were measured with TOVA before and after
training for blood flow increase in the frontal cortex with
Hemoencephalography (HEG). The probands were divided into 2 groups.
Training for the control group was divided into ten sessions of one
ten minute segment each. The members of the experimental group
received ten sessions of three ten minute segments each
-
- Results:
- The experimental group gained significantly more TOVA
points than the control group. When correction was applied for trainer
efficiency the experimental group gain was proportional to exposure
time within 5%
-
- Conclusions:
- HEG blood oxygenation exercise increases speed and
accuracy of decision-making. This finding suggests HEG can be used an
as simple non-invasive treatment for brain dysfunctions.
- Discussion:
- This study has shown a direct relationship between an
improvement of a frontal lobe brain
function, TOVA, and trained increases in available frontal blood
supply. PET
studies by Zametkin 1990 showed frontal lobe hypoperfusion in ADD/ADHD
boys This suggests that further brain functions may be
similarly enhanced.
-
- TOVA and Trained EEG
- TOVA was developed to
measure and titrate stimulant medication in ADD/ADHD children. All
published studies using TOVA as a dependent variable have also shown a
direct proportionality between TOVA gain and training time. (Toomim H.
2002)
-
- The frontal lobes are inhibitory executive
areas in the brain, which control attention, decisions, impulsivity,
TOVA variables, and emotions as well as regulation of the motor areas
of the brain..
-
- The brain¹s electrical patterns are
subject to modification through training, a fact discovered in
research done in the late 1960s by Doctor Barry Sterman, now a
professor emeritus at UCLA. His work was originally in animals, though
it was replicated in humans starting in the 1970s.
The technique of training the brain to behave in a new and
different way is now called Neurothreapy or Neurofeedback.
-
- Neurotherapy is non invasive, utilizes the
brain’s own voluntary activity and has less likelihood of having
side effects than medication. It takes a number of training sessions
before the effect is noted and becomes more permanent.
-
- Hypoperfusion; EEG and HEG
- A research project performed at UCLA by
Ian. A. Cook, et al. in 1998 showed that the brain¹s electrical
activity, or electroencephalogram (EEG), also has specific correlates
of blood perfusion. This is useful in that the EEG is capable of
showing when perfusion is low, as seen frontally in ADD/ADHD and
distributed frontally or otherwise in other brain deficits.
-
- Regulation
and measurement of blood supply
- The brain controls it’s own blood supply through
neuronal metabolic demand for construction, dilation and constriction
of blood vessels. The
blood flow is directed to areas that are active through this
self-regulation. The blood supply flow, along with the utilization of
oxygen, is measured as "perfusion", clearly seen in some of
the modern imaging techniques, such as Positron Emission Tomography
(PET) and Single Photon Emission Computed Tomography (SPECT)
technology.
-
- Brain structure and exercise
- That the brain changes structurally when
it learns is now recognized. Microscopic changes in the structure,
forming and reinforcing of dendrites, is a normal brain metabolic
function. This highly changeable connective nature is referred to as
neural plasticity, a descriptor of the malleability or change-ability
of materials or structures.
-
- Glial feet and blood flow
- Brain capillaries, which
constitute only 0.1% of the brain mass (Bar, 1980), are responsible
for the transport of glucose for the entire brain.
Glucose is the prime energy substrate utilized by the high
metabolic demand of the brain. The bulk of the brain's oxygen supports
this glucose metabolism. The
breach of the blood brain barrier by glial cell feet transport glucose
from blood to brain (Fuglsang, Lombolt, & Gjedde, 1998, Lund &
Anderson, 1979.
-
- Oxygen Availability and Cortical Blood
- Oxygen availability in
cortical blood is measured by the HEG technique.
Its relationship to cortical blood flow is supported by Schore
- "It is now known that
the capillary network in a region is directly correlated with the
region's oxygen consumption (Cragie, 1945), that regional blood flow
and regional metabolism are coupled to local synaptic activity
(Greenberg, Hand, Sylvestro, & Reivich, 1979), and that
differences between blood flow and oxygen consumption exist not at the
macroregional but at the microregional level (Reivich et al.,
1977)."
-
- Use
it or lose it
- The brain has a method of developing and
expanding the pathways that are used, and "pruning" the
connections that aren’t utilized. This process is most dramatic
early in life, but continues throughout life. The pathways that are
more consistently utilized are protected from the pruning process
through a mechanism still unknown to science, though the fact of the
change is irrefutable.
-
- Another time when this is evident is
following damage, stroke or head injury. Further disability results
from disuse of supporting brain areas. The surrounding functions may
take over an area not utilized. As Marion Diamond says “Use it or
lose it”
-
- Growth-through-utilization, brain exercise, is the
process that we want to focus on (Taub, Scheibel, McDonald). This
process is how we build additional capacity for the nervous system to
do its work. Analogous to exercise building muscle mass, the
utilization of the brain builds the mass of the brain¹s dendritic
connections.
-
- Brain Development
- "In light of the facts
that synaptic overproduction operationally defines a critical period
and that brain vasculature is intimately involved in the metabolic and
functional support of synapses, experience-dependent regional blood
flow events, influenced by subcortically exported catecholamines,
may thus be a critical regulating factor in the development of
regional differences in the time course of human cortical
synaptogenesis."
- Vascularization and therapy
- Vascularization of the
brain is of particular interest in therapeutic interventions to
improve poorly developed areas. The following citation from Schore
makes clear reference to this process.
- "The developing brain
produces an angiogenesis factor (Gospodarowicz, Chang, Lui, Baird,
& Bohlen, 1984; Risau, 1986) a peptide growth factor that
influences the vascularization
of the nervous system (Gaspadorowicz, Massoglia, Chang, Fuji 1986) and
promotes development of dopaminergic
(Engele and Bohn, 1991) and cerebral cortical
(Morrison, Sharma, DeVillis, & Bradshaw, 1986) neurons.”
-
- Localized
Brain work
- An important part of work
with young and mature brains is location and treatment of areas
involved in easily recognized behaviors. With this knowledge a
therapist can locate the training HEG tool to develop those areas most
involved in brain deficits. In pursuit of this goal, readings from Affect Regulation
and the origin of the Self: The Neurobiology of Emotional Development
by Allan N. Schore Ph.D. present areas of functional development.
-
- It is now recognized that
brain growth continues throughout life. It is therefore useful to
follow infant brain development, so well outlined by Alan Schore.
The following quotations from his trenchant book lead to
recognition of brain areas specifically devoted to recognition of
functional brain areas.
-
- Schore is especially
interested in prefrontal regions because they form early essential
connections between the intelligent cortical areas and the limbic
emotional life-sustaining brain regions.
-
- Body position in space
- Jonides
et al. (1993) report positron emission tomography (PET) studies of
human regional cerebral blood flow that reveal activation in right
hemisphere prefrontal, occipital, parietal, and premotor cortices
accompanying spatial working memory processes.
In this study of the circuitry of working memory, the activated
prefrontal region, Brodmann’s area 47, is part of the orbitofrontal
cortex and is in the right and not left hemisphere. Brodmann’s right
hemisphere area 37 locates a prime treatment area for deficits in
“sense of direction”.
-
- Deep brain structures and cortical functions (Schore)
- Treatment of deep brain
areas with HEG is limited by their connections to surface cortical
positions. Shore provides support for this position:
-
- “The next question is,
what sites are delivering axons to these prefrontal dendrites? In
other words, what kinds of connections need to be made in order to
sustain mature function? Subcortical input from the magnocellular
portions of the mediodorsal nucleus of the thalamus (Corwin et al.,
1983; Leonard, 1969; Rose & Woolsey, 1948) and regions of the
amygdala (Porrino, Crane, & Goldman-Rakic, 1981) and hippocampus
(More-craft et al., 1992) are known to be delivered to this cortex.
Ingrowing axons to deep orbital neurons are also derived from
the lateral. medial, and posterior regions of the hypothalamus (Morecraft
et al., 1992). It should
he remembered that these orbitofrontal columns receive the convergent
input of processed sensory information (olfactory, somesthetic,
visual, and auditory) from all cortical association cortices (Yarita
et al., 1980)."
-
- Functional location of speech and memory (Schore)
- "Speech production,
long considered a product of the "verbal" left hemisphere is
particularly dependent upon prefrontal functioning.
Recent tomographic and blood flow studies reveal that verbal
fluency is specifically associated with an increase in metabolic
activity of the left dorsolateral prefrontal cortex (Frith Inston,
Liddle, & Frackowiak, 1991; Warkentin et al., 1991).
This prefrontal area is operative in the analysis of sequences
of phonemes (Alexander, Benson, A Stuss, 1989).
However, the orbital cortex is also known to be implicated in
auditory functions (Fallon & Benevento, 1978).
In fact, Ross (1983) points out the often overlooked finding
that the right hemisphere is centrally and uniquely involved in the
recognition and expression of the prosodic, affective components of
language. It is now
thought that the two hemispheres contain unique representational
systems, affective-configurational in the right. and lexical-semantic
in the left( Watt I 99()). Bruner
(I986) postulates a narrative form of thought which arises earlier
than a paradigmatic form is associated with autobiographic
self-in-interaction-with-other experiences and is heavily affectively
charged. Vitz (1990)
concludes narrative thought is expressed in intonation and
emotion-associated images and is characterized as 'language in the
service of right hemisphere cognition.'"
- Growth-through-utilization,
brain exercise, is the process that we want to focus on (Taub,
Scheibel, McDonald). This process is how we build additional capacity
for the nervous system to do its work. Analogous to exercise building
muscle mass, the utilization of the brain builds the mass of the brain¹s
dendritic connections. HEG and EEG neurotherapy is simple and
effective exercise technique.
-
- An important part of work with young and mature
brains is location and treatment of areas involved in easily
recognized behaviors In pursuit of this goal readings from Affect
Regulation and the origin of the Self: The Neurobiology of Emotional
Development by Allan N. Schore Ph.D. present
areas of functional development in the infant, less than two
years old.
-
- It is now recognized that brain growth continues
throughout life. It is therefore useful to follow infant brain
development , so well
outlined by Alan Schore. The
following
quotations from his trenchant book lead to recognition of brain areas
specifically devoted to recognition
of functional brain areas.
-
- Schore is specially interested in prefrontal regions
because they form early essential connections between the intelligent
cortical areas and the limbic emotional life sustaining brain regions.
-
- "In light of the facts that synaptic
overproduction operationally defines a critical period and that brain
vasculature is intimately involved in the metabolic and functional
support of synapses, experience-dependent regional blood flow events,
influenced by subcortically exported catecholamines, may thus be a
critical regulating factor in the development of regional differences
in the time course of human cortical synaptogenesis."
-
- Oxygen availability in cortical blood is measured
by the HEG technique. Its relationship to cortical blood flow is
supported by Schore
-
-
"It is now known that the capillary network in a region is
directly correlated with the region's oxygen consumption (Cragie,
1945), that regional blood flow and regional metabolism are coupled
to local synaptic activity (Greenberg, Hand, Sylvestro, & Reivich,
1979), and that differences between blood flow and oxygen consumption
exist not at the macroregional but at the microregional level (Reivich
et al., 1977)."
-
- As becomes clear in the following quotation, it is
important to note that the mere development of brain tissue is
insufficient in itself to insure useful outcomes of brain exercise.
Numerous recent brain imaging studies have implicated bioamines in
promotion of blood flow in specific brain regions.
This is of particular interest because brain exercise of
specific brain regions can be expected to result in activation of
these regions.
-
-
"Dopamine, a neuromodulator that increases arousal,
(Iverson 1997) has been shown to specifically increase prefrontal
metabolism (McCulloch,
Savaki, & McCulloch 1982). These findings suggest that the initial increased energy
demands of growing prefrontal cortical tissue are met by localized
dopamine-enhanced uptake of glucose, some of which is utilized in the
oxidative arm of the pentose phosphate shunt (Hothersall et al.,
1982), the biochemical pathway that supports biosynthetic processes.
Indeed, catecholamines have pronounced effects on cerebral
oxidative metabolism and blood flow, especially in areas with an
incomplete blood-brain barrier (Berntman, Dahlgren, & Siesjo,
1978). Dopamine, in particular, functionally increases blood flow in
various brain areas (Ekstrom-Jodal, Elfverson, & Von Essen, 1982;
Von Essen, 1974), including a brain region with an incomplete barrier
(choroid plexus; Townsend, Ziedonis, Bryan, Brennan, & Page.
1984). In addition, the
catecholaminergic regulation of the permeability of water into this
local brain region via its effects on the rate of cerebral blood flow
(Raichle, Eichling, & Grubb, 1974) may allow for transport of an
optimal amount of water into the developing parenchyma that facilitates cell
growth and differentiation and thereby synaptogenesls."
-
-
Vascularization of the brain is of particular interest in
therapeutic interventions to improve poorly developed areas. The
following citation from Schore makes clear reference to this process.
-
- "The developing brain produces an angiogenesis
factor (Gospodarowicz, Chang, Lui, Baird, & Bohlen, 1984; Risau,
1986) a peptide growth factor that influences the
vascularization of the nervous system (Gaspadorowicz, Massoglia,
Chang, Fuji 1986) and promotes development of dopaminergic (Engele and Bohn, 1991) and cerebral cortical
(Morrison, Sharma, DeVillis, & Bradshaw, 1986) neurons.
Active capillary sprouting and branching is observed
postnatally in the cerebral hemispheres (Bar &
Wolf, 1972). By
the end of the first year the capillary density of the human cortex
doubles (Purves, 1972)
-
- Brain capillaries, which constitute only 0.1% of the
brain mass (Bar, 1980), are responsible for the transport of glucose
for the entire brain. Glucose
is the prime energy substrate utilized by the high metabolic demand of
the immature brain, as its metabolism accounts for the bulk of the
brain's oxygen metabolism. It
is the blood brain barrier that regulates the transport of glucose
from blood to brain (Fuglsang, Lombolt, & Gjedde, 1998, Lund &
Anderson,1979."
-
- Recent advances have shown that glucose and oxygen
are transferred from the capillaries to the neurons via stellite glial
cells. Glial cell feet on
capillaries breach the blood brain barrier. (Refs…)
-
- A notable feature of voluntary activation of brain
blood flow is activation as shown by skin conductance measures.
When a person's upper limit in flow is neared there is a rapid
increase in arousal mediated by the reticular activating system.
The reference below points out the importance of such
stimulation in developing brain vasculature
by expressing local regional needs. [ED]
-
-
"Observers have noted that stimulation of the brainstem
reticular formation influences cerebral blood flow and oxygen
consumption (Meyer, Nomura, Sakamoto, & Kondo, 1969), that
highly branched fibers originating in brainstem catecholaminergic
neurons innervate blood vessels in widely dispersed areas of the brain
(Swanson & Hartman, 1975), and that catecholamines regulate
vascular permeability and influence blood flow in the cerebral
microcirculation (Raichle et al., 1975).
Catecholaminergic modulation of microvascular transport of
glucose into orbito-frontal columns would represent a control
mechanism by which oxygen, energy substrate, and catalytic hormonal
factors would be more efficiently delivered into the expanding
orbitofrontal neuropil. The anatomical maturation of this subcortical system could
support emergent functions that result from more complex synaptic
events. According to
Hartman and Udenfreind (1972) the innervation of brain vasculature by
distant catecholaminergic neurons operates as a regulator that
responds to the local needs of the brain regions.
I suggest that this underlies the mechanism whereby
subcortically manufactured biogenic amines regulate the biochemical
response of an individual cerebral cortical cholinergic synapse
(Shimizu, Creveling, & Daly, 1970) and by which a single dopamine
axon can modulate a large number of cortical pyramidal cells (Smiley
et al., 1992). The
monoaminergic control of brain microvascular systems thus mediates an
essential homeostatic role.
-
-
-
-
"In discussing his work on the induction of cortical
structure by early experience. Greenough (1987) finds a common
pattern---dendritic growth followed by exuberant-synaptogenesis
followed by synaptic pruning and preservation.
With regard to this last step, he refers to an
'activity-dependent selective preservation of synapses.'
Rosenzweig et al. (1972) also report that cortical development
involves an initial period of increased growth followed by a
diminution in cortical depth. This
ontogenetic decline in cortical depth is influenced by environmental
stimulation-induced neural activity (Cummins, Livesey, & Bell,
1982). It is important to
note that imprinting-influenced expansive changes coincide with a
selective degeneration of other local neural systems (Wolff, 1979),
that imprinting involves the construction of some new synapses and the
elimination of other previously existing ones (Horn, Bradley, &
McCabe, 1985; Patel, Rose, & Stewart, 1988).
Changeux and Dehaene, (1989) describe the essential
developmental phenomenon of the activity-dependent Darwinian
elimination and selective stabilization of synapses.
This adaptive process occurs, for example, in developing
cortical association areas (Price & Blakemore, 1985) during
postnatal imprinting sensitive periods.
Huttenlocher (1990) emphasizes that there is a very significant
loss of cortical synapses in the postnatal period, and that cortical
synapse elimination plays an especially important role in the
development of complex systems.
-
- Further emphasis of the importance and
interconnectivity of the frontal regions
with deep subcortical structures such as the thalamus,
hippocampus and in particular the orbito-frontal regions is clear in
the following : [ED]
-
- "The imprinting-induced amplification of
cholinergic receptors on dendrites in the deep layers of the
orbitofrontal cortex would allow for an increased number of synaptic
connections with incoming axons.
The next question is, what sites are delivering axons to these
prefrontal dendrites? In other words, what kinds of connections need
to be made in order to sustain mature function? Subcortical input from
the magnocellular portions of the mediodorsal nucleus of the thalamus
(Corwin et al., 1983; Leonard, 1969; Rose & Woolsey, 1948) and
regions of the amygdala (Porrino, Crane, & Goldman-Rakic, 1981)
and hippocampus (More-craft et al., 1992) are known to be delivered to
this cortex. Ingrowing axons to deep orbital neurons are also derived from
the lateral. medial, and posterior regions of the hypothalamus (Morecraft
et al., 1992). It should
he remembered that these orbitofrontal columns receive the convergent
input of processed sensory information (olfactory, somesthetic,
visual, and auditory) from all cortical association cortices (Yarita
et al., 1980)."
-
-
"For example, with the emergence of upright locomotion
that signals the onset of the practicing period, orbital neurons may
simultaneously receive afferent input from both posterior parietal (Cavada
& Goldman-Rakic, 1989) areas that provide an image of the position
of the body in space with respect to objects in the surrounding
space (Hecaen & Albert, 1978), and input from posterior visual
areas (Squatrito, Galletti, Majali, & Battaglini, 1981).
This combination would allow for this prefrontal structure to
play an essential role in 'recording movements of the visual
environment relative to the body' and in 'the adjustment of motor
behavior to such movements' (Mucke et al., 1982)
-
- Stimulation of the dorsal medullary reticular
formation elicits noradrenergic-induced alterations in blood flow in
the cortex, including prefrontal areas (Iadecola, Lacombe, Underwood,
Ishitsuka, & Reis, 1987)."
-
-
"Speech production, long considered a product of the
"verbal" left hemisphere is particularly dependent upon
prefrontal functioning. Recent
tomographic and blood flow studies reveal that verbal fluency is
specifically associated with an increase in metabolic activity of the
left dorsolateral prefrontal cortex (Frith Inston, Liddle, &
Frackowiak, 1991; Warkentin et al., 1991).
This prefrontal area is operative in the analysis of sequences
of phonemes (Alexander, Benson, A Stuss, 1989).
However, the orbital cortex is also known to be implicated in
auditory functions (Fallon & Benevento, 1978).
In fact, Ross (1983) points out the often overlooked finding
that the right hemisphere is centrally and uniquely involved in the
recognition and expression of the prosodic, affective components of
language. It is now
thought that the two hemispheres contain unique representational
systems, affective-configurational in the right. and lexical-semantic
in the left( Watt I 99()). Bruner
(I986) postulates a narrative form of thought which arises earlier
than a paradigmatic form is associated with autobiographic
self-in-interaction-with-other experiences and is heavily affectively
charged. Vitz (1990)
concludes narrative thought is expressed in intonation and
emotion-associated images and is characterized as 'language in the
service of right hemisphere cognition.'"
-
-
"Goldman-Rakic's proposal is supported by Jonides et al.
(1993), who report positron emission tomography (PET) studies of human
regional cerebral blood flow that reveal activation in right
hemisphere prefrontal, occipital, parietal, and premotor cortices
accompanying spatial working memory processes.
Most importantly, in this study of the circuitry of working
memory, the activated prefrontal region, area 47, is part of the
orbitofrontal cortex (see Figures 4.7 and 4.8), and is in the right
and not left hemisphere."
-
-
"Brain capillaries are composed of contiguous endothelial
cells separated by a tight junction (see Fig. 11.4), and in the brain
microvasculature the two ends of the same endothelial cell completely
surrounding the capillary lumen abut at a junction (see Fig. 11.2).
These occluding junctions are the morphological basis for the
blood-brain barrier, and it is known that agents that affect the
permeability of the cerebral vasculature do so by causing
leakages in the tight junctions.
In a classical work on the effects of monoamines on vascular
permeability, Majno and Palade (1961a) found that these agents cause
endothelial openings along intercellular junctions, and speculate that
the opening of a gap is due to the contraction of epithelial cells.
This principle is now well established, and the molecular
biology of epithelial control mechanisms and gap formation is now
being 'worked out (Currry. 1992)"
-
-
"Blood flow is known to correlate with changes in arousal
levels (Obristet al., 1975)
- and to be an indicator of regional oxidative
metabolism (Raichle et al., 1976).
Both
- regional
blood flow and regional metabolism are known to be coupled to local synaptic activity (Greenherg et al 1979)…This
mechanism identifies Luria's (1973) structural systems in the
subcortex and brainstem that maintain and regulate the tone of the
cerebral cortex. 'Cortical
tone' may thus specifically refer to the tone of the cerebral
microvasculature."
-
- "It is well established that the number of
actively functioning cerebral capillaries (Mchedlishvili, 1964) and
capillary permeability (Lorenzo, Fernandez, & Roth, 1965) may vary
with the physiological state of the brain.
At the end of the last century, Roy and Sherrington (1890) were
the first to suggest a concept of intrinsic control of the circulation
and propose that this is focally adapted to the region's metabolic and
functional needs. We now
know that the innervation of the brain's vasculature by monoaminergic
neurons operates as a regulator that responds to the local needs of
brain regions (Hartman & Udenfriend, 1972).
Dopamine produces a significant increase in blood flow in the
frontal cortex, and this has been suggested to reflect the activation
of specific receptors located on endothelium (Tuor et al., 1986).
Noradrenergic axons in the frontal cortex also show a low
incidence of 'true' synaptic terminals (Lapierre, Beaudet, Demianezuk,
& Descarries, 1973). The
noradrenergic effects on cerebral blood flow have also been proposed
to be mediated by endothelial receptors on the cerebral vasculature (Aubineau,
Sercombe, Lusamvuku, & Seylaz, 1982).
The nucleus of the solitary tract, site of medullary
noradrenergic neurons, is now being referred to as the 'gateway to
neural circulatory control' (Andressen & Kunze, in press).
The importance of an optimal microcirculation to the
chemical and structural aspects of brain development is only now
beginning to be appreciated (Casaer, I 993)"
[Emphasis ED]
-
- "Majno and Palade (l96lb) reported that the site
of action of serotonin is on the venous side of the vascular tree.
Taking this idea further, different classes of serotonin
receptors in the brain microcirculation may reside in the minute
postcapilliry venules, more permeable sites that display only limited
tight junctions (Simtonescu Simionescu, & Palade, 1975).
Different classes of dopamine receptors could occupy the
endothelial cells of minute precapillary arterioles and the various
noradrenaline receptors could be represented on single-cell
capillaries. Furthermore,
these systems may appear in a regular ontogenetic fashion.
For example, cortical serotonin receptors develop in an orderly
ontogenetic sequence (Uzbekov, Murphy, & Rose, 1979).
Like the catecholamines, serotonin neurons in the brainstem (raphe
nuclei) project to small vessels in the brain (Reinhard, Liebman,
Schlossberg, & Moskowitz, 1979), induce increased blood flow
(Jacobs & Fornal, 1993), and have modulatory effect on brain
systems (Fornal & Jacobs, 1987) and neural information processing
(Spoont, 1992). Although
serotonin, by itself, produces little or no change in neuronal
activity, when combined with an excitatory amino acid or electrical
stimulation, it induces a neuronal state transition, a shift from a
stable hyperpolarization state of neuronal inactivity to a new stable
depolarized "plateau" state with tonic neuronal activity
(Jacobs & Fornal, 1993)."
-
-
"Serotonin axons are capable of collateral sprouting (Azmitla
Buehan & Williams, 1978), and the branching of serotonin axons in
the cerebral cortex thought to take place in postnatal stages of
development (Aitken & Lork 1988).
Serotonergic axon terminals in the frontal cortex also exhibit
mostly nonsynaptic terminals (Descarries, Beaudet & Walkins 1975).
In addition serotonin also shares other properties of the
catecholamines---it stimulates the hexose monophosphate pathway in the
neonatal cortex (Appel & Parrot 1970), induces glycogenolysis (Qitach
et al., 1982) disaggregates brain
polysomes (Weiss Wurtman, & Munro, 1973), influences the
differentiation of other neurons (Laudcr & Krebs, 1986), and
regulates neuronal architecture and sculpts connectivity (Haydon,
McCobb, & Kater, 1984). Serotonin
receptors coupled to adenylate cyclase are very frequent in newborn
brains (Leysen, 1985). Importantly,
in the period immediately after birth serotonin plays a critical role
in very early neonatal experience (Julian, McEwen, & Pohorecky,
1974). This bioamine is
known to play an important role in sleep, thermoregulation, and
appetitive behavior (Brownstein 1981), prominent features in neonatal
repertoire."
-
-
-
Numerous recent brain imaging studies have implicated bioamines
in promotion of blood flow in specific brain regions.
This is of particular interest because brain exercise of
specific brain regions can be expected to result in activation of the
amines specific to these regions. [ED]
-
-
"Dopamine, a neuromodulator that increases arousal,
(Iverson 1997) has been shown to specifically increase prefrontal
metabolism (McCulloch,
Savaki, & McCulloch 1982). These findings suggest that the initial increased energy
demands of growing prefrontal cortical tissue are met by localized
dopamine-enhanced uptake of glucose, some of which is utilized in the
oxidative arm of the pentose phosphate shunt (Hothersall et al.,
1982), the biochemical pathway that supports biosynthetic processes.
Indeed, catecholamines have pronounced effects on cerebral
oxidative metabolism and blood flow, especially in areas with an
incomplete blood-brain barrier (Berntman, Dahlgren, & Siesjo,
1978). Dopamine, in particular, functionally increases blood flow in
various brain areas (Ekstrom-Jodal, Elfverson, & Von Essen, 1982;
Von Essen, 1974), including a brain region with an incomplete barrier
(choroid plexus; Townsend, Ziedonis, Bryan, Brennan, & Page.
1984). In addition, the
catecholaminergic regulation of the permeability of water into this
local brain region via its effects on the rate of cerebral blood flow
(Raichle, Eichling, & Grubb, 1974) may allow for transport of an
optimal amount of water into the developing parenchyma that facilitates cell
growth and differentiation and thereby synaptogenesls."
-
-
Vascularization of the brain is of particular interest in
therapeutic interventions to remediate poorly developed areas. The
following citation makes clear reference to this process. [ED]
-
- "The developing brain produces an angiogenesis
factor (Gospodarowicz, Chang, Lui, Baird, & Bohlen, 1984; Risau,
1986) a peptide growth factor that influences the
vascularization of the nervous system (Gaspadorowicz, Massoglia,
Chang, Fuji 1986) and promotes development of dopaminergic (Engele and Bohn, 1991) and cerebral cortical
(Morrison, Sharma, DeVillis, & Bradshaw, 1986) neurons.
Active capillary sprouting and branching is observed post
natally in the cerebral hemispheres (Bar &
Wolf, 1972). By
the end of the first year the capillary density of the human cortex
doubles (Purves, 1972)"
-
-
"Brain capillaries, which constitute only 0.1% of the
brain mass (Bar, 1980), are responsible for the transport of glucose
for the entire brain. Glucose
is the prime energy substrate utilized by the high metabolic demand of
the immature brain, as its metabolism accounts for the bulk of the
brain's oxygen metabolism. It
is the blood brain barrier that regulates the transport of glucose
from blood to brain (Fuglsang, Lombolt, & Gjedde, 1998, Lund &
Anderson,1979."
-
- Recent advances have shown that glucose and oxygen
are transferred from the capillaries to the neurons via stellite glial
cells. Glial cell feet on
capillaries breach the blood brain barrier. [ED]
-
- A notable feature of voluntary activation of brain
blood flow is activation as shown by skin conductance measures.
When a person's upper limit in flow is neared there is a rapid
increase in arousal mediated by the reticular activating system.
The reference below points out the importance of such
stimulation in developing brain vasculature
by expressing local regional needs. [ED]
-
-
"Observers have noted that stimulation of the brainstem
reticular formation influences cerebral blood flow and oxygen
consumption (Meyer, Nomura, Sakamoto, & Kondo, 1969), that
highly branched fibers originating in brainstem catecholaminergic
neurons innervate blood vessels in widely dispersed areas of the brain
(Swanson & Hartman, 1975), and that catecholamines regulate
vascular permeability and influence blood flow in the cerebral
microcirculation (Raichle et al., 1975).
Catecholaminergic modulation of microvascular transport of
glucose into orbito-frontal columns would represent a control
mechanism by which oxygen, energy substrate, and catalytic hormonal
factors would be more efficiently delivered into the expanding
orbitofrontal neuropil. The
anatomical maturation of this subcortical system could support
emergent functions that result from more complex synaptic events.
According to Hartman and Udenfreind (1972) the innervation of
brain vasculature by distant catecholaminergic neurons operates as a
regulator that responds to the local needs of the brain regions.
I suggest that this underlies the mechanism whereby
subcortically manufactured biogenic amines regulate the biochemical
response of an individual cerebral cortical cholinergic synapse
(Shimizu, Creveling, & Daly, 1970) and by which a single dopamine
axon can modulate a large number of cortical pyramidal cells (Smiley
et al., 1992). The
monoaminergic control of brain microvascular systems thus mediates an
essential homeostatic role.
-
- b
-
-
-
-
- As becomes clear in the following quotation, it is
important to note that the mere development of brain tissue is
insufficient in itself to insure useful outcomes of brain exercise.
Education and use of newly formed brain tissue is necessary for long
lasting abilities.
- An important part of work with brain deficits is
location and treatment of areas involved in easily recognized
behaviors. With this knowledge a therapist can locate the training HEG
tool to develop those areas most involved in brain deficits
-
- Abstract:
- Objective:
- Method:
- Results:
- Conclusions:
- Discussion:
-
TOVA and Trained EEG
-
Hypoperfusion: EEG and HEG
-
Regulation and measurement of blood
supply
-
Brain structure and exercise
-
Glial feet and blood flow
- Oxygen
availability in cortical blood
-
Use it or lose it
-
Brain development
-
Vascularization and therapy
-
Vascularization of poorly developed areas
-
Localized brain work
-
Body position in space
-
Deep brain structures and cortical
functions (Schore)
- Blood
flow and bioamines
-
-
-
Functional location of speech and memory (Schore)
-
-
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