120
H. Schmid-Schönbein
under the provision that in the individual subject or patient the photoplethysmographic, electrocardiographic and anemometric records are only taken after the
0.15 Hz band activity has emerged. All experimental results to be described in
Sect. 7.5 were obtained under these highly restrictive experimental conditions, and
it was this situation, which allowed the physiological interpretation we are now in a
position to propose.
7.3 Subjective and Objective Techniques for “Feature
Extraction” from Non-invasively Obtained Time Series
As an added dividend of the synergetic interpretation of fluctuating data obtained
non-invasively from awake human subjects, the Haken–Koepchen “quasi-attractor”
hypothesis proved to be highly successful in distinguishing (on the basis of both
subjective and objective criteria) the highly variable influences of the determinants
mentioned above. Obviously, neuronally mediated vasoconstrictor activity stems
from periodically modulated activities in the neuronal pools (studied by the Gothenburg group) which by its typically “nonlinear” or “eruptive” kinematics which due
to lack of regular periodicity can be clearly distinguished from that originating in the
membranes of arteriolar smooth muscles. As shown by Siegel, the latter is characterised by sinusoidal modulated myogenic activity with a stable attractor and, most
importantly, a “discharge pattern” reminiscent of a linear oscillator. To comprehend this latter claim, it must be taken into account that the direct measurements of
sympathetic efferent activity in both animals and man have not only produced reliable criteria distinguishing between skeleto-muscular and cutaneous vasoconstrictor
ensembles in the spinal cord, but have shown that—again by temporality criteria—are
clearly separable from cardio-accelerator, sudomotor and pilomotor neurons. Exclusively on the basis of the temporal configuration of the discharge patterns (see Häbler
for a review of this topic), a differentiation between various subpools of sympathetic
efferent neurons has become possible. Since the now classical work of the Gothenburg group, it is positively established from detailed and synchronised neurographic
and hemodynamic data, that in keeping with the quasi-attractor concept, the cutaneous microcirculation is indeed linked to discrete “volleys” of the efferent activity
of the sympathetic neurons responsible for cutaneous vasoconstriction.
There are, however, other influences that must be taken into account. After our
group as well as that of Jepsen et al. using only Laser-Doppler measurement have
proven the influence of gravitational effects (presumably by the effect on the transmural pressure and thence the myogenic tone of vascular smooth muscle), the Haken–
Koepchen logic can be applied on the basis of experimentally established physiological knowledge. The configuration of “episodal neurogenic vasoconstriction” is identifiable on the basis of their “non-sinusoidal” configuration and asymmetry of rapid
constriction and slow relaxation (Fig. 7.4), and their predominance can be clearly
related to environmental conditions (ambient temperatures well below 27 °C) and to
H. Schmid-Schönbein
under the provision that in the individual subject or patient the photoplethysmographic, electrocardiographic and anemometric records are only taken after the
0.15 Hz band activity has emerged. All experimental results to be described in
Sect. 7.5 were obtained under these highly restrictive experimental conditions, and
it was this situation, which allowed the physiological interpretation we are now in a
position to propose.
7.3 Subjective and Objective Techniques for “Feature
Extraction” from Non-invasively Obtained Time Series
As an added dividend of the synergetic interpretation of fluctuating data obtained
non-invasively from awake human subjects, the Haken–Koepchen “quasi-attractor”
hypothesis proved to be highly successful in distinguishing (on the basis of both
subjective and objective criteria) the highly variable influences of the determinants
mentioned above. Obviously, neuronally mediated vasoconstrictor activity stems
from periodically modulated activities in the neuronal pools (studied by the Gothenburg group) which by its typically “nonlinear” or “eruptive” kinematics which due
to lack of regular periodicity can be clearly distinguished from that originating in the
membranes of arteriolar smooth muscles. As shown by Siegel, the latter is characterised by sinusoidal modulated myogenic activity with a stable attractor and, most
importantly, a “discharge pattern” reminiscent of a linear oscillator. To comprehend this latter claim, it must be taken into account that the direct measurements of
sympathetic efferent activity in both animals and man have not only produced reliable criteria distinguishing between skeleto-muscular and cutaneous vasoconstrictor
ensembles in the spinal cord, but have shown that—again by temporality criteria—are
clearly separable from cardio-accelerator, sudomotor and pilomotor neurons. Exclusively on the basis of the temporal configuration of the discharge patterns (see Häbler
for a review of this topic), a differentiation between various subpools of sympathetic
efferent neurons has become possible. Since the now classical work of the Gothenburg group, it is positively established from detailed and synchronised neurographic
and hemodynamic data, that in keeping with the quasi-attractor concept, the cutaneous microcirculation is indeed linked to discrete “volleys” of the efferent activity
of the sympathetic neurons responsible for cutaneous vasoconstriction.
There are, however, other influences that must be taken into account. After our
group as well as that of Jepsen et al. using only Laser-Doppler measurement have
proven the influence of gravitational effects (presumably by the effect on the transmural pressure and thence the myogenic tone of vascular smooth muscle), the Haken–
Koepchen logic can be applied on the basis of experimentally established physiological knowledge. The configuration of “episodal neurogenic vasoconstriction” is identifiable on the basis of their “non-sinusoidal” configuration and asymmetry of rapid
constriction and slow relaxation (Fig. 7.4), and their predominance can be clearly
related to environmental conditions (ambient temperatures well below 27 °C) and to