An Inter-Disciplinary Resource Website to Effects on Human Electrodynamic Physiology
www.uncg.edu/~t_hunter/sound.html |
Site Map |
Patent No. 6238333 Remote magnetic manipulation of nervous systems (Loos, May 29, 2001)
Abstract
Apparatus and method for remote manipulation of nervous systems by the magnetic dipole field of a rotating bar magnet. Reliance on modulation of spontaneous spiking patterns of sensory nerve receptors, and exploitation of a resonance mechanism of certain neural circuits, allows the use of very weak magnetic fields. This, together with the large magnetic moments that can be obtained with a permanent bar magnet, makes it possible to effectively manipulate the nervous system of a subject over a distance of several hundred meters, using a small portable battery-powered device. The method can be used in law enforcement for standoff situations.
Notes:
BACKGROUND OF THE INVENTION
The invention relates to stimulation of nerves by pulsed magnetic fields. Such
fields induce in the body of an exposed subject eddy currents that are proportional
to their rate of change. The currents may cause classical nerve stimulation
wherein the nerve membrane is depolarized enough for the nerve to fire. At low
frequencies, such a mechanism requires rather large magnetic fields. Fortunately,
low-frequency magnetic manipulation of the nervous system is possible by another
mechanism which allows the use of very much weaker fields. Instead of relying
on causing the firing of normally quiescent nerves, the method uses modulation
of the spiking patterns of spontaneously firing nerves. That this can be done
with very small tissue electic fields was discussed more than four decades ago
by C. A. Terzuolo and T. H. Bullock in "Measurement of Imposed Voltage Gradient
Adequate to Modulate Neuronal Firing", Proceedings of the National Academy of
Sciences U.S.A., Physiology, 42, 687 (1956). The effect can be exploited in
magnetic as well as in electric stimulation, because the physiological effects
of the former are solely due to the electric field that is induced by the rate
of change of the magnetic field, and by the electric polarization that occurs
as the consequence of the induced eddy currents.
The human nervous system exhibits a sensitivity to certain low-frequency stimuli,
as is evident from rocking a baby or relaxing in a rocking chair. In both cases,
the maximum soothing effect is obtained for a periodic motion with a frequency
near 1/2 Hz. The effect is here called "the 1/2 Hz sensory resonance". In the
rocking response, the sensory resonance is excited principally by frequency-coded
signals from the vestibular end organ. However, the rocking motion also induces
body strains, and these are detected by stretch receptors residing in the skin
and elsewhere in the body. In addition, relevant signals may originate from
thermal receptors which report skin temperature fluctuations caused by air currents
that are induced by the rocking motion. All these receptors employ frequency
coding in their sensory function, and it must be that their signals are combined
and compared in the brain with the vestibular nerve signals in an assessment
of the somatic state. One may thus expect that the sensory resonance can be
excited not only through the vestibular nerve, but also separately through the
other sensory modalities mentioned. This notion is supported by the observation
that gently stroking of a child with a frequency near 1/2 Hz has a soothing
effect. Further support derives from the successful excitation of the 1/2 Hz
sensory resonance by weak external electric fields, as discussed in "Method
and Apparatus for Manipulating Nervous Systems", U.S. Pat. No. 5,782,874. The
1/2 Hz sensory resonance involves the autonomic nervous system, and it can be
used to induce relaxation, sleepiness, or sexual excitement, depending on the
precise stimulation frequency and the affected afferent nerves. Another sensory
resonance has been found at about 2.4 Hz; it involves the cortex since it can
slow the speed of silently counting from 100 to 60, with the eyes closed, as
discussed in the '874 patent and in U.S. Pat. No. 5,800,481. For both electric
field and thermal stimulation, prolonged exposure to fluctuating electric fields
near 2.4 Hz has been found to have a sleep-inducing and dizzying effect. The
same physiological effect is expected for pulsative magnetic stimulation, since
electric fields are induced in the tissue by the changing magnetic field. When
using the nerve modulation method, reliance on resonance mechanisms further
reduces the stimulation strength required for manipulating the nervous system.
SUMMARY
Oscillatory magnetic fields induce electric fields in exposed biological tissue
and can therefore act on nerves. Considerable tissue electric fields are needed
to cause firing of otherwise quiescent nerves, but very much smaller fields
suffice for modulation of spontaneous nerve spiking. Still weaker fields can
be used for exciting resonances in certain neural circuits through evoked signals
from afferent somatosensory nerves which carry the modulated spiking patterns
to the brain.
It has been found that, in this manner, weak oscillatory magnetic fields with
an amplitude between 5 femtotesla and 50 nanotesla can be used for manipulating
the human nervous system, when the fields are tuned to certain frequencies near
1/2 Hz that cause excitation of sensory resonances. Observable physiological
consequences of the resonance include ptosis of the eyelids, relaxation, sleepiness,
and sexual excitement, depending on the precise frequency used, and on the location
and duration of the magnetic field application.
Both topical and systemic field administration have been found effective. For
the latter case the field can be produced over a considerable distance by a
rotating permanent magnet that has a large magnetic moment. This makes it possible
to manipulate a subject's nervous system over a range of several hundred meters,
such as to cause relaxation and drowsiness. The method can be used in law enforcement
for standoff situations.
Simple devices which use a rotating bar magnet are disclosed. Multiple rotating
bar magnets can be used, and the phase angles of the magnets may then be arranged
to cause constructive interference of the magnetic fields induced in the subject.
DETAILED
DESCRIPTION
It has been found in our laboratory that a weak oscillatory magnetic field can
be used to excite the 1/2 Hz sensory resonance. Sinusoidal magnetic fields have
been observed to induce ptosis of the eyelids, relaxation, sleepiness, a "knot"
in the stomach, a soft warm feeling in the stomach, a tonic smile, sudden loose
stool, and sexual excitement, depending on the precise frequency used, the part
of the body exposed, and the strength and duration of the field application.
The frequencies for these effects are all close to 1/2 Hz. The physiological
effects are experienced after the subject has been exposed to the field for
an extended time, ranging from minutes to hours. Even for optimum frequency,
the effects have been observed only for weak fields with amplitudes roughly
in the range from 5 femtotesla to 50 nanotesla.
Use of square waves for the time dependence of the magnetic field gives similar
results, but there is a peculiar harsh feeling that is absent for sine waves,
attributed to the strong higher harmonics in the square wave.
The effects have been obtained with systemic field applications as well as with
topical applications of a localized magnetic field, either administered to the
head or to body regions away from the head; successful excitation in the latter
case shows that the magnetic field can act on somatosensory nerves.
Fixing all experiment parameters but the magnetic field amplitude, the described
physiological effects are observed only for field amplitudes in an interval,
called "the effective intensity window". This feature of sensory resonances
may be understood as due to nuisance-guarding neural circuitry which blocks
impertinent repetitive sensory signals from higher processing. For the guarding
circuitry to spring in action, the amplitude of the nuisance signals needs to
exceed a certain threshold. This explains the upper boundary of the effective
intensity window. The lower boundary of the window is simply due to the detection
threshold for the sensory signals.
Systemic application of an approximately uniform rotating magnetic field at
a frequency of 0.55 Hz and an amplitude of 2.3 nanotesla results in wooziness
after about two hours of exposure; sexual excitement sets in about one hour
later. The rotating magnetic field for this experiment was obtained by using
a 33 rpm phonograph turntable which carries two permanent magnets with a total
magnetic moment of 6.5 Am.sup.2 ; the distance to the subject was 10.4 m. Allthough
the use of the 33 rpm turntable is convenient, the frequency is not quite optimum
for excitation of the 1/2 Hz sensory resonance. This explains the long exposure
times needed to obtain a physiological response, accounting for the drift in
resonance frequencies described in the '874 patent. Other experiments with systemic
application of magnetic fields, albeit with slightly greater nonuniformity,
have given results that are similar to those obtained with topical applications
of sharply localized fields. The rotating magnet device shown in FIGS. 3-5 is
discussed later in the context of law enforcement in standoff situations, but
it may be employed for therapeutic purposes as well. The device can be used
for collective treatment of a number of subjects in a single building or in
a complex of buildings.
The physiological effects induced by the magnetic field over an extended time
often linger for as much as an hour after ending the application. This suggests
that the endocrine system is affected, either directly or indirectly.
Experiments with magnetic field therapy for mild insomnia have been conducted
for over 200 nights, using a variety of voltage generators and coils. Among
the various wave forms, sine waves have given the best results when used with
very weak fields, of the order of 10 femtotesla, applied to the lower lumbar
region of the body. A typical frequency used in these experiments is 0.49 Hz.
A virtue of the very weak fields is that habituation to the stimulus is at a
minimum, so that the treatment remains effective over many nights. Habituation
is further minimized by using multipole magnetic fields. Such fields are sharply
localized, and they have strongly nonuniform spatial distributions. As a result,
the evoked somatic signals received by the brain from the various parts of the
body are strongly nonuniform and localized. Therefore, changes in sleep position
cause a large variety of sensory patterns of limited duration. Another successful
approach for controlling habituation is to limit the magnetic field application
to half an hour or so; larger field strengths can then be used.
Experiments for inducing sexual excitement by sinusoidal magnetic fields have
been performed using topical as well as systemic field application. Topical
application of a sinusoidal multipole magnetic field of order six to the lower
lumbar region, with maximum field amplitude of about one nanotesla, usually
causes after about 13 minutes of exposure an erection that can be maintained
as long as an hour. Effective frequencies depend somewhat on physiological conditions,
but a typical frequency for obtaining this effect is 0.62 Hz.
The experiments suggest a method and apparatus for manipulating nervous systems
by fluctuating magnetic fields. The method has two fundamental features: use
of modulation of spontaneous spiking activity of certain types of somatosensory
receptors, and the exploitation of sensory resonances. Both these features allow
reduction of the magnetic field amplitude, and in combination they make possible
small and compact battery-powered devices that can be used by the public for
induction of relaxation, sleepiness, or arousal, and clinically for the control
and perhaps the treatment of tremors and seizures, and disorders of the autonomic
nervous system, such as panic attacks.
A sensory resonance has been found near 2.4 Hz, that can be excited by weak
pulsed external electric fields, or by weak heat pulses delivered to the skin,
or by subliminal acoustic pulses, as discussed respectively in U.S. Pat. Nos.
5,782,874 and 5,800,481, and U.S. patent application Ser. No. 08/961,907. It
is expected that this resonance can also be excited magnetically. Other sensory
resonances may perhaps be found, with frequencies below 45 Hz.
An embodiment of the invention is shown in FIG. 6, where a voltage generator
1, labeled "GEN", is connected through a thin coaxial cable 2 to a coil assembly
3; the latter is placed some distance beneath the subject 4 near the body region
selected for topical field application. The frequency of the voltage generator
1 can be manually adjusted with the tuning control 5, so that by manual scanning
frequencies can be found at which sensory resonances are excited. Upon being
energized by the generator 1, the coil assembly 3 induces a magnetic field with
field lines 6, which at large distances is a multipole field. The coil 3 can
be conveniently placed under the mattress of a bed. The setup of FIG. 6 has
been employed in the insomnia therapy experiments and the sexual arousal experiments
discussed.
A simple near-sine-wave generator suitable for driving the coil of FIG. 6 is
shown in FIG. 8. The battery-powered generator is built around two RC timers
16 and 17, and an operational amplifier 18. Timer 17 (Intersil ICM7555) is hooked
up for astable operation; it produces a square wave voltage with a frequency
determined by potentiometer 19 and capacitor 20. The square wave voltage at
output 21 drives the LED 22, and serves as the inverting input for the amplifier
18 (MAX480), after voltage division by potentiometer 23. The noninverting input
of amplifier 18 is connected to an intermediate voltage produced by resistors
24 and 25. Automatic shutoff of the voltage at point 26, that powers the timer
and the amplifier, is provided by a second timer 16 (Intersil ICM7555), hooked
up for monostable operation. The shutoff occurs after a time interval determined
by resistor 27 and capacitor 28. Timer 16 is powered by a three-volt battery
29, controlled by a switch 30. The amplifier 18 is hooked up as an integrator;
additional integration is performed by the capacitor 31 and resistor 32. The
resistor 33 limits the output current to the terminals 34 that are connected
to the coil assembly by the coaxial cable 2.
For topical magnetic field applications, such as illustrated by FIG. 6, it is
important to have a sharply localized magnetic field, either to avoid unwanted
exposure of body regions away from the region of application, or to decrease
habituation, as discussed above. A planar coil assembly suitable for the induction
of such sharply localized magnetic field is shown in FIG. 7. The assembly consists
of four coils, referred to as 7, 8, 9, and 10, with alternating winding directions.
The series assembly of coils is connected to the coaxial feed cable 2. The coils
7-10 are mounted on an adhesive sheet 11 of insulating material, and the assembly
is covered with adhesive tape. The coil diameters are proportional to 1, 2,
3, and 2, and the number of windings are respectively proportional to 4, -6,
4, and 1, where positive and negative numbers denote respectively clockwise
and counterclockwise windings. For clarity the connecting wires between coils
are shown as running at some distance from each other, but these wires should
actually be laid very close together, in order that their induced magnetic fields
cancel each other as much as possible. With this understanding, the coil assembly
of FIG. 7 can be shown to induce at large distances a magnetic field that falls
off as the ninth power of distance.
Eddy currents are induced in tissue by time-varying magnetic fields. Time dependence
can of course be achieved by rotating an otherwise steady magnetic field. Since
large steady fields can be obtained from a permanent magnet without spending
energy, it is sensible to produce the rotating field by mechanically rotating
a permanent magnet. There are several patents, such as U.S. Pat. Nos. 4,727,857
and 5,667,469, wherein such an approach is used for topically inducing therapeutic
low-frequency eddy currents by means of equipment placed closely adjacent to
the patient's skin.
As aluded to earlier, rotating magnetic fields can also be used for remote systemic
magnetic manipulation of the nervous system of a subject, "remote" meaning at
a distance exceeding three meters. The dominant field far away from a magnet
is a dipole field, which falls off as the third power of distance. The very
small field strengths that suffice for magnetic excitation of sensory resonances,
together with the large magnetic moments that can be achieved with permanent
magnets, make remote magnetic manipulation of nervous systems with small and
compact devices a practical possiblity. For instance, for a device of 20 cm
overall diameter the magnetic moment of a fitting bar magnet can easily be as
large as 52 Am.sup.2, and such a magnet is capable of inducing a 0.39 pT magnetic
field at a distance of 300 m. By tuning the magnet rotation to a sensory resonance
frequency near 1/2 Hz, such a field amplitude is sufficient to cause drowsiness.
The arrangement is thus suitable for a non-lethal weapon which may be used,
for instance, in law enforcement standoff situations. Such an application is
illustrated in FIG. 1, where subjects are holding out in a house 52. Shown are
squad cars 53, one of which is equiped with a rotating magnet device. The magnetic
dipole field emanating from the device is illustrated schematically by field
lines 54. The rotation of the permanent magnet causes the magnetic field to
rotate, and FIG. 2 shows field lines 54' a short time later, after the magnet
has made a quarter turn. When the magnet rotation is tuned to the appropriate
sensory resonance frequency, the oscillatory eddy currents induced in the subject's
bodies may cause sleepiness, which would diminish the subject's alertness and
clarity of thought. It is noted that the physiological effects of the magnetic
excitation of sensory resonances appears to be larger when 60 or 50 Hz power
fields are absent, so that there may be merit in turning off the electric power
to the house, if this can be done safely and is not contraindicated by other
considerations.
A suitable rotating magnet device may be designed along the following lines.
The magnetic field projected upon the remote subject must have, at the large
range involved, an amplitude in the effective intensity window. Since this field
is predominantly of dipole nature, and is therefore approximately proportional
to the magnetic moment of the magnet, it is advantageous to maximize the magnetic
moment within the imposed constraints. The moment is the product of the distance
between the magnetic poles and the strength of the poles, expressed as the emanating
magnetic flux. Thus, other things remaining the same, the poles need to be as
far away from each other as possible. Clearly, a horse-shoe magnet will not
do; rather, the optimum configuration is a bar magnet. A second issue pertains
to the orientation of the bar magnet with respect to the rotation axis. This
orientation is expressed as the angle .gamma. between the rotation axis and
the bar magnet axis, defined as the line connecting the centers of the pole
faces (this line is also the direction of the magnetic moment vector). Since
the eddy currents induced in the body of the exposed subject are proportional
to the rate of change of the magnetic field, the amplitude of the field oscillation
needs to be maximized. This is done by choosing the angle .gamma. as ninety
degrees. The next question is how to choose the angle .beta. between the rotation
axis and the line that connects the magnet with the subject. To answer this
question it must be noted that the field along the front direction of the magnet,
i.e., along the magnet axis, is twice as large as the field along the side direction,
i.e., ninety degrees away from the magnet axis. It follows that the angle .beta.
best be chosen as ninety degrees, because the field oscillation amplitude then
benefits from the strong field along the front direction of the magnet.
A rotating magnet device designed along the aformentioned lines is illustrated
in FIG. 3, which shows a shaft 62 that is free to spin in a bearing 63, and
is driven by a stepper motor 78. The spinning motion may be continuous or may
proceed in discrete steps. Mounted on the shaft is a bar magnet 55 with pole
faces 57 and 58, that have polarities labelled "N" and "S". The bar magnet has
an axis 79 that connects the centers of the pole faces. The angle .gamma. between
the magnet axis 79 and the axis 59 of the shaft 62 is substantially ninety degrees.
A subject 4' is located remote, i.e., at least 3 meters, from the rotating magnet
device. The device is oriented such that the angle .beta. between the shaft
axis 59 and the geometric straight line 56 that connects the shaft 62 with the
subject 4' is substantially ninety degrees. To define the line 56 precisely,
it is specified to go through points A and B, where point A is the position
of the apparatus, taken as center of gravity of the shaft 62, and point B is
the location of the subject, taken as the center of gravity of the body of the
subject 4. The angles .beta. and .gamma. are not critical, and "substantially"
may be read as "within 20 degrees". With the mentioned angle .gamma., the pole
faces of the bar magnet will be substantially parallel to the shaft axis. Further
shown are field lines 54 of the magnetic field induced by the bar magnet 55.
As the latter is rotated by the stepper motor 78, the nearly uniform magnetic
field induced in the body of the subject 4' varies in time, so that eddy currents
are induced in the electrically conductive body.
One may use a composite bar magnet that consists of two magnets separated by
a ferromagnetic spacer, for the purpose of inexpensively increasing the magnetic
moment.
Driving circuitry for the rotating magnet of FIG. 3 is illustrated in FIG. 4,
showing a clock 70 which generates a square wave train of clock pulses 71 that
are processed by a counter 72 which outputs a pulse 50 at every Nth clock pulse,
the integer N being provided by the output of a counter 73, and shown by the
display 67. The integer N can be increased or decreased by push buttons 74 and
75, respectively labelled "UP" and "DOWN". The counter 73 together with the
buttons 74 and 75 is therefore effectively a tuner for controlling the frequency
of the pulses 50. These pulses are processed by the driver 77, connected to
the stepper motor 78.
The law-enforcement personnel present at the standoff site will of course also
be subjected to the rotating magnetic field, and this constitutes a major drawback
of the method. The effective intensity window may relieve this problem to some
extent, since the personnel experience large fields that may lie outside the
window. Yet, frequent changes of personnel may be required in order to have
an alert crew at all times.
Multiple devices may be used; all magnets then should rotate with the same frequency,
although interesting beat effects arise when the individual frequencies are
somewhat different. Use of multiple devices raises two new issues. Let all devices
be located in the ground plane, i.e., a plane through the local ground surface,
or, in hilly or mountanous terrain, tangent to the ground at the subject's location.
Let devices n=1, 2, . . . m be located at .theta..sub.n, r.sub.n, where (.theta.,r)
are polar coordinates in the ground plane, centered at the subject. The angle
.phi..sub.n between the shaft axis of the nth device and the ground plane is
pertinent and needs to be specified. For the setup depicted in FIGS. 1-3, the
angle .phi. is ninety degrees. The second issue concerns phases. For the standard
case with both .beta. and .gamma. equal to ninety degrees, the phase .alpha..sub.n
of bar magnet n may be taken as the angle, at a fixed time, between the magnet
axis and the line that connects the magnet with the subject; in FIG. 3 these
lines are respectively shown as 79 and 56. It is advantageous to choose the
phase angles .alpha..sub.n such that at the subject the magnetic fields induced
by the individual rotating magnet devices interfere constructively, since that
results in a larger total field oscillation amplitude. How to achieve this depends
on the angles .alpha..sub.n. One choice is to take all .alpha..sub.n zero, so
that the magnets rotate in planes that are perpendicular to the ground plane.
For m=2, the choice .theta..sub.1 =0, .theta..sub.2 =.pi. is advantageous, and
should be used with a phase difference .alpha..sub.2 -.alpha..sub.1 =.pi.. The
fields at the subject then interfere constructively and result in a total oscillatory
field amplitude that is the sum of the amplitudes for the single devices. For
three devices located at about equally spaced angles .theta..sub.n around the
circle one can take .alpha..sub.2 -.alpha..sub.1 =.pi. and .alpha..sub.3 -.alpha..sub.1
=.pi., and get considerable constructive interference, but for a larger number
of devices placed at about equally spaced angles .theta..sub.n around the circle
it is better to choose all .phi..sub.n equal to .pi./2 so that the magnets rotate
in planes that are parallel to the ground plane and the field along the side
directions of the magnets can contribute to constructive interference. Finding
the optimum values for the phases .alpha..sub.n requires some work. To show
how this may be done, consider a Cartesian coordinate system (x,y) in the ground
plane, centered at the subject, such that the y-axis coincides with the direction
.theta.=0, with the the x-axis chosen such that rotation from the y-axis to
the x-axis involves an increasing angle .theta.. It can be easily shown that
the magnetic field induced at the subject by the nth device has the Cartesian
components
where M.sub.n is the magnetic moment of the nth magnet, the permeability .mu.
should be taken as 4.pi..times.10.sup.-7 henries/m, and t denotes time. The
resultant magnetic field vector B is found by calculating the sum B.sub.x of
the B.sub.nx for all n, and the sum B.sub.y of the B.sub.ny for all n; the vector
B then has the components B.sub.x and B.sub.y. As time proceeds, the end point
of the vector B circulates with the radian frequency .omega. along an ellipse
with long axis 2B.sub.max. The task at hand is to find the phase angles .alpha..sub.n
that optimize B.sub.max. This problem can be solved numerically with a grid
of values .alpha..sub.n ; since the maximum in B.sub.max is rather broad, the
grid can be chosen as coarse. Tables of solutions can be prepared once and for
all for typical configurations involving a few rotating magnet devices. In practice,
device configurations must be chosen such that B.sub.max lies in the effective
intensity window for the chosen sensory resonance.
In the best mode no separate stepper motor is used, and the necessary torque
on the magnet is supplied by magnetic fields induced by coils placed close to
the magnet. This is illustrated in FIG. 5, where the bar magnet is composite,
consisting of two permanent magnets 60 mounted on a ferromagnetic spacer 61,
which is fastened to the shaft 62 that can rotate freely in bearings 63. Coils
64 are mounted such as to cause the magnet assembly to engage in a spinning
motion, when pulsed currents are passed through the coils in properly phased
manner. The currents are caused by a driver 65 connected to the coils by wires
66. The period of rotation of the magnet assembly is determined by the pulse
frequency of the driver 76, and is shown by the display 67; the period can be
changed by operating the up and down buttons 68 and 69. The driver may include
a control unit 51 which can be programmed to provide a chosen schedule of activity
times and frequencies. The driver and the control unit are standard circuits
well known to those skilled in the art.
For military applications the device
of FIG. 5, properly designed for compactness and for withstanding shock, can
be air dropped or shot by mortar to locations near foes so that the latter can
be subjected to magnetic manipulation. It is then suitable to arrange for radio
control of the device. Since the rather slow rotation of a well-balanced magnet
assembly can be maintained by small coil currents, battery power is viable.
A startup circuit needs to be provided to get the magnet rotation going.
Human sensitivity to very weak magnetic fields at sensory resonance frequencies
is not understood. U.S. Pat. No. 5,935,054 contains a discussion of several
aspects of this problem. In addition, it is noted that cutaneous stretch
receptors may be involved in the response to the weak magnetic fields, because
the polarization charges that accumulate on surfaces of discontinuity of the
electric conductivity as a result of the eddy currents decay slowest on the
skin, if the subject is electrically isolated from the surroundings. Thermal
smearing of the polarization charges in the epidermis over a layer with thickness
of the order of the Debye length then may cause an electric field to act on
susceptable stretch receptors that lie close to the epidermis or protrude from
the dermis into the epidermis. This electric field oscillates with the frequency
of the applied magnetic field and may perhaps cause frequency modulation of
the spontaneous spiking of the stretch receptors.
The method is expected to be effective also on certain animals, and application
to animal control is therefore envisioned. The nervous system of mammals is
similar to that of humans, so that sensory resonances are expected to exist.
The disposition towards the 1/2 Hz resonance is thought to have its origin in
the fetal state, developed through the rythmical sensations caused by the mother's
walk, associatively coupled with hormone concentrations. For mammals, one expects
a resonance of this type at about the frequency of the mother's relaxed walk.
Accordingly, in the present invention, the subjects are mammals.
The invention is not limited by the
embodiments shown in the drawings and described in the specification, which
are given by way of example and not of limitation, but only in accordance with
the scope of the appended claims.