CA2173202A1 - Hair regrowth method and apparatus - Google Patents

Abstract

Hair regrowth is promoted or hair loss mitigated by positioning two or more electrodes (11) closely proximate, but not touching, a subject's scalp. A low voltage positive or negative polarity pulse train signal having a pulse repetition frequency in the range of about 5 to 35 hertz is applied to the electrodes (11) for about twelve minutes. The subject undergoes a treatment cycle spanning a period of about thirty-two weeks during which one or two of the treatments aforesaid are applied per week.

Description

2 ~ 7 3 2 0 2 PCT/CA93/00408 ~IAIR REGROWTH I~ Ol~ AND APPARAT~JS

Field of the In~ention This application pertains to a method and appar-atus for promoting hair regrowth and/or mitigating hairloss in hllm~n~

~3ackground of the Invention Many individuals are troubled by premature baldness, receding hairlines, or other conditions in which hair is lost from the head. Over the years, a variety of chemicals have been marketed as hair regrowth aids but with mixed, generally disappointing results. Many individuals have invested considerable sums in artificial hair pieces.
Some individuals have even undergone surgical hair implan-tation procedures requiring the exercise of highly skilled medical expertise which is generally unavailable to a wide cross-section of potential beneficiaries. It will thus be appreciated that there is a need for a reasonably inexpen-sive hair regrowth process capable of being ~m;n;stered byrelatively unskilled personnel and capable of promoting hair regrowth in the widest possible population cross-section.

The prior art discloses that a variety of elec-trical stimuli have been employed in an effort to promote hair growth. For example, United States patent No. 861,349 issued 30 July, 1907 for an invention of R.E. Beaubien entitled "Apparatus for Treating the Scalp" discloses an "apparatus for promoting the growth of hair upon the hllm~n head". The apparatus appears to rely upon a combination of pneumatic, vacuum and electrical effects, in combination with the application of medicated lotions and massage to the scalp. According to Beaubien, any desirable form of electrical battery or current may be used. The present applicant however believes that this is not the case and that in order to satisfactorily promote hair regrowth, specific electrical signals must be employed.

WO95/09671 ~ 73 2 0 2 2 - PC~/CA93/00408 .
United States patent No. 735,581 issued 4 August, 1903 for an invention of Pollacsek, et al. entitled "Thera-peutical Apparatus" discloses a device "by means of which vibrations of diseased parts of the body can be produced~.
Pollacsek, et al. indicate that the device may be shaped as a cap to be placed on the head and that the cap may be introduced into a magnetic field produced by -n electric current passing through the windings of an iron core.
However, there is no indication of the specific nature of the electric or magnetic signals or fields employed, nor is there any suggestion that Pollacsek, et al. considered applying their device to promote hair regrowth.

United States patent No. 740,385 iss~ed 6 Octo-ber, 1903 for an invention of W.B. Bassell entitled "Elec-trotherapeutic Appliance" provides another device ~adapted to subject the wearer to the action of a currert of elec-tricity for curative purposes". Bassell explains that his invention is to be utilized for the relief and cure of nervousness, insomnia, headache, and other kildred trou-bles. He suggests that this may be accomplished by sub-jecting the head of the wearer to the action of a compara-tively mild current of electricity provided by a small battery. Again however there is no suggestion that Bassell considered the use of his device to promote hair regrowth, nor are any specific electrical signals discussed.

United States patent No. 3,872,859 issued 25 March, 1975 for an invention of Pitzen, et al. entitled ~Method and Device for Stimulating the Organs Associated with the ~llm~n Scalp" P~mines the problem of promoting hair growth in some detail. Pitzen, et al. provide a method and apparatus in which a plurality of wave form generators output signals having frequencies varying from 230 hertz through 2650 hertz. The waveform gen~rators are also pulsed at repetition rates varying from 3 times per second to 26 times per second. The signals so produced are WO95109671 ~ 17 3 2 0 ~ PCT/CA93/U04~8 applied to hand-held massaging electrodes which are in turn applied to the subject's scalp.

Published French patent application No. 2,484,262 - 5 of Paul Maurice Viallis provides another electrical appar-atus and method for treating the human scalp to combat seborrhoea, hair loss, dandruff, etc. A conducti~e e ec-trode cap is fitted over the scalp and a secondary eLec-trode is placed in contact with another area of the body.
A current of the order of 8-15 mA is applied for a period of 5 to 30 minutes depending upon the type of complaint and type of treatment prescribed. The object of Viallis' invention is apparently to ionize the scalp area so that ointments or other applied treatment compositions may penetrate the scalp with greater effectiveness.

Published West German patent application No.

3!618,933 discloses an invention of Masaki, et al. pertain-ing to an electrotherapeutic device for promoting eyebrow hair growth. The apparatus is shaped to fit on a patient's head. Electrodes are applied to the eyebrows. A pulse-like current preferably having a square or trapezoid waveform is applied to the electrodes, with a biphasic action, potential-like oscillation ha~ing a frequency in 2~ the 1/500 to 1/200 second range and pulsed at a frequency of .5 to 2 seconds is preferably applied to the electrodes.

Two published British patent application Nos.
2,160,426A and 2,160,427A of Masaki appear to correspond to the West German application aforesaid, although the British applications do not appear to restrict themselves to eyebrow hair growth.

United States Patent No. 3,946,745 Hsiang-Lai et al teaches a system in which electrical pulses are applied directly to a living body, for example by attaching elec-woss/os671 2 ~ 7 3 2 0 2 PCT/CA93/00408 trodes to the body by means of an acupuncture needle orspring-loaded earring.

German patent application DE 29 52 850 A1 teaches the use of electromagnetic pulsating fields for stimulat-ing the body functions furthering the growth of hair. Fre-quencies in the 400-420 hertz range are mentioned, with the subject undergoing continuous exposure to the fields, for example by having the subject carry a batte-y powered apparatus on his/her person.

French patent No. 1,350,890 teaches a hair dryer having an electrode structure to which a high frequency voltage generator is electrically coupled in ord~r to apply an intense high frequency electric field to the hair so as to heat and evaporate water from the hair. The patent mentions that the applied field also has a stimulating effect on the cells of the skin and improves blood circula-tion, which is favourable to the metabolism and to healthy growth of hair.

Although not wishing to be bound by any theory, the inventors believe that dormant body hair cells (i.e.
hair cells from which hair is not actively growing) may be electrically stimulated to promote active hair growth from such cells. More particularly, the inventors b~lieve that hair regrowth can be promoted if the body's hair cells are stimulated by subjecting them to a low voltage pulse train having a pulse repetition frequency in the rance of about 5 to 35 hertz. The higher portion of this freq~ency range is considered appropriate for subjects who exhibit normal or hyperactive energy levels. The lower portion of the frequency range is considered appropriate for individuals who exhibit hypoactive or slow metabolism energ~! levels.

WO9S/09671 ~ ~ 3 ~ a 2 PCT/CA93/00408 Summary of the Invention In accordance with the preferred embodiment, the invention provides a process for promoting hair regrowth and/or mitigating hair loss in which two or more electrodes are positioned closely proximate to, but not contact~ the subject's scalp. A low voltage electrical pulse train signal having a pulse repetition frequency in the range of about 5 to 35 hertz is continuously applied to the elec-trodes for about twelve minutes. The polarity o~ the signal may be either positive or negative. A complete hair regrowth treatment cycle typically spans about thirty-two weeks, during which time the subject undergoes a sequence o~ twelve minute treatments as aforesaid. Throughout the treatment cycle the subject undergoes one or two twelve minute treatments per week, during which the treatment fre~uency, signal polarity and voltage level are pre~erably varied according to the following s~he~ e:
Number o~ Voltage Treatments Polarity Level 1st week 2 Positive 110 v.
2nd week 2 Positive 110 v.
3rd week 1 Negative 110 v.
4th week 1 Negative 110 v.
25 5th week 1 Negative 110 v.
6th week 1 Negative 110 v.
7th week 1 Negative 110 v.
8th week 1 Negative 110 v.
9th week 1 Negative 110 v.
30 10th week 1 Negative 110 v.
11th week 1 Negative 110 v.
12th week 1 Negative 110 v.
13th week 1 Negative 110 v.
14th week 1 Negative 110 v.
35 15th week 1 Negative 110 v.
16th week 1 Negative 110 v.
17th week 2 Positive 55 v.
18th week 2 Positive 110 v.
l9th week 1 Negative 55 v.
40 20th week 1 Negative 110 v.
21st week 1 Negative 55 v.
22nd week 1 Negative 110 v.
23rd week 1 Negative 55 v.
24th week 1 Negative 110 v.
45 25th week 1 Negative 55 v.
26th week 1 Negative 110 v.

WO95/0967l ~~1 73 2 V~ pcTlcAs3mo4o8 27th week 1 Negative 55 v.
28th week 1 Negative 110 v.
29th week 1 Negative 55 v.
30th week 1 Negative 110 v.
5 31st week 1 Negative 55 v.
32nd week 1 Negative 110 v.

The invention also provides a hair regrowth apparatus having at least two electrodes which are adapted 0 to be positioned closely proximate to, but not touching a subject's scalp. A voltage pulse generator is electrically coupled to the electrodes for application ther*to of a low voltage pulse train. A frequency selector is electrically coupled to the voltage pulse generator for varying the pulse repetition frequency of the pulse train. A polarity selector is electrically coupled between the voltage pulse generator and the electrodes, for varying the polarity of the pulse train. A voltage selector is electrically coupled between the voltage pulse generator and the elec-trodes, for varying the voltage of the pulse train.

Advantageously, a plurality of electrodes are provided. The electrodes are mounted within -L hood posi-tionable over the subject's head to fonm ~n array of concentric electrically conductive electrode rings. The rings can be applied to an outer surface o~ an electrically insulating liner insertable within the hood. The array preferably comprises five rings mounted within the hood to subtend a 90 arc on both sides of a central perpendicular axis of the hood. The four upper electrodes e~ch subtend-an arc of about 15 and the fifth (lower) electrode sub-tends an arc of about 6, with 6 arc gaps between each pair of electrodes on either side of the cen-ral perpen-dicular axis. The ~oltage pulse generator's O-ltpUt signal is applied across the two upper electrode pairs, with alternate electrodes being connected to one of the two output terminals of the voltage pulse generator. A voltage WO 95/09G71 ~17 3 2 Q 2 PCT/CA93/00408 divider applies a reduced voltage signal to the lower electrode.
n Brief Description of the Drawings " 5 Figure lA is an elevation view of a schematically represented hood liner bearing an electrode array configured for use in practising the invention. Figure lB
is a top view of the Figure lA structure.

Figure 2 is a block diagram of a hair regrowth apparatus constructed in accordance with the preferred embodiment of the invention.

Figure 3 is a partial schematic/block diagram depicting further details of the circuitry utilized with the preferred electrode array.

Figure 4 is an electronic circuit schematic diagram depicting additional details of the preferred apparatus.

Petailed Description of the Preferred Embodiment As shown in Figures lA, lB and 2, the exterior surface of hood liner 10 carries a plurality of electrodes 11. When liner 10 is inserted within hood 13 and the hood placed over a subject's head, electrod~s 11 are positioned closely proximate to, but do not touch the subject~s scalp.

The apparatus is turned on and off with the aid of a mechanical, electrical or electronic timer 12 (Figure 2) operatively con~cted to power supply 14 which may be a conventional 110 volt A.C. to 12 volt D.C. transformer.
The 12 volt D.C. signal output by power supply 14 is regulated down to 8 volts D.C. by voltage regulator 16 and the resultant 8 volt D.C. signal is then used to power the r~m~;n;ng electronic components depicted in Figure 2.
Instead of directly coupling a 110 volt A.C. power source WO95/09671 ~ 7 ~ 2 ~ ~ PCT/CA93/00408 to the circuitry as aforesaid, one may alternatively use power supply 14 to charge a 12 volt D.C. battery. The charged battery can then be used to fulfil the apparatus' power requirements and power supply 14 can be d-sconnected from the llo volt A.C. power source while the apparatus is in use with a subject.

A voltage pulse generator means 18 such as an astable multivibrator is electrically coupled to electrodes 11. Pulse generator 18 applies a low voltag~ train of short duration pulses to electrodes 11 at a selectable pulse repetition frequency. Specifically, frequ~ncy selec-tor switch 20 is electrically coupled to pulse generator 18 to enable the operator to vary the pulse repetition fre-quency within the preferred range of about 5 to 35 hertz.Lamp driver 30 provides a visual indication, via lamp 32, of the selected pulse repetition frequency (i.e. lamp 32 blinks on and off at the selected frequency).

The low voltage pulse train output by pulse generator 18 is amplified by current amplifier ~2 and then presented to pulse transformer 24 which outputs one of two operating voltages (55 volts peak-to-peak; or, 110 volts peak-to-peak). A "signal polarity selector means~; namely, rectifier/filter 26, is electrically coupled between pulse transformer 24 and electrodes 11, thereby en-bling the operator to vary the polarity of the signals output by pulse transformer 24 through m~nll~l selection of one of two positions for polarity switch 28. A "voltage selector means~; namely, two position switch 34 is p-ovided to enable the operator to select one of the two operating voltages aforesaid for the pulse train applied to elec-trodes 11.

Further details of the preferred circuitry are now provided with reference to Figures 3 and 4. The 12 volt D.C. signal output by power supply 14 is electrically WO95109671 ~ 3 ~ ~ 2 PCT/CA93/00408 coupled to voltage regulator 16 which, in the preferred embodiment, is an LM7808 integrated circuit 8 volt regula-tor with internal current limiting, thermal shutdown capability and safe area compensation for the internal pass transistor. Capacitors C~ and C5 respectively provide low frequency filtering for the input and output of regulator 16, which produces an 8 volt D.C. output signal used to power the rem~; n; ng electronic components.

Astable multivibrator 18 is a NE555 integrated circuit pulse generator. The trigger input of astable multivibrator 18 is connected to the threshold input thereof (represented by the dashed line shown in integrated circuit U2 in Figure 4) in order to continuously retrigger the circuit for astable operation thereof. Resistors R1, R2 and R5, together with potentiometers R3 and R4 and timing capacitors C1 and C2 control the frequency o~ the pulse train output by astable multivibrator 18. The output frequency is selected by m~n.l~l positioning of switch SW1 (reference No. 20 in Figure 1) which is a single pole, double throw switch (assuming configuration of the appar-atus to supply pulse trains of two different frequencies;
comparable switching arrangements can be provided if the apparatus is to be configured for use with three or more such frequencies). When switch SW1 is in the "F1" posi-tion, astable multivibrator 18 produces a low voltage, pulse train at a first frequency. When switch SW1 is in the "F2" position astable multivibrator 18 produces a low voltage, pulse train at a second frequency. More particu-larly, when switch SW1 is in the "F1" position, the steadystate frequency of the voltage pulse train output by astable multivibrator 18 is determined by:
F1 = T1 = .693(R2 + R4 + R5)C2 Similarly, when frequency selector switch SW1 is in the "F2" position, the steady state frequency of the voltage WO 95/09671 ~ ~ 7 3 2 ~- 2 Pc~/cAg3mo408 pulse train output by astable multivibrator 18 is deter-mined by:

F2 = T2 = .693(R1 + R3 + R5)C2 The frequency selected is visually indicated ~y flashing light emitting diode D1, which is driven through current limiting resistor R7 and inverting amplifier transistor Q3.
Resistor R8 provides current limiting for ligkt emitting diode D1.
Capacitor C1 is used to bypass pin 5 of the astable multivibrator 18 to ground, preventing noise from altering the width of the pulses output by ast~ble multi-vibrator 18. Capacitor C3 is a bypass capacitor which eliminates high frequency noise on the power line.

The low voltage pulse train output by astable multivibrator 18 passes to a current amplifier ~2 compris-ing transistors Q1 and Q2, which are configured to operate in a class B switching mode to provide the highe- peak cur-rents passed through pulse transformer 24. More particu-larly, when pulse transformer 24 is switched on, a pulse is imposed on the transfonmer primary winding. ~ecause the transformer provides D.C. isolation, the higher~oltage end of the transformer can safely be used to produce a positive or negative-going pulse through the polarity selector means comprising pulse transformer 24 together with a first rectifier means (i.e. diode D2 shown in Figure 3), a second rectifier means (i.e. diode D3 shown in Figure 3) and polarity switch SW2 (reference No. 28 in Figure 1). When switch SW2 is in the "positive~ polarity position, diode D2 in combination with filter capacitor C6 and discharge resistor R9 shape the pulses output by switching trans-former 24, while blocking negative-going portions of the pulse train. Similarly, when polarity selector switch SW2 is in the "negative" polarity position, diodel D3 blocks positive-going portions of the pulse train. The voltage WO95/09671 ~ 3 ~ ~ ~ PCTIC~93/0~408 output across resistor R9 is coupled to the electrodes within hood 13. Limit resistor RlO and voltage selector switch SW3 (reference No. 34 in Figure l) enable the operator to select between one of two operating voltages (55 volts peak-to-peak; or, llO volts peak-to-peak in the preferred embodiment.

Reverting to Figures lA and lB, the preferred electrode array consists of five electrodes ll, each compr_~ing a thin band of conductive material such as copper foil. The bands are applied to fonm approximately concentric rings on the outer surface of hood-shaped liner lO, which is formed of an electrically insulating material such as plastic. Liner lO supports the electrode bands and prevents them from contacting the subject when liner lO iæ
inserted within hood 13. More particularly, hood 13 (which may be a conventional commercial hair dryer hood) is placed over the subject's head so that the inner (i.e. non-electrode bearing) surface of liner lO is adjacent the subject's head. Typically, the subject's scalp is separ-ated from the inner surface of liner lO by a gap of several centimetres.

The number of bands, the width of each band, the spacing between each band, and the relative placement of each band on liner lO are selected so that the electric fields imposed on the subject's scalp under each band are approximately equal and to prevent imposition of excessive electric fields on the subject's ~calp outside the region thereof adjacent electrodes ll. In the preferred embodi-ment, electrodes ll subtend a 180 arc (i.e. 90 on either side of the central perpendicular axis of hood 13 as seen in Figure lA), with the four upper electrodes each subtend-ing arcs of about 15 and the fifth (lowermost) electrode subtending an arc of about 6, with 6 arc gaps between each pair of electrodes on either side of the central perpendicular axis.

W O 95/09671 ~ ~ 7 ~ 5 ~ ~ PC''/CA93/00408 C~ ~ U ~

The full voltage signal output by rec ifier/fil-ter 26 is applied across electrode pair A and B; and, across electrode pair C and D. A voltage divider 36 supplies a half-strength voltage signal for application to electrode E. This reduced voltage assists in preventing imposition of excessive electric fields to the subjectls scalp outside the region thereof adjacent to the elec-trodes, as mentioned above. As shown in Figure 3, voltage divider 36 comprises three series-connected re~-istors R11, R12, and R13. Electrode bands A and C are electrically connected to the voltage dividing point between R11 and R12, band E is electrically connected to the voltage dividing point between R12 and R13, and bands B and D are lectrical-ly connected to the opposite end of R13. In the preferred embodiment, the resistance values of R11 and R13 = 1.2 MQ and R12 = 39 MQ.

Figure 3 also shows further details of recti-fier1filter 26, polarity switch 28 and voltage selectorswitch 34. Specifically, rectifier/filter 26 preferably includes a capacitor C6 connected in parallel across a pair os series-connected resistors R~, R1o; with the capacitance value of C6 = 1.8 pf, and the resistance values of ~ and R1o = .~6 MQ. Polarity switch 28 preferably includes a pair of diodes D2, D3 which may be alternatively switched into the circuit path emanating from either one of the two output leads of pulse transformer 24. (The polarity of the voltage signal applied across any pair of electrode bands is the sign of the voltage difference across those elec-trodes. In the case of the Figure l electrodP array, the polarity is the sign of the vo~tage applied to electrode band A.) Voltage selector switch 34 is coupled across R1o such that, in one position of switch 34 the vo_tage devel-35 oped across ~ is applied to voltage divider 36, and in theother position of switch 34 the voltage developed across WO95/09671 - pcTlcAs3loo4o8 ~73202 the seri~-connected combination of ~ and R10 is applied to voltage divider 36.

In operation, the subject's head is positioned within hood 13, so that electrodes 11 lie closely proximate to ut do not touch the subject's scalp. Power is applied to i-he circuit and switches 20, 28 mAnl-Ally positioned to select a desired signal output frequency and polarity.
Signals of the selected frequency and polarity are applied to electrodes 11 ~or about 12 minutes, following which the power is disconnected and hood 13 remov~ rom the sub-ject's head. Repetitive treatments over many weeks will be required, depending upon the individual characteristics of the particular subject.
An entire hair regrowth/hair loss mitigation treatment cycle will typically span about 32 weeks, during which time the subject undergoes one or two 12 minute treatments as a~oresaid per week. The following table provides the weekly treatment frequency, the signal output polarity and the voltage level preferably employed (accord-ing to empirical determinations) during each week of the 32 week treatment cycle:

Number of Voltage Treatments Polarity Level 1st week 2 Positive 110 v.
2nd week 2 Positive 110 v.
3rd week 1 Negative 110 v.
4th week 1 Negative 110 v.
5th week 1 Negative 110 v.
6th week 1 Negative 110 v.
7th week 1 Negative 110 v.
8th week 1 .Negative 110 v.
9th week 1 . Negative 110 v.
10th week 1 Negative 110 v.
11th week 1 Negative 110 v.
12th week 1 Negative 110 v.
13th week 1 Negative 110 v.
14th week 1 Negative 110 v.
15th week 1 Negative 110 v.
16th week 1 Negative 110 v.

~ 7~2 WO9S/0967l PC /CA93/00408 17th week 2 Positive 55 v.
18th week 2 Positive 110 v.
lsth week 1 Negative 55 v.
20th week 1 Negative 110 v.
5 21st week 1 Negative s5 v.
22nd week 1 Negative 110 v.
23rd week 1 Negative 55 v.
24th week 1 Negative 110 v.
25th week 1 Negative 55 v.
26th week 1 Negative 110 v.
27th week 1 Negative 55 v.
28th week 1 Negative 110 v.
29th week 1 Negative 55 v.
30th week 1 Negative 110 v.
31st week 1 Negative 55 v.
32nd week 1 Negative 110 v.

Some subjects may respond more favourably ~o alternative signal polarities than those set forth above.
Accordingly, based upon professional review, the treatment regimen may be varied by, for example, replacing two of the negative polarity treatments with two positive polarity treatments and then returning to negative polarity treat-ments as prescribed for the balance of the treatment cycle.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance def-ned by the following claims.

Claims (16)

WHAT IS CLAIMED IS:

1. A method of improving the bodily appearance of a human, in which two or more electrodes are positioned closely proximate to but not in contact with said human's scalp, said method characterized by:
(a) applying to said electrodes a low voltage pulse train signal having a pulse repetition frequency in the range of about 5 to 35 hertz;
(b) continuing application of said signal to said electrodes for about 12 minutes; and, (c) repeating steps (a) and (b) at approximately weekly intervals until cosmetically beneficial hair regrowth or mitigation of hair loss is attained.

2. A method as defined in claim 1, further comprising varying said signal's polarity to utilize positive polarity during steps (a) and (b) for some of said weekly interval spaced repetitions, and to utilize negative polarity during steps (a) and (b) for the remainder of said weekly interval spaced repetitions.

3. A hair regrowth treatment cycle spanning 32 weeks, in which two o? more electrodes are positioned closely proximate, but not touching, a human subject's scalp during each one of a sequence of approximately 12 minute treatments to attain cosmetically beneficial hair regrowth, said treatment cycle characterized by:
(a) applying to said electrodes a low voltage pulse train signal having a pulse repetition frequency in the range of about 5 to 35 hertz;
(b) said treatments being applied to said subject at the rate of either one or two treatments per week;
(c) the polarity of said signal is either positive or negative, and the voltage level of said signal is either 110 volts or 55 volts, as follows:

Number of Voltage Treatments Polarity Level 1st week 2 Positive 110 v.
2nd week 2 Positive 110 v.
3rd week 1 Negative 110 v.
4th week 1 Negative 110 v.
5th week 1 Negative 110 v.
6th week 1 Negative 110 v.
7th week 1 Negative 110 v.
8th week 1 Negative 110 v.
9th week 1 Negative 110 v.
10th week 1 Negative 110 v.
11th week 1 Negative 110 v.
12th week 1 Negative 110 v.
13th week 1 Negative 110 v.
14th week 1 Negative 110 v.
15th week 1 Negative 110 v.
16th week 1 Negative 110 v.
17th week 2 Positive 55 v.
18th week 2 Positive 110 v.
19th week 1 Negative 55 v.
20th week 1 Negative 110 v.
21st week 1 Negative 55 v.
22nd week 1 Negative 110 v.
23rd week 1 Negative 55 v.
24th week 1 Negative 110 v.
25th week 1 Negative 55 v.
26th week 1 Negative 110 v.
27th week 1 Negative 55 v.
28th week 1 Negative 110 v.
29th week 1 Negative 55 v.
30th week 1 Negative 110 v.
31st week 1 Negative 55 v.
32nd week 1 Negative 110 v.

- 16a-

4. Apparatus for applying a low voltage train of short duration electrical pulses to at least two electrodes positionable closely proximate to, but not touching a subject's scalp, said apparatus characterized by:
(a) voltage pulse generator means (18) electrically coupled to said electrodes for application thereto of a low voltage pulse train; and, (b) frequency selector means (20) electrically coupled to said voltage pulse generator means, for varying the pulse repetition frequency of said pulse train.

5. Apparatus as defined in claim 4, further comprising signal polarity selector means (26) electrically coupled between said voltage pulse generator means and said electrodes, for varying the polarity of said pulse train.

6. Apparatus as defined in claim 4, further comprising a plurality of said electrodes.

7. Apparatus as defined in claim 4, further comprising voltage selector means (34) electrically coupled between said voltage pulse generator means and said electrodes, for varying the voltage of said pulse train.

8. Apparatus as defined in claim 5, further comprising a plurality of said electrodes.

9. Apparatus as defined in claim 5, further comprising voltage selector means (34) electrically coupled between said voltage pulse generator means and said electrodes, for varying the voltage of said pulse train.

10. Apparatus as defined in claim 5, wherein said signal polarity selector means (26) comprises:
(a) a voltage transformer (24);
(b) rectifier means (26) for blocking selected nega-tive-going or positive-going portions of said pulse train; and, (c) polarity switch means (28) for selectably coup-ling said rectifier means between said trans-former output and said electrodes.

11. Apparatus as defined in claim 10, wherein said elec-trodes are mounted within a hood (13) positionable over said subject's head.

12. Apparatus as defined in claim 4, wherein said elec-trodes further comprise an array of concentric elec-trically conductive rings mounted within a hood (13) positionable over said subject's head.

13. Apparatus as defined in claim 12, wherein said rings are applied to an outer surface of an electrically insulating liner (10) insertable within said hood.

14. Apparatus as defined in claim 12, wherein said array comprises five rings (A, B, C, D, E) mounted within said hood to subtend a 90° arc on both sides of a central perpendicular axis of said hood.

15. Apparatus as defined in claim 14, wherein said array further comprises four upper electrodes (A, B, C, D) each subtending an arc of about 15° and a fifth lower electrode (E) subtending an arc of about 6°, with 6°
arc gaps between each pair of said electrodes, on either side of said central perpendicular axis.

16. Apparatus as defined in claim 15, wherein said voltage pulse generator means output signal is applied across said electrode pair (A, C) and across said electrode pair (B, D) and further comprising voltage divider means for applying a reduced voltage signal to said electrode (E).