Magnetic field stimulation techniques

• US 6,572,528 B2
• Filed: 04/20/2001
• Issued: 06/03/2003
• Est. Priority Date: 04/20/2001
• Status: Expired due to Term

• Current Assignee: Mclean Hospital (Mass General Brigham, Inc.)
• Original Assignee: Mclean Hospital (Mass General Brigham, Inc.)
• Inventors: Renshaw, Perry F., Parow, Aimee, Rohan, Michael L.
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): Veniaminov, Nikita R
• Application Number:
  US09/839,258
• Publication Number:
  US 20020169355A1
• Time in Patent Office: 774 Days
• Field of Search: 600/9, 600/13-15, 607/3, 607/65, 607/72, 607/48-52
• US Class Current: 600/14
• CPC Class Codes: A61N 2/006 for magnetic stimulation of nerve tissue
• CPC Class Codes: A61N 2/02 using magnetic fields produced by coils, including single turn loops or electromagnets A61N2/12 takes precedence

Abstract

The invention involves enhancing brain function by stimulating the brain using magnetic fields. Applications of the new methods include improving the condition of individuals with cognitive disorders, such as depression, and studying the effects of neural stimulation using induced electric fields. These techniques can avoid deleterious effects of psychotropic pharmaceutical treatments, and provide a relatively safe, comfortable, inexpensive means of direct cranial stimulation.

Claims

1. A method of enhancing brain function, comprising:

(a) selecting a subject for enhancement of brain function using a magnetic field

(b) generating a time-varying magnetic field with a maximum strength of less than about 50 G using a sequence of pulses, wherein the duration of each pulse in the sequence is about 1 millisecond and wherein the sequence of pulses has a frequency of about 1 kHz; and

(c) subjecting the subject'"'"'s head to the time-varying magnetic field.

2. A method of enhancing brain function, comprising:

(a) selecting a subject for enhancement of brain function using a magnetic field; and

(b) generating a time-varying magnetic field with a maximum strength of less than about 50 G, wherein the magnetic field induces an electric field in air comprising a series of electric pulses, wherein the electric pulses are monophasic and separated by periods of substantially no electric field; and

(c) subjecting the subject'"'"'s head to the time-varying magnetic field.

3. The method of claim 2, further comprising:

(d) evaluating the subject for enhanced brain function after subjecting the subject to the magnetic field.

4. The method of claim 2, wherein the maximum magnetic field strength is less than about 10 G.

5. The method of claim 2, wherein the magnetic field is a gradient magnetic field that is substantially uniform over at least a region of the brain.

6. The method of claim 5, wherein the gradient is less than 5 G/cm.

7. The method of claim 2, wherein the magnetic field is a gradient magnetic field that is substantially unidirectional over at least a region of the brain.

8. The method of claim 7, wherein the region is a prefrontal cortex.

9. The method of claim 2, wherein

the subject'"'"'s head has a first side and a second side opposite the first side;

the magnetic field is a gradient magnetic field; and

the gradient is substantially oriented from the first side to the second side.

10. The method of claim 9, wherein the first side is an anterior side of the head according to the subject and the second side is a posterior side of the head.

11. The method of claim 2, wherein the subject is human.

12. The method of claim 2, wherein a sequence of pulses is used to generate the magnetic field, and wherein each pulse in the sequence is trapezoidal.

13. The method of claim 12, wherein successive pulses in the sequence have alternating polarity.

14. The method of claim 2, wherein selecting a subject involves identifying a subject showing symptoms of anxiety, depression, or an affective disorder.

15. The method of claim 2 wherein the electric field pulses have an amplitude less than about 5 V/m.

16. The method of claim 2, wherein the electric field is substantially unidirectional over at least a region of the brain.

17. The method of claim 16, wherein the region is an interior region of a brain.

18. The method of claim 16, wherein the unidirectional electric field is oriented from one ear of the subject'"'"'s head to the other ear of the subject'"'"'s head.

19. The method of claim 2, wherein successive electric pulses have alternating polarity.

20. The method of claim 2, wherein the duration of each electric pulse in the sequence is less than or equal to about 1 millisecond.

21. The method of claim 2, wherein the frequency of the series of electric pulses is about 1 kHz.

22. A method of enhancing brain function, comprising:

(a) selecting a subject for enhancement of brain function using a magnetic field;

(b) generating a time-varying gradient magnetic field that is substantially uniform and unidirectional; and

(c) subjecting the subject'"'"'s head to the time-varying magnetic field.

23. The method of claim 22, wherein the magnetic field is generated using a coil having a diameter greater than about 35 cm.

24. The method of claim 22, further comprising:

(d) evaluating the subject for enhanced brain function after subjecting the subject to the magnetic field.

25. The method of claim 22, wherein the maximum magnetic field strength is less than about 10 G.

26. The method of claim 22, wherein the gradient is less than about 5 G/cm.

27. The method of claim 22, wherein the head has a first side and a second side opposite the first side and the gradient is substantially oriented from the first side to the second side.

28. The method of claim 27, wherein the first side is an anterior side of the head according to the subject and the second side is a posterior side of the head.

29. The method of claim 22, wherein the subject is human.

30. The method of claim 22, wherein the a sequence of pulses is used to generate the magnetic field, and wherein each pulse in the sequence is trapezoidal.

31. The method of claim 22, wherein successive pulses in the sequence have alternating polarity.

32. A method of enchancing brain function, comprising:

(a) selecting a subject for enhancement of brain function using a magnetic field;

(b) generating a time-varying magnetic field using a sequence of pulses, wherein the duration of each pulse in the sequence is less than about 10 milliseconds and wherein the pulses in the sequence alternate in polarity; and

(c) subjecting the subject'"'"'s head to the time-varying magnetic field.

33. The method of claim 32, wherein the duration of each pulse in the sequence is about 1 millisecond.

34. The method of claim 32, further comprising:

(d) evaluating the subject for enhanced brain function after subjecting the subject to the magnetic field.

35. The method of claim 32, wherein the magnetic field is a gradient magnetic field that is substantially uniform over at least a region of the brain.

36. The method of claim 35, wherein the gradient is less than about 5 G/cm.

37. The method of claim 32, wherein the magnetic field is a gradient magnetic field that is substantially unidirectional over at least a region of the brain.

38. The method of claim 37, wherein the region is a prefrontal cortex.

39. The method of claim 32, wherein

the head has a first side and a second side opposite the first side;

the magnetic field is a gradient magnetic field; and

the gradient is substantially oriented from the first side to the second side.

40. The method of claim 39, wherein the first side is an anterior side of the head according to the subject and the second side is a posterior side of the head.

41. The method of claim 32, wherein the subject is human.

42. The method of claim 32, wherein each pulse in the sequence is trapezoidal.