This document discusses evoked potentials and several studies that examined the effects of yoga on auditory evoked potentials (AEPs). It describes preparing participants for EEG/EP recordings, the different types of AEPs (brainstem, middle latency, long latency), and how yoga practices like meditation and yoga breathing techniques have been found to impact the latencies and amplitudes of peaks within the AEP waveforms. Several studies found decreased latencies and amplitudes changed during and after yoga interventions compared to control conditions.

1. Yoga and evoked potentials
Yogastha Club, Indian Institute of Technology Bombay
Yogastha e-conference
Presented by:
Dipak Chetry
Patanjali Research Foundation, Haridwar
www.patanjaliresearchfoundation.com
10 July 2020

2. Contents
Neurophysiology lab
Preparing a participant for EEG/EP
Evoked potentials
Studies on yoga & AEPs

3. Our Neurophysiology lab
BrainVision actiCHamp system
Nicolet EDX System, U.S.A
Participant connected
with EEG-FNIRs
Participant ready for AEPs
Monitoring EEG-FNIRs
ATES Neurotravel LIGHT-
EEG

4. Preparing a participant for EEG/EP
Before recording:
The participant is asked to sign a consent form
that gives him permission to do the procedure.
The participant must wash his hair with
shampoo, but conditioner must not be used the
night before the test.
We ensure that participants don’t have any
metallic objects with him. Not taking medication,
history of smoking, using intoxicants, cognitive or
hearing deficits.
The patient must avoid fasting the night before or the day of the procedure.

5. During the EEG procedure:
Electrodes Placement:
To measure the electrical activity in various parts
of the brain, we attach electrodes to different sites
of the scalp based on International10/20 system.
The brain generates electrical impulses that
these electrodes pick up.
We use Gold-plated cup electrodes.
To improve the conduction of these impulses to
the electrodes, a skin preparation gel and
conductive paste is applied to them.

6. Contents of paste:
Calcium Carbonate
Potassium Chloride
Sodium Chloride

7. Recording Conditions:
Participants are seated in a sound attenuated cabin.
Monitored on a closed circuit television to detect if they moved or fell asleep.
Instructions are given through a 2-way intercom, so that participants could remain
undisturbed.
The temperature is maintained at 24.0 ± 1.0°C.
Amplifier Settings & Stimulus:
Standard settings for AEPs recording
Averaged sweeps
The low/ high cut filter
Sensitivity
Artefact reject
Audio setup
Acquisition duration
Montage setup
Rate
Intensity
Delivered through acoustically shielded earphones (Amplivox, UK).

8. Recording of EP during yogic interventions:
After EEG procedure:
After the recording is complete, the technician removed the electrodes.
Participant ready for AEPs
Monitoring Room

9. Artefacts
Physiological Artefacts
Eye movement
Eye blink
Muscle Artefacts
Glossokinetic
Cardiac Artefact
External Artefacts
Phone
Lead Movement
Physical movement
Other risks may be present, these include:
Low blood sugar (hypoglycemia by fasting).
Lights, especially bright or flashing ones
Drinks containing caffeine, such as coffee and cola
Oily hair or the presence of hair spray
Temperature
Noise

10. The electrical potentials produced after stimulation of specific neural tracts.
The brain's time locked response to a sensory stimulus.
CLASSIFICATION OF EVOKED POTENTIALS :
1. SENSORY EVOKED POTENTIALS
 VISUAL EVOKED POTENTIAL
 AUDITORY EVOKED POTENTIAL
 SOMATOSENSORY EVOKED POTENTIAL
2. MOTOR EVOKED POTENTIALS
3. EVENT RELATED POTENTIALS
Introduction to EPs

11. Different types of AEPs:
Brainstem auditory evoked potentials (BAEPs)
Middle Latency Auditory Evoked Potentials (MLAEPs)
Long-latency auditory evoked potentials (LLAEPs)

12. MLAEPs and their neural generator:

13. Types of
AEPs
Citations Interventions Results
LLAEPs Telles et
al., 2015
Meditation The P2 peak latency↓ during and after
meditation. The P1, P2, and N2 peak
amplitudes ↓ during random thinking
and non-meditative focused thinking.
MLAEPs Raghuraj &
Telles,
2004
Right uninostril
yoga breathing
The peak of Na and Nb amplitudes
↑on the right side during practice.
P300
ERPs
Joshi and
Telles,
2009
HFYB The P300 peak latency ↓ after HFYB.
Studies on Yoga and AEPs:

14. Clinical EEG and Neuroscience 2015, 46(4), 299 –309.
The P2 peak latency↓ after meditation.

15. Thank you