vestibular system and lit review stuff

Question 1

describe vestibular system anatomy

Answer 1

p 16

Question 2

describe vestibular physiology

Answer 2

p 17

Question 3

describe the vestibular reflexes

Answer 3

p 18/19

Question 4

Day, 1997

Answer 4

• Measurement of the displacement of the COP using a tracked marker placed on the head while exposed to GVS reveals an increase of the total length of the displacement of the COP over a given period of time

Question 5

Yang, 2015

Answer 5

• A study using sway recordings from a force pate over a period of 5 s revealed peak COP displacements up to 4.5 cm laterally from the center of pressure - threshold of GVS exposure producing an acute postural control response to be 0.32 mA

Question 6

Fitzpatrik and Day 2004

Answer 6

• one of the most thorough investigations of mechanisms of action for GVS - current of 1 mA through a mastoid electrode induces a 0.001 mA current in the perilymph fluid

Question 7

Nadeem et al 2003

Answer 7

100 mA/m2 current density can be induced in brain tissue near the inner ear with a 1 mA current (GVS)

Question 8

Miranda et al 2006

Answer 8

• maximum values of 100 mA/m2, corresponding to a 0.22 V/m electric field, could be obtained at levels 3.5 cm below the scalp (2 mA current GVS)

Question 9

salvador et al 2012

Answer 9

highlighted the importance of taking appropriate conductivities of different regions in the head when calculating the induced electric fields produced by tDCS. This highlights the complexities of predicting the exact induced electric fields produced in the human head using modeling studies. In terms of the level of the vestibular system, numerous different fluids and structures with different conductivities must be considered, complicating the induced electric field prediction process.

Question 10

describe how tACS affects the brain

Answer 10

p 23

Question 11

Ferdjallah, Bostick, & Barr, 1996

Answer 11

tACS modeling - a maximum current density of 50 mA/m2 can be reached using a 1 mA stimulus (at the thalamus - deepest portion of brain - corresponds to an electric field value of 0.15 V/m)

Question 12

Merlet et al., 2013

Answer 12

tACS modeling - Induced electric fields reach maximal values (0.198 V/m using a 1.12 mA tACS exposure) just beneath the electrode surface

Question 13

summarize the literature on MFs and the vestibular system

Answer 13

-

Question 14

Theysohn et al. (2014)

Answer 14

7T MRI

• p 24

Question 15

Glover et al. (2007)

Answer 15

studied vertigo with respect to static, pulsed, and time varying magnetic fields

p 24, 29

Question 16

Roberts et al. (2011)

Answer 16

static MF (3 and 7T) produced by an MRI

• p 25

Question 17

Mian et al. (2013)

Answer 17

25 participants to a static MF produced by a 7 T MRI while recording eye movement patterns and reported sensations of motion.

• p 25

Question 18

Van Nierop et al. (2013)

Answer 18

p 26

Question 19

Van Nierop et al. (2015)

Answer 19

• p 26

Question 20

Legros et al. (2012)

Answer 20

p 29

Question 21

(Thomas, Drost, et al., 2001) - 2 studies!

Answer 21

p 30

Question 22

(Prato, Thomas, & Cook, 2001)

Answer 22

p 31

Question 23

explain the 3 proposed mechanisms of action ang who proposed them?

Answer 23

p 32

Question 24

summarize the proposed mechanisms of action table

Answer 24

Question 25

Gandhi, Kang, Wu, & Lazzi, 2001)

Answer 25

described the condictivity of different tissues in the human body

• measured based on electric shavers

Question 26

Gauger, 1985

Answer 26

when measuring at a distance of 3 cm from the source, exposure levels can reach up to 2 mT when using hair dryers

Question 27

(Lambrozo, 2013)

Answer 27

These values can rise however when near a switchboard (1.0 – 3.0 μT, measured at a 300 mm distance from the source) or when standing directly under power lines, reaching values of 20 μT for 225 kV power lines and 30 μT for 400 kV power lines

Question 28

(Mezei et al., 2001)

Answer 28

Considering electrical household appliances, mean MF exposure levels are highest among microwave ovens (> 0.6 μT), coffee grinders (> 0.6 μT ), electric shavers (0.3 μT), and electric hair dryers (0.3 μT)

• using portable mf measuring device

Question 29

(d’Arsonval, 1896)

Answer 29

These flickering perceptions (magnetophosphenes) were first reported in 1896

Question 30

(Lovsund, Oberg, Nilsson, & Reuter, 1980)

Answer 30

The reference study in the domain is from 1980 and it reports a lowest threshold for magnetophosphene perception at 8.1 mT in the dark for a MF stimulus delivered at 20 Hz

Question 31

(Attwell, 2003)

Answer 31

suggested that this perception is due to the modulation of rod cells in the retina, due to their specific properties including a sensitivity to weak membrane depolarization, on the order of 0.6 to 200 μV

Question 32

how does faraday’s law apply to the human body

Answer 32

states that changing the MF flux density, for example by moving through a static MF, induces a current in the human body

Question 33

describe the AC GVS studies

Answer 33

• see file

Question 34

How long does it take GVS to work?

Answer 34

1-2 seconds based on:

Inglis et al. 1995, Day et al. 1997, Yang et al. 2015, Fitzpatrick and Day 2004 (review study)