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Methods of Cognitive Neuroscience > Problem 7 > Flashcards

Problem 7 Flashcards

1
Q

Functional near infrared spectroscopy

fNIRS

A

Are non-invasive safe portable, low cost methods of direct + indirect monitoring of the brain activity

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2
Q

Why is fMRI still more widely used than fNIRS ?

A

Due to lower spatial resolution and less familiarity of fNIRS

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3
Q

Functional optical imaging

A

Capitalizes on the changing optical properties of the brain

–> using light in the near-infrared range to measure physiological changes

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4
Q

Oxygenated hemoglobin

A

Refers to a molecule which transports oxygen throughout the body

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5
Q

Why can the near infrared light range discern a change in the concentration of hemoglobin during neurovascular coupling ?

A

Because deoxygenated and oxygenated hemoglobin have different characteristic optical properties

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6
Q

Neurovascular coupling

A

Refers to a mechanism where local cerebral blood flow + volume are increased

–> due to an increase in local arteriolar vasodilation as a result of reduced local glucose + oxygen

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7
Q

How does the fNIRS device work ?

A
  1. Comprised of a light source, coupled to the participants head via

a) Optode/Source
- -> send light (e.g. LEDs, fiber optical builds
b) Light detector
- -> receives + detects light after it has been reflected from tissues

  1. A photodector is placed 2-7cm away from the optode to collect light after it has passed through the tissue
  2. When the distance between optode + photodetector is set at 4 cm the fNIRS signal becomes sensitive to hemodynamic changes within the top 2-3 cm of the cortex

THUS: measures the change in oxygenated hemoglobin since it absorbs some of the light

  1. the difference in the amount of light absorbed by photodetectors will tell us how much oxygen the brain region used
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8
Q

hemodynamic

A

Dynamics of blood flow

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9
Q

Event related optical signal

EROS

A

Capitalizes on the changes in the optical properties of the cell membranes which occur as a function of the ionic fluxes during firing (depolarization)

–> more controversial method

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10
Q

Types of fNIRS implementations

A
  1. Time resolved fNIRS
  2. Frequency domain systems
  3. Continuous wave spectroscopy measurements
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11
Q

Continous wave fNIRS systems

CW

A

Apply light to tissue at a constant amplitude

–> measures the attenuation of amplitude of the incident light

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12
Q

What are the advantages of CW systems ?

A
  1. Can use LEDs rather than lasers, which is more safe for eyes
  2. Can be manufactured more cheaply
  3. Can be designed to be very small, which is practical
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13
Q

Disadvantages of fNIRS

A
  1. Limited spatial resolution
  2. Limitations in use of cranial reference points
  3. Skin + hair pigmentation affects signal detection
  4. Early developmental stage, more cross validation needed
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14
Q

Advantages of fNIRS

A
  1. Non-invasive, safe, low cost
  2. Low sensitivity to herd motion
  3. Portable technology, can provide the continuous measurement of neurobiological signals within variable environmental conditions
  4. Can be integrated with other technologies
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15
Q

Explain why the fMRI is still superior to fNIRS.

A

The fMRI has

  1. Higher spatial resolution
  2. Images the entire brain whereas the fNRIS is restricted to the outer cortex
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16
Q

In which respect may the fNIRS be superior to the fMRI.

A
  1. Cheap
  2. Can be integrated with EEG + TMS
  3. Quiet
  4. People can sit up and move around, head must not be positioned in a certain way
17
Q

Brain computer interface

BCI

A

Refers to a system that connects the brain with a computer

–> allows for controlling external devices without having to rely on motor output

18
Q

How does the BCI work ?

A
  1. Measure brain activity
    - -> via funcional neuroimaging method
  2. Extracting specific features
  3. Translating these features into commands
    - -> by means of algorithms
  4. Command transferred to computer
  5. Neurofeedback
19
Q

EEG-based BCI

A

Use the P300 component

–> Computer detects the p300 component that is elicited when metric elements contain the chosen alphabetic character are presented

20
Q

MEG based BCI

A

Can instantly measure + compute magnetic field perturbation as a result of neuronal activity

–> used in real-time BCI

21
Q

fMRI-based BCI

A

Individuals can receive info on the state of their own brain activity on-line

–> can thus try to control it

22
Q

NIRS-based BCI

A

Detects the hemodynamic responses corresponding to the p300 component

–> good version to use because it is flexible and portable, affordable

Methods of Cognitive Neuroscience (9 decks)

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