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Brain and behaviour > Lecture 7 > Flashcards

Lecture 7 Flashcards

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1
Q

Manipulating brain-behaviour interactions

A

DBS, TMS

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2
Q

Measuring the brain’s electrical activity

A

EEG, MEG

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3
Q

Anatomical imaging techniques

A

CT, MRI

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4
Q

Functional brain imaging

A

fMRI, fNRI, PET

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5
Q

Postmortem examination in humans with brain lesions

A
  • Focus on the substantia nigra
  • Healthy SN will show cell bodies of dopamine neurons
  • Weakened SN will show degenerated dopamine neurons - contributing to symptoms of Parkinson’s disease
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6
Q

Neuropsychological testing of humans with brain lesions

A
  • Examiner taps out a sequence of blocks. The block numbers are visible in the examiner’s side of the board but not the participants side.
  • Participants’ task is the trace between the two outlines of the star like looking at their hand in a mirror. Crossing a line constitutes an error.
  • Participants’ task is to identify which picture they saw most recently.
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7
Q
A
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8
Q

Brain research techniques (5)

A
  • Spatial resolution
  • Temporal resolution
  • Invasiveness
  • Anatomical (static)
  • Functional (dynamic)
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9
Q

Sterotaxic appartus

A

Allows targeting of a specific part of the brain.

  • Psychosurgery (ablation, lesions, gamma “knife” radiation)
  • Deep brain stimulation
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10
Q

Psychosurgery

A
  1. Irreversible lesion techniques
  2. Reversible lesion techniques
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11
Q

Irreversible lesion techniques

A
  • Electrolytic
  • Neurotoxic
  • High-intensity focused ultrasound (HIFU)
  • Permanent lesions lead to compensation (neuroplasticity)
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12
Q

Reversible lesion techniques

A
  • Regional cooling
  • Local administration of a GABA agonist
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13
Q

Electrolytic

A

Burning by passing current through electrode

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14
Q

Neurotoxic

A

Intoxication through infusion of neuron-killing chemical

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15
Q

High intensity focused ultrasound

A

Heating with focused ultrasonic beams

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16
Q

Deep-brain stimulation (DBS)

A

Electrodes implanted in the brain stimulate a target area with continuous pulses of low-voltage electrical current to facilitate behaviour

17
Q

Four major techniques for measuring the brains electrical activity

A
  1. Single cell recording (action potentials)
  2. EEGs (graded potentials)
  3. ERPs
  4. MEGs
18
Q

Single cell recording

A
  • Extracellular: record electrical activity of multiple neurons at once (clusters)
  • Intracellular: allows study and recording of electrical activity of a single neuron

Main disadvantage is that it works well for dish grown neurons but requires surgery when recording brain cells in living organisms

19
Q

EEG

A

Measures graded potentials (EPSP & IPSP) of similarly orientated neurons that are simultaneously active

  • High temporal resolution
  • Poor spatial resolution
20
Q

Why can EEG not record action potentials?

A

Potentials can only be recorded at the scalp if they occur at approximately the same time across thousands or millions of neurons.

  • Action potentials have very short duration (1ms)
  • Neurons rarely fire at exactly the same time
    Axons are relatively randomly orientated
21
Q

EEG recording postsynaptic potentials

A
  • EPSPs and IPSPs typically last longer (10s-100s ms)
  • EPSPs and IPSPs occur instantaneously
  • EPSPs and IPSPs occur at dendrites and cell bodies, which are typically orientated perpendicular to the surface of the cortex

NB: graded potentials recorded at the scalp reflect summed EPSPs and IPSPs

22
Q

MEGs

A

Magnetic counterpart of EEG and ERP.
Main disadvantage: more expensive than EEG, ERP

  • High temporal resolution
  • High spatial resolution
23
Q

Why does MEG have a higher spatial resolution than EEG?

A

Magnetic waves undergo less distortion through brain tissue and scalp compared to EEG or ERP

24
Q

Source localisation in EEG and MEG

A

Record data first, the ntry to infer what sources ‘caused’ data.

Inverse problem: no unique solution - multiple sources might yield the same data
Possible solutions can be derived using models involving prior knowledge of brain functioning

25
Q

CT scan

A
  • Low temporal resolution
  • High spatial resolution
    Appropriate for localising bone fractures, brain tumours and lesions.
  • Grey and white matter cannot be distinguished on CT scan.
  • Main advantage: relatively inexpensive
  • Main disadvantage: uses X-ray radiation.
26
Q

MRI

A

Magnetic counterpart of CT
More expensive, slower compared to CT.
Based on the principle that hydrogen atoms behave like spinning bar magnets in the presence of a magnetic field.

  • Low temporal resolution
  • High spatial resolution
  • Disadvantage: subjects must lie motionless in a noisy tube for a long time
  • NB: grey and white matter can be distinguished
27
Q

DTI

A

MRI method that detects directional movements of water molecules

  • Water can move relatively free along the axon but less freely across cell membranes
  • Used to create visual images of nerve fibre tracts in the brain and identify changes in axon myelination
28
Q

MRA

A

MRI focused on blood vessels

29
Q

fMRI

A

Functional MRI
When the brain region is active, the amount of blood, oxygen and glucose flowing to the region increases.
NB: oxygen-rich blood is less magnetic than oxygen poor blood.

  • Low temporal resolution
  • High spatial resolution
30
Q

fNIRS

A

Functional near-infrared spectroscopy

  • Good temporal resolution
  • Fairly high spatial resolution
  • Main advantage: inexpensive, noninvasive
    Main disadvantage: max dept of 2cm so only superficial layers.
31
Q

PET

A

Positron emission tomography
Used to study metabolic activity of the brain cells by injecting a small amount of water labeled with radioactive molecules into the blood stream.

  • Low temporal resolution
  • Fairly high spatial resolution
  • Often combined with CT, MRI or EEG.
  • NB: biggest disadvantage: required preparation of radiochemicals = very expensive.
32
Q
A

Brain and behaviour (14 decks)

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