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Psych 1 > Brain Imaging > Flashcards

Brain Imaging Flashcards

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1
Q

Electroencephalography (EEG)

A
  • measures electrical activity of brain
  • number of electrodes applied to scalp
  • main diagnostic tests for epilepsy
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2
Q

EEG Strengths

A
  • good temporal resolution (discriminates v brief events in time)
  • cheap + safe
  • portable + possible to record EEG while people are moving around
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3
Q

EEG Limitations

A
  • poor spatial resolution (hard to determine precisely from which area of the underlying brain the signal has come)
  • hard to detect activity from central regions (mainly on surface)
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4
Q

Electrophysiology - single neurons

A
  • Hodgkin & Huxley recorded action potentials in the giant axon of Atlantic squid
  • much of sensory + motor cortex mapped this way
  • Hubel & Wiesel mapped development + organization of visual system
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5
Q

Electrophysiology Strengths

A

records directly from individual neurons

so is best way to know what the neurons are doing

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6
Q

Electrophysiology Limitations

A
  • high risk of infection as it is invasive (penetrates brain)
  • neurons DONT work in isolation but rather as large networks
  • so network activity of multiple neurons impossible to investigate with this method
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7
Q

MRI (correlates brain activity w behaviour)

A
  • magnetic field passes through person’s head, causing H atoms to align with magnetic field
  • radio frequency waves temporarily disrupt this alignment causing a signal that can be detected by machine
  • because dif areas of brain tissue have dif amounts of WATER, they emit dif signals
  • analysis software converts detected signals into v detailed images of dif structures of brain
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8
Q

MRI (Diffusion tensor imaging)

A

uses the same MRI equipment to detect the large axon tracts (white matter) that flows through the brain & connect dif regions of cortex

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9
Q

fMRI

A
  • cognitive processes use energy
  • as brain region uses energy there is INCREASE in blood flow to that region (for more O2 to be used up)
  • bc fMRI images the INCREASE IN BLOOD FLOW caused by the USE of oxygen, not the use of oxygen in the first place – there is delay in signal associated w/ brain activity
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10
Q

What is BOLD in fMRI studies

A

blood-oxygen-level-dependent effect
- oxygenated blood: doesn’t distort surrounding magnetic field, but deoxygenated blood does
- can be detected by scanner

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11
Q

MRI Strengths

A
  • v high spatial resolution (exact locations)
  • identifies specifical anatomical / structural / functional properties of dif brain regions
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12
Q

MRI Limitations

A
  • large equipment so requires specialist facility w/ multiple rooms (machine must be kept in magnetically shielded room) + specialist staff
  • safety risks
  • expensive
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13
Q

PET

A

uses radioactive substances known as TRACERS to visualize GLUCOSE METABOLISM or the neurotransmitter / receptor function

  • can also use radioactive tracers to bind selectively to proteins of interest
  • used as diagnostic tool for Alzheimer’s disease (detecting buildup of Amaloid protein)
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14
Q

PET Strengths

A
  • can detect dif chemical in brain associated with METABOLISM or functional properties (e.g. neurotransmitter levels or proteins)
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15
Q

PET Limitations

A
  • expensive + specialist facilities + staff
  • low SPATIAL RES compared to MRI
  • risks associated w radioactive tracers being injected into participant’s blood
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16
Q

Brain modification

A
  • medical treatment (abnormal brain functions - brain regions removed OR drugs used)
  • enhancement (improvement of healthy function to ABOVE or BETTER than normal)
  • scientific research (using brain imaging techniques like fMRI only give us correlational info - BRAIN MODULATION otoh gives info abt causation & whether a given brain region is NECESSARY for particular task)
17
Q

Ablations

A

deliberate lesions allow a relatively high degree of precision
e.g. frontal leucotomy

18
Q

Describe frontal leucotomy

A
  • a leucotome was inserted into one of several holes drilled in skill
  • a core of tissue removed
  • or cutting implement inserted above eyelid & pushed through to frontal loves
    CONSEQUENCES: profound personality consequences (e.g. apathy, emotional unresponsiveness, inability to plan)
19
Q

Who popularised frontal leucotomy?

A

Walter Freeman in the 40s & 50s - 40,000 operations in USA

20
Q

Electrical brain stimulation (old fashioned)

A
  • reveals precise localisation of cortical function
  • electrically stimulated part of the frontal
    cortex in dogs; induced contractions of specific
    muscles on the opposite side of the body
21
Q

Non-invasive electrical brain stimulation - ECT

A
  • electroconvulsive therapy
  • seizure-inducing agents were used to treat psychiatric conditions as early as 1500s
  • now used to treat severe depression
  • electrical stimulation of frontal lobes needs to be strong enough to cause a seizure
22
Q

transcranial direct current stimulation
(tDCS)

A

used to treat many psychological disorders
due to the lasting modulation of cortical excitability

a coil carrying an electrical
current generates a brief, focal magnetic pulse which activates a small
region of cortex (approximately 10 – 15 mm, depending on the size of the
coil) underlying the coil.
§ The activation acts like a ‘virtual lesion’, temporarily disrupting the tissue for
a few hundred milliseconds. The technique is painless (unless it triggers
muscle contraction)

Psych 1 (12 decks)

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