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PSCY2020 2019 > Week 1 > Flashcards

Week 1 Flashcards

1
Q

What are the orientations in the vertebrate NS?

A 
Dorsal - the top
Anterior - the front
Ventral - the bottom
Posterior - to the back
Medial - to the middle (central line)
Lateral - to the outside 
Superior - above
Inferior - below
Rostral - towards the head
Caudal - towards the tail
Contralateral - the other side
Ipsilateral - the same side
Bilateral - both sides
Unilateral - same side
Proximal - close to the main body mass
Distal - far form the main body mass
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2
Q

Synonyms for below

A

Inferior
Sub
Hypo
Infra

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3
Q

Synonyms for fibre bundles or neural pathways

A

Tract
Fasciculus
Funiculus
Lemniscus

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4
Q

Reference planes

A

Sagittal plane - the plane between the hemispheres (mid-sagittal - down the middle vs para-sagittal - off centre)
Horizontal plane - also transverse
Frontal plane - also coronal, splits the front and the back
Cross section - straight cut through
Oblique plane - in any odd direction

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5
Q

Structure

A

tells about the morphology or form of things
• CT scan may show brain structure and indicate a
tumour that may be causing some observable
behaviour

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6
Q

Function

A

tells us about activity
• an EEG may show abnormal brain activity that is
indicative of a seizure

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7
Q

Invasive

A

Invasive - “Puncture or incision of the skin and denoting
procedures or tests that require an insertion of an
instrument or material that is foreign into the body.”
(psychologydictionary.org)
• Single cell recordings require electrodes to be implanted
into the brain – highly invasive
• PET scans require the injection of radioactive isotopes –
somewhat invasive

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8
Q

Non-invasive

A

• EEG requires the placement of electrodes on the external

scalp – non-invasive

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9
Q

Spatial resolution

A

To how small a region in space can you resolve 2
locations – smaller the region, higher the SR
• EEG can provide information about brain activity
localised to several centimetres – low SR
• fMRI can provide information at the mm level – high SR
• Single cell recordings provide information at the micro
level – super high SR

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10
Q

Temporal resolution

A

To how small an interval of time can you resolve 2
events – smaller the interval, higher the TR
• fMRI can tell you when something occurred within
seconds – low TR
• EEG can tell you when something occurred within ms – high TR
• Single cell recordings can tell you when something
occurred within microseconds (or faster) – super high
TR

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11
Q

Correlation

A

A reliable relationship between 2 things
Correlative – fMRI BUT just because activity in a
region is correlated with a behaviour does not
mean that the activity caused the behaviour

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12
Q

Causation

A

Does X cause Y ????
1. There is a reliable relationship between X and Y – e.g. when X occurs, Y occurs (1a - X must happen before Y)
2. If you take away X then Y stops happening
Causative - stimulation that interferes with the
behaviour indicates that the affected brain region is
necessary to perform the behaviour normally

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13
Q

Physiological response - startle response

A 
startle response - brainstem reflex for protection eg. loud noise causes blinking
The fear-potentiated
startle - amplitude of is
increased when
presented with a cue
that has been
previously paired with
an aversive stimulus
• Measure fear
conditioning
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14
Q

Physiological response - Electrodermal activity (EDA)

A 
Skin conductance response (SCR) or galvanic skin response or
electrodermal response (EDR) or psychogalvanic reflex (PGR)
or sympathetic skin response (SSR)
• Fight or flight response
• Index of autonomic activity
– measure of emotional
arousal
• Skin momentarily becomes
a better conductor
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15
Q

Acquired brain injury

A 
Anytime brain damage after birth eg stroke, alcohol/drugs, TBIPierre Paul Broca – Patient Tan
• Could only say ‘tan’ (initially at
least, no other problems)
• Autopsy revealed a large legion
in the posterior inferior frontal
gyrus
• Broca’s area
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16
Q

Lesion studies - Stimulating/disrupting activity

A 
• Removing or disabling a portion of the
brain and observing the resulting
behaviour.
• Aspiration lesion
• Radio frequency lesion
• Knife cuts
Rarely administered with 100% accuracy.
• Some neighbouring tissue is lesioned.
• Functions are inadvertently attributed to
the target structure that are actually
carried out by the neighbouring tissue.
• Sometimes a portion remains - as well as
some function.
17
Q

Transcranial Direct Current Stimulation - Stimulating/disrupting activity

A 
• Small current between anode and cathode
• Transiently disrupt neural activity
• Neurons under anode become
depolarised – more likely to fire
• Neurons under cathode become
hyperpolarised – less likely to fire
• Changes in behavioural performance –
general – anodal improves, cathodal
hinders
18
Q

Drug Blocks - Stimulating/disrupting activity

A

• Injection of local anaesthetics
• Wada test
• Prior to ablative surgery – determine
lateralisation of vital functions (e.g. speech)
• Inject left or right internal carotid then assess

19
Q

Cryogenic Block - Stimulating/disrupting activity

A

• Cryoprobe cools neurons near tip so they
stop firing – virtual lesion
• Invasive

20
Q

Transcranial Magnetic Stimulation (TMS) - Stimulating/disrupting activity

A 
Single magnetic pulses are
applied to specific locations on
the scalp at specific times during
a behavioural task; or
repetitively prior to task
performance (rTMS).
• Magnetic activity causes
neurons to fire – focal
stimulation - cognitive or
behavioural consequences are then observed.
Stimulation effects (e.g. motor or
visual activation)
• Disruption effects - synchronised
discharge interferes with normal
activity – timing important (e.g.
disrupt letter recognition)
• rTMS – longer effects – maybe
related to LTP/LTD but unclear
• Permits causal inference about the
necessity of a specific brain region
for performing a given task.
• rTMS in clinical – depression and
neuropathic pain
21
Q

Magneto-encephlography (MEG) - Recording associated activity

A

• Electric currents generate small magnetic fields
• Measure at the scalp
• Very high temporal resolution
• Relativity direct measure of activity
• But … no good for subcortical, hard to model
sources, very expensive equipment

22
Q

Electroencephalography (EEG) - Recording associated activity

A 
• Electrical activity generates electric
fields which can be measured
• Scalp – measures gross electrical
activity of the brain
• Sum of electrical events – action
potentials, postsynaptic potentials,
muscle activity, etc
• Measured electrical activity
correlates with underlying neural activity
• Idiosyncratic waveforms
associated with different
states of consciousness
• Relaxed – alpha (8-12 Hz)
• Deep sleep – delta (<4 Hz)
• Focussed – beta (16-31 Hz)
23
Q

Electroencephalography (EEG) - Recording associated activity

Event Related Potentials

A

• Name peaks based on polarity – N (negative) or P (positive)
• But note – weird convention that N is up!
Typical ERPs
• Sensory processes within less than 100ms
• 100ms modulated by attention – N100 and P100 selective attention
• N200 – mismatch negativity – stimulus physically deviates from previous
• P300 – attended stimulus appears
• P400 – unexpected stimulus (surprise)
Or compare conditions
Attended versus
unattended stimulus

24
Q

EEG - Advantages

A
  • High temporal resolution
  • Measure of activity
  • No drugs, tracers - non invasive
  • Relatively low cost
25
Q

EEG - Disadvantages

A 
• Low spatial resolution (although
source modelling possible)
• Poor for activity below
superficial layers (cortex – gyri)
• Low signal to noise and signals
easily contaminated – need lots
of trials and lots of subjects –
time consuming
26
Q

Positron Emission Tomography (PET) - Imaging the brain

A

• Radioactive tracer coupled to biologically active molecule
• Inject a radioactive isotope e.g. 2-deoxyglucose (2-DG).
• Inhale C15O2
(a radioactive isotope of CO2)
• Isotope is taken up by active portions of the brain but not brokendown - accumulates
• Radioactivity is short-lived. Half life of the isotopes is less than 3 hours.
-Paired image subtraction method (finding the difference between pic A and pic B)

27
Q

Magnetic Resonance Imaging (MRI) - Imaging the brain

A

• Hydrogen atoms line up in a strong magnetic field
• Perturb with a RF pulse and detect EM waves emitted as
they return
• Additional magnetic fields permit 3D imaging
• High spatial resolution structural imaging

28
Q

Diffusion Tensor Imaging (DTI) - Imaging the brain

A 
Variant of MRI
• Measures density
and motion of water
molecules –
restricted movement
along axon fibres
• Measure diffusion
anisotropy
29
Q

Functional Magnetic Resonance Imaging (fMRI) - Imaging the brain

A

Measures neural activity (indirectly)
• Active neurons – blood flow increases bringing oxyhemoglobin
• Oxyhemoglobin increase greater than oxygen consumption
increase so increased ratio oxy to deoxy in veins
• Oxy and deoxy different magnetic properties
• Less deoxy relative to oxy – MR signal increased intensity – BOLD
– blood oxygen level dependent contrast
- fMRI subtraction = stimulus image - blank stimulus image = area associated with stimulus

30
Q

fMRI - Advantages

A 
• Compared to PET - no tracers,
better temporal and spatial
resolution, faster acquisition.
• No known health risks.
• Structural and functional
information in the same image.
• 3-D images of activity over the
whole brain.
31
Q

fMRI - Disadvantages

A 
• Low temporal resolution
• Indirect measure of neuronal
activity – correlated but
relationship between BOLD and
neural activity complex and
variable
• 2-3 seconds to create an image
• Not causal

PSCY2020 2019 (18 decks)

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