Methods for studying living brain: L6

Question 1

clinical neuropsychology

1. goals
2. key principles
3. this provides

Answer 1

1. • diagnosis, management and treatment of patients with neurological disorders
     - explain normal brain-behaviour relationships by assessing how the system breaks down after damage
2. establish patterns of association and dissociation in the behaviour of brain damaged individuals
3. a way to describe the functional modules of perceptual and cognitive processing affected by the damage and those spared

Question 2

Brocas aphasia

1. patients had
2. patients lost
3. concluded

Answer 2

1. • lesions in the left hemisphere
2. ability to communicate through speech, but could make lips, tongue and mouth movements normally & understand what was said to them
3. area located in the posterior part of the inferior frontal gyrus = responsible for expressive language. This area is now called Broca’s area

Question 3

Broca’s aphasic

1. characteristics

Answer 3

1. • non fluent speech
     - meaningful (contentful)

• agrammatism =comprehending or using grammar
• anomia = remembering words
• apraxia of speech = impairment of tongue, lips and throat movement to produce sounds

Question 4

Wernickes aphasia

1. characteristics
2. damage to

Answer 4

1. • lost ability to comprehend speech
     - fluent speech
     - normal prosody
     - meaningless content
     - > unaware of impairment
2. left hemisphere in the posterior superior temporal gyrus = Wernicke’s area

Question 5

Limitations of clinical neuropsychology (4)

Answer 5

1. patients with brain lesions may have medical problems = prevents testing
2. no two patients will have identical brain pathology (brain lesions) = difficult to replicate experimental findings
3. damage to one structure will change the inputs and outputs of many other regions (doesn’t leave other areas unaffected)
4. can’t control the size or location of damage as cases are ‘experiments of nature’

Question 6

Ablation studies in animals - hippocampus in memory

1. what is ablation?
2. how is it done?
3. advantage
4. HM

Answer 6

1. make small lesions in distinct parts of the brain to observe effects
2. surgically, radio frequency energy or injecting toxic chemicals to destroy neurons
3. location of lesion = high degree of precision
4. hippocampus + amygdala = critical for learning and memory (found out due to removal of medial temporal lobes)

Question 7

Delayed non-matching to sample

1. tests
2. procedure

Answer 7

1. learning and memory in monkeys
2. (1) food covered with a symbol card
   (2) card removed & monkey shown response -> reward
   (3) repeated, different symbol card
   = after a few trials monkey will learn the food will always be hidden under the card that was NOT rewarded on the first trial

Question 8

effects of hippocampal lesions on learning and memory

1. monkeys with ablation
2. limitations of ablation

Answer 8

1. (1) take longer to learn non-matching to sample than control monkeys.
   (2) More extensive lesions (H++) = impairment greater compared to less extensive lesions (H+)
   (3) make more errors
2. lesion might affect other structures of the brain

Question 9

Extracellular micro electrode recording (or single-unit recording)

1. what is it?
2. 2 cases
3. electrical signal must be
4. limitation
5. way around the limitation

Answer 9

1. technique using animals, recording a single neuron using a micro electrode to record EPs.
2. (1) recording of EPs while animal is under anaesthetic = limited scope (no task performance)
   (2) recording of EPs while electrode is mounted to skull with wound surgically closed. electrode remains in place over extended period of time
3. amplified many times as it is small
4. not possible to guarantee that the electrical signal is from a single neuron (could be from multiple)
5. place a micro electrode inside the cell body of a neuron

Question 10

extracellular recording from monkey primary visual cortex

1. aim
2. all neurons have
3. therefore this experiment looks for
4. visual cortex attribute, neurons respond to
5. in primary visual cortex adjacent neurons have + representation of external space

Answer 10

1. • determine the manipulations that will produce the most consistent change in a neurons firing rate
2. baseline or resting rate of spontaneous spiking activity
3. alternations to the baseline level of activity that are correlated with a particular stimulus or task
4. location of the stimulus, stimuli that appears in a limited region of space
5. overlapping receptive fields. A representation of external space is reflected in a continuous map across the cortical surface = retinotopic

Question 11

1. structural brain imaging is

2. functional brain imaging is

Answer 11

1. static snapshot of anatomy of brain

2. which areas of the brain are metabolically active

Question 12

Computerised tomographic (CT) scanning

1. use
2. how it works
3. based on
4. CT scan appearance of structures (colour)
5. limitation

Answer 12

1. delineate site and extent of brain injury or disease
2. • series of 2D slices to be reconstructed into 3D space
     - x-ray beam passed through head
     - radiation detector picks up amount of X ray energy from the opposite side of the head
     - x-ray source and detector moved around the head
3. different density of tissue absorbs different amounts of x-ray
4. bone (radio-opaque, absorbs large amount of x-ray) = white, CSF = black, grey + white matter = shades of grey
5. (1) grey and white matter isn’t clearly differentiated (they absorb similar amounts of x-ray)
   (2) poor spatial resolution (unable to discriminate fine structures)

Question 13

Magnetic resonance imagining (MRI)

1. uses
2. how does it work
3. precession
4. produces

Answer 13

1. magnetic field 1.5-4 tesla
2. superconducting magnet inside scanner. MRI sensitive to the behaviour of protons in the nuclei of hydrogen atoms. radio frequency (RF) pulse passed through the head. synchronised relaxation of protons produces energy that is picked up by detectors. Output of detectors constructs 3D image
3. strong magnetic field -> proton axis aligns = their magnetic field becomes strong enough to be measured
4. high spatial resolution, can discriminate structures down to around 1mm

Question 14

Scalp-recorded electroencephalogram (EEG)

1. uses
2. how does it work
3. waveforms indicate
4. EEG has
5. how can spatial resolution be improved

Answer 14

1. determine underlying function of brain areas. map brain regions that are selectively active during performance
2. measures weak electrical signals produced by brain. electrodes placed on scalp. electrical signals sent to an amplifier and displayed on a computer monitor
3. strength and rhythmicity of electrical activity in brain
4. good temporal resolution (can discriminate brief events in time) but poor spatial resolution ( cant discriminate structures well)
5. more electrodes places on scalp, but still difficult to determine the precise area from which the signal has come from.

Question 15

Scalp recorded event related potentials (ERP)

• definition
• stimulus onset after
• EEG & ERPs have
• clinically ERP can be used for

Answer 15

• EEG = brains evoked response to stimulus -> very noisy
• provide snapshot of electrical activity in region of brain (100 x EEG trials averaging gets plotted into a waveform
• 700ms
• good temporal, poor spatial
• diagnosing neurological conditions

Question 16

fMRI

1. measures brain activity by
2. which is more susceptible to magnetic forces
3. spatial resolution

Answer 16

1. ratio of oxygenated to deoxygenated haemoglobin = BOLD effect
2. deoxygenated haemoglobin is more susceptible to magnetic forces
3. good (3mm)

Question 17

TMS

1. what happens
2. advantage

Answer 17

1. coil placed on cortex, virtual lesion, temporarily disturbs tissue
2. effects last <500ms = when and what brain areas are involved

Question 18

1. Functional brain imaging methods

Answer 18

1. EEG, fMRI, TMS