Workshops 1 - 5

Question 1

In assessing a person’s state of mind, what does the term affect mean? (noun not verb)

Answer 1

A person’s emotional responsiveness

Question 2

Define hallucination

Answer 2

False perception that occurs in the absence of a causative sensory stimulus yet is experienced as real. (Could be due to activity in temporal lobes)

Question 3

Define delusion

Answer 3

A delusion is a firmly held belief that is false or bizarre with reference to a conventional view of reality.

Question 4

Failure of reality testing refers to?

Answer 4

Abnormal mental processing leads to faulty perceptions and/or fixed ideas that are incorrect or bizarre – i.e. inconsistent with conventional reality.

Question 5

There are three requirements for clinical diagnosis of schiz

Answer 5

1) Presence of some characteristic symptoms
2) Significant reduction in social or occupational functioning
3) Prolonged abnormality, that is active psychosis for at least 1 month and continuing disturbance for at least 6 months.

Question 6

Thought disorder

Answer 6

Thoughts and conversation appear illogical and lacking in sequence and may be delusional or bizarre in content

Question 7

Difference between second and third person auditory halluncinations

Answer 7

A second person verbal hallucination is the voice of some other person that addresses the subject as “you”.

A third person verbal hallucination is one or several voices that talk about the subject as “she” or “he”.

Question 8

Do antipsychotics reduce positive or negative symptoms in schiz?

Answer 8

Positive - makes negative symptoms worse

*Curative not palliative

Question 9

Fundamentally, MRI is based on “reading” a signal from each voxel, individually. What is the relationship between slices and voxels? What is the relationship between voxels and pixels in MRI?

Answer 9

Voxel - small cube of tissue (each pixel in 2D image is a visual rep of signal strength from corresponding voxel)

Slice - array of voxels

Pixels have one to one relationship with voxel (smaller the voxels = the better the resolution)

Question 10

How does MRI work?

Answer 10

As H2 is paramagnetic, it’s like a spinning magnet. Due to the water, tissues have lots of protons spinning around with random orientation of the spin axis. Strong magnetic fields align the spin axes. Radiowaves disrupt this alignment, when they re-align, they give off radio waves. Hence, MRIs measure radio waves (harmless) and hence water in brain hence grey & white matter is different as there is a difference in water distribution.

Question 11

How does fMRI work?

Answer 11

BOLD - blood oxygen level dependent - exploiting haemoglobin (paramagnetic) where properties differ whether its bound to O2 or not. Increased oxy-Hb = increased MR signal
*BOLD effect is 4 to 5 secs after onset of neural activity

Question 12

Approximately, what is the best possible temporal resolution with any type of current brain MRI?

Answer 12

Under 1 second

Question 13

With any form of brain MRI, we generally lose spatial resolution if we improve temporal resolution, or vice versa. Explain why this is. Voxel size is important for this. Which resolution requires many small voxels? Which resolution is favoured by fewer, larger voxels?

Answer 13

Good spatial resolution needs to be done as long as possible where else good temporal resolution needs to be done ASAP
Small voxels = spatial
Large voxels = temporal

Question 14

List some strategies for reducing image acquisition time to improve temporal resolution in fMRI.

Answer 14

• Limit scanning to regions of interest (less slices with fewer voxels)
• Larger voxels – again fewer voxels, and also each one is easier to scan. This sacrifices a detailed view for a quick view.
• Using a quicker pulse sequence (each voxel requires at least one BOLD-suitable pulse sequence).
• Optimising the electronics and software for imaging and data processing.

Question 15

T/F: fMRI can capture a single thought

Answer 15

F

Question 16

Do BOLD signals require small or large voxels?

Answer 16

Voxel must be large enough to contain some capillaries and enough tissue to drive blood flow changes.

Question 17

Is the temporal resolution of the fMRI similar to that of ERP-mapping

Answer 17

No - ERP is faster (< 1 ms)

Question 18

Which commissure connecting the two hemispheres is responsible for sharing images between hemispheres? What other routes are there?

Answer 18

Corpus callosum

Cerebellum, Brainstem, Spinal cord, the other commissures (Ant, post, hippocampal, habenula)

Question 19

Consider a scenario where the written word “bell” is presented visually to the right hemisphere, and the written word “music” is presented visually to the left hemisphere. What would be the likely response if the person was asked “what word did you see?” Also, what would be the likely response if that person was instead asked to point, with their left hand, to an image that represents the word they saw?

Answer 19

They would respond to the verbal question with “music”; they would point to the image of a bell when asked to indicate which image best represents the word they saw.

Question 20

Wernike’s aphasia

Answer 20

Receptive aphasia (fluent aphasia) - Damage PSTG = X sensory area = X Inability to understand language (written or spoken)
*Patient unaware of problem
*Wernicke's like What?
Wernicke's is all confused.
Makes Word salads for a living.

Question 21

Broca’s aphasia

Answer 21

Expressive aphasia - Damage frontal lobe = X motor area = X speech production area

• Patients have insight to their problem and are frustrated
• Broca is broke - speaks broken words - frustrated because he is broke

Question 22

In reading, would you expect the phonological strategy to be faster than lexical word recognition, or vice versa? Explain why.

Answer 22

The lexical pathway would be expected to be faster, as it takes in the word in one hit, rather than deconstructing it to graphemes and then phonemes, before running through the speech pathways using your internal voice.

Question 23

Why does it take longer to identify pseudo-words compared to real words when we are presented to them?

Answer 23

Reaction time is consistently lower for words v. nonwords. This may be due to the need to run through every possible word (or word structures) in the lexicon to ensure it is not an English word, while English words may be confirmed before the whole lexicon is searched. The latter will, on average, be quicker.

*An alternative explanation for the slowness to recognise nonsense words is that nonsense words will have to analysed phonologically as they are all by definition unfamiliar. The need to use the slower phonological route may explain some of the difference in reaction time.

Question 24

Explain what you think “priming” is

Answer 24

Priming is thought to subliminally activate the language pathways. In doing so, it is thought to activate all words associated with the prime. All possible associations seem to be primed, including synonyms, antonyms, homophones, semantically related words and words that often occur together

Question 25

She reports seeing “furry white walls”, “moving pink squares”, and “snakes coming out of the ground”. Can you relate each of these to a particular level of the visual hierarchy?

Answer 25

V2 – low level visual features like texture, colour, shapes
The mixture of motion is probably just overactivity in the dorsal stream of the visual processing that is getting incorporated into the picture too

Question 26

Why are hidden objects (face in coffee bean) so hard to see?

Answer 26

Visual processing is aided by conscious expectation and when the brain is forced to work with incomplete data, it needs time to extract an explanation that makes sense. Once you know what you are looking for, it becomes easier and quicker.

Question 27

Colour spreading phenomenon

Answer 27

2 errors:

• Illusory contour defining a circular shape
• Misplacement of colour information that gives the illusory shape a ghostly colour.

Perhaps the subsystem trying to recognise a circle somehow exaggerates / extends colour perception to help it define the shape.

Question 28

2-D cubes have same coloured surface but looks to be different colours in alternating rows- why?

Answer 28

The illusory difference in luminance between alternate rows of cube top/bottom surfaces is primarily due to the fact the retina detects relative contrast (centre-surround organisation).. It is probably exaggerated perceptually (in visual cortex) because it supports a 3D interpretation.

Question 29

Similar texture is grouped as one item

Answer 29

Similar texture is grouped as one item

Question 30

Charles Bonnet syndrome

Answer 30

Visual hallucinations are vividly conscious visual perceptions occurring when there is little or no damage to V1. They correspond to abnormal cortical processing, probably hyperactivity or sensitisation of V1 cortex or other visual cortical regions. Typically, V1 is deprived of normal inputs because the retinas are damaged.