volitie 2

Question 1

what happens if there is damage to the pathways to the M1

Answer 1

both pathways contribute to voluntary action

damage to these pathways can impact the capacity to exercise volition

Question 2

What is optic ataxia

Answer 2

ataxia - lack of coordination
optic - visual

problems using visual information to coordinate movement

Question 3

which pathway is optic ataxia associated with

Answer 3

optic ataxia is associated with damage to the parietal pathway - involved in sensory guided actions

damage through stroke - disrupts the flow of info in this pathway

Question 4

parkinson’s disease

Answer 4

difficulty performing voluntary actions

tremor
stooped posture

difficulty getting movements up and running

Question 4

which pathway is parkinson’s associated with

Answer 4

damage to subcortical pathway

Question 4

how does parkinson’s affect the brain

Answer 4

loss of dopamine producing cells in substantia nigra - these cells project up to the striatum

striatum represents the input to the basal ganglia

if there is less dopamine producing cells, basal ganglia is not able to do its job - so signals are not being sent up to the cortex

Question 4

disorders in the experience of voluntary action

Answer 4

unusual experiences of control where the experience of movements seems to be dissociated from what they are able to do

there are patients with disorders in which they experience of action seems to be abnormal

patients experience a persistent dissociation between the ability to act and the experience of action

Question 4

anosognosia

Answer 4

lack of awareness of disease

different types of anosognosia:

• anosognosia for hemianaesthesia - sensory loss - no longer able to experience sensation in certain parts of the body but patient seems to be unaware of that
• anosognosia for cerebral achromatopsia - loss of colour vision - feels they still have colour vision

Question 4

anosognosia for hemiplegia AHP

Answer 4

patient unable to move a particular body part bc it’s paralysed

but patients is unaware of this deficit

Question 4

where is AHP located in the brain

Answer 4

lesions to right perisylvian regions

paralysis on opposite side
if right side is damage, left side of body is paralysed

Question 4

AHP example

Answer 4

presented patients who had anosognosia and without with a screen

asked to place paralysed hand behind screen

on screen is live video footage of hand that is told is their paralysed hand - but it’s just a rubber hand

patients instructed to move the hand, let experimenter move their hand, remain stationary

so for each of these 3 instructions the rubber hand would either move or not move

patient had to say whether or not they moved after each trial

RESULTS
when the patient is being asked to make movement and rubber hand on screen doesn’t move - they still report they have moved

Question 4

conclusions

Answer 4

patients rely on their intentions to move

intending to perform movements is sufficient to generate a feeling of having actually moved

Question 4

schizophrenia

Answer 4

positive symptoms - presence of something that shouldn’t be there

delusions
hallucinations

Question 4

passivity symptoms - delusions of control

Answer 4

they can move but they feel like something else is controlling them

not a problem with a control of action - problem with experience of action

Question 4

study on passive symptoms

Answer 4

tested healthy controls
patients with delusions
patients without delusions

they made hand movements that they could not see - they saw visual feedback abt the movements presented onto a screen

movements they saw on the screen were either own movements shown in real time, movements of experimenter performing similar movement to ppt or movement of experimenter performing different movement

was the movement on the screen your own or the experimenter’s

when the experimenter was doing the same movements, all groups errors shoot up but especially in delusional patients - difficult to judge whether movement is their own

Question 5

experiment of delusions of control in schizophrenia

Answer 5

3 groups

patients with delusions
patients without delusions
healthy controls

made movements and saw feedback of movements

1 condition: feedback was presented on a different level of spatial distortion - saw movement in perfect alignment or feedback was rotated to an increasing degree

2 condition:
introduced a time delay between the movement that was made and movement shown on screen - time delayed increased as condition progressed

do the hand movements on screen match your own movements

patients with delusions in both conditions take much longer to recognise discrepancies between what they are doing and what they are shown on the screen

so if feedback is rotated, they take longer to detect
if there is delay, patient with delusions take longer to detect delays

Question 5

why do distortions in the experience of action happen in Sz patients with delusions

Answer 5

inability to predict consequences of their own movements

Question 5

what cognitive processes give rise to the normal experience of voluntary control

Answer 5

the comparator model - how one controls movements and if we are in control of our actions or not

prediction gives us a sense of voluntary control over our actions

the experience of voluntary control is based on our ability to predict sensory consequences of movements

when we make a movement we start with a goal and we are in a desired state
controllers can issue a motor command - to achieve a desired state
motor command gets sent from motor cortex to spinal cord and to muscles

that produces movement
that is producing sensory feedback
person is able to estimate the state of the system - where their body is

when motor command issue is sent, a copy of motor command is read by predictors and they use this command to predict that the state of the system is going to be

if predicted state doesn’t match the desired state then system needs to put breaks on and update motor command

if we were able to predict accurately what happens, this tells the system we were in control

prediction is crucial for giving us a sense of control

Question 5

whats the comparator model like in SZ

Answer 5

in sz there is problem with predicting future states

Question 5

what evidence is there that patients can’t predict the future sensory consequence of their movements

Answer 5

when we can predict the consequences of our actions accurately, our brains don’t care about the sensory information - they ignore it

if we can’t predict, our brain processes that info - Sz patients can tickle themselves

Question 5

tickle in Sz patients

Answer 5

sz patients with and without delusion symptoms and healthy controls

apply a tactile stimulus to hand or experimenter do it for them

rate how tickly it was

control experienced self applied tactile stimulation as less tickly than when it was applied by experimenter

same with non-delusional patients

those with symptoms don’t report any difference in the tickle sensation