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Action > Task 1: Response Selection > Flashcards

Task 1: Response Selection Flashcards

1
Q

A1: What brain structures/systems are involved in planning an action in response to visually presented object?

A 
Visual targets --> Intraparietal Cortex
Motor goal --> FEF
Combining them --> lPFC
Action selection --> PreSMA
Movement specification --> dPreMC/PMC
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2
Q

A2: Explain Wong’s scheme
(1) Identifying the motor goal
name steps/functions + brain regions

A

What: perceptual decision-making/selection of motor goals: generally takes time

o 1) Observation of environment (Occipitoparietal cortex)

o 1a) Attention (lateral intraparietal area), salience/priority map for spatial attention

o 2) Task Rules (encoded in lateral PFC), higher order decisions to define the motor goal

o 1 & 3 kind of form a dorsal attention system

o 3) Object selection (FEF), transition from decision about stimulus to decision about motor action

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3
Q

A2: Explain Wong’s scheme
(2) executing an action to achieve the motor goal
name steps/functions + brain regions

A

How: movement decision-making/motor planning; set of processes describing how motor goal will be achieved; generally very fast, despite 4)

o 4) Abstract Kinematics (parietal cortex)
Stores multiple movement options to reach goal –> how movement will look; optional/for complex tasks

o 5) Action Selection (vPreMC, (Pre)SMA; related to ventrodorsal pathway)
Choice & decription of motion of the end-effector (e.g. body part, tool) independent of arm posture

o 6) Movement Specification (dPreMC, PMC; related to dorsodorsal pathway)
Complete motor command of limb and any posture adjustments are determined

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4
Q

A2: What dos the Drift Diffusion Model say about how motor goals are reached?

A

Evidence about motor goal is accumulated until a threshold is reached to make a decision.

  • relates to FEF (object selection)
  • Can be seen in movements of uncertain individuals
  • Study with jumping target
    • Response briefly after switch: still old response, somewhat certain
    • Response after switch: new response, somewhat certain
    • Response long after switch: new response, very certain
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5
Q

Motor planning vs. Motor execution

Keywords: Null space & Dynamic Systems Model

A

Same areas: mPMC and PreMC

Different firing-rate space
Motor planning: average firing rate remains constant –> null space
Motor execution: drives muscle activity –> moving away from null space

Dynamic Systems Model (DSM)
Motor Cortex is a dynamic system: it can be active without movement execution–> aka it can be active without leaving the null space –> this is the case in motor planning

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6
Q

A2: Clarify the role of feedback control policies (draw parallel with inverse models from the course Functional Neuroanatomy)

A

Optimal Feedback Control

Determines complete movement trajectory taking into account:
current state of the limb
motor target (endpoint)
cost between the two

–> inverse model (process defined based on goal)

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7
Q

A3: Where does the exogenous path of action run along?

A

Exogenous path/How pathway
- overlaps with dorsaldorsal stream

Visual Cortex -> IPS (LIP/MIP) + SPL -> PostCS

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8
Q

A3: What is the function of the exogenous pathway? Why is it called “how” pathway

A

Dorsal stream –> How –> action/movement initiation

Lesion in superior PPC –> Optic Ataxia

  • inability to use visual info to guide action
  • still intact visual/spatial perception
  • can be unilateral
    e. g. can tell where something is but cannot point to it
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9
Q

A3: Describe the dorso-dorsal subpathway (Binkofski & Buxbaum, 2013)

Mention its anatomical organization & functional relevance

A

Dorsodorsal –> exogenous path

Visually guided motor control
(e.g. reaching)
Movement specification

Via V1 –> IPS –> SPL –> PostCS

Lesion in sPPC –> optic ataxia
(impaired use of visual info to guide action)

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10
Q

A3: Describe the ventro-dorsal subpathway (Binkofski & Buxbaum, 2013)

Mention its anatomical organization & functional relevance

A

Ventrodorsal –> endogenous path

Praxis, skilled motor acts & tool use, more cognitive/based on LTM
(e.g. grasping & manipulating)
Action selection

Via V1 –> Angular Gyrus –> SMG

Lesions in IPC, vPreMC & connections–> Ideomotor apraxia/limb apraxia
(cannot fulfill instructed movements, interact with an object or mime those actions,
intact reflexive/unconscious movements)

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11
Q

Briefly describe the ventral pathway

Function & What if lesion?

A

Ventral stream –> what –> object identification

Lesion –> visual form agnosia

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12
Q

A4: What is self-generated movement? (vs. non-self-generated action)

A

Self-/internally generated action

  • Operant behaviour: response on own accord –> initial change inside respondent
    vs. respondent behaviour: response to external stimulus –> initial change in environment

Flexible depending on goal

  • change in goal –> change in action
  • failed to obtain goal –> change in action

Automatic inhibition mechanism of prepotent responses
–> needed for flexible voluntary behaviour

In accordance with rules/task demands
- representation of goal to retrieve correct action

Other conditions for self-generating actions

  • specified by time they needed
  • one action can cue the next one
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13
Q

A4: What is the role of the (Pre)SMA in self-generated movement?

A

Activity in (Pre)SMA

  • -> neurons fire earlier & only for self-initiated movements
  • -> code for time intervals needed
  • -> code for specific transaction between actions

Lesion (Passingham)

  • Monkeys tested in the dark to eliminate cues for exogenous actions
  • -> reduced self-initiated movements & inability to learn movements
  • -> anarchic hand syndrome/Dr. Strangelove Syndrome
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14
Q

A5: Explain the study by Sumner et al (2007)

- Task paradigm

A

Masked-prime task
- “invisible” primes cueing target location followed by actual target

–> trigger automatic cue-response associations

  • Conditions:
    Button-press (motor) vs. saccades (oculomotor)
    Compatible vs. incompatible trials
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15
Q

A5: Explain the concepts of Positive and Negative compatibility effect

A

Time between prime & stimulus < 100ms

  • -> PCE/facilitatory priming
  • -> compatible trials vs. incompatible –> faster RTs

Time between prime & stimulus > 100ms

  • -> NCE/automatic inhibition
  • -> compatible trials vs. incompatible –> slower RTs
  • -> due to auomatic inhibitory mechanism

-> we expect a difference between compatible & incompatible trials in how the NCE affects RTs in healthy people

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16
Q

A5: Explain the study by Sumner et al (2007)

- Hypotheses & results

A

CB: lesion in SMA & right SEF
- Hypothesis
Impaired saccades & manual movements
- Result:
No NCE, but always PCE for both type of movements

JR: left SEF
- Hypothesis:
        Impaired saccades only
- Results:
        No NCE, but PCE for saccades only
AG: no relevant lesion (PreSMA)
- Hypothesis:
        No impairment of NCE
- Results:
       Normal NCE in both
RS, VC: no relevant lesion (lPreMC)
- Hypothesis:
        No impairment of NCE
- Results:
        Normal NCE in both

In summary:

  • -> Automatic inhibition is effector-specific
  • -> Unilateral lesions lead to loss of automatic inhibition (NCE) on both sides of body –> thus, important for self-initiated movement
  • -> SMA lesion –> issues with manual tasks
  • -> SEF lesion –> issues with oculomotor tasks
17
Q

Explain object affordances

A

Object affordances:

Association between potential actions & perceived object
–> link between object selection & action selection

Determined by:
- Pragmatic features of objects (e.g. size, shape, …)
- Motor capacities (e.g. strength, agility of limb…)
- Context
No semantic knowledge needed
Takes effort to override strong object-action associations
- Needs top-down control

18
Q

A6: Describe Ideomotor (IMA)/limb apraxia

  • Lesions
  • Dysfunction
  • Conclusions about motor system
A

Ideomotor apraxia/limb apraxia

Lesions

  • dorsoventral pathway (V1 -> AngularG -> SMG)
  • IPC (includes AG & SMG), vPreMC & parieto-premotor-connections

Dysfunction

  • impaired fulfillment of instructed movements
  • Impaired interaction with an object (tool use)
  • Impaired pantomiming/miming of interactions with objects
  • intact reflexive/unconscious movements

Conclusions

  • > both HPs store gesture representation
  • > left BG controls spatial & temporal features of learned movements/sequences & inhibition
  • > PPC involved in preparation & execution of eye movement, grasping, reaching & hand position
19
Q

A6: Describe Optic Ataxia

  • Lesions
  • Dysfunction
  • Conclusions about motor system
A

Optic Ataxia

Lesion
- dorsodorsal pathway (V1 -> IPS -> SPL -> PostCS)
- sPPC (mainly SPL & IPS)
(impaired use of visual info to guide action)

Dysfunction

  • impaired coordination between visual input & motor outputs
  • intact general motor abilities

Conclusions

  • -> PPC (+ part of frontal cotex that follows it) is involved in reaching, saccades, grasps, attention & state estimation
  • -> these functions are important for hand-eye movement
20
Q

A6: Describe Dr Strangelove Syndrome

  • Lesions
  • Dysfunction
  • Conclusions about motor system
A

Anarchic hand syndrome/Dr. Strangelove Syndrome

Lesion

  • PreSMA (also ACC and PCC)
  • also caused by callosum surgery

Dysfunction

  • contrallesional hand is not under voluntary control
  • dysfunctional hand performs complex, goal-oriented actions
  • often oppositional behaviour

Conclusions
–> damage to parietal cortex can cause lack of awareness of movements due to loss of feedback

21
Q

What is the relation between dorsodorsal & ventrodorsal pathways with the area AIP

What is the relation between ventral & dorsal

A

Relevance of area AIP

  • has motor dominant cells, visuomotor cells & visual dominant cells
  • -> combine visual info with motor info for action

Ventral connected with dorsal
But dorsodorsal & ventrodorsal are dissociated

22
Q

Describe light-motor sensitivity in the intraparietal area (AIP)

A 
Area AIP (anterior intraparietal)
Motor dominant cells
- Active for manipulation in light &amp; dark
- Doesn’t fire when there’s no movement
-> only motor

Visuomotor cells

  • Fire when manipulating in light, bit less in dark
  • Even just object fixation has some activation
  • > both visual & motor response

Visual dominant cell

  • Fire when manipulating in light and when just fixating
  • > only visual

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