executive skills part 1: definition, over-view, brain basis
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Executive Skills Part 1: Definition, over-view, brain basis. Isabelle Rapin Seminar in Developmental Disabilities March 21, 2013 No conflict of interest. NIH Tool Box Definition* Neurology March 12, 2013: S54-64. - PowerPoint PPT PresentationTRANSCRIPT
Executive Skills Part 1: Definition, over-view, brain basis
Isabelle Rapin
Seminar in Developmental Disabilities
March 21, 2013No conflict of interest
NIH Tool Box Definition*Neurology March 12, 2013: S54-64
Executive function (cognitive control) = top-down cognitive modulation of goal directed activity• Set shifting
Lateral prefrontal, anterior cingular, inferior parietal network
• Attention and inhibitory control (visual)Frontal eye fields, posterior parietal, anterior cingulate, thalamus, basal ganglia network
• Working memoryPrefrontal, posterior parietal network
* Tests for uniform research projects
Definition Top-down executive/control system(s) --
enable(s) endogeneously-generated goal-directed behaviors
Some on-line requirements:• Planning (awareness of the future)• Motivation• Cognitive/behavioral flexibility (shifting)• Selective/focused attention• Inhibition of automatic sensory/affective responses• Sustaining active working memory• Exploit long-term memories (learning)
1. Schema of STM systems
Short Term Memory
Sensory buffers Working memory
Sensory cortices Prefrontal cortex
LTM declarative systems
Long term memory
Declarative(explicit,items))
Non-declarative(implicit skills, etc)
Episodic (individual)
Several subtypesSemantic
(knowledge)
More requirements
Awareness of problem to be solved Advance planning Self-awareness, -monitoring Meta-cognition/multi-tasking Self-control, delay gratification Attend to feedback, shift accordingly
Executive function: slowly maturing
Requires repeated experiences to develop Modular aspects
• Visuo-motor
• Sensori-motor
• Verbal
• Implicit/social
Considered “mature” @ start of 3rd decade Actually continues to develop life-long Susceptible to decay: dementia, frontal damage
Brodmann map in color
Brodmann (1909)
52 histologically distinct cortical areas
Prefrontal cortex
Gross anatomo-functional
approximations (most
functions are not localized)
Dorso-lateral prefrontal
~ area 48 working memory
Orbito-frontal
~ areas 10, 11, 47 inhibitory
Mesial prefrontal
~ areas 8-11, 13, 32 limbic
Scott, Schoenberg
Developmental disorders with prominently affected executive
skills
ADHD (attention deficit hyperactivity disorders)
ASD (autism spectrum disorders) Conduct disorders Etc.
Attention - Definition
Presupposes vigilance (RAS) Ability to make choices among a myriad of
competing stimuli in order to match task demands by• Enhancement of attended stimuli
• Suppression of unattended stimuli
Requires executive skills (prioritize, etc.) “ working memory
Overlaps with attention
Control of attention
Exogenous (reflexive, bottom-up – does not require conscious awareness)
Endogenous (cortical, top-down choices to match on-going needs)• Monitor & maintain goal directed activities
• Deactivate inappropriate tasks
• Prepare activation of relevant tasks
• Modulation by on-going affective signals
Major anatomic circuitry
Subcortical areas (multiple neurotransmitters)
• Midbrain (ascending RAS, raphé, etc.)
• Intralaminar nuclei of thalamus
• Diencephalon, caudate
Cortical areas (right dominant > left)• Inferior parietal – multimodal sensory processing
• Lateral prefrontal - working memory, executive
• Anterior cingulate - interface cognition & emotion
ADHD
↓ sustained attention → distractible ↓ working memory → forgetful ↓ response inhibition → impulsive ↓ input inhibition and response monitoring ↓ awareness of affective signals &
environmental rewards
Autism
Rigidity, narrow focus, perseveration Impaired awareness of social/
environmental cues But
• Selective/focused attention may be OK
• Inhibition of irrelevant sensory inputs may be OK
• Memory (working and long-term) may be OK
Overlaps with memory
Multiple Memory Systems
Short term memory systems• Sensory buffers (for each modality +
endogenous inputs from memory)
• Working memory
Long term memory systems• Declarative (or explicit)
• Non-declarative (or implicit)
Retrieval systems
1. Schema of STM systems
Short Term Memory
Sensory buffers Working memory
Sensory cortices Prefrontal cortex
Working Memory Circuitry
Prefrontal cortex: in continuous on-line reciprocal connections with• Sensory cortices for each modality (specific buffers)• Limbic circuits• Arousal circuits• Motor output circuits
* * * Note: Hippocampus circuitry: (data from amnestic
patients) • Not critical on-line, • Critical for long term storage
LTM declarative systems
Long term memory
Declarative(explicit,items))
Non-declarative(implicit skills, etc)
Episodic (individual)
Several subtypesSemantic
(knowledge)
Declarative (explicit) LTM1. Episodic (Tulving)
Uniquely human Powerful tool Specific particular facts/events
(autobiographical) Late to develop evolutionarily (man only?)
and ontogenitically (infant amnesia) Fragile to degeneration Critically dependent on (not limited to!)
hippocampal/medial temporal cortices
Declarative LTM Memory 2. Semantic Memory
Knowledge (as opposed to remembrance of specific facts)
“Picked-up” knowledge Starts at birth, long before episodic
memory Broad and powerful Much more resilient than episodic memory
Hippocampus system
Binds inputs from all sensory modalities with limbic and prefrontal executive inputs
Reciprocally connected with relevant cortical and subcortical circuitry
Required for declarative LT memory• For fresh and midterm declarative memories
• Not for very long term “ “
Not required for non-declarative memories
Executive Skills Part 2
Puja Patel
Seminar in Developmental Disabilities
March 20, 2013No conflict of interest