PSY2001 Lecture 3 - Executive Functions

Three core executive functions

(Miyake et al., 2000)

• Inhibition

  • Controlling attention/behaviour/thoughts and/or emotion to override a prepotent response

• Working Memory

  • Holding information in mind whilst simultaneously processing it

• Cognitive Flexibility

  • Changing perspectives/approaches to a problem, flexibly adjusting to new demands/rules/priorities.

Development of inhibitory control - childhood

• Very difficult for children

• Rapid Growth in early childhood

Wiebe et al. (2012)

• 3-6 years

• Button press response inhibition task

• Accuracy increased by 30%

Development of inhibitory control - early adulthood

Ordaz et al., (2016)

• Longitudinal data - growth curve modelling

• Continued maturation of error-processing abilities

• Supports protracted development of inhibitory control over adolescence

Working memory development - Infancy

Kibbe & Leslie (2016; 2013)

• A WMC of 1 item at 6 months → 3-4 items by the end of 1st year

PROBLEM: Tasks for infants cannot provide comparable data to children and adult data

Working memory development - School-aged children

Roome et al. (2014; 2019)

Capacity of 1.5-2.5 items

Working memory development - Cowan et al.

Takes a long time to develop

Measuring development of cognitive flexibility

Zelazo et al. (1996): Dimensional Change Card Sort Test

One dimensional version of Wisconsin Card Sorting Task

• 4yo: can sort by colour or shape, but cannot switch from one dimension to another

• 7-21 yo: shift difficulty decreased with each age group, but 15yo did not differ from adults (Huizinga et al., 2006)

Ferguson et al., (2021)

Compared developmental trajectories of EFs

• Controlled for IQ and SES (environmental factors)

• Inhibition and WM show similar developmental trajectories

Theodoraki et al., (2020)

Found correlations between:

• Inhibition and Color Naming Speed

• Inhibition and Working Memory

• Shifting Measures (3 & 4)

Measuring development via. factor loading

3 different tests:

• 7-21 yo: 2 FL (Huizinga et al., 2006)

• 7-14 yo 3 FL (Wu et al., 2011)

• 8-13 yo: 4 FL (Agostino et al., 2010)

Criticisms of Fractionation of executive functioning

• Too many tasks testing the same concept

• Tasks are complex and multi-dimensional

  • Difficult to pinpoint the specific skills being assessed

• Conceptual ambuiguity

  • Is perserveration due to inability to inhibit or inability to switch rules?

Study criticising fractionation of executive functioning

Switches in which EFS predict behaviour

• Tower of Hanoi - Senn et al. (2004)

  • Younger than 4 → predicted by inhibition

  • Older than 4 → predicted by WM

Maturation of the whole brain

Gogtay et al. (2004)

• Maturation at age 5 vs 20

Structural prefrontal cortex (PFC) development - Progressive changes

• Myelination,

• Neuron proliferation,

• Synaptogenesis

Structural prefrontal cortex (PFC) development - Regressive changes

• Cell death,

• Synaptic pruning,

• Loss in grey matter.

Perseveration

The involuntary repetition of a behavior, speech, or thought that continues even after the original stimulus has changed or ended

Neural proliferation

The process of generating new brain cells, or neurons, during embryonic development

Synaptogenesis

The formation of synapses that occurs throughout an individual’s lifespan, occurs most during early childhood.

Cell death

A natural process that occurs when cells that are not used stop working and die.

Synaptic pruning

• The process in which the brain removes neurons and synapses that it does not need.

• Usually takes place between 2–10 years old

Grey matter loss

• Occurs as a result of myelination and synaptic pruning

• Volume decreases but density increases

Maturation of the prefrontal cortex in infancy (12-18 months)

(Huttenlocher et al., 1997)

Peak in synaptogenesis in the middle frontal gyrus

Maturation of the prefrontal cortex in infancy (6-12 months)

Koenderink etal. (1994)

Increases in dendritic trees in layer III of the PFC

Maturation of the prefrontal cortex in infancy - (childhood vs adulthood)

(Glantz et al., 2007)

Synaptogenesis in the PFC vs reduction in synapses

Cerebral blood volume (CBV)

Franceschini et al. (2007)

• Frontal region: increases linearly from birth to 8-9 months of age.

• Occipital, parietal and temporal regions: Exponential increase seen only from birth to 2.5 months

Spread of myelination

Deoni et al. (2011)

• 1st year of life: cerebellum, pons, internal capsule

• 4-6 months: occipital and parietal lobes

• 6-8 months: frontal and temporal lobes

remember: back to front

Grey matter volume

Giedd et al (1999)

• Increases in frontal and parietal lobes

• Peak 10yo in girls, 12yo in boys

• Followed by decreases in these lobes

Grey matter density

Gogtay et al (2004) - Longitudinal data

Loss starting at puberty

1. In the sensorimotor areas

2. Then spreading over the frontal cortex (rostrally) and the parietal

3. Then temporal cortex (caudally)

4. DLPFC loses grey matter last

Maturation rate of the PFC

• Structural and metabolic changes in the first years of life

• Relatively late maturation in comparison to other brain regions

• Connectivity evident within pre-school years

Difficulty studying structural development - Holmboe et al (2018)

• Individual differences

• Variations in attentional control at 6 months were predictive of inhibitory control abilities at 12 months

• Aligns with Deoni et al., (2011)

Difficulty studying structural development - Baird et al. (2002)

• Brain scans often require children to stay still, where as NIRS doesn’t.

• Found that 5-12 month-old infants recruit the DL-PFC when holding objects in visual WM.

Difficulty studying structural development - Mehnert et al. (2013)

Go/NoGo task in 4-6yo and adults

• Adults: R frontal and parietal regions during inhibition (no-go)

• Children: R frontal and parietal regions during go, and no-go

Task may not be appropriate for children

Difficulty studying structural development - Moriguchi et al. (2009; 2011)

• 3 yo who could switch in the DCCS task showed a bilateral increase in oxygenation in the ventral and dorsolateral PFC.

• Individual differences in cognitive flexibility

Functional connectivity

How different areas of the brain communicate and work together, during specific tasks or at rest

Functional connectivity of the PFC in infants

Ezekiel et al., (2013) - fMRI

• Weaker between the lateral pFC, ACC, inferior parietal cortex

• At 3yo: Weak neural interactions within the frontal cortex and unrefined frontoparietal connectivity

• At 4.5yo: Stronger neural connections and a refined pathways with efficient connectivity

Conclusion of Ezekiel et al., (2013)

• Confirms the involvement of the PFC in early EF

• Shows PFC does not work in isolation

Quantitative changes in functional connectivity - Englehardt et al. (2019)

• Compared the location of the adult regions of interest (ROI) to the children’s common task activity

  • Switching, updating and inhibition tasks

• Taken the centre of the clusters

  • Child samples were within 15mm of the adult-based ROIs

Qualitative and quantitative changes of functional connectivity - Moisala et al. (2018)

2 tasks: Attention and WM tasks (division of attention, inhibition distractors, WM and attentional switching)

13-14 yo: brain regions unique to one task, connectivity is spread

20-24 yo: brain regions active for all tasks, connectivity is short and dense

Importance of executive functions

Mental and physical health, quality of life, school readiness,

school and job success, marital harmony, public safety.