Chpt 12: Exercise & Cognition in Children

Chronic effects (fitness)

• appear early in processing (~10 yrs old)

• Improvements in performance

• Changes in ERP (P1, P300, ERN, CNV)

• Morphological changes (BG, HC, white matter integrity)

Chronic effects (fitness) - Performance

• Oddball task: faster, > accurate (engagement) - P300

• Flanker: Nominally faster, > accuracy (< difficulty inhibitiing pre-potent) - P300, ERN

Chronic effects (fitness) - ERP components

• > P300 amp: engagement

• > ERN + P300: > efficient cog strategies during effortful tasks (> performance)

• > P1 amp: early - parietal; V1 activity; modulated by attn (visual)

• > CNV amp: better task preparation

Morphological Changes - Basal ganglia

• > volume in caudate, putamen (dorsal striatum), globus pallidus

• Less interference (< incongruent trial rxn time & accuracy)

• Putamen volume - correlated w/ rxn time (> volume, < rxn time - > performance)

• Putame: cogntiive control, rxn resolution

Morphological Changes -HC

• Item/relational memory (which go together; which were seen)

• d’ (sensitivity) = ability to differentiate btwn things that went tg or not

• Nominally better performance, > HC volume

• For > difficult task (relational mem): HC vol correlate w/ performance

• Exercise impacts memory thru HC (volume)

Fractional Anisotropy - White matter integrity

• Proportion of hoz H20 diffusion vs vertical (should be hoz)

• Occurs in tightly bunded, structurally compact fibres w/ > integrity

Morphological Changes - White matter Integrity

• > directionality of H20 diffusion (hoz)

• Performance correlated w/ FA (fractional anisotropy)

• High FA = > accuracy (> insulative integrity, > connectivity)

• High FA = < interference (faster rxn tiime during incongruent)

Effect beyond lab tests

• Correlated to results of lab tests (NO-GO - > P300 amp, > academic performance)

• > P300 amplitude: > cog demand (WM, attention)

• > reading performance, > P300

• > arithmetic performance, > P300

Acute effects in children

• Larger P300 after exercise

• < RT overall, < interference (incogruent rxn time)

• Nominal but x sig > improvements in spelling/arithmetic

• Sig > in reading comprehension score

Acute effects - Improvement for low performers

• More room for improvement

• < interference, > accuracy on No-GO task

• N2 (rxn Inhibition, error monitoring): Resembled > performance at rest (< amp)

• P300 (engagement): > amp (more than > performers)

Neural development - synapses

• # synapses > until age 4

• Up to 42% synapses eliminated after that

• Use it or lose it (active = strong, inactive = pruned)

Neural development - Pruning

Synapse formation: > from gestation → 2 years old

Synapse pruning: 4 years → 6 years & onward

Neural development - Myelination

1. Spinal cord (24 wk after conception)

2. Hindbrain

3. Midbrain

4. Forebrain (adolescence/early adulthoold) - 25 yrs

Development of cognitive & emotional control

1. Self-regulation: moving to goal state

2. Regulation: with conflict (little conflict stops here)

3. Control

   1. Self-control: HOT EF

   2. Cognitive control: Cool EF

4. Conflict

   1. Hot EF → conflict = goals

   2. Cool EF - conflict = cognitive/motor processes

Hot Executive Function

• Conflict is motivation/emtion

• Knowing how you feel

• Representations for rewards/losses over time

• Making good decisions (consequences)

• Delay for a larger reward (1 cookie now, 2 later)

Cool Executive Function

• Conflict is behavioural/thoughts (pros vs cons list)

• Working memory

• inhibition (stroop, flanker)

• Flexibility to changing rules (WCST)

Cerebellum - Inputs

• Small powerhouse (10% mass, 50% neurons)

• Multiple inputs:

  • Motor cx (what body is doing)

  • Brainstem motor nuclei (sent to muscles for movement)

  • Somatosensory/vestibular sys (where body is in space; balance)

  • Midbrain

  • Limbic sys (memory/emotional ctrl)

• Dmg causes issues w/ cog/emotional control

Cerebellum - Lobes

• Anterior: muscle tone, coordination of skilled movements

• Posterior: planning of voluntary activity (EF)

• FN lobe: balance, movement ctrl

Cerebellum - Roles

• Fine-tuned motor coordination (ctrls force, amplitude, velocity)

• General timing mechanism for sensorimotor & cog processes

• More active during demanding/novel tasks

• Along w/ acitivty in PFC

Cerebellar Cognitive affective syndrome (CCAS) - difficulties

• Executive: planning, shifting, WM, abstract reasoning (like frontal lobe dmg)

• Spatial: visuo-spatial org, memory

• Personality: blunt affect, disinhibition (inappropriate behavi)

• Language: agrammatism, aprosodia (rhythm = off)

Exercise & the cerebellum

• Increased gray matter

• Increased BDNF

Basal Ganglia - Anatomy

• Caudete (D1 & D2 DA receptors - signal:noise ratio; receive from SN)

• Putamen

• Globus pallidus

Basal Ganglia - Function

• Control of voluntary movement

• Motor learning

• Implicit learning

Basal Ganglia - Tracts

• Mesolimbic tract: reward/memory

• Nigrostriatal tract: movement

• Mesocortical tract: organization

• Tuberoinfundibular tract: hormone release

BG - Probabalistic Learning

• Learning from outcomes of multiple trials

• Learn about probabilities (correctly predict outcome)

• Relies on striatum

Weather Prediction Study

• Probabalistic: Ctr & HC patients are able to learn abt probablities (predict outcome)

  • BG is intact (Parkinsons didn’t do well)

• Declarative: Ctlr & Parkinson’s could report facts abt the task

  • HC is intact

Engaging the Cerebellum & BG w/ Exercise (coordinated vs cardio)

• Coordinated exercise vs cardio exercise (to same %HR)

• Coordination > performance more than cardio (d dash & immediate/delayed recall)

• > cognitively demanding activity leads to better outcome)

• Through recruitment of cerebellum & BG

Engaging the Cerebellum & BG w/ Exercise - Mechanism

• Enriched exercise serves as stressor

• Coordination exercise engages neural circuitry responsible for motor/cog coordination

• Engaging physical activities recruit cogntiive function (theory of mind)

Cortisol

• Cortisol receptors in neocortex, cerebellum, HC

  • Mineralocorticoid: acitivated at moderate intensities

  • Glucocorticoid: activated at high intensities

• Glucocorticoid: < binding affiinity, req > intensity exerice (> [cortisol])

Cortisol (HPA Axis) - Moderate Increase

• Supports LTP (new connections, > NT released at synapse)

• Impacts cognitive performance (EF, learning/mem, men consolidation)

• Mineralocorticoid = activated

Cortisol (HPA Axis) - High Increase

• Generates LTD (degrades connections, < NT released at synapse)

• Impacts cognitive performance

• Glucocorticoid = activated

Hormonal Dev - Cortisol Threshold/Stress rxn

Adults:

• Need > intensity exercise (>80% VO2max)

• Mod intensity (40-80%) for at least 50 mins

Teens (14-16):

• Similar threshold (most have gone thru puberty)

Younger children:

• Stress rxn & cortisol threshold differs

Puberty

• Chronological age x perfectly align w/ puberty stage

  • Pubic hair development

  • Testicular volume)

• Generally x pre-pubescent (P1/P2) at 15-16 yr old)

• Gradual change

Hormonal Dev - Cortisol

• Baseline cortisol lvls correlated w/ chronological age & puberty stage

  • < baseline for younger children/pre-pub

• Cortisol lvl > after exercise

• Effect is greater for younger children (> room for improvement)

Cortisol - Fitness & Developmental stage

• Cortisol > dep on BOTH fitness & dev stage

• Pubescent = increase

• Pre-pub = > if high fit

Hormonal Dev - Testosterone

• Baseline T lvls correlated w/ age & puberty stage

• T > after exercise (greater for younger children)

Testosterone - Fitness

• Fit: exercise > T lvls (> active you are, > reactive the body is to a single bout of exercise)

• Low-activity: < T w/ exercise

Testosterone - Intensity

• > intensity, > lvls of T

Testosterone - Performance

• For low performers: sig > WM performance w/ > intensity

• High performers: slight improvement w/ mod; decline w/ low/high

• Lowest verbal fluency scores had highest T

• Suggests an optimal lvl of T for performance

T - Androgen Receptors in cytoplasm

• Found in PFC (EF) & HC (memory

• T binding to androgen R upregulates mRNA transcription/translation

Improved Cognition - Mechanism

• Exercise > testosterone

• > T binding to androgen Receptors

• Triggers mRNA upregulation

• Increases synapses & # dendritic spines

• Improves cognition (through improved neural communication)