ageing and physiology Flashcards
sensory abilities change with age
Baltes’ model
loss in sensory abilities with age — occurs similarly in many countries
e.g. vision, hearing
in line with Baltes model → prediction that cultural & environmental factors would become less important than biological factors when explaining age changes in cognition
neural dedifferentiation
young adults = functions are specific localised, distinct, differentiated brain areas
older adults = brain functions become less differentiated, distinct, localised, selective with age
by compromising neural representations that support episodic memory and other cognition aspects
examples of sensory, perceptual, motor abilities (+ shared variance)
examples of cognitive abilities
visual, hearing, balance, walking, gait, grip strength, proprioception
shared variance in these functions implies latent variable that reflects this – associations between these common factors and age
working memory, episodic memory, fluid intelligence, processing speed
common cause hypothesis
indirect effect of age on sensorimotor and cognitive ability via a common cause
find common cause through shared variability of age related differences
sensorimotor ability decline indicates issues with biological integrity of the brain - could predict cognitive decline
reduced brain health as a common cause for ability decline
mediation model
map general intelligence against age
— shows decreased intelligence with age
control model for sensorimotor functioning = correlation is no longer significantly negative
— shows the presence of sensorimotor functioning as a third variable
— therefore attribute a lot of importance to this factor to explain age and cognitive ability
sensorimotor function could fully mediate age-related variability in cognitive abilities
common cause: neurological processes decline theory
neurological process decline causes cognitive and sensorimotor decline
sensory ability as an indicator of biological integrity of brain – predicts decline
sensory function has a causal role in cognitive tasks - therefore maybe should attribute to sensory function not age
sensory deprivation impact on cognitive abilities
indirect effect of sensorimotor ability on cognitive abilities through increased social disengagement and withdrawal
therefore less intellectually stimulating activities and knock on effects on cognitive abilities
cognitive load effect on sensory performance
inverse of idea that sensory impacts cognitive
–different causal direction
deficits in sustained attention may diminish individuals capacity to detect auditory or visual stimuli
which explanation of direction is correct? (cog to sensory or sensory to cognitive)
they aren’t mutually exclusive
could operate interdependently in a cycle of cumulative and reciprocal effects - could be bidirectional
e.g. limited cognitive resources + sensory decline from brain ageing → increased cognitive load → increased likelihood of social withdrawal → limits opportunities to moderate adverse effects of brain ageing
longitudinal studies show more modest associations between sensorimotor and cognitive declines
both indirect and direct effects are at work:
* indirect = age → common cause → SM and cog ability decline
* direct = age → SM and cog ability decline
other factors not explained by common cause
would explain how correlation isn’t perfect
duration of sleep change with age
decreases with age
sleep stages changes with age
increased WASO (waking after sleep onset)
decreased SWS (slow wave sleep) - greatest decrease – therefore less SWA (slow wave activity) esp in PFC and so decreased sleep spindle density
time in REM is unchanged - but less phasic REM in older adults
overall - older adults sleep less and awaken more frequently in the night
role of SWS + odour study
slow wave sleep
long-term memory consolidation
Rasch et al (2007)
play memory game before sleep
presented with odour during learning
4 experiments:
1 = same odour given in SWS
2 = give a different odour in SWS
3 = give odour in REM sleep instead
4 = present odour before sleeping not during sleep
found memory improved when representing odour during SWS versus control → no difference in other experiments where same odour wasn’t presented in learning and SWS
hippocampo-neocortical dialogue in sleep
wakefulness = info is encoded in neocortical and hippocampal networks
SWS = repeated activation of recently learnt info within hippocampal networks
reactivations stimulate transfer of memory toward neocortical sites for long term storage
therefore ageing affects sleep-dependent memory consolidation
reactivations associated with sharp waves/ripples → driven by slow oscillations that synchronise hippocampal memory reactivations with sleep sindles
with age:
reduced SWS means less hippocampo-neocortical dialogue
changes in hypothalamo-pituitary-adrenal axis
leads to increased cortisol levels in evening
low cortisol needed during sleep for memory
hippocampus has many cortisol receptors and therefore this high cortisol could impair hippocampal function to transfer memories for long term storage
sleep and memory in young vs old adults
sleep benefits memory in younger adults but not older adults
time in SWS → correlated with memory in younger but not older adults
rate of forgetting: reduced in younger adults after they slept vs no difference in older adults whether they had slept or been awake
link between episodic memory and SWS observed in younger adults - weakened in healthy older adults
critical - how much can sleep effect cognitive abilities changes with age
optimal times of day (and this as a critique of studies)
more effective suppressing of irrelevant info during optimal times than not - in young and old adults
more early when older and later when younger
this could confound studies → don’t perform as well if studied at non-optimal TOD
