brain plasticity + ways of studying the brain + biological rhythms

What is neuroplasticity

?The brain’s ability to adapt to change, whether from injury, illness, learning, or experience

What is structural plasticity

?Changes within brain structures over time, e.g., increased grey matter in the posterior hippocampus due to learning or experience

What is functional plasticity (functional recovery)?

The brain’s ability to replace lost or damaged functions by using existing healthy brain regions

What is axonal sprouting

?New growth of nerve endings from surviving neurons that link up with other undamaged cells to form alternative neural circuits

What is reformation of blood vessels in recovery

?Damaged tissue stimulates angiogenesis, restoring oxygen and nutrient supply to recovering areas

What is recruitment of homologous areas

?Regions in the opposite hemisphere adopt functions of injured zones, e.g., right Broca’s area compensating for left-side damage

What is neural (synaptic) pruning

?Unused synapses are cleared out while frequently used synapses grow stronger, making neural networks more efficient

What did Maguire et al. (2000) find about taxi drivers

?London taxi drivers had increased grey matter in the posterior hippocampus compared to controls, linked to spatial navigation

What did Draganski et al. (2004) find about juggling

?Learning a juggling routine increased grey matter in the mid-temporal cortex

when juggling stopped for three months, grey matter decreased

What did Gotink et al. (2016) find about mindfulness

?Participants showed increased grey matter in prefrontal cortex and decreased grey matter in amygdala, reducing stress and anxiety

Who is EB and what does his case show

?Danelli et al. (2013) studied a boy who had his left hemisphere removed at age 2

language function recovered via functional plasticity in the right hemisphere

What did Schneider et al. (2014) find about cognitive reserve

?Patients with higher education were more likely to recover after brain injury, suggesting cognitive reserve supports functional recovery

What is fMRI and how does it work

?Measures oxygenated blood flow in the brain

more active areas receive more oxygenated blood, detected by magnets and shown as colored 3D images (voxels)

Strengths of fMRI

?Good spatial resolution (~1mm) and non-invasive, allowing precise, ethical measurement of brain activity

Limitations of fMRI

?5-second delay, expensive equipment, small sample sizes

indicates correlates, not causation

What is EEG and how does it work

?Electrodes on the scalp measure electrical activity of underlying neurons

shows brain waves indicating amplitude (intensity) and frequency (speed)

Strengths of EEG

?Important for studying sleep patterns

systematic methods increase reliability and replicability

Limitations of EEG

?Can only detect surface activity

electrode placement can vary, causing unrepresentative findings

What are ERPs and how are they derived from EEGs

?Event-related potentials are measured voltages in response to stimuli, extracted by averaging EEG recordings to isolate specific cognitive processes

Strengths of ERPs

?Cheaper than fMRI, measures real-time brain activity with millisecond precision

Limitations of ERPs

?Electrode cap can be uncomfortable

source of signal not pinpointed perfectly

What is a post-mortem examination (PME)?

Examining a brain after death to determine cause of dysfunction, often used historically or when other methods are unavailable

Strengths of PME

?No harm to living person

can confirm diagnoses like Alzheimer’s

Limitations of PME

?Cannot fully represent living brain function

consent may be limited in some cases

What are biological rhythms

?Changes in body processes or behaviour that repeat regularly in a cycle, influenced by endogenous pacemakers and exogenous zeitgebers

What are circadian rhythms

?Biological rhythms with a 24-hour cycle, e.g., sleep-wake cycle

What are endogenous pacemakers

?Internal mechanisms controlling biological rhythms, e.g., SCN in hypothalamus

What are exogenous zeitgebers

?External cues that reset biological rhythms, e.g., light and social cues

What is the SCN and where is it located

?Suprachiasmatic nucleus in the hypothalamus at the point where optic nerves cross

master circadian clock

What does the pineal gland do

?Releases melatonin in response to SCN signals

promotes sleepiness when light decreases

How does the SCN respond to light

?Receives input from retina

suppresses melatonin when light is present, promotes wakefulness

releases melatonin when dark, promoting sleep

What did DeCoursey et al. (2000) find about destroying SCN cells in chipmunks

?Sleep-wake cycle disappeared

many chipmunks were killed by predators, demonstrating SCN’s role

What are ethical issues with DeCoursey’s study

?Animals were placed at risk and harmed

raises concerns about welfare

What did Siffre (1962) find in cave studies

?Without natural light, his circadian rhythm extended by a few hours, showing importance of exogenous zeitgebers

What did Aschoff and Wever find

?Participants in a WWII bunker showed 24–25 hour sleep-wake cycles, some up to 29 hours, demonstrating endogenous generation of circadian rhythms

How can exogenous zeitgebers reduce jet lag

?Exposure to light and social cues at the new location helps reset circadian rhythms

How can parents entrain a baby’s sleep cycle

?Set regular sleep and mealtimes

Why might older adults experience disrupted sleep patterns

?Reduced exposure to natural light and activity

increased insomnia can be alleviated with daylight exposure and activity (Hood, 2004)

Define entrainment

?Using exogenous zeitgebers to reset circadian rhythms

What happens if SCN is destroyed

?Sleep-wake cycle disappears

behaviour becomes unregulated (e.g., chipmunks killed by predators)

Give an example of interaction between SCN and pineal gland

?SCN receives light info → signals pineal → melatonin secretion suppressed in daylight, released at night.