L8-14 Flashcards
alzheimers symptoms
- loss of memory
- impaired reasoning
- reduced language skills
- loss of daily living skills
alzheimers test
Phonemic and Semantic Verbal Fluency (SVF)
- 1 min, how many words wither starting with a letter or belonging to a semantic category (e.g. animals)
alzheimers primary risk factor
AGE – after 65, risk of developing doubles every 5 years
alzheimers brain changes (4)
- brain atrophy, especially hippocampus and cortex
- plaques = clumps of beta amyloid
- neurofibrillary tangles = inside cells
- degeneration in basal forebrain
beta amyloid plaques
- anyloid precursor (APP) → role in synaptic plasticity
- B-amyloid when APP is cut up
- overproduces in AD, sticks together and clumps
- leads to degeneration of the cells
new AD drug relating to plaques
- Donanemab - antibdy medicine
- reduces beta amyloid and reduces cognitive decline
- doesn’t stop but slows down
neurofibrillary tangles
- tangled microtubules - the scaffolding in cells
- stabilised tau protein
- in AD, tau disintegrates and forms clumps
- location of tangles corresponds will with symptoms
degeneration in basal forebrain
- nuclei send projections into cortex, especially to release ACh
- degeneration = decreased cholinergic transmission
= decreased memory - mild-moderate AD can be treated with cholinesterase inhibitors (inhibit reuptake)
APOE gene variation - role in AD
- three major variations (alleles) of the APOE gene- called APOE2, APOE3, APOE4
- ApoE mainly produced by astrocytes, and transports cholesterol to neurons
- having ApoE4 allele, esp 2 of them, leads to increased AD risk
- has to do with maintaining pericytes at BBB
protective factors against AD
better education early on either prevents AD or encourages more intellectual activities throughout life
higher idea density scores in early life are associated with intact cognition in late life despite the presence of AD lesions.
n-back test
indicate when the current stimulus is the same as the one n back from it
- fMRI shows DL PFC active
- ability to repress irrelevant info (e.g. lures)
define inhibitory (self)-control
Where previously reinforced, highly reinforcing, or well learned (habitual) responses have to be suppressed
- important for group living
Hot/cold framework
hot = emotional, reflexive, accentuated by stress
cold = cognitive, complex, slow, reflective
utilisation behaviour
- behaviour driven by stimulus
- e.g. glasses on desk, hammer and nail
- when PFC damaged
Wisconsin Card Sorting Task with PFC damage
PFC damage = makes it really hard to change behaviour when criteria changes
role of dorso-lateral PFC in self control
DLPC has connectivity that allows it to in modulate action execution and
evaluation
Raven’s Progressive Matrices
- test for non-verbal reasoning
- finish the pattern etc
- activation in dorsolateral region
Frontal Lobe Syndrome - symptoms and why
- Cognitive impairments = deficits in temporal ordering, goal directed behaviour and abstract reasoning. Poor decision-making
- Emotional changes = apathy, anergia, socially inappropriate outbursts
- Behavioural deficits
= Utilization behaviour, perseveration, environmental dependency, socially inappropriate behaviour, risky behaviour
Balint syndrome
= can only perceive one object at a time
- e.g. spoon or pen
- associated with parietal lobe lesions
PFC damage + creativity
in most cases, PFC associated with decreased performance on task of creativity - originality, flexibility, fluency
- need divergent thinking, combining available knowledge
2 systems of decision making
system 1 = experiential-affective
- rapid, undemanding, associative, mostly automatic
system 2 = analytical
- rational, controlled, slow, conscious
parallels hot/cold model
system 2 takes into account…
external factors: commodity, quanity, delay, risk, ambiguity, cost
internal factors: motivation, patience, risk attitude, ambiguity attitude
temporal discounting (common with what kind of brain damage?)
- discounting because it’s in the future
- prevalent with orbital frontal cortex damage
marginal value theorem
- for foraging in animals: they’ll tend to leave to keep exploring at an optimal point when gaining less energy than they could from other patches
- humans foraging for information
- Anterior Cingulate Cortex neurons encode value and firing is related to patch leaving
system 1 key structure, and explain
amygdala
- emotional processing, fear, with links to memory
- for things with evolutionary relevance, pathway from visual cortex straight to amygdala = quick fear response before conscious processing of what you’re actually seeing
Damasio’s Somatic Marker Hypothesis (SMH)
somatic emotional responses help us make a decision
- grounded in
states of bodily physiology and on the processing of those states in the
entire nervous system
- is shaped by a person’s past experiences in
similar situations
PFC activity can be inhibited by…
- alcohol
- fear –> vmPMC = starts to shut down the closer you get to a threat
what side of brain is language lateralised in?
- in most RHers in left hemi
- in LHers, some in right hemi, or less lateralised
wada test
can anaesthetise left hemi → can’t speak
lateralised language – split brain patients with words/drawings
can’t say the word that came in left eye but can draw it with LH → saw it but couldn’t verbalise
prosody
the patterns of stress and intonation in a language
- emphasis, pitch pauses, loudness
decoding speech (4 steps)
- Separating out the individual units from a text or speech-stream
- Accessing the mental lexicon (dictionary), which includes semantic and syntactic attributes
- Lexical selection (what word is the best match?)
- Integrating these words into a full sentence so as to understand the whole message.
damage to weirneke’s
fluent aphasia → nonsensical speach
damage to broca’s
broca’s aphasia = can’t find words, difficultly expressing
Semantic dementia
- lose ability to understand words, then how to use objects or recognise people
- damage primarily to anterior temporal lobe - maybe a hub for these memories
- hippocampus is important for activating other brain areas in cortex
parsing sentences
- information contained in the words of a sentence and in the context around the
sentence are used to make predictions about how the sentence should be parsed. - involves prediction which illustrates the top-down processes that occur simultaneous to the bottom-up sensory-lexicon-conceptual hierarchy.
titled vs untitled ambiguous story
Titled ambiguous story = more meaning, understanding and brain activity → default mode network
default mode network
- Activated when individuals are focused on internal mental state processes
- shuts down for explicit task
Social behaviour in 2 dimensions
- affiliative [make connections] vs antagonistic [push people away, compete]
- self vs other benefitting
Simulation theory
proposes that some aspects of our ability to understand others is based on our ability to mimic their experience - to mentalise and empathise
mirror neurons
- same neurons as for motor movement fire when behaviour is observed
- first described in ventral premotor cortex, but since
discovered in a wide range of brain regions
evolutionary basis for social connection/isolation
The perception of social isolation may be a response to a biological need, shaped by evolution
key points on social isolation
- risk factor for dementia
- triggers increases in cortisol
- is increasing but is potentially modifiable
mirror self recognition task
- dot on nose, do they reach up and touch their own nose?
- if yes, understand that the mirror image is a reflection of themselves
argument against mirror self recognition task
could solve without self awareness
1. Look at image in mirror
2. Be familiar with mirror image
3. Move arm and discover that kinaesthetic
sense of arm movement corresponds to
visual change in mirror
4. Be aware that image has changed (red dot).
5. Move arm or trunk so that object (finger) in
mirror touches red dot.
Neural Correlate of Consciouness (NCC)
It is probable that at any moment some active neuronal processes in our head correlates with consciousness, while others do not
rate these states of consciousness in terms of awareness and wakefulness
- coma/general anaesthesia
- deep sleep
- light sleep
- REM sleep
- lucid dreaming
- unresponsive wakefulness syndrome
- minimally conscious state
- locked in syndrome
increasing awareness and wakefulness:
coma -> deep sleep -> light sleep -> drowsy -> conscious wakefulness, also locked in syndrome
low wakefulness, higher awareness = REM sleep, lucid dreaming (even more aware)
low awareness, high wakefulness = unresponsive wakefulness syndrome, minimally conscious state
bistable task
- 2 perceptions of the same image
- e.g. binocular rivalry
- demonstrates fluctuating conscious experience despite fixed physical stimulus
- occipital and parietal activation → correlate of change in conscious perception
- frontal activation more to do with the decision making and motor
Anaesthetic
shows consciousness requires connectivity between brain regions
Transcortical magnetic stimulation (TMS) - effect when sleeping vs not
- repeated oscialltion after burst when awake
- just one burst when sleeping - consistent with reduced connectivity/spread of activity when sleeping
TMS study shows…
- Evidence for a breakdown of long-range effective connectivity during non-REM sleep.
- Thus, an impairment in the ability to integrate information may underlie the fading of consciousness in non-REM sleep early in the night.
basis of consciousness
functional connectivity between brain regions
lucid dreaming
consciously aware that you are dreaming, can manipulate
- increased activity in ant PFC, parietal and temporal cortex
