1.2 brain plasticity and injury (c5) Flashcards
define neuroplasticity
the ability of the brain and other parts of the nervous system to change in response to experience
used specifically to brain’s ability to change sometimes
what are synapses
the site where adjacent neurones communicate by transmitting neural signals to one another
why are individual neurones and their connections modified
for diff reasons
example: during brain development when young, learning, using drugs, response to brain injury
can new neural pathways form and link w existing pathways?
yes
can existing pathways interconnect with other pathways?
yes
define synaptic plasticity
the ability of the synapse to change in response to experience
what does synaptic plasticity involve
strengthening or weakening of connections between the neurones at a synapse
how does strengthening occur
through continual use of synaptic connections or through growth of new, additional connections
how does weakening occur
through disuse of synaptic connections resulting in decay or elimination of a synapse
how does the brain reorganise and reassign its neural connections and pathways
through synaptic plasticity, reassigns and reorganises neural connections and pathways based on which parts of it are overused and underused
what is experience-expectant plasticity
involves brain change in response to environmental experience that is ordinarily expected
what is experience-dependent plasticity
involves brain change that modifies some part its neuronal structure that is already present
what is functional/adaptive plasticity
neuroplasticity in response to brain injury
brain can recover from or compensate for lost function and/or to maximise remaining functions in the event of brain injury
why is functional/adaptive plasticity called that
to distinguish it from the plasticity primarily associated w the developing brain
what are the 3 types of change in the brain
generation of new networks
reassignment of function
neurogenesis
generation of new networks?
neuronal connections and networks that have been disrupted by injury may change by forming new connections
reassignment of function?
functions that were performed by certain areas of the brain can sometimes be reassigned to other undamaged areas of the brain to compensate for changing input from the enviro
either a pt or all of a function previously performed by the injured area may be transferred
what is neurogenesis
the production/birth of new neurons
what is sprouting
the creation of new extensions on a neuron to allow it to make new connections with other neurones
occurs thru growth of nerve endings (sprouts) on axons or dendrites, thereby enabling new links to be made, including the rerouting of existing connections
what is rerouting
new connections made between neurones to create alternate neural pathways
may involve new or old synaptic connections
what is pruning
the elimination of weak, ineffective or unused synapses
experience determines which synapses will be retained and strengthened and which will be pruned
way of fine-tuning brain’s neural circuits to maintain efficient brain functioning
also enables neurones to restore or compensate for lost function following a brain injury and/or to maximise remaining functions
what are the 4 levels of the severity of brain injuries
- Mild
- Moderate
- Severe
- Very severe
symptoms of mild brain injury
good recover, limited concentration, able to return to work
symptoms of moderate brain injury
improvement over time, difficulties w coordinating movements, inability to organise, may require diff line of work
symptoms of severe brain injury
decreased movement control
decreased ability to communicate
requires daily living support
unable to return to work
symptoms of very severe brain injury
unable to control movement
unable to communicate
requires 24 hour support
unable to return to work
define brain injury
brain damage that impairs or interferes w the normal functioning of the brain, either temporarily or permanently
why is the term acquired brain injury used
used to differentiate brain injury from neurodevelopmental disorders (such as autism)
define traumatic brain injury
type of acquired brain injury that occurs when an external force causes damage to brain
can result from blow to head, head forced to rapidly move, or when object enters brain tissue
what are some biological changes due to frontal lobe injury
range of problems w motor activites
example: less facial expressions, reappearance of reflexes from infancy (ex. grasping reflex of hand)
what are some psychological changes due to frontal lobe injury
impact on emotion, personality, cognition -> impacts behaviour
example: apathy, verbal/physical aggressiveness
what are some social changes due to frontal lobe injury
breakdown in personal relationships, loss of social support
define aphasia
language disorder that results from acquired brain injury to an area responsible for language production or processing
primary signs of aphasia?
difficulty in expressing oneself when speaking
trouble understanding speech
difficulty w reading and writing
what are the 3 types of aphasia?
fluent aphasia
nonfluent aphasia
pure aphasia
what is fluent aphasia
speech easily produced and flows freely but sentences don’t make sense and the person often has difficulties understanding what is heard or read
what is nonfluent aphasia
difficulties in speaking clearly, often in short sentences w words omitted
speech is effortful and includes only key words necessary for communication but no difficulties understanding what is heard or read
what is pure aphasia
specific impairments in reading (alexia), writing (agraphia) or recognising spoken words despite being able to hear them (word deafness)
define neurological disorders
nervous system disorders
may involve any part of nervous system
is epilepsy a single condition
no there are many diff types
what is the main symptom of epilepsy
repeated seizures
3 common symptoms in epilepsy?
onset of an aura
loss of consciousness- can range from complete loss to staring blankly into space // often accompanied by amnesia
movement- abnormal movements after onset of seizure
what is onset of an aura
an unusual subjective sensation, perceptual experience (ex. unusual smells/tastes), motor experience (tingling in arms or legs) that precedes and marks the onset of an epileptic seizure
what are some causes of epilepsy
traumatic brain injury
lack of oxygen to the brain for a long period (e.g. due to stroke, cardiac arrest, drowning)
brain infection (e.g. meningitis)
brain abnormality at birth
brain tumour
neurodegenerative disease (e.g. Alzheimer’s)
genetic factors (e.g. genetic conditions w associated brain malformations)
does everyone have seizure triggers
no some ppl have seizures triggered by certain events but others dont
common seizure triggers:
missed medication
sleep deprivation
stress
infection/illness
hormonal changes
dehydration
low blood sugar
alchohol
drugs
use of certain medications
bright lights
define concussion
type of traumatic brain injury caused by blow to head or by a hit to the body that causes the head and brain to move rapidly
disrupted neuronal activity, sometimes stretches/damages brain tissue and cells
common sports that cause concussions
boxing, AFL football, rugby, horse riding, cycling, skiing, trail bike riding
what are concussions categorised as
mild bc they are usually not life-threatening
can effects of a concussion be serious
yes its more likely when a person has a previous history of concussion(s)
what does CTE stand for
chronic traumatic encephalopathy
what is CTE
a progressive brain degeneration
what causes CTE
repeated blows to the head and repeated episodes of concussion
is CTE fatal
yes
is CTE rare
yes so it is not yet well understood
when was CTE first diagnosed
in the early 2000s by an American dr during an autopsy of the brain of a former profession NFL player
how common is CTE
theres still debate
why is there still debate about CTE
they still dk and the Australian Sports Brain Bank started identifying CTE in explayers of high contact sports (e.g. AFL, rugby) a few years ago
what are some symptoms of CTE
it varies and its similar to other degenerative conditions like Alzheimer’s and Parkinson’s
typical symptoms are
- loss of memory
- mood changes
- personality changes
- difficulty controlling impulsive or erratic behaviour
- increased confusion, disorientation
- difficulty thinking (e.g. difficulty making decisions, impaired judgements)
- motor impairments (e.g. tremor, slow movements, balance difficulties, slurred speech)
can symptoms of CTE progress
yes its typically mild at first but it progresses over time to become more severe
when are symptoms of CTE often experienced
may not be experienced until years of decades after brain injury occurs
how do u diagnose someone with CTE
no medical or psychological test to diagnose CTE in living person
changes to brain dont always show up on brain scans
why are assessments are undertaken when CTE is suspected
taken to rule out other possible causes
how is CTE properly diagnosed
autopsy-
brain areas may have gradually wasted away (atrophy)
abnormal build up of tau (protein that interferes w the functioning of neurones- strongly associated with Alzheimers)
other recognition still limited and diagnosis is still difficult and unclear
how is CTE treated
using supportive treatments like other neurodegenerative diseases
no treatment for CTE itself, but we can treat symptoms- e.g. medication for depression
can you have CTE without brain injuries
yes
whats the number or types of head impacts that increase risk for CTE
no one knows some people w repeated head trauma never gets CTE
does genetics affect risk for CTE
not really no one knows “its not adequately accounted for in the research evidence”
what is epilepsy?
a neurological disorder involving recurrent, spontaneous seizures brought on by interference in normal brain activity
why is epilepsy classified as a neurological disorder?
because it is a disease of a nervous system and involves recurring abnormal brain seizures
why can epilepsy be described as a spectrum disorder
there are different epilepsies with different causes and seizure types that vary in severity and impact on individuals in different ways
Define the meaning of epileptic seizure
A sudden burst/surge of electrical activity in the brain that disrupts normal neuronal activity and causes involuntary changes in a person’s movement, behaviour, level of awareness and/or feelings.
characteristics of epileptic seizures
triggered by bursts of electrical activity in the brain that disrupt normal neuronal activity and cause involuntary changes depending on the affected brain area
start somewhere in the brain
point of origin may be known (e.g. focal, generalised) or unknown
many different types
not due to a health condition not associated with epilepsy
may be provoked or unprovoked/have or not have triggers
repeated/recurrent i.e. at least two unprovoked seizures
variable in duration
may stop without intervention
specific types are primarily classified according to point of origin, awareness and whether they involve movement.
define focal seizure
Originate in one brain area in one hemisphere (a ‘focal point’) and affect the part of the body controlled by that brain area
define generalised seizure
Originate in both brain hemispheres simultaneously and therefore tend to involve the whole body
define seizures with unknown onset
Neither focal or generalised as onset of seizure is not known
characteristics of a focal seizure
may affect a small area in one of the lobes or a large part of one hemisphere
usually last for less than 2 minutes
may spread to both hemispheres (and become a focal to bilateral seizure).
characteristics of a generalised seizure
there is no focal onset
many different subtypes
almost always affect awareness and loss of consciousness is common.
why are some epilepsy cases classified as seizures with unknown onset
classification may be due to insufficient information for a diagnosis to be made or the symptoms of the seizure are unusual
what determines the behaviour changes that may occur during a seizure
reactions depend on the type of seizure and the area of the brain being affected.
What do all known causes of epilepsy have in common?
All disrupt the neuronal activity somewhere in the brain (more than once) in a way that results in epileptic seizures.
What is the most common treatment for epilepsy?
anti-epileptic medication
what is the difference between brain injuries with suden or insidious onsets
sudden onset: occurs abruptly often a single point in time
insidious onset: gradual development over a period of time in an imperceptible way showing few signs or symptoms
an example of brain injury with sudden onset
e.g. due to a blow to the head, infection, stroke or drug overdose
an example of brain injury with insidious onset
e.g. due to prolonged use of alcohol or another substance, a tumour or a neurodegenerative disease
where does Broca’s aphasia affect
broca’s area
which hemisphere does Broca’s aphasia affect?
left
which lobe does Broca’s aphasia affect
front
what is the main language of communication difficulty of Broca’s aphasia?
speech production
are individuals with Broca’s aphasia aware of their difficulties
usually yes
where does Wernicke’s aphasia affect
wernicke’s area
which hemisphere does Wernicke’s aphasia affect
left
which lobe does Wernicke’s aphasia affect
temporal
what is the main language or communication difficulty of Wernicke’s aphasia
speech comprehension and meaningful production
are individuals with Wernicke’s aphasia aware of their difficulties
usually no, but if they do its very little
what happens when the primary motor cortex of the left hemisphere is damaged
impairment of voluntary movements on the right side of the body (e.g. limbs)
what happens when the prefrontal cortex is damaged
impaired higher order mental functions e.g. decision making, planning, change in personality e.g. as per Phineas Gage
what happens when the parietal lobe of the right hemisphere is damaged
impaired spatial abilities
what happens when the auditory cortex is damaged
impaired hearing
what happens when the medulla is damaged
impaired vital survival functions
what happens when the substantia nigra is damaged
voluntary movement impairments like those of Parkinson’s disease (due to loss of dopamine producing neurons in the substantia nigra)
what happens when the RAS is damaged
impair consciousness, possibly even coma
factors that may influence the brain injury that occurs due to a stroke.
the individual e.g. brain health/condition, general health condition, personal circumstances, prior stroke
type of stroke
location of the blocked or burst artery
the brain area that was damaged
extent of damage/how much brain tissue is damaged
severity of damage/how badly brain tissue is damaged.
what does FAST stand for (how to quickly identify the most common signs that someone is having a stroke)
Face Check their face. Has their mouth drooped or face fallen on one side? Ask: Can you smile?
Arms Can they lift both arms? Ask: Can you raise your arms for me?
Speech Is their speech slurred? Can you say ‘Hello’ and tell me your name?
Time Is critical and there may be a need to urgently call an ambulance. One of these signs indicates the person could be having a stroke. If you see any of the signs, call 000 straight away.
What is the technical term for a mini-stroke?
transient ischaemic attack
Distinguish between ischaemic and haemorrhagic strokes.
Ischaemic strokes are caused by blood clots that block blood flow to the brain:
haemorrhagic strokes are caused by bleeding in or around the brain.
Construct a definition for stroke that includes a reference to brain injury or damage.
brain injury due to blockage of blood flow to the brain or due to the rupture of vessels that supply blood
symptoms of stroke
numbness or weakness in the face, arm or leg, especially on one side of the body
speech disturbance, such as slurring or decreased speech fluency or comprehension
trouble walking, dizziness, loss of balance or lack of coordination
trouble seeing in one or both eyes
headache, usually severe with no known cause
difficulty swallowing
nausea or vomiting.
how are strokes diagnosed
by carrying out a physical examination, checking results of blood tests and studying neuroimages
what does a physical examination for diagnosing a stroke emcompass
by carrying out a physical examination - (heart rate, blood pressure and other symptoms)
what is the purpose of checking blood tests for a stroke
used to assess blood clotting, blood sugar level and the presence of infection)
what is the purpose of studying neuroimages to diagnose a stroke
to evaluate the type of stroke, the brain area affected and the severity of the injury.)
overall purpose of the diagnosing process of strokes (other than to diagnose the stroke)
to ensure the symptoms are definitely due to a stroke and not another possible cause.
is there a medical treatment that will repair brain damage caused by a stroke
no
what is recovery from a stroke dependent on
stroke rehab therapy and activities
why is the timing of stroke rehab important
the sooner it begins, the greater are the chances to recover lost skills and function
