nurons Flashcards
Neurons
Neurons are nerve cells that enable the communication of information around the body. They do this by receiving, transmitting, and processing information in the form of neuronal messages (messages which can be sent via neurons).
Structure of the neuron
dendrites - receive aural messages
myelin - insulate the nuron and prevent disturbance from other nurons
axon terminal - sends neural messages to the next nuron
The synaptic gap
The synaptic gap is a tiny space between two neurons, where they communicate with each other. Nerves in the brain do not physically touch each other- they are separated by this ‘synaptic gap’
Neuronal messages are communicated at the synapse, which refers to the region that includes the axon terminals of the presynaptic neuron
The synapse
Refers to the entire junction between two neurons or between a neuron and a target cell, which includes the presynaptic terminal of one neuron and the postsynaptic cell. This is where neurotransmitters are released
neuroplasticity
The term neuroplasticity refers to the ability of the brain and other parts of the nervous system to change in response to experience. This includes the brains capacity to recover from or compensate for loss of function through injury.
The brain changes as a result of neuroplasticity is:
- Long-term potentiation- this refers to the strengthening of synaptic connections as a result of repeated activation.
- Long-term depression- this refers to the weakening of synaptic connections because of repeated low-level activation of certain synaptic connections.
Neuroplasticity occurs in response to two kinds of experience:
- Developmental plasticity
- Adaptive plasticity
Developmental plasticity
Developmental plasticity are changes in the brain that occur in response to ageing and maturation.
Synaptogenesis-
is the formation of synapses between neurons as axon terminals and dendrites grow.
Synaptic pruning-
the elimination of underused synapses. (as a result of LONG-TERM DEPRESSION)
Underused synapses are cut off, or ‘pruned’ to free up space in the brain and allow for the strengthening of frequently used synapses- this occurs throughout the lifespan but the periods which occur after infancy (ages two to three) and during adolescence and the most intense periods of synaptic pruning.
Myelination
is the formation and development of myelin around the axon of a neuron.
The axon a neuron becomes myelinated to facilitate more efficient communication of messages. This is done by protecting the neuron from interference from other neurons. This means that as we develop and learn new skills, communication in the brain can happen quickly and smoothly.
Adaptive plasticity
Adaptive plasticity enables the brain to recover from or compensate for lost function and/or to maximise remaining functions in the event of brain injury- rehabilitation after injury supports this process.
Sprouting-
Sprouting- the ability of a neuron to develop new branches on the dendrites or axons. This expands the reach of a neuron, particularly when the neuron has been damaged from the trauma, enabling new neural connections to be formed in areas of the brain where the neural activity has been prevented or depleted.
Rerouting-
is a neuron’s ability to form a new connection with another undamaged neuron. The neuron that is rerouting abandons its connection with a damaged neuron, enabling new neuronal connections to be formed after trauma and, by extension, cognitive functioning to be re-developed.
Critical periods
Critical periods refer to the rigid developmental period in which a specific function or skill must be learnt.
Sensitive periods
Sensitive periods refer to the optimal developmental period for a specific function or skill to learnt in the fastest and easiest way.
An acquired brain injury
An acquired brain injury refers to all types of brain injuries that occur after birth. Types of brain injuries include:
* Traumatic brain injuries
* Non- traumatic brain injuries
Traumatic brain injuries
Traumatic brain injuries occur when there is a sudden physical trauma to the brain from an external force.
Surrounding and protecting the brain is a clear fluid called cerebrospinal fluid. When a person’s head is hit very hard, the cerebrospinal fluid is not enough of a cushion to stop the brain from hitting the thick surrounding membranes or bones of the skull.
Traumatic brain injuries examples
vehicle accidents
* Falls
* Violence or physical assaults
* Sporting accidents
A non-traumatic injury
A non-traumatic injury is caused by internal factors, such as lack of oxygen or a tumour.
A non-traumatic injury example
- Stroke- involves either a interruption to the blood supply in the brain or bleeding from the vessels in the brain. Both causes can result in the death of brain tissue. Blood carries oxygen and nutrients to the brain, so when blood cannot get to the brain via the arteries due to stroke, neurons and other cells in the brain die.
Chronic traumatic encephalopathy
Chronic traumatic encephalopathy (CTE) is a progressive and fatal brain disease associated with repeated head injuries and concussions.
CTE is an example of neurovegetative disease, which is a disease characterised by the progressive loss of neurons in the brain. The damage to neurons occurs over time and brain functioning progressively worsens as a result.
symptoms of CTE
symptoms of CTE are shown in older athletes who have been retired for some time. Disturbingly, younger people have started to have symptoms from repeated concussions. Symptoms typically appear 8-10 years after repeated concussions.
- Disruption to higher order thinking and reasoning skills
- Memory loss
- Behavioural changes
- Mood changes such as aggression and large sudden emotional expression
- Depression or depressive symptoms
- Anxiety
cte stage one
- Headaches.
- Loss of attention and concentration
stage 2
- Depression
stage 3
- Memory loss
stage 4
- Dementia
- Aggression
- Paranoia
CTE can only be confirmed as a diagnosis through
a post-mortem (autopsy). This is basically a biopsy, but once the person has passed away. Neuroimaging can show changes in structure and function in the brain, but it is not possible to diagnose CTE through neuroimaging.
One of the indicators of CTE
is the build-up of a particular protein called p-tau in regions of the brain.
the build up of p tau causes nurophbical tangles in the nuron.
