Lecture 2 Flashcards
Assessment & neurophysiology
4 issues in neurological assessment
- Reliability & Validity
- Premorbid functioning (tests usually tell us current functioning other than NART)
- Comorbid mental disorders, ie, depression commonly comorbid w brain injury, which reduces motivation, thus performance on tasks=invalid assessment resulting from depression not injury
- Compliance & malingering - client may not cooperate, motivated to perform well, or exaggerate or feign illness in order to escape duty or work (malingering)
What are glial cells
- Supportive cells in CNS
- surround neurons & hold them in place
- supply nutrients & oxygen to neurons
- insulate neurons from each other
- play role in neurotransmission and synaptic connections by regulating clearance of neurotransmitters from the synaptic cleft
- Don’t conduct messages like neurons
What is a neuron
Basic units of the nervous system.
most important part is the brain
What are the parts of a neuron
- Cell body (soma)
- Dentrites
- Axon
What is neurogenesis
growth of neurons
What invertebrate was used to study the “axon”?
Why?
The giant squid.
The axon of the squid is 1000x larger than the mammalian axon, size of a pencil lead
- Showed the movement of ions in and out of the membrane allowing us to study the action potential
4 structural types of neurons
Unipolar - only 1 neurite extending from the cell body
Bipolar - has 2 extensions (one axon and one dendrite). These are specialized sensory neurons for transmission of special senses (smell, sight, taste, etc)
Pseudounipolar - 1 process serving as an axon and a dendrite. Type of sensory neuron in PNS
Multipolar - single axon and many dendrites, allowing integration of info from other neurons
3 types of neurons according to function
Afferent/sensory neurons
Efferent/motor neurons
Interneurons
How does the neuron work?
- Neurons send messages electrochemically
- nerve cells are surrounded by a semi-permeable membrane, allowing some ions to pass through and blocks the passage of other ions
- Movement of ions is key to every electrical event that happens in neurons
Anterograde amnesia
Inability to remember information learned after the injury (form new memories)
What are ions
“electrically charged” chemicals
What are the important ions in the nervous system?
Sodium and potassium (both have 1 positive charge, +)
Calcium (has 2 positive charges, ++)
Chloride (has 1 negative charge, -)
Resting membrane potential
- neurons “at rest” when inside of neuron is negative relative to outside
- Resting membrane potential of a neuron is about -70mV (70mV less than outside)
- ion concentrations attempt to balance out on both sides of membrane but can’t because the cell membrane:
- lets potassium ions (K+) cross easily, while chloride ions (CL-) and sodium ions (Na+) have difficult time. Protein molecules (A-) cannot cross. Therefore, there are more negative ions inside the neuron/more positive outside at rest
- has pump using energy to move 3 sodium ions out for every 2 potassium ions it puts in
Hyperpolarization
When the membrane potential becomes more negative at a particular spot on the neuron’s membrane
(hyper/depolarization occur when ion channels in the membrane open/close, altering the ability of different ions to enter or exit cell)
Depolarization
when the membrane potential becomes less negative (more positive)
What is an action potential?
- A large enough depolarization event can lead to production of an action potential
- (some event (a stimulus) causes the resting potential to move toward 0 mV
- When depolarization reaches -55 mV a neuron will fire an action potential. This is the threshold. If it’s not reached, no action potential will fire!
- An action potential in the neuron sends info down the axon
- For any given neuron, the size of the action potential is always the same (there are no big or small action potentials in one nerve cell) aka: All-or-none principle
What is PET and what does it measure?
Positron Emission Tomography Measures brain function via the measurement of brain oxygen consumption, blood flow and glucose metabolism. Of these 3 measures, blood flow appears to be the most reliable
Steps of an action potential
- Resting potential: -70 mV, due to
- Depolarization
- Repolarization:
- Hyperpolarization:
“Synapse” = derived from “syn” and “haptein” meaning:
syn= together, haptein=to clasp
It is “THE GAP”
most drugs affect the presynaptic ending w neurotransmitters, mitochondria and other cell organelles, synaptic cleft, or the postsynaptic ending?
Postsynaptic ending, containing receptor sites for neurotransmitters
what is synaptic plasticity
Synaptic plasticity is the biological process by which specific patterns of synaptic activity result in changes in synaptic strength and is thought to contribute to learning and memory. Both pre-synaptic and post-synaptic mechanisms can contribute to the expression of synaptic plasticity.
4 examples of synaptic plasticity
- Memory: loss of synapses in brain due to degenerative disease like Alzheimer’s or Parkinsons will cause a corresponding loss of function related to whatever those synapses did
- Neuropsychotherapy
- Gratefulness exercises
- Mindfulness
What is Neuropsychotherapy?
changing the brain, not directly, but through focusing on life experiences encountered by the person. Life experiences are meaningful with regard to the needs that are embedded within the brain structures of each human.
Neuropsychotherapy strives to shift the brain into a state that enables these basic needs to be fully satisfied
Excitatory neurotransmitters
- Increase the rate or likelihood of a neuron firing by depolarizing the neuron
- neurotransmitters bind to ion channels allowing Na+, sometimes Ca2+ (calcium) into the cell, exciting the neuron
