Exam 2 Flashcards
Neuron regeneration (PNS)
- Regeneration does occur.
2. Schwann cells support cell regeneration and new axonal connections.
What is synaptic strengthening?
- Changes underlying strengthening
- presynaptic action potential -> increases release of neurotransmitter.
- larger current induced in post synaptic cell.
- Presynaptic activity must be consistently followed by post synaptic activity (Hebb’s rule).
- Induced by repetitive stimulation.
Effects of brain damage
Cell death Neural degeneration Diaschisis Altered cortical excitability Hypoperfusion
Neuron regeneration (CNS)
- Oligodendrocytes do NOT support cell regeneration.
- Damage more extensive than in PNS.
- Glial cells from scar tissue -> barrier to new axonal growth.
- Limited regeneration occurs, but not sufficient to make up for large cell loses.
Recovery of function
- learning reorganizes the damaged brain even w/o therapy.
- person develops compensatory behaviors that alter brain structure and function.
compensatory behaviors that alter brain structure and function
- ex. reliance on less affected limb in hemipelegia.
- can be adaptive and improve function.
- can be maladaptive and interfere with improvements that could be made with therapy.
Experience dependent plasticity relies on what?
- use it or lose it. 6. time matters.
- use it and improve it. 7. salience matters.
- specificity. 8. Age matters.
- repetition. 9. Transference.
- intensity. 10. interference.
Transcranial Magnetic Stimulation (TMS)
-adjunct to behavioral therapy-
- coil placed on skill induces current in the cerebral cortex.
- current suppresses or enhances cortical excitability.
Transcranial direct current stimulation (tDCS)
-adjunct to behavioral therapy-
- surface electrodes placed on skull.
- electrodes induce current in the brain.
- Influences neuronal excitability.
Neurological examination
- examine the cranial nerves, motor system, sensory system.
- examine reflexes.
- Higher cortical function.
* *Informs of structure and function.
EEG
Electroencephalogram
- studies electrical activity in brain.
- uses surface electrodes.
- used most often to diagnose seizures.
- informs of functon.
EMG/nerve conduction studies
EMG=Electromyography.
- used to diagnose neuromuscular disease.
- EMG: measure electrical activity of muscles at rest and during movement. Used to diagnose ALS, myasthenia gravis. Function.
- Nerve conduction study: Measures nerve impulse propagation in LMNs. Used to diagnose Guillain-Barre Charcot-Marie-Tooth. Structure and function
fMRI
functional magnetic resonance imaging.
- done in a MR scanner.
- indirect measure of neuronal function.
- Used for pre-surgical planning.
- resting state fMRI.
- *Funtion**
PET
Positron emission computed tomography.
- Measures metabolic rates for oxygen, glucose or blood flow (rCBF).
- radioactive tracer injected into vein -> tracer collects in organs/tissues.
- “GOLD STANDARD” for tumor detection.
- Aid in differential diagnosis of movement disorders.
- *Function**
Spinal tap
- CSF drawn from lumbar cistern.
- examined for: White blood cells (infection, tumor, demyelinating disease.
- Red blood cells (bleeding).
- Excess protein (tumor, infection, diabetes.)
- Glucose (elevated or decreased)
- *Structure**
cerebral angiography
visualize arteries.
- incision made in an artery.
- catheter passed through arterial system, then in to the carotid artery.
- contrast medium forced through catheter and thus into the cerebral circulation.
- x-rays are taken.
* *Structure**
plasticity
ability of the brain to change its structure and function over the course of the lifetime.
conditions where neuroplasticity occurs
- normal childhood brain development.
- Learning/memory throughout lifetime.
- Reorganization after brain injury.
developmental plasticity
-synaptogenesis and synaptic pruning-
synaptogenesis- new synapses created as a result of experiences.
synaptic pruning- the number of synapses are reduced, the stronger ones stay and the weaker ones are pruned.
in which order do the systems develop?
1st-> sensory system develops
2nd-> language system develops
3rd-> cognition develops