Techniken der Neurobiologie Flashcards
EEG
- surface potential
- differential potential
- 10-20 system
- diagnostic of epileptic focal- and generalized seizures
evoked potentials -> different compartments
different components:
- subcortical
- primary cortex
- secondary cortex
sensory evoked potential
nerves -> Leg: tibialis, fibularis -> arm: median, ulnar
trigger -> square wave stimuli
intensity -> above the motor threshold
frequency -> 3 Hz
repetitions -> 1000-1200
visual evoked potentials (VEP)
- the VEP tests the function of the visual pathway from the retina to the occipital cortex
- it assesses the integrity of the visual pathways from the optic nerve, optic chasm and optic radiations to the occipital cortex
VEP
Waveforms
- the initial negative peak (N1 or N75)
- a large positive peak (P1 or P100) Negative peak (N2 or N145)
use of VEP in neurology
- diagnosis of multiple sclerosis (MS) (optic nerve demyelination, optic neuropathy is often the first sign of MS, in definite cases of MS - abnormalities in VEP occur in about 85-90% of patients, the changes in the P100 response include interocular difference in latency, prolonged absolute latency, decreased amplitude and distorted shape)
- compression of the optic nerve and chasm by tumors - decreased amplitude and prolonged latency of the P100 response
TMS Basics - single pulse TMS
- corticospinal excitability
-> motor threshold
->MEP Amplitude (NMDA, GABAa)) - corticospinal inhibition
-> contralateral silent period (at low TMS intensities GABAa; at high TMS intensities GABAb)
-> ipsilateral silent period
TMS Basics - paired pulse TMS
- sensorymotor integration
-> short interval afferent inhibition (SAI)
TMS in Parkinsons Disease
- short interval intracortical inhibition
-> reduced SICI or enhanced ICF - short interval afferent inhibition (SAI)
-> conflicting findings
The nervous system
the central (CNS) + the peripheral nervous system (PNS)
CNS
brain + spinal cord
PNS
somatic and autonomic nervous system
Human brain
- weight = 1400 g
- protected by the meninges, skull and cerebrospinal fluid (CSF)
- shape of a walnut
- on the surface: Gysi = bumps and various sulk (or fissures) = grooves
- two hemispheres
- grey and white matter: neurons and fibers
Structures of the brain
- Corpus
- Callosum
- Pituitary
- Pons
- Medulla
- Spinal Cord
- Cerebellum
the Cerebrum
The cerebral cortex is responsible for many “higher-order” functions
- sulcus centralis
- main motor region (M1) and main sensory region (S1)
functional divisions of the cerebral cortex
- auditory association area
- auditory cortex
- speech center
- prefrontal cortex
- motor association cortex
-primary motor cortex - primary somatosensory cortex
- sensory association cortex
- visual association area
- visual cortex
- Wernickes area
Higher order function
- frontal lobe (planning, decision making, problem solving, language)
- occipital lobe (vision)
- Parietal lobe (reception and processing of sensory information)
- temporal lobe (memory, emotion, hearing, language)
Higher order function: language
• Most of the language processing takes place in the left hemsphere.
• Language comprehension: Wernicke’s area .
Without this area, people can hear the words or read the letters, but have difficulty attributing meaning to them.
• Speech production: Broca’s area.
When damaged, people are unable to produce language properly. They may speak in disconnected words, for example. Hence, broca’s area is most associated with.
Aphasia: Loss of the ability to produce and/or comprehend language
the basal ganglia - modification of movements
• Extrapyramidal System
• Various nuclei connected in a
complex network: putamen, caudate, globus pallidus, substantia nigra, subthalamic nucleus (and thalamus as output structure)
• Neurotransmitters:dopamine, acetylcholine, glutamate
“Too little or to many” -> movement disorders (hypokinetic / hyperkinetic)
the cerebellum
incoordination, imbalance, speech disorder (dysarthria), eye movement abnormalities
Causes: alcohol, strokes, tumors, neurodegenerative disease
anatomy of the cerebellum
- Archicerebellum
- Paleocerebellum
- Neocerebellum
Cerebellar connections
Input
- inferior cerebellar peduncle (sensory)
- middle cerebellar peduncle (efference copy)
Output
- superior cerebellar peduncle (information to cortex)
Afferents
- Spinal cord -> Spinocerebellum
- Cerebral cortex -> Neocerebellum
- Vestibular nerves -> Vestibulocerebellum
Efferents
- dentate nucleus -> Thalamus
- Nucleus interpositus -> Nucleus ruber
- Ncl. fastgii -> Formation reticularis
- L. flocculonodularis -> Vestibular nuclei
Cerebellar systems
- vestibulo cerebellar
- reticulo cerebellar
- rubro cerebellar
basic neurophysiology
- identify mechanism that make the nervous system work
- molecules, cells, groups of cells, functional systems
- investivem time consuming, small number of “subjects” studied
clinical neurophysiology
- diagnose disease in patients
- correlates of functions of the intact human body
- reliable, fast, cheap, benefit justifies the risk
parts of nerve cells
- dendrites -> summation of input
- cell body -> metabolism
- axon -> propagation of the signal
- synapse -> transmission of the signal
functions in nerve cells
- reception of information (chemical and electrical)
- calculation (electrical)
- signal transport (electrical)
- Signal transmission (chemical)
Biological membranes
- lipid bilayer (glycerol ester)
-> electrical isolation
-> chemical isolation
membrane proteins
-> transport
-> signal transduction
-> mechanical stability
-> immune mechanisms
resting potential
initial situation
- concentration difference between intracellular and extracellular
- conduction across membrane only for kations
equilibrium
- zero NET current
- positive NET charges on the outside
action potential
- increase in Na conductivity
- reversal in the membrane potential: “depolarisation”
- increase in the K conductivity
- membrane potential returns to baseline: “depolarization”
- Na channels inactivated
- membrane potential below resting potential: “Hyperpolarisation”