Tutorial 01 – Part 1 Flashcards by Sarah A

What are the three parts of the brain stem from top to bottom?

Mesencephalon/midbrain
Pons („bridge“)
Medulla (oblongata)

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What parts are at/head from the mesencephalon?

cerebral peduncles on ventral side with substantia nigra
quadrigeminal plate with superior and inferior colliculi on dorsal side

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What is at the base of the pons and what is the pons connected to?

connected to cerebellum by thick fiber tracts
at base of pons (ventral aspect), there is the unpaired basilar artery (blood supply to vital brain stem structures)

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What does the medulla look like?

Like a thicker continuation of the spinal cord

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What does the medulla contain?

Vital centers for circulation and respiration

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What decussation is at the medulla?

Decussation of the pyramidal tract

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How many cranial nerves are there?

12 on each side -> 24 in total

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Cranial nerve 2

Optic nerve

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Cranial nerve 3

Oculomotor nerve

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Cranial nerve 4

Trochlear nerve

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Cranial nerve 1

Olfactory nerve

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Cranial nerve 5

Trigeminal nerve

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Cranial nerve 6

Abducens nerve

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Cranial nerve 7

Facial nerve

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Cranial nerve 8

Vestibulocochlear nerve

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Cranial nerve 9

Glossopharyngeal nerve

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Cranial nerve 10

Vagus nerve

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Cranial nerve 11

Spinal accessory nerve

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Cranial nerve 12

Hypoglossal nerve

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What can small brain stem lesions entail?

Selective dysfunction of specific nerves while sparing others, allowing for clinical localization

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Where do cranial nerves get input from?

Input from the head‘s sensory systems and motor control of facial and laryngeal muscles

Where does cranial nerve 1 end in?

Basal forebrain (above brainstem)

Where does cranial nerve 2 send collaterals to?

Cranial nerve 2 (optic nerve) only sends collaterals to brain stem (superior colliculi)

Where does cranial nerve 11 ascend from?

Spinal cord (fake cranial nerve)

What can emotional processing signal presence of?

Emotional processing can signal presence of (or prospect for) reward or punishment and initiate motor programs to pursue or avoid

What does dopamine code for?

Reward prediction

Which circuitry do most drugs of abuse act on?

Elements of limbic circuitry

What can neurotransmitter release trough drugs cause and which neurotransmitters are at play?

Neurotransmitter release (dopamine from VTA, but also noradrenalin, serotonin, and others) through drugs causes unphysiologically elevated levels with psychological alterations

What happens to the receptors when overstimulated?

Internalization of receptors

What response does drug abuse dampen?

Response of the emotional reinforcement circuitry to natural (less potent) awards

Two distinct dopaminergic systems in midbrain

Substantia nigra pars compacta (SNc) Ventral tegmental area (VTA)

Classifying dopaminergic cells according to gene and protein expression shows…

A variety of subtypes, some of which not strictly adhere to a SNc-VTA separation, show mixed properties, or extended to surrounded nuclei

Typical SNc-type neurons

SOX6, ALDH1A1, PITX3, DCC, GIRK2

Typical VTA-type neurons

CALB1, ALDH1A1, CALB1, PITX3, DCC, GIRK2

Which pathways is VTA origin of?

Mesolimbic pathway (to basal ganglia and amygdala) Mesocortical pathway (to prefrontal cortex)

What is the main target site for VTA

Ventral striatum (nucleus accumbens and ventral parts of putamen)

Which area are aversion-encoding VTA neurons targeting?

Nucleus accumbens shell region

Which region are VTA neurons activated by motivation and reward are densely innervating?

Nucleus accumbens core region

VTA neurons are implicated in

Incentive-based behavior, motivation, cognition

What neurotransmitters do VTA neurons co-transmit dopamine with?

Glutamate or GABA

What is the origin of the nigrostriatal pathway?

Ventral SCn

What do ventral SNc neurons traget (which part)?

Dorsocaudal part of striatum (caudate nucleus and dorsal putamen)

What lead to deficit in acquiring new motor skills while having no effect on consolidated skills in rodents?

Selective ablation of a ALDH1A1 subtype

What is phasic ventral SNc neuronal firing associated with?

Start-stop signals and acceleration in movement

What are dosal and lateral neurons of the Snc similiar to?

More similar to VTA neurons

What are dorsal and lateral neurons of the SNc implicated in?

Salience and novelty and novelty detection, reward prediction, and contribute to the mesolimbic pathway

Which cells are selectively lost in parkinson disease and what do they contain less of?

Ventral SNc cells – contain less neuromelanin pigment than dorsal cells and are selectively lost in PD

What do neuromelanin sequest from and what does that lead to?

Neuromelanin sequester toxic dopamine metabolites (quinones) and bind iron – leading to less intracellular aggregation of α-synuclein (Lewi bodies) and mitochondrial dysfunction, believed to be the cause of premature cell death

What may intensify vulnerability to Parkinson disease?

Gene variants

What do ventral SNc cells look like (what attributes do they have)?

They are much larger than VTA cells and have extremely branched axonal endings and show high intensity burst firing

What baseline activity do ventral SNc cells have and what does that lead to?

High baseline activity and little capacity to increase mitochondrial respiratory activity in case of stress

What makes ventral SNc cells more vulnerable than other dopaminergic cells?

Multiple hits