L1 - 3 Flashcards
Why did Aristotle hold a cardio-centric view of mind?
- The heart moves, the brain is stationary
- Simple animals move and react, but have no brain
- Warmth (=life) emanates from the heart
Descarte’s view of brain function?
A mechanism of fluid and tubes (and the pineal gland)
What was the issue Paul Broca found with “Tan”?
Legion on the left side of his frontal lobe hence unable to produce speech.
Which brain region is associated with action?
Ventral part of brain associated with action - cerebellum, basal ganglia
What does the NS do? (3)
- Reveal the universe and ourselves in it
- Provide a capacity for action
- Control the milieu interieur - homeostatic regulation
3 Repugnant ideas (early 1700s)
- Spirits running through hollow nerve fibres, conveying impressions to the brain and activating muscles
- Mini explosions caused by fermentation upon mixing fluid droplets from nerve ends & blood, activating muscle
- Vibrations, light of different E transferred vibrations to nerves, conveying sensations to the brain
How did experimentation prove the repugnant ideas wrong?
- Limbs do not increase in V when muscles are activated
- Nerves cut underwater did not result in bubbling ferment
- Ligation (tying a knot) of nerves did not cause them to accumulate fluid
- Fluid doesn’t move fast enough to match speed of NS
What did Luigi Galvani discover?
Nerves convey “animal electricity” and this signal activates muscle
E.g. Spark from scalpel tip to nearby nerve = muscle contraction -> spark activated natural process by which nerves activate muscle
What are the electrodes inserted into a neuron made of?
Hollow glass tubes
Why are nerve impulses slow?
The current travels orthogonal (right angles) to the direction the slow burning fuse is going down the axon (fastest: 120m/s)
How do Myelin sheaths increase conduction velocity AP?
Forces AP to occur in nodes of Ranvier in between the myelin sheaths, aka saltatory conduction, the propagation of AP along myelinated axons from one node of Ranvier to the next node.
Why do young brains provide clearer photos?
Older brains are covered in more myelin and messier.
Cajal was known for?
Superior staining in developing tissue led him to discover growth cones and evidence of dynamic morphology of growing neurons (how fixed is the structure of neurons in the mature brain).
Charles Sherrington’s studies of degeneration of the NS always resulted in what?
A discrete, demarcated pattern of loss (rather than diffuse)
What is Sherrington most famous for?
His work on reflexes, where reflex conduction is unidirectional and the reflex responses which he was studying were much slower than was explicable by the speed of nerve conduction (there was a delay somewhere – this was the communication b/n sensory and motor neurons)
Etymology of Synapse
From the term Synapsis which means to clasp
Early views (from Ancient Egyptians through to Aristotle and up to the Enlightenment) of the brain did not give it a role in thought or experience; these functions were ascribed to the ____
heart
Hippocrates, in Ancient Greece, then Galan, in Ancient Rome, appreciated the role of the brain in experience and behaviour, but saw its function in terms of _____
the 4 humours of the body - blood, yellow bile, black bile, and phlegm
Who was first to suggest that the NS was, like other tissues, composed of discrete cells
Purkinje
Who introduced the term neuron, dendrite and axon?
Wilhelm von Waldeyer
Camilo Golgi’s believed that his silver stain showed that
Fibres interconnect and not single cells
Electrical synapses: active or passive transmission? Fast or slow? Uni or bi-directional?
Passive, fast, bi-directional (typically)
What can be inferred about the post-synaptic effect of a NT based on its chemical nature and structure?
Nothing, it’s the post synaptic receptor that determines the effect.
Hippocampus circuit
Perforant path -> Granule Cell -> CA3 -> CA1
What does adding inhibitor of protein synthesis do?
EPSP amplitude decreases (decays exponentially) hence LTP doesn’t occur
Synapses are not binary, they are quantal but essentially analogue in operation
Synapses are not binary, they are quantal but essentially analogue in operation
What did George Oliver do?
Injected adrenal extract into son and saw vasoconstriction in the arteries
Otto Loewi’s experiment
Stimulate vagus nerve of heart 1 which will spill over NT in surrounding fluid, place heart 2 in the same fluid and the inhibi. effect of vagus was transferred
Who’s experiments provided evidence for localisation of discrete functional capacity to particular regions of the cebrum?
Paul Broca
