lecture 3 Flashcards
(25 cards)
what are the oldest channels
calcium - primitive behaviours in single cell organisms mediated by ion channels similar to hum and
- endo and exocytotic machinery basics seen early on
cnidarians nervous system
nerve net: little or no collection of neutrons into ganglia
no “brain”
have neural plexi (loose collections of neurons- similar to enteric nervous system in vertebrates)
non-segmented flatworm
- appearance of bilateral symmetry came cephalization
concentration of neutrons into ganglia at anterior end
segmented worm
with the appearance of segmentation: segmental ganglia
arthropods
fusion and specialization of segments accompanied fusion and specialization of ganglia
- able to serve specific functions
- photoreceptors and chemoreceptors need a more complex brain to interpret and process info
pro cerebral lobe
small neurons to process olfactory and probably olfact-spatial information
retinotopy
invertebrates maintain retinotopy by having multiple optical nerves
what is the limitation of invertebretes
having an open circulatory system means they have low pressure and no sufficient system to deliver to brain
not designed for a long life
what are the two ways to construct a central pattern generator
- the half centre oscillator
2. the neurogenic leech heart (rhythm generator)
what is the effect of hyper polarization on central pattern generators
resets the rhythm
how do central pattern generators fire
disinhibition of the neurons will lead to firing
what are polymorphic networks (CPG)
different receptors change strength and excitability of neurons
where are CPG located in vertebretes
in the spinal cord
lap ray CNS
easy to study CPG because they’re distributed along cord, notochord is cartilaginous (not bone) and easy to access
what did the vertebrate hindbrain divide into
medulla oblongata - autonomic and somatic pathway (breathing, blood pressure and heart beat
cerebellum- became much larger: balance, equilibrium and muscular coordination/learning
pons
what did the midbrain become specialized for ?
visual centres associated with the optic nerves
- optic lobes
what did the forebrain become divided into
cerebrum
olfactory bulbs
hypo/thalamus
what parts of the forebrain expanded the most
association areas - not primary sensory or motor but the areas that take sensory information and integrate it
what will happen to the brain if there is a large amount of processing to be done
that portion of the brain devoted to processing will expand over time
ex. star nosed mole has whiskers covered in sensory receptors and a larger portion of the brain to process that information
cerebellum in weakly electric fish
fish cerebellum are normally small but in electric fish the cerebellum is devoted to generating and interpreting electric field signals
this is the largest part of electric fish brains
neocortex
a new kind of multi layered cerebrum that appeared in mammals
paleoxortex
piriform cortex in mammals
during course of evolution the cerebrum went from only having a few layers of cells to a neocortex with 6 layers
what type of neutrons are in the neocortex
projecting neurons (principal) ex. cortical pyramidal neurons
what is different about the top layer of the neocortex
it does not have pyramidal neurons
