Lecture 2 Flashcards
3 ways a group is reproductively isolated from other organisms
- geographically
- historically
- behaviourally
evolution of vertebrates
chordates: dorsal nerve cords.
vertebrates : bones protecting NS
boney fish; branch off to amphibians; reptiles - layed eggs; pro-mammals (mammary glands); placental mammals
define exaptations
evolved functions that were coopted to serve additional functions.
FOXP2
increase in brain size, increase in neural connections –> language and communication.
high level motor sequencing which allows for various things.
HAR1
allows for increased cortex folding. may have provided better complex thinking and problem solving.
analogous vs homologous
analogous: result from convergent evolution. similar solution to same enviro problem
homologous: from same origin. same structure from common ancestor
brain structure related to IQ
relative cerebrum to brain stem is the best predictor of intelligence.
HAR1 - more convolution, lot of surface area in brain compared to brain stem.
epigenetics
regulation of gene expression by environment.
sequences between genes are super variable.
non-coding RNA - translated to functional protein which degrades other RNA.
in twins - identical = super different DNA
acetylation of histones
if histone is wrapped by DNA, DNA is not available. acetylation attaches to histone and allows unwinding of DNA and expression.
methylation of DNA
targeted, methyl group attached to DNA - interrupts expression of gene.
3 layers of meninges
dura - hard, outer layer. sinus = drains deoxyblood and CSF waste
arachnoid - subarachnoid space: filled with CSF. provides CSF with nutrients.
pia: adheres to surface of CNS. encloses CSF in.
CSF - function, location
- cushion/shock aborption.
location: subarachnoid space, central canal (runs length of spinal cord), ventricles (2, 3, 4) cerebral aqueduct (leads CSF down to spinal cord)
what is choroid plexus
cells that line ventricles and produce CSF.
- gives CSF nutrients it needs from capillary on the other side.
- takes away waste products
- protrude into ventricles via pia mater.
blood brain barrier - what it is, what is made of.
keeps CNS physiologically separated from CNS
semipermeable: no fenestrations in cells - nothing can pass through easily. needs transport mechanisms.
made up of astrocytes - tightly packed around endothelial cells to further control entering of things.
keeps molecules outside of brain.
breaking down the blood brain barrier
high blood pressure
not completely formed @ birth - dangerous if exposed to illness/disease
if there’s high [non-permeable molecules] diffusion principles apply.
brain injury/ disease
infection - astrocytes stop attaching to cells
microwaves and radiation.
astrocytes
- endfoots of glia sit in synapse - wrap around axon terminal to locally modulate.
- sucks out glutamate to inhibit excitotoxicity.
- astrocyte wraps around capillary to extract glucose and function. metabolize glucose anaerobically = lactate pushed to neuron.
- provide metabolic support to neurons
- hold neurons in place.
- regulate ions, blood flow.
- astrocyte synctium: complex network of integrated astrocytes, connected by gap junctions.
microglia
- macrophage - engulf debris
- multiply in response to injury/disease & mediate cell death
- active immune defense
- fast acting
- synaptic plasticity = fomration and pruning.
oligodendrocytes
- only in CNS
- rich in myelin
- forms myelin sheath = increase speed of conduction, nourish axons.
schwann cell
- each cell has only one axon segment
- guide axon regeneration in PNS
myelin sheath
synthesized by oligodendrocytes and Schwann cells. speed conduction by saltatory conduction.
myelin sheath
synthesized by oligodendrocytes and Schwann cells. speed conduction by saltatory conduction.
2 nerve roots - dorsal and ventral
dorsal = sensory, afferent. unipolar.
dorsal horn = sensory axon terminal
ventral = motor, efferent, multipolar.
ventral horn = cell body of efferent .
4 regions of the spinal cord
cervical
thoracic
lumbar
sacral
4 regions of the spinal cord
cervical
thoracic
lumbar
sacral
dermatomes
sections of body associated with sections of the spine. dermatomes carry sensory info to certain regions of the spinal cord.
spinal cord - internal structure
white matter in periphery - myelinated axon.
grey matter in middle - cell bodies, unmyelinated.
CSF in central canal.
spinal cord - internal structure
white matter in periphery - myelinated axon.
grey matter in middle - cell bodies, unmyelinated.
CSF in central canal.
differs across 4 regions - lower regions -
more grey than white because they have less afferent and efferent nerves
spinal cord - 4 main columns
dorsal horns - somatosensory nuclei, axon terminals of sensory nerves.
ventral horn - motor neurons dendritte and cell body
lateral horn - autonomic nerves innervate visceral and pelvic organs
immediate column - autonomic nerves inntervate visceral and pelvic organ
5 major divisions of brain
myelencephalon, metencephalon, mesencephalon, telencephalon, diencephalon
myelencephalon
most posterior. AKA medulla - ascending and descending tracts at core. white matter.
reticular formation - spans medulla to diencephalon. – mediates heart rate, breathing, arousal, overall overt function.
metencephalon
cerebellum : sensorimotor coordination, maintain fine motor skills, role in cognition/language/attention
pons: contains reticular formation, swelling on ventral surface of brainstem, transfer info between the brainstem and the cerebellum.
mesencephalon
midbrain. tectum = roof -- superior colliculi -- inferior colliculi tegmentum -- reticular formation (arousal) -- red nucleus -- substantia nigra -- periaqueductal grey
diencephalon
thalamus - 2 lobes = massa intermedia: white matter. independent nuclei: plays -role in sensory processing.
- sensory relay nuclei - LGN; MGN; VPN
- feedback bidirectional btw thalamus and cortex.
- intralaminar nuclei
- hypothalamus
- mammilary bodies
- optic chiasm
superior colliculi - where and what does it do?
tectum of mesencephalon
visuomotor
inferior colliculi - where and what does it do?
tectum of mesencephalon
determining auditory information
reticular formation - where and what does it do?
spans myelencephalon (medulla) to diencephalon. arousal, heart rate, breathing rate.
red nucleus - where and what does it do?
in mesencephalon
(sensorimotor): motor coordination, direct connection with cerebellum, hemoglobin & ferritin
substantia nigra - where and what does it do?
in mesencephalon (sensorimotor): reward, addiction, movement. dopaminergic rich projections to basal ganglia. melanin pigment - appears black.
periaqueductal grey - where and what does it do?
In mesencephalon (analgesia): lots of grey matter, defensive behaviour, gate control theory of pain, release endorphin = analgesia. PAG - super close to CSF - whole brain gets endorphins
lateral geniculate nucleus - where? fxn?
LGN - thalamus/ diecncephalon
vision
medial geniculate nucleus - where? fxn?
MGN - thalamus/ diencephalon
audition
ventral posterior nuclei- where? fxn?
VPN - thalamus/diencephalon
touch
intralaminar nuclei- where? fxn?
thalamus/diencephalon
on/off may dictate consciousness. hard to target because it’s so small.
effects of LSD mediated through this area
hypothalamus - where? fxn?
diencephalon
controls endocrine system alongside the pituitary gland
mammilary bodies - where? fxn?
diencephalon
modulate hippocampus & it’s ability to create/solicit memories
damage = karsakoff - dementia in alcoholics.
damage = cut white matter in mammilary body = amnesia
optic chiasm - where? fxn?
define: decussate, contralateral, ipsilateral
diencephalon where optic nerve turns to optic tract decussate = cross over contralateral = opposite side ipsilateral = same side
telencephalon
cerebral lobes corpus callosum limbic system basal ganglia neocortex
4 cerebral lobes
frontal
parietal
temporal
occipital
major fissures of the cerebrum
centrall fissure - separates frontal and parietal
sylvian fissure - separates occipital and rest of brain
longitudinal fissure - between two hemispheres
corpus callosum
major tract connecting two hemispheres
prefrontal cortex
nonmotor, used for highly human-specific behaviours.
determines how to behave in environment, inhibits behaviour.
neocortex
6 layers - 1 at surface, 6 in middle. columnar organization = vertical flow of info. minicircuit - each column responds slightly differently.
pyramidal cells
found in neocortex:
large, multipolar, large dendrites, log axon
stellate cells
found in neocortex:
interneurons, small star shaped
limbic system
in telencephalon. controlling motivating behaviours : 4 F’s
- hippocampus
- cingulate cortex (wraps around hippocampus to septum)
- amygdala
- fornix
- septum
- mammilary bodies
hippocampus
primitive cortex of limbic system = telencephalon.
spatial learning and memory (episodic)
amygdala
subcortical structures - limbic system/ basal ganglia in telencephalon.
emotional memory. important to feel emotion so that NS can respond properly.
fornix
in telencephalon - subcortical structure of limbic system.
tract from hippocampus to septum. helps in declarative memory.
septum
in telencephalon - subcortical structure.
important for modulating activity for hippocampus. communicated to mammilary bodies and deeper structures in brain.
basal ganglia
motor system. - voluntary, needed for procedural learning
- amygdala
- nucleus accumbens
- striatum (caudate nucleus + putamen)
- globus pallidus
nucleus accumbens
in basal ganglia
reinforcement learning.
striatum
in basal ganglia = caudate nucleus & putamen.
projections from substantia nigra.
high dopaminergic area. thought to be important for drug addiction and reinforcement learning.
helps modulate planned motor outputs for proper execution.
globus pallidus
output from striatum. pushes output to cortex. Gives the “OK” to push signal on.
