neuronal connections Flashcards
make more connections=
cortical thickening
- via typical development, enriched and stimulating environment
- via stimulus-specfic, deliberate, repetitive practice
make fewer connections =
- cortical thinning
- prune away unneeded or redundant or inefficient connections = selective thinning
arborization of dendrites
- increase receptive connectivity of each neuron
- which in turn supports development of rich neural networks and efficient connections
divergent pools
one presynaptic cell engages several postsynaptic cells
convergent pools
many presynaptic cells engage one post synaptic cell
what do neural networks do?
- engage in simultaneous firing of a group of linked neurons
- wired up to perform a specific task of cognitive or motor or sensory activity
white matter in the CNS
-axons of billions of neurons, which move away from the cell body
-trasmit neural impulses to the dendrites of other neurons which then “wire up” to form connections
which are insulated with a fatty/lipid substance called myelin
nerves in the white matter
TRACTS
where is white matter in the CNS
- cerebrum
- subcortex
- cerebellum
- brainstem
white matter in the cerebrum
connecting grey matter/ cortical structures; connecting BG and limbic system to all places they need to go
white matter in the sub cortex
running through thalamic nuclei, on way to and/or from the cortex to the brain stem or cerebellum
white matter in the cerebellum
moving to/from thalamus, limbic, cortex
white matter in the brainstem
movong to/from cranial nerves, or to/from spinal cord, to connect with spinal nerves
DTI imaging of white matter in the CNS
- can isolate the direction that the fibers are moving
- can determine what structures are coming from and moving to
- can determine what networks are operating in certain testing circumstances
projection fibers
- travel in a vertical manner; carry motor and sensory
- project “far away” in the CNS
- axons are relatively long
- many are heading down/up from either spinal or cranial nerves
association fibers
- bidirectional channels of communication bw areas of one hemisphere
- “shorter” one exist within one lobe
- “longer” ones move between lobes
commissural fibers
-travel in horizontal manner, connecting 2 hemispheres
corona radiati
- PROJECTION FIBERS
- one in each hemisphere
corona radiati anterior limb
- corticothlamic tracts
- thalamocortical tracts
- corticopontine tracts
corticothalamic tracts
- anterior limb of the corona radiati
- from cortex to thalamus
- generally excitatory
- forms circuit with thalamocortical tracts
thalamocortical tracts
- anterior limb of the corona radiati
- from thalamus to cortex
- mostly sensory processing and pre motor
- generally inhibitory motor movement
corticopontine tracts
- anterior limb of the corona radiati
- from motor cortex to pons
- eventually to cranial nerves
genu
- part of the corona radiati
- corticibular tracts
- from motor cortex to brainstem, in general, for cranial nerve output
posterior limb of the corona radiati
- corticospinal tracts
- innverate spinal neurons for motor output
- sensroy projections fibers, from spinal input
- from skin, joints to primary sensory cortex
internal capsule
the convergence of fibers within the corona radiati
stroke below the decussation
ipsilateral weakness/paralysis
stroke before the decussation
contalateral weakness/paralysis
3 types of association fibers
- superior longitudinal fasciculus
- arcuate fasiciculus
- unicinate fasciculus
superior longitudinal fasciculus
- connects frontal lobe with occipital lobe
- longer of the association fibers
- originates in the occipital and carries upward through the parietal lobe and all the way to the frontal lobe
arcuate fasciculus
- many of the SLF take a sharp curve and head down through the temporal lobe
- part of the SLF
- picks up info at Wernickes area
- damage to this=aphasia
unicinate fasciculus
- inferior aspect, from anterior temporal horn to inferior aspect of prefrontal cortex
- takes the low road through the temporal lobe up the frontal lobe
cingulus
- ASSOCIATION FIBER
- C-shaped and connects limbic system with the temporal lobe
- right below cingulate gyrus
- just above the corpus callous
corpus callosum
- commissural fiber
- connects R and L hemispheres
R hemisphere
spatial, musical, temporal
-biological movement of people and objects
L hemisphere
language, analytic, verbal
subcallosal area
-limbic structures, thalamus, hypothalamus, BG
anterior commissures
-anterior to the corpus callous
-connects 2 olfactory bulbs
amygalae
temporal poles
posterior commissures
- posterior to the corpus callosum
- connects the 2 thalmai
- not everyone has this
connectomics
-the process of using high-resolution imaging to create a map of the brain’s neural networks
principles of neural transmission
- convergence – multiple neurons (axons) converge to fire ONE individual neuron
- divergence – one neuron (axon) has an impact on multiple other receiving neurons
