Neuroscience Exam 2 Flashcards
Presynaptic Neurons
Transmits signals towards the synapse
Excitatory post-synaptic potential (ESPS)
-can be AP or not
-temporary depolarization of post-synaptic membrane
-from entrance of sodium ions into the cell
-increase frequency of AP above spontaneous rate
Spatial Summation
-synaptic inputs from separate locations combine their effect on a neuron
-timing important
Postsynaptic Neurons
Receives signals from the presynaptic neuron
Inhibitory post-synaptic potential
-temporary graded hyper-polarization of postsynaptic membrane
-potassium ions of chlorine ions (negatively charged) enter cell
-less likely to fire AP
-purpose: inhibit neurons (e.g. sleep)
-decrease frequency of AP below spontaneous rate
Charles Scott Sherrington
-came up with the name synapse
-observed that speed of conduction through the reflex arc was slower (15m/s) than action potential along sensory or motor axons (40m/s)
Temporal Summation
-repeated stimulus within a brief time have a cumulative effect
-combined excitations can exceed threshold to produce AP
Spontaneous firing rate
-periodic production of AP even without synaptic input
-important for perception
Neuronal Synchronization
-brain waves from different regions will synchronize (network communication)
-can give rise to oscilliations
Role of Calcium
-In response to AP, Ca(2+) channels open in the axon terminal and Ca(2+) ions enter triggering the proteins (SNAREs) that cause exocytosis
Metabotrophic receptors
-(pain, attention, emotion)
-initiates a metabolic reaction, second messenger communicates to many areas within cell
-effects slower and longer lasting
-for complex signals
Dopamine Pathway 1
-Mesocortical
-Ventral Tegmental area(VTA) <–> Prefrontal Cortex(PFC)
-for long term/delayed gratification
Exocytosis
-Vesicles containing neurotransmitters in presynaptic neuron fuse w/ membrane and neurotransmitters are released in the synaptic cleft
Ionotrophic receptors
-(hearing and vision)
-neurotransmitter binds to this receptor and opens its channels
-simple on/off signal
-effects are fast
Dopamine Pathway 2
-Mesolimbic
-Ventral Tegmental area(VTA) <–> nucleus accumbens (NAc)
-REWARD PATHWAY
-instant reward
-linked to addiction
monoamines
-modified amino acids
-includes dopamine, serotonin, and norepinephrine
Dopamine Pathway 3
-Nigrostriatal
-Substantia Nigra (SN) <–> Basal Ganglia (striatum) (BG-S)
-important fro movement
-impacted in parkinson’s
Dopamine
-voluntary movement
-reward, motivation, cognitive control
(prediction of reward)
-psychosis
Dopaminergic drugs
-antipsychotics
-stimulants
-recreational drugs
-nicotine
Conditions involving dopamine
-ADHD (reward/motivation)
-Parkinson’s (voluntary movement)
Norepinephrine /noradrenaline synthesizers
-main synthesizer in brain: locus coeruleus
-in PNS: adrenal cortex (above kidney)
Norepinephrine /noradrenaline
-energy, arousal, mood (depression and anxiety)
Norepinephrine /noradrenaline receptors
alpha and beta
What 2 neurotransmitters move in the “same direction”
norepinephrine and dopamine
brain region where there are a lot of nuclei to synthesize neurotransmitters
pons
Serotonin
-sleep and wakefulness
-mood (depression): general contentment
-linked to aggression (serotonin dysfunction –> more aggression)
Serotonin synthesizer
Raphe nuclei (in pons)
Serotonin drugs and how they work
-SSRIs, TCAs, MAOI
-block proteins that recycle seritonin
what direction does serotonin move
opposite to norepinephrine and dopamine
glutamate
-most important excitatory neurotransmitter
-receptors: AMPA, NMDA
-psychosis
-caused by influx of sodium
-excitotoxicity: damage from excessive glutamate release
GABA
-most important inhibitory neurotransmitter
-receptors: GABA(A), GABA(B), GABA(C)
-influx of chloride
-Drugs: benzodiazaphines
Acetylcholine
-receptors: nicotinic, muscarinic
-synthesized in: nucleus basalis of Meynert
-muscles: junctions
-memory and attention (Alzheimer’s)
processes in development of neurons
-proliferation
-migration
-differentiation
-myelination
-synaptagenesis
proliferation
-production of new cells
-overproliferation: megacephaly (big head)
-reduced proliferation: microcephaly (smaller head)
migration
-chemicals guide neuron migration
-deficit in chemical –> small brain size, decreased axon growth
-impacted by environmental factors during pregnancy
differentiation
-cell change into specialized type of neuron (axon/dendrites formed)
-axon first
-dendrites formed after migration
myelination
-process in which axons covered by myelin sheath
-changed based on environments
-e.g. socially isolated mice –> underdeveloped myelin (PFC)
synaptogenesis
-neurons form new synapses and discard old/useless ones (SYNAPTIC PRUNING)
-hyperconnectivity: too many synapses –> synethesia, ASD
-too much synaptic pruning
–>schizophrenia, Alzheimer’s, memory loss
fine tuning by experience
-stimulating environment –> enhances sprouting of axons and dendrites in many species
-prolonged experiences (language, instruments, sports) !!
hierarchy of function
more sophisticated from spinal cord to cortex
spinal cord
-reflexes
-communicates w/ sense organs and muscles
-receives motor commands from brain, sends sensory input to brain
Hindbrain
-postural support
-disconnection of hindbrain from the rest of brain = vegetative state
-consciousness is effected
Midbrain
-operant movements
-reaction to stimulus (not motivated)
-i.e. to attack, get food…
-superior(vision) and inferior(hearing) colliculus
Diencephalic
-thalamus
-hypothalamus: important for motivated behavior (sleep, sex, eating), thermoregulation
-pituitary gland: hormones
Basal Ganglia
-self maintenance
-behaviors more biologically adaptive
-simple sequence of movements (grooming, copulation, feeding)
-why animals can learn without cortex (conditioning)
Cortex
-intention
-skilled movements and sequences
-allows us to extend usefulness of learned behaviors to new situations
-problem solving and planning
Cortical layers
-INPUT/OUTPUT
-different amount of neurons in each layer depending on region
-superficial layers (II and III): receive inputs from other cortical areas
-middle layer (IV) sensory analysis
-layers V and VI: output zone
Cortical columns
-INTERACTION(function)
-neurons within column are functionally similar
-most interactions take place vertically
-most apparent in primary sensory regions
-develop with experience/use
ocular dominance column
-different columns activate with different line orientation
transduction
-transforms energy into electrical energy (originally light, pressure, chemicals)
-occurs in receptors
visual receptors
-retina (cones and rods)
retina
-neural tissue that receives light
-contains rods and cones
-has a fovea and periphery
fovea
small area specialized for acute, detailed vision
periphery
better sensitivity to dim light
cones
-mostly in fovea
-for higher light levels (color)
rods
-mostly in periphery
-for lower light levels
ipsilateral
-brings sensory visual info from one eye to THAT side of brain
contralateral
-brings sensory visual info from one eye to THE OTHER side of brain
Geniculostriate
-pattern, color, and motion recognition
-lateral geniculate nucleus –> striate cortex
Tectopulvinar
-spatial location of objects
-tectum (midbrain)–> superior colliculus–>thalmus pulvinar nucleus and parietal lobe
V1
-straite cortex
-primary visual cortex
v1 and v2
functionally heterogeneus
v4
-colored vision
v5
-Middle temporal MT
-perceive objects in motion
ventral stream
-“what”
-Fusiform face area (FFA): face analysis
-extra straite body area(EBA): body analysis
-superior temporal sulcus(STS): biological motion
-parahippocempal place area (PPA): places
hemianopia/hemianopsia
-blindness of have visual feild
dorsal stream
“where” and “how”
-parietal reach region: visually guided reach
blindsight/cortical blindness
-can respond to stimulus you don’t consciously see
cortical color blindness/ achromatopsia
-effects color in imagery and memory as well
apperceptive
-type of visual agnosia
-inability to develop perception of object (cant draw)
associative agnosia
-inability to recognize an object despite its apparent perception
