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Flashcards in 4: normal aging 1 Deck (25):

learning vs. memory (def)

learning = acquisition of knowledge (environment modifies behavioural expression). memory = maintenance


3 rat models for hippocampal dependent (spatial) memory

barnes circular maze. 8 arm radial maze. morris water maze.


in rodents: what is an important function of hippocampus? damage causes?

spatial memory. rats with hippocampal damage perform poorly on circular maze, radial maze, water maze tests


how do aged rats do on barnes circular maze?

impaired in learning excape location, remembering learned location, learning new escape location


aged rats in 8 arm radial maze?

make more errors, impaired in remember locations of arms visited. no deficits in the non-spatial, tactile version


aged rats in morris water maze?

impaired in learning platform location, but no deficits in the non-spatial cued version


aging: effects on anatomy of hippocampus (2)?

loss of volume (35%) and reduction of cholinergic inputs


loss of volume in hippocampi due to? not

not due to loss of neurons: due to loss of connections between cells like anatomical synapses and synaptic markers


effects of aging on physiology: basic intrinsic neuronal properties?

unchanged: RMP, input resistance, time constant, spike threshold, firing rates


effects of aging on physiology: calcium regulation? ACh? interconnectivity?

increase in Ca currents and density of high threshold L type calcium channels. reduced influence of ACh. mixed evidence in impairments in functional interconnectivity


Aged dentate gyrus vs. CA1: presynpatic fiber potential and field EPSP?

DG: decreased presynpatic potential, decreased field EPSP. CA1: same presynpatic, decreased field EPSP. so overall ratio of field EPSP to presynpatic fiber potential: increased for aged DG, decreased for ca1


aged DG vs. CA1: AMPA? NMDA?

DG: same AMPA sensitivity, decrased NMDA EPSP. CA1: decreased AMPA sensitivity, decreased NMDA EPSP


summary of effects of aging on dentate gyrus (4)

reduction of input fibers, decrease in number of synapses, increased in synaptic strength of remaining synapses, decrease in relative NMDA component


summary of aging effects on CA1 (4)

no chage in input fibers, decreased in synapse number. no change in synaptic strength or NMDA compoenent


brain is the organ of? so changes?

behaviour. changes in behaviour must involve changes in the brain - environmental influences that modify behaviour/thought must reflect functional/structural changes in NS


how can functioning of brain be changed (2)?

modify properties or responsiveness of neurons. modify connections and interactions between neurons


modify properties/responsiveness of neurons: characteristics? ex?

intrinsic, non-specific, fast, short term alterations. ex: state changes like arousal vs. sleepy


modify connections/interactions b/w neurons: characteristics? ex?

synaptic, specific, slower, longer term alterations. ex: reflex strengthening with practice


LTP: definition?

enduring increase in synaptic efficacy resulting from an activity dependent (Hebbian) process


LTP requires? 3 properties?

requires presynaptic and post synaptic activity. specific, cooperative, associative


where does LTP happen

exists at most if not all glutamatergic synapses


3 phases of LTP

early = induction. medium = expression. late = maintenance.


what happens during early/induction LTP? depends on?

NMDA receptors activation, dependent on calcium


medium/expression LTP: what happens (2)

changes to receptors and release machinery, local protein synthesis


late/maintenance LTP: 2 things happen? dependent on?

genomic involvement, translation dependent, anatomical changes