Hippocampal ripples and memory consolidation during sleep

Local field potential

electrical activity generated at synapses summate in space and time

passively propagate through extracellular space and through skull and scalp to electrodes

Hippocampal LFP

when animal stops moving and is inattentive, theta oscillations stop and dominated by large amplitude random activity

sharp-waves occurring aperiodicly —> generated by large barrage of excitatory input from CA3

Layers of CA1

Stratum oriens contains pyramidal neuron basal dendrites

stratum pyramidale contains pyramidal neuron somas

stratum radiatum contains the proximal 75% of apical dendrites (receives CA3 input)

stratum lacunosum-moleculare contains distal aspect of apical dendrites (recieves entorhinal cortex input)

ripples

fast frequency oscillations during sharp-waves

important for consolidation

primarily observed in SWS

Acetylcholine

high ach = encoding/retrieval theta oscillations

low ach = consolidation sharp-wave/ripples (ripples has replay sequencing of waking experiences)

Where do ripples go

passed from HC to subiculum, entorhinal cortex, and postsubiculum