The Hebbian CS–US convergence model of lateral amygdala plasticity is inconsistent with the timing and brevity of LA CS responses¶

Claim · All claims
Evidence · 1 study · theoretical r3 · q1
Currency · newest study 2017 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q1 i? Because LA CS responses are transient and conditioning works best with CS–US offsets of 10–30 s, NMDA-dependent Hebbian plasticity seems unlikely to be engaged when the US occurs. → Paré 2017

Evidence¶

Paré 2017¶

Paré, D. & Quirk, G. J. (2017). When scientific paradigms lead to tunnel vision: lessons from the study of fear. npj Science of Learning. https://doi.org/10.1038/s41539-017-0007-4

q1 · i? · theoretical · r3

The article's analytical argument against the 1990s Hebbian model: conditioning is most effective with the US offset 10–30 s after CS onset, yet LA CS responses are transient bursts returning near baseline, and prolonged stimuli evoke synaptic potentials that rapidly become sub-threshold. The article states "it seems unlikely that NMDA receptors are engaged when the US is presented".

"given the time course of LA activity and afferent inputs during the CS, it seems unlikely that NMDA receptors are engaged when the US is presented 20 –30 s after CS onset"

Discussion¶

Related Claims¶

• The timing rule of fear conditioning contradicts the Hebbian coincidence rule because simultaneous CS–US pairing is less efficient than CS onset preceding the US with co-termination tens of seconds later — possibly the same claim (merge candidate)
• STC associative interactions occur across intervals of hours, extending the temporal contiguity needed for association well beyond the tens of milliseconds typical of Hebbian associativity — a broader claim this one bears on
• A biophysical LA model showed both auditory thalamic plasticity and intra-amygdala plasticity contribute to fear memory, with thalamic responsiveness essential during learning but dispensable after training — related
• A biophysical model suggested that more excitable LA neurons are preferentially recruited into the fear memory trace via competitive synaptic interactions, validated experimentally — related