Cerebellar learning: eyeblink conditioning in the Marr–Albus–Ito circuit

A trial-by-trial rate model of the cerebellar cortex, cerebellar nuclei and inferior olive, including the olivary feedback loop. It is schematic: firing rates and time constants are in physiological ranges but are not fitted to any data set.

Circuit

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CEREBELLUM BRAINSTEM mossy fibres mossy-fibre collateral parallel fibres (plastic) climbing fibre nucleo-olivary airpuff signal reflex blink pathway (brainstem only — not cerebellar) Granule cells → parallel fibres different groups fire at different delays after the tone Interneurons basket / stellate Purkinje cell sole output of the cortex simple spikes Nucleo-olivary GABA → olive Projection interpositus Cerebellar nuclei Cerebellar cortex Pontine nuclei tone (CS) → mossy fibres Trigeminal nucleus airpuff to the eye (US) Inferior olive airpuff excitation − nuclear inhibition Red nucleus magnocellular Facial nucleus → eyelid closure

Click any cell group or connection to read about it below. Moving dots are spikes, slowed down while a trial plays; the climbing fibre shows each climbing-fibre spike as a single large dot.

Current trial

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Experiments

Paused
Each trial presents
Manipulations
Trial
0
naive
Learned blink (CR)
0%
closure at airpuff time
Climbing-fibre response
0%
chance per trial
Purkinje minimum
60 Hz
during the tone
Nuclei peak
40 Hz
during the tone

Learning across trials

Synaptic weights for each parallel-fibre group