Learning of anticipatory responses in single neurons of the human medial temporal lobe.

Marlene Poncet,Linda Douw,Edwin Van Dellen,Leila Reddy,Matthew W Self,Pieter R Roelfsema,Johannes C Baayen,Steven Claus,Jaap C Reijneveld,Judith C Peters

doi:10.1038/ncomms9556

Abstract

Neuronal processes underlying the formation of new associations in the human brain are not yet well understood. Here human participants, implanted with depth electrodes in the brain, learned arbitrary associations between images presented in an ordered, predictable sequence. During learning we recorded from medial temporal lobe (MTL) neurons that responded to at least one of the pictures in the sequence (the preferred stimulus). We report that as a result of learning, single MTL neurons show asymmetric shifts in activity and start firing earlier in the sequence in anticipation of their preferred stimulus. These effects appear relatively early in learning, after only 11 exposures to the stimulus sequence. The anticipatory neuronal responses emerge while the subjects became faster in reporting the next item in the sequence. These results demonstrate flexible representations that could support learning of new associations between stimuli in a sequence, in single neurons in the human MTL.

Highlights

Neuronal processes underlying the formation of new associations in the human brain are not yet well understood
We report that sequence learning causes an increase in neuronal firing rates in anticipation of the neuron’s preferred stimulus, within 11 trials of learning
Each associative learning (AL) session consisted of 60 repetitions of a sequence of 5–7 images presented in a predetermined, predictable order, and subjects had to learn the order of the sequence

Summary

Introduction

Neuronal processes underlying the formation of new associations in the human brain are not yet well understood. We report that as a result of learning, single MTL neurons show asymmetric shifts in activity and start firing earlier in the sequence in anticipation of their preferred stimulus. The anticipatory neuronal responses emerge while the subjects became faster in reporting the item in the sequence These results demonstrate flexible representations that could support learning of new associations between stimuli in a sequence, in single neurons in the human MTL. We report that sequence learning causes an increase in neuronal firing rates in anticipation of the neuron’s preferred stimulus (that is, a stimulus that would elicit a selective neuronal response when presented outside the sequence), within 11 trials of learning These anticipatory responses could play an important role in predicting future events based on what has been recently learned

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Conclusion