Past experience shapes the neural circuits recruited for future learning

Lateral hypothalamic GABAergic neurons are necessary to encode fear memories after reward learning. Usually, GABAergic neurons in the lateral hypothalamus are involved in learning about positive or rewarding experiences. Here, we tested whether optogenetic inhibition of GABAergic neurons in lateral hypothalamus would have any impact on the encoding of a fear memory. To test this, we opotogenetically inhibited GABAergic neurons in the lateral hypothalamus during a stimulus that was predictive of shock, to see if this would impact on the ability of subjects to associate the stimulus and shock together, usually indexing the creation of a memory of the fearful event. We found that inhibition of these neurons during a shock-predictive stimulus had not impact in naive subjects (left). However, this same manipulation significantly reduced the encoding of the stimulus-shock memory in rats that had previously experience reward learning (right). This demonstrates that GABAergic neurons in the lateral hypothalamus are recruited for learning about fearful experiences after experience with reward learning.

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Hot Off the Press – February 18, 2021

Past is prologue, at least that is the saying. Yet modern behavioral neuroscience, particularly in animals, strives to minimize the effect of past experience, using young and typically naïve subjects for testing. This is done in an effort to understand brain function without the confounding effects of prior training; however what if prior experience shapes how the brain processes new information, perhaps even changing the neural circuits critical to particular learning? The current study presents evidence to that effect, showing that the lateral hypothalamus – an area most famously required for feeding – becomes recruited to support fear conditioning as a result of prior appetitive learning. This concrete demonstration, and the other associated experiments, challenge the notion that there are sharp boundaries between the neural systems involved in different forms of learning.

Publication Information

Sharpe, Melissa J; Batchelor, Hannah M; Mueller, Lauren E; Gardner, Matthew P H; Schoenbaum, Geoffrey

Past experience shapes the neural circuits recruited for future learning Journal Article

In: Nature Neuroscience, 2021, ISBN: 1546-1726.

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