Stimulation reverses memory and learning deficits in mice

Learning and memory deficits caused by brain lesions in rats have been completely reversed through stimulation of the hypothalamus. The research, conducted by scientists at University of Barcelona, aimed to explore the effects of Deep Brain Stimulation (DBS) treatment on the recovery of the ability to learn and store memories after severe lesion damage.

The lesions were localised to the amygdala, a critical region of the brain responsible for basic emotions and involved in learning and fear conditioning. Dysfunction of this part of the brain prevents the ability to learn stimulus association and can result from a number of factors, from biochemical alterations of neurotransmitters to extremely tense situations.

The animals used in the study had experienced more than 70% damage to the amygdala. After several sessions of treatment, involving sending electric impulses to the hypothalamus, the subjects underwent a full recovery in the ability to learn and remember, an effect that lasted up to three months after ten 60-minute treatment sessions.

The hypothalamus is a small area of the brain responsible for a number of functions, and it appears that its stimulation can compensate for damages in the amygdala. Researchers have shown that the activation produces structural changes in the brain while increasing neural connections and expression of genes related to neural plasticity and protection. In the area of undamaged amygdala, increased acetylcholinesterase activity was found – a key enzyme in the metabolism of the neurotransmitter, acetylcholine, essential to learning and remembering.

Coordinator of the study, Pilar Segura, explained, “this makes us think that the stimulation of the hypothalamus does not affect only one part, rather it has several action paths and depending on where the lesion is located, it can stimulate different mechanisms with the aim of repairing different dysfunctions.”

The study clearly demonstrates the therapeutic power of DBS, but may also provide a mechanism of disabling emotions and ‘unlearning’, which could lead to potential treatment in such conditions as post-traumatic stress disorder.