The human brain is a masterful machine that makes decisions based on associations between stimuli in our environment. But did you know that these decisions can also be influenced by indirect associations between seemingly unrelated events? A recent study by the Cellular Mechanisms in Physiological and Pathological Behavior Research Group at the Hospital del Mar Research Institute has shed new light on this process, revealing how a specific scent can alter our mind’s decision-making processes.

The research team, led by PhD student José Antonio González Parra and supervised by Dr. Arnau Busquets, conducted experiments with mice to understand the mechanisms behind indirect associations between different stimuli. They trained the mice to associate two distinct smells – banana and almond – with sweet and salty tastes respectively. Later, a negative stimulus was linked to the smell of banana, causing the mice to reject the sweet taste associated with it.

The researchers used genetic techniques to observe which brain areas were activated throughout this process. They found that the amygdala, a region linked to responses such as fear and anxiety, played a crucial role in encoding and consolidating these associations. Other brain areas also interacted with the amygdala, forming a brain circuit that controls indirect associations between stimuli.

Dr. Busquets explained that if amygdala activity was inhibited while the mice were exposed to the stimuli, they were unable to form these indirect associations. This finding has significant implications for treating mental disorders linked to amygdala activity, such as PTSD and psychosis.

The researchers believe that the brain circuits involved in decision-making processes in humans are similar to those in mice. Therefore, understanding these complex cognitive processes can help us design therapeutic strategies for humans, including brain stimulation or modulation of activity in specific areas.

In conclusion, this study has revealed how a scent can change our mind’s decisions by altering indirect associations between stimuli. By exploring the neural mechanisms behind this process, we may be able to develop innovative treatments for mental disorders that affect millions of people worldwide.

The gene PTEN has emerged as one of the most significant autism risk genes. Variations in this gene are found in a significant proportion of people with autism who also exhibit brain overgrowth. Researchers at the Max Planck Florida Institute for Neuroscience have discovered how loss of this gene rewires circuits and alters behavior, leading to increased fear learning and anxiety in mice – core traits seen in ASD.

PTEN has been linked to alterations in the function of inhibitory neurons in the development of ASD. The researchers focused on the changes in the central lateral amygdala driven by loss of PTEN in a critical neuronal population – somatostatin-expressing inhibitory neurons. They found that deleting PTEN specifically in these interneurons disrupted local inhibitory connectivity in the amygdala by roughly 50% and reduced the strength of the remaining inhibitory connections.

This diminished connectivity between inhibitory connections within the amygdala was contrasted by an increase in the strength of excitatory inputs received from the basolateral amygdala, a nearby brain region that relays emotionally-relevant sensory information to the amygdala. Behavioral analysis demonstrated that this imbalance in neural signaling was linked to heightened anxiety and increased fear learning, but not alterations in social behavior or repetitive behavior traits commonly observed in ASD.

The results confirm that PTEN loss in this specific cell type is sufficient to induce specific ASD-like behaviors and provide one of the most detailed maps to date of how local inhibitory networks in the amygdala are affected by genetic variations associated with neurological disorders. Importantly, the altered circuitry did not affect all ASD-relevant behaviors – social interactions remained largely intact – suggesting that PTEN-related anxiety and fear behaviors may stem from specific microcircuit changes.

By teasing out the local circuitry underlying specific traits, researchers hope to differentiate the roles of specific microcircuits within the umbrella of neurological disorders, which may one day help in developing targeted therapeutics for specific cognitive and behavioral characteristics. In future studies, they plan to evaluate these circuits in different genetic models to determine if these microcircuit alterations are convergent changes that underlie heightened fear and anxiety expression across diverse genetic profiles.

The field of neuroscience has made significant strides in understanding the complex mechanisms behind Alzheimer’s disease. A recent study by researchers at the University of California San Diego School of Medicine offers a glimmer of hope for those affected by this debilitating condition. By developing a gene therapy that targets the root cause of Alzheimer’s, these scientists may have found a way to not only slow down but also potentially reverse memory loss.

Alzheimer’s disease is a progressive disorder that affects millions worldwide. It occurs when abnormal proteins build up in the brain, leading to the death of brain cells and declines in cognitive function and memory. While existing treatments can manage symptoms, they do little to halt or reverse the progression of the disease. This new gene therapy, however, promises to address the underlying issue by influencing the behavior of brain cells themselves.

The researchers conducted their study using mice as models for human Alzheimer’s patients. They found that delivering the treatment at the symptomatic stage of the disease preserved hippocampal-dependent memory – a critical aspect of cognitive function often impaired in Alzheimer’s patients. Moreover, the treated mice had a similar pattern of gene expression compared to healthy mice of the same age, suggesting that the treatment has the potential to alter diseased cells and restore them to a healthier state.

While further studies are required to translate these findings into human clinical trials, this gene therapy offers a unique and promising approach to mitigating cognitive decline and promoting brain health. As researchers continue to refine and develop this technology, we may soon see a future where Alzheimer’s patients can experience a significant reversal of memory loss – a truly remarkable prospect that could revolutionize the way we understand and treat this devastating disease.