How Neurons in the Brain Influence Attention

Attention is the ability to focus on what matters while ignoring distractions. This skill is essential for many daily tasks, like reading, driving, and even having conversations. However, some people struggle with attention due to conditions like ADHD, depression, or schizophrenia. When attention is lacking, it can lead to difficulties in functioning and a lower quality of life. Therefore, understanding how attention works in the brain can help find new ways to help those who have trouble with it.

#Measuring Attention

One common way to measure attention is through a test known as the Continuous Performance Test (CPT). In this test, participants must respond to certain stimuli while ignoring others. This test has been used to study attention deficits in people with brain damage and various mental health conditions.

For animals, a similar test called the rodent Continuous Performance Test (rCPT) has been developed. In this version, mice are trained to distinguish between a reward (a target stimulus) and something that does not offer a reward (a non-target stimulus). Research has shown that results from the rCPT in mice can predict how humans might perform on similar attention tests. This suggests that the underlying brain processes may be similar across species.

#Brain Regions Involved in Attention

A part of the brain known as the Dorsal Anterior Cingulate Cortex (dACC) plays a significant role in attention. Imaging studies have shown that this area is activated when people perform tasks that require a lot of attention. In those with attention-related disorders, the activity in the dACC is often reduced. In mice, the Prelimbic Cortex (PrL) is thought to be similar to the human dACC. Activity in the PrL also appears to correlate with attention levels.

Researchers have found that when the PrL is inhibited or its connections are disrupted, attention is negatively impacted. Additionally, changes in brain wave patterns in the PrL, specifically involving a part of the brain called the locus coeruleus, have been observed during tasks requiring sustained attention. However, the exact way individual neurons in the PrL contribute to attention is not yet fully understood.

#Studying Neurons in the PrL

To better understand how neurons in the PrL are involved in attention, researchers used a technique called in vivo Calcium Imaging. This method allows them to observe the activity of individual neurons in living mice while the mice perform the rCPT.

Mice were trained to participate in the rCPT and their brain activity was recorded at different points during training. By doing this, researchers aimed to see how the activity of PrL neurons changed as the mice improved at the task and faced different levels of difficulty.

#Results of the Study

#Neuronal Activity During Task Performance

The study found that the responses of PrL neurons varied based on whether the mice were performing well or struggling. When mice responded correctly, especially as they became more skilled in the task, a greater number of PrL neurons showed heightened activity. This suggests that as attention improves, more neurons become involved in the task.

Specifically, during sessions when the mice were proficient at the task, a higher percentage of neurons were active compared to sessions where they were still learning. This indicates that the PrL plays a role in supporting attention when the demands of the task increase.

#Attention Lapses

One crucial aspect of attention is that it can fluctuate over time. In humans, attention often wanes, leading to lapses. The study aimed to see if similar lapses occurred in mice during the rCPT. Researchers observed that, within sessions, the mice would alternate between responsive periods (where they were engaged with the task) and non-responsive periods (where they did not respond).

The length of these non-responsive periods varied from mouse to mouse. The number of these lapses increased in harder stages of the rCPT, suggesting that as tasks become more demanding, mice may become fatigued or lose motivation.

#Calcium Activity in PrL Neurons

Further analysis revealed variations in calcium activity among PrL neurons, depending on whether the mice were responding to stimuli or not. Some neurons became more active during non-responsive periods, while others showed decreased activity.

It was found that fewer neurons were modulated during the non-responsive periods in the more challenging stages of the rCPT compared to earlier stages. Additionally, the overall activity of neurons decreased during these non-responsive periods. This suggests that as tasks become harder, the network of neurons in the PrL may be less coordinated overall.

#Impact of Rewards on Engagement

Interest in how receiving rewards impacts attention led researchers to consider whether or not the mice received enough rewards to stay engaged. There was a noticeable decline in the number of rewards mice obtained before they began to disengage during the harder sessions. This decline was not directly linked to the number of responses they made, indicating that cognitive demand rather than simply a lack of rewards was likely leading to these lapses.

#Conclusion

The ability to maintain attention is critical for navigating daily life, and understanding how the brain manages attention can pave the way for new treatments for those with attention deficits. The study on the activity of neurons in the PrL provides valuable insights into how brain regions interact during sustained attention tasks in mice.

The investigation highlighted that as tasks became more challenging, the engagement of neurons varied. It also pointed out the importance of knowing when attention lapses occur, as these lapses can have significant effects on performance. Future research can build on these findings to further explore how different brain regions work together during attention and how this understanding can lead to better support for individuals experiencing attention difficulties.