Lecture 3: The brain is key to our mind

From the perspective of cognitive neuroscience, that means we need to learn the role of our brain. The first thing that we need to know is that the human brain is an organ of information processing. It is very similar to the digestive system, which processes food into nutrients. However, the brain does everything in a reverse way – it digests information by reorganizing it, transforming pieces of information into a holistic experience.

Because the brain has multiple functions and a complex structural organization, it is very intuitive to think that different anatomical regions will correspond to different functions. For example, there might be different ‘brain centres’ for different mental functions specifically. While it is true that brain functions are bounded by brain structure, the mapping between brain function and structure is very complicated. For example, from gross anatomy, we can identify the precentral gyrus, the postcentral gyrus and the occipital lobe here. We can even link these regions to specific information processing. For example, the precentral gyrus is designated as the primary motor cortex and its cortical layers have a rich connection with the motor system.

And neural activity in the occipital lobe is much associated with visual stimuli. However, that does not mean these regions are specific ‘centres’ only for that functions. And a full mental function is associated with the integration of different regions. For example, to identify what an object is and where it is, the information of the visual cortex needs to be integrated with other brain regions. In this case, the visual cortex is essential for visual function, which means a deficit in the occipital lobe may compromise our vision. However, visual functions rely on the participation of multiple regions, not just the visual cortex.

So earlier research of neuroimaging focuses on the association between a brain region and a mental function. It assumes that each region specializes in a function. However, from many years of research, now we know the brain is connected as a collective unit. That means a mental function is associated with the activity of multiple brain regions, as shown here. When I say ‘multiple brain regions’ that means the collaboration between some brain regions is preferential for some function. For example, here the light-grey area may work together for a function, and the dark-grey area may work for another function. In other words, there is a tendency for the brain to have segregated communities or ‘modules’ for different functions.

Finally, these communities or modules still need to communicate with each other. That means all the information will be integrated, from a whole-brain scale. All these concepts are about the efficiency of the information processing of the brain. In functional specialization, we assume that information processing can be identified by the activity of a specific region. In functional segregation, we look into the formation of a community or a module, which is preferentially associated with a function. In functional integration, we focus on the global efficiency of information processing within the whole brain, i.e., not just within each functional module but also between the functional modules.

And before we conclude this section, there is one thing that needs to mention. For many years of research, now we are very sure that not just our behaviour is flexible, the brain function and structure is flexible and plastic. The term ‘plasticity’ refers to the potential for the brain to change, in accordance with the complexity of behaviour. In fact, the brain is plastic because its function and structure can be modified by experience. And that is why we usually put the terms ‘the brain and behaviour’ together. But we should be careful saying ‘from the brain to behaviour’ because we should not presume that the brain determines our behaviour.

It is very possible that long-term experience and learning, such as chronic pain and training of oral rehabilitation, would reversely modify our brain structure and function.

Please keep in mind that these concepts have been widely supported by scientific evidence, including animal and human studies. For example, neuroplasticity has been found when people are learning juggling. I meant the practice of juggling will induce changes in the structural connection of the brain. There have been many reports about the change of brain structure and function associated with fine sensorimotor skills, such as the case of artists and sportspersons. I will not feel surprised if people find neuroplasticity associated with the development of dental skills of dental students.