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Child Neuropsychology A blog by Dr Jonathan Reed
  • A new way of looking at how the brain works

    I want to discuss an important new book for understanding how the brain works, which I have just read and is called Subcortical Structures and Cognition: Implications for Neuropsychological Assessment by Leonard Koziol and Deborah Budding.  Our current understanding of how the brain works using Neuropsychology has traditionally focused on the cortex part of the brain – frontal, temporal, parietal and occipital lobes and has looked at what happens psychologically when there is damage to these particular areas.  From this we understand perception, memory, language etc pretty well.  However we have tended to ignore subcortical brain areas such as the basal ganglia and cerebellum and have considered these areas as being responsible mainly for motor co-ordination.   This new book by Koziol and Budding challenges this view and presents a view of sub cortical structures being central to the way the brain works.  It is a detailed book with many arguments (a summary can be seen on the website here) and needs to be read carefully, but some of the important points for me were:

    1.  The brain responds to the environment in two key ways.  Firstly most of the time it responds in an automatic way (subconscious way using procedural memory) which requires little thought, is fast and is adaptive.  You don’t need to work out how to respond to most everyday occurrences you just do it.  However, when a new situation arises, maybe a threat, maybe something you need to learn, the front part of the brain takes control and thinks about how to respond (i.e. executive function).  Both systems operate in tandem and are connected by the basal ganglia.  The default setting for the brain, however, is to make unfamiliar familiar.  This is more efficient.  Hence there is a drive to turn new information into automatic memory.

    2. Koziol and Budding argue that the basal ganglia is key in determining this process i.e. linking controlled and automatic responses.   It does this by being part of a feedback loop connecting the cortex to the limbic system (thalamus) and acting as a gate between the two. Basically the cortex is stimulated by sensory input and the sub cortex inhibits responses by deciding what information is returned to the cortex.

    3. The other main sub cortical area the cerebellum works to further fine tune responses using a mix of excitation and inhibition.

    4. The book details how and why such a system would have evolved.  This is often missing in neuropsychology accounts.  The book offers a plausible explanation of what any organism needs to function and how brains have evolved to meet these needs.  The key purpose of an organism is to survive.  In order to survive an organism needs to recognise objects, locate objects and detect movement (all cortex functions) and then to know what to do, how to do it and when to act (all mediated by the subcortex).  Koziol and Budding compare the subcortical structures in vertebrates, primates and humans to illustrate this point.

    5. The  basal ganglia acts as a gate to switch responses on and off, which is the key to regulation.  Knowing when to start a behaviour (initiation) and when to decease from a behaviour (inhibition) is key to how we function (and yet is rarely explored). The cerebellum further fine tunes this process.

    6.  Traditionally the sub cortical structures have been though of as mainly involved in motor responses.  However one of the many interesting ideas in the book is that  the same structures may have a similar  function for emotion, behaviour and cognition.  This would make sense from an evolution and developmental point of view.  Undertaking complicated motor sequences such as kicking a ball i.e. judging when to move and adjust can be similar to knowing how to control anger, social response or thoughts.

    7. Why this is important in my opinion is that it starts to offer explanations for disorders of regulation, which are so common in children, e.g. ADHD, TBI, OCD, emotional disorder, motor co-ordination and speech disorders.  Neuropsychology does not provide very good explanations for these disorders at present and yet they are the most common difficulties encountered especially with children.  The key issues in these disorders is regulating and adjusting responses to the environment.

    8.  Another reason the book is important is that it gets away from the view that we need to focus on a single brain area and it’s function and looks instead about how different brain areas act in circuits in relation to one another.  The circuits work by involving different brain areas in feedback loops using excitation and inhibition to regulate the system.   This makes sense biologically, developmentally and from an evolutionary point of view.

    Therefore I would highly recommend this book to anyone interested in neuropsychology and how the brain works.  It challenges existing thinking.  It is a specialist book but is well written and informative.   There are detailed sections on neuropsychological assessment for those interested, although these sections are in my opinion of more limited interest because most tests don’t assess subcortical functions that well.  The important thing the book does for me as well as explaining sub cortical anatomy and function is to start to provide a more coherent framework for understand brain regulation, which I think is fundamental for understanding child neuropsychology.   I think that ultimately this understanding will help us better assess and help children with brain dysfunction and particularly regulation difficulties.

    Published on January 3, 2011 · Filed under: adhd, behaviour, brain development, head injury, neuroscience, subcortical function;
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