The flexibly ordered brain
File(s)
Author(s)
Daws, Richard
Type
Thesis
Abstract
I investigate the human brain systems involved in the cognitive control of behaviour.
Using novel cognitive paradigms and brain imaging, I identify brain systems that
support the flexible structuring of behaviour. I then observe how these systems are
implicated in patients with depression as they respond to psilocybin therapy. In the
first of three experiments, I observe the changes in healthy adult brain activation
that are associated with task-switching. This demonstrated that remapping rules
introduces a switching-cost to response speed and activates the multiple-demand
(MD) network. Critically, switching-costs and MD activation were greater when the
rules being remapped were of an abstract and higher-order nature. Going deeper, in
the second experiment, I investigate how healthy adult brains mitigate
switching-costs by structuring behaviour into efficient routines. I observe that
learning to optimise and structure behaviour covaries with changes in MD and
default mode network (DMN) activation alongside increases in between-network
connectivity. These concurrent behavioural and neural adaptations imply that
cognitive demand is minimised when behavioural routines are structured. Indeed,
these mechanisms are known to have broad roles in flexibly adapting behaviour
and, subsequently, they have been implicated in disorders such as depression.
Using these insights, in the third experiment, I examine the neural basis of the
treatment response to psilocybin in patients with depression. In two clinical trials, I
find that treatment response covaried with global increases in between-network
connectivity. Converging functional cartography measures indicated that this global
shift in network organisation related to increased dynamic flexibility and integration
of the MD and DMN. Together, the findings in this thesis indicate that a ‘flexibly
ordered brain’, the adaptive sequencing of neurocognitive states, is a necessary
feature of well-being and for successfully navigating the demands of daily life.
Using novel cognitive paradigms and brain imaging, I identify brain systems that
support the flexible structuring of behaviour. I then observe how these systems are
implicated in patients with depression as they respond to psilocybin therapy. In the
first of three experiments, I observe the changes in healthy adult brain activation
that are associated with task-switching. This demonstrated that remapping rules
introduces a switching-cost to response speed and activates the multiple-demand
(MD) network. Critically, switching-costs and MD activation were greater when the
rules being remapped were of an abstract and higher-order nature. Going deeper, in
the second experiment, I investigate how healthy adult brains mitigate
switching-costs by structuring behaviour into efficient routines. I observe that
learning to optimise and structure behaviour covaries with changes in MD and
default mode network (DMN) activation alongside increases in between-network
connectivity. These concurrent behavioural and neural adaptations imply that
cognitive demand is minimised when behavioural routines are structured. Indeed,
these mechanisms are known to have broad roles in flexibly adapting behaviour
and, subsequently, they have been implicated in disorders such as depression.
Using these insights, in the third experiment, I examine the neural basis of the
treatment response to psilocybin in patients with depression. In two clinical trials, I
find that treatment response covaried with global increases in between-network
connectivity. Converging functional cartography measures indicated that this global
shift in network organisation related to increased dynamic flexibility and integration
of the MD and DMN. Together, the findings in this thesis indicate that a ‘flexibly
ordered brain’, the adaptive sequencing of neurocognitive states, is a necessary
feature of well-being and for successfully navigating the demands of daily life.
Version
Open Access
Date Issued
2021-09
Date Awarded
2022-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
Advisor
Hampshire, Adam
Leech, Robert
Hellyer, Peter
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/L016737/1
Publisher Department
Department of Brain Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)