Movement, cognition and perception arise from the collective activity of neurons within cortical circuits and across large-scale systems of the brain. While the causes of single neuron spikes have been understood for decades, the processes that support collective neural behavior in large-scale cortical systems are less clear and have been at times the subject of contention.
Breakspear M (2017). Dynamic models of large-scale brain activity. Nature Neuroscience, 20, 340-352.
Do we control our muscles individually? In this paper we use network analysis of surface EMG to investigate how muscles are coordinated by the central nervous system: http://www.nature.com/articles/srep17830
Network dysfunction of emotional and cognitive processes in those at genetic risk of bipolar disorder.
The emotional and cognitive vulnerabilities that precede the development of bipolar disorder are poorly understood. Using Dynamic Causal Modelling to analyse fMRI data, we suggest dysfunction in the processes that support hierarchical relationships between emotion and cognitive control in prefrontal cortex.
Fluctuating oscillations are a ubiquitous feature of neurophysiology. Are the amplitude fluctuations of neural oscillations chance excursions drawn randomly from a normal distribution, or do they tell us more?
We consider how brain-network topology shapes neural responses to damage, highlighting key maladaptive processes (such as diaschisis, transneuronal degeneration and dedifferentiation), and the resources (including degeneracy and reserve) and processes (such as compensation) that enable adaptation. We then show how knowledge of network topology allows us not only to describe pathological processes but also to generate predictive models of the spread and functional consequences of brain disease.
Fornito A, Zalesky A, Breakspear M (2015). The connectomics of brain disorders. Nature Reviews Neuroscience 16: 1-14.
This study shows that early preterm brain activity is characterized by scale-free dynamics which carry developmental significance, hence offering novel means for rapid and early clinical prediction of neurodevelopmental outcomes.
Iyer KK, Roberts JA, Hellström-Westas L, Wikström S, Hansen-Pupp I, Ley D, Vanhatalo S, Breakspear M (2015) Cortical burst dynamics predict clinical outcome early in extremely preterm infants. Brain 138:2206-2218.
Disrupted effective connectivity of cortical systems supporting attention and interoception in melancholia
In this study, we observed reduced effective connectivity in resting-state functional magnetic resonance imaging between key networks involved in attention and interoception in melancholia. We propose that these abnormalities underlie the impoverished variety and affective quality of internally generated thought in this disorder:
Hyett MP, Breakspear M, Friston KJ, Guo, CC, Parker G (2015). Disrupted effective connectivity of cortical systems supporting attention and interoception in melancholia. JAMA Psychiatry 72: 350-358.
When large groups of neurons interact they generate synchronous brain rhythms. These brain rhythms, in turn, influence when individual neurons fire and hence coordinate their distributed activities. In this paper we show that in human subjects who perform rapid movements towards a target the frequency of synchronous brain rhythms only changes when they make a movement error. This reorganization in synchronous brain activity likely reflects changed information processing involved in parsing prediction errors and updating motor commands.
Large-scale organizational properties of brain networks mapped with functional magnetic resonance imaging have been studied in a time-averaged sense. This is an oversimplification. We demonstrate that brain activity between multiple pairs of spatially distributed regions spontaneously fluctuates in and out of correlation over time in a globally coordinated manner, giving rise to sporadic intervals during which information can be efficiently exchanged between neuronal populations. We argue that dynamic fluctuations in the brain’s organizational properties may minimize metabolic requirements while maintaining the brain in a responsive state.
We now encourage interested applicants to peruse our "join the team" page for exciting projects in brain dynamics, networks and energy optimization. These involve varying combinations of computational models plus analysis of time series and functional neuroimaging data.