Dr John Porrill BA, PhD

Address
The University of Sheffield
Sheffield S10 2TP
UK
Tel: (+44) 0114 222 6557
Fax: (+44) 0114 276 6515
Email J.Porrill@sheffield.ac.uk
Room: G-15

Qualifications

BA, PhD (Cantab)

Teaching and administrative duties

I am module organiser for module 336. I am also responsible for U/g admissions and sit on the Psychology Management Committee, Psychology Teaching Committee, Computing Committee and Postgraduate Studies Committee.

Research Interests

My research is aimed at developing a computational understanding of the brain and its role in behaviour.

Mathematical modelling
Very fruitful collaborations with psychologists and neuroscientists (my own training is as a mathematician and theoretical physicist) have allowed me to develop a programme of research based on combining rigorous mathematical modelling with a detailed understanding of the underlying neuroscience.

Identifying the cerebellar algorithm
The central theme of my current research is to identify the cerebellar algorithm. With colleagues I have developed a view of cerebellar function which emphasises the importance of a basic 'decorrelation control' algorithm implemented in the repeating microcircuit based around the Purkinje cell.

This research has been more successful than we could have hoped. For example:

• It provides a unified description of sensory and motor functions;
• It has revealed a surprising functional role for closed cerebellar loops which have recently been traced in detail and whose function is regarded as a challenge to theorists;
• It has provided a computational answer to the longstanding puzzle as to why there are two sites of plasticity in VOR adaptation;
• In addition the algorithm has been implemented in hardware by our collaborators in Bristol Robotics Lab and is successfully learning to stabilise a robot mounted camera.

Our enthusiasm for a cross-disciplinary approach makes myself and my close colleague Paul Dean natural partners in current and planned multi-site research programmes linking neuroscience and robotics.

Grants

BBSRC, Dean & Porrill Sheffield, lead by UCL with Cambridge: Cerebellum as a neuronal machine: behavioural, electrophysiological and computational analysis of classical conditioning. (2004 for 3yrs) c. £750K

EPSRC, lead by Dean & Porrill, Sheffield with Edinburgh & UWE: Functions of Distributed Plasticity in a Biologically-Inspired Adaptive Control Algorithm: From Electrophysiology to Robotics. (2004for 3yrs) £767K.

BBSRC, Dean & Porrill: Neural Control of Eye Movements (2000 for 3yrs) £120,000

Activities and Distinctions

• I was an invited participant in recent workshops on the future of cerebellar research held at the University of Tuebingen & St Louis and co-author of the workshop review in Cerebellum.
• I was an invited participant in the Foresight Cognitive Systems Project InterAction conference organised in 2003 by the DTI and in a number of Cluster Group Meetings supported by the EPSRC in 2004.
• I was elected Fellow of the Institute of Mathematics and its Applications in 2001.

Invited presentations include

• London 2006: invited discussant Gatsby Foundation International conference on the Cerebellum
• Edinburgh 2005, 2006: Neurosciences Graduate Program
• Antwerp 2005: Neuro-IT Cerebellar Modeling Workshop
• Dorchester 2005: Quinetiq Symposium: Learning in Neuronal Networks
• Warwick 2005: Mathematical Neuroscience: network analysis
• Tuebingen 2004: International Conference on the Cerebellum
• Oxford 2004: Symposium on Biological and Computational Vision
• Edinburgh 2003: EPSRC Novel Computation Initiative

Key Publications

PORRILL J & DEAN P (2006),
Recurrent cerebellar loops simplify adaptive control of redundant & non-linear motor systems
Neural Computation (in Press).

SKLAVOS, S., DIMITROVA D M, GOLDBERG S J, PORRILL J & DEAN, P. (2006).
Long time constant behaviour of oculomotor plant in barbiturate-anaesthetized primate,
J Neurophysiol, 95:774-782.

PORRILL J, DEAN P AND STONE JV (2004)
Recurrent cerebellar architecture solves the motor error problem,
Proceedings of the Royal Society of London Series B - Biological Sciences, 271, 789-796.

SKLAVOS, S., PORRILL, J., KANEKO, C. R. S., & DEAN, P. (2005).
Evidence for a wide range of time scales in oculomotor plant dynamics: Implications for models of eye-movement control.
Vision Research, 45(12), 1525-1542.

WARREN, P. A., PORRILL, J., & DEAN, P. (2004).
Consistency of Listing's law and reciprocal innervation with pseudo-inverse control of eye position in 3-D.
Biological Cybernetics, 91, 10-22.

DEAN, P., PORRILL, J., & STONE, J. V. (2002).
Decorrelation control by the cerebellum achieves oculomotor plant compensation in simulated vestibulo-ocular reflex.
Proceedings of the Royal Society of London, Series B, 269(1503), 1895-1904.

View a full list of John Porrill's publications.

Postgraduate Students

• I am currently co-supervising Adrian Haith, a PhD student at the University of Edinburgh in the Neuroinformatics Doctoral Training Centre.

Research Assistants

• Dr Nathan Lepora (BBSRC)
• Dr Sean Anderson (EPSRC)