Systems Neuroscience

Understanding how the cooperative activity of different neuronal types contribute to the encoding of behaviourally relevant information in the brain is one of the greatest challenges of Systems Neuroscience. It necessitates an understanding of the “chronocircuitry” of the brain. This term – coined by Professor Peter Somogyi – describes brain function at two interrelated levels: The first relates to the structural context of specific neuron types, namely their position within a neuroanatomical framework and the nature of their inputs and outputs; the second is a description of neuron firing patterns in time in relation to the behaviour of the animal and ongoing neural-network activity. Although work under anaesthesia has led to the identification of cell type-specific firing patterns in the rat hippocampus – a structure thought to be crucial to the encoding of episodic and spatial experience – anaesthesia is known to alter brain activity compared to the non-anesthetized, waking state. My doctoral work explored how this complex relationship between anatomy, brain states and the activity of neuronal types changes between waking, sleep and anaesthetised conditions. This work led to a characterization of anaesthesia’s different effects on a variety of neuronal cell types, suggesting a degree of caution should be taken when viewing anaesthetised brain states as analogous in some form to either waking or sleep conditions. A number of new strategies for classifying neuronal cell types emerged.


  • Huxter JR, Senior TJ, Allen K, Csicsvari J (2008). Theta phase-specific codes for two-dimensional position, trajectory and heading in the hippocampus. Nat Neurosci, 11(5):587-94
  • Senior TJ, Huxter JR, Allen K, O’Neill J, Csicsvari J (2008). Gamma oscillatory firing reveals distinct populations of pyramidal cells in the CA1 region of the hippocampus. J Neurosci, 28(9):2274-86
  • O’Neill J, Senior TJ, Allen K, Huxter JR, Csicsvari J (2008). Reactivation of experience-dependent cell assembly patterns in the hippocampus. Nat Neurosci, 11(2):209-15
  • Csicsvari J, O’Neill J, Allen K, Senior TJ (2007). Place-Selective Firing Contributes to the Reverse Order Reactivation of CA1 Pyramidal Cells during Sharp Waves in Open Field Exploration. Eur J Neurosci, 26:704-16
  • O’Neill J, Senior TJ & Csicsvari J (2006). Place-selective firing of CA1 pyramidal cells during sharp wave/ripple network patterns in exploratory behaviour. Neuron, 49:143-45


  • Senior TJ, Klausberger T, Csicsvari J (2007). An in vivo approach to the classification of interneurons in the hippocampus of the rat. Inhibition in the Central nervous system – Gordon Conference, Colby College Maine. Poster presentation.
  • Senior T, O’Neill J, Klausberger T. & Csicsvari J  (2006). Hippocampal theta oscillations in the anaesthetised and drug-free rat”. 5th Forum of European Neuroscience – Vienna. Poster presentation. Abstract vol. 3, A197.15).
  • Senior, T.J & Csicsvari, J (2005). Theta oscillations under urethane + ketamine/xylazine anaesthesia”. BNA National Meeting – Brighton. Poster presentation. Abstract 37.03 


  • Jacobs University (Fall semester, 2010). Undergraduate Course: “Behavioural Neurobiology”