Computation of instinctive decisions
tel: +44 20 3108 8019
Instinct and intuition are two fundamental components of behaviour. From the innate reaction of a prey to the sight of predator, to the departure from rationality in human economic decisions, information that is rapidly accessed without reaching consciousness can be used to influence behavioural choices. Our goal is to understand how neurons in the brain compute instinctive decisions. We aim to determine how sensory input, motivation and expectations from past experience are integrated to reach instinctive choices, and how this integration is computed at the level of synapses and ion channels. We hope to advance the mechanistic understanding of how decisions are made, and provide a framework for investigating causes and therapies for maladaptive decision-making during mental illness states, such as anxiety and depression.
We currently use defensive behaviours in the mouse as a model system, and we are investigating how exposure to innately aversive threats is converted into behaviour, including during conflict situations created by competing motivations and past experience. All projects in the laboratory start at the behavioural level, with the development and application of quantitative assays, followed by development of behavioural models that we then aim to map onto biophysical mechanisms using a variety of experimental tools and techniques. We record neuronal activity in vivo in freely moving animals using miniature endoscopes and high density silicone probes, as well in head-fixed animals with whole-cell patch-clamp and two-photon microscopy. These approaches are complemented by circuit level analysis using viral tracing tools, and a variety of high-resolution in vitro patch-clamp recording methods, together with molecular perturbations of ion channels using shRNA and CRISPR technologies.
We are actively pursuing two main questions:
1) How do neural circuits represent threat and compute the decision to engage in defence?
We focus on midbrain circuits, including the Superior Colliculus (SC) and the Periaqueductal Gray (PAG), and their neuronal activity during the decision-making process of starting defensive actions in response to visual, auditory and olfactory stimuli that innately threatening. We investigate information transfer between these two networks, as well as the computations performed by the PAG intrinsic network, with a strong emphasis on mechanisms of synaptic integration by diverse cell types.
2) How is the choice between different defensive strategies computed
We are investigating how threats of varying intensities and qualities are converted into different defensive behaviours, such as escape and freezing, as well as how these behaviours are gated by learned knowledge about the spatial environment.
- Group Members
- Selected Publications
- Prefrontal cortical control of a brainstem social behavior circuit, Franklin TB, Silva BA, Perova Z, Marrone L, Masferrer ME, Zhan Y, Kaplan A, Greetham L, Verrechia V, Halman A, Pagella S, Vyssotski AL, Illarionova A, Grinevich V, Branco T, Gross CT. Nat Neurosci. 2017. doi:10.1038/nn.4470.
- Near-Perfect Synaptic Integration by Nav1.7 in Hypothalamic Neurons Regulates Body Weight. Branco T, Tozer A, Magnus CJ, Sugino K, Tanaka S, Lee AK, Wood JN, Sternson SM. Cell. 2016 Jun 16;165(7):1749-61. doi: 10.1016/j.cell.2016.05.019.
- Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss. Henry FE, Sugino K, Tozer A, Branco T, Sternson SM. Elife. 2015 Sep 2;4. doi: 10.7554/eLife.09800.
- Dendritic spikes enhance stimulus selectivity in cortical neurons in vivo. Smith SL, Smith IT, Branco T, Häusser M. Nature. 2013 Nov 7;503(7474):115-20. doi: 10.1038/nature12600.
- Synaptic integration gradients in single cortical pyramidal cell dendrites. Branco T, Häusser M. Neuron. 2011 Mar 10;69(5):885-92. doi: 10.1016/j.neuron.2011.02.006.
- The single dendritic branch as a fundamental functional unit in the nervous system. Branco T, Häusser M. Curr Opin Neurobiol. 2010 Aug;20(4):494-502. doi: 10.1016/j.conb.2010.07.009. Review.
- Dendritic discrimination of temporal input sequences in cortical neurons. Branco T, Clark BA, Häusser M. Science. 2010 Sep 24;329(5999):1671-5. doi: 10.1126/science.1189664.
- The probability of neurotransmitter release: variability and feedback control at single synapses. Branco T, Staras K. Nat Rev Neurosci. 2009 May;10(5):373-83. doi: 10.1038/nrn2634.
- Local dendritic activity sets release probability at hippocampal synapses. Branco T, Staras K, Darcy KJ, Goda Y. Neuron. 2008 Aug 14;59(3):475-85. doi: 10.1016/j.neuron.2008.07.006.