How do place cells learn about the environment? It has long been known that the place cells use visual information such as landmarks and optic flow. But how the visual information is being transformed from an representation as seen by the eyes (egocentric) into representation of the world (allocentric) in the hippocampal formation is as yet unknown. By simultaneously recording from a large population of neurons in the two areas we are addressing some of these questions.
Saleem, Harris, Carandini, Submitted
(DiI stain of electrode tracks in visual cortex and Hippocampal area CA1 , from Saleem et al. in prep.)
VISION DURING ACTION
Vision is one of the most commonly studied areas of the brain. However, our understanding of vision is limited to when one is sitting in a fixed spot. Little is know about vision during movements such as walking or navigation.
Many naturalistic visual stimuli cause an almost instinctive behavioural response. For example, an object looming towards our eye causes us to instinctively blink. Such responses are innate and do not require any learning. In collaboration with the Solomon Lab, we explore 'visually evoked' behavioural responses in rodents, and investigate the neural underpinnings of such innate behaviours. (More Info)
De Franchesci, Vivattanarsarn, Saleem*, Solomon*,Current Biology, (2016).
Saleem*, Longden*, et al, Journal of Neuroscience (2012).
Image taken by Aman in the backwaters of Kerala, India (2014)
NEURAL CODING IN POPULATIONS
With new technologies we now are able to record simultaneously from large populations of neurons from single or multiple areas. Part of our research focus is to understand how signals regarding the world are encoded by populations of neurons.
Rossant, Kadir, et al, Nat Neuro, 2016
Schovinck et al, J Neurosci, 2015
Saleem, et al, Nat Neuro, 2013;
Benucci et al, Nat Neuro, 2013;
Busse et al, J Neurosci, 2011;
Image from Rossant et al, Nature Neuroscience, 2016
MEMORY REPLAY AND SLEEP
During sleep or rest, there are often re-activations of sequences of cell firing, most commonly place cell firing. These sequences follow the order of activations of the same cells during awake experience, and are though to be 'replay' of a previously experienced memory. Some of these sequences simulate path through yet unexplored regions of space. In collaboration with the Barry and Spiers labs, we investigate the replay and preplay of memories during sleep.
Related publications: H F Olafsdottir*, C J Barry*, A B Saleem, D Hassibis, H Spiers, eLife, 2015