NEUReka! 2015/16 Inaugural Seminar with Florian Engert


“By carefully observing a behaving zebrafish we gained a profound insight –
the fish has two eyes!”
Florian Engert, 7 September 2015

How can we understand the brain? Florian Engert tackled this basic yet fundamental question during the first NEUReka! seminar of 2015/16 at King’s College London on September 7. Florian is one of those rare scientists who cleverly manage to convey complex messages in a very straightforward and funny way. In his talk, titled ‘A sensory motor circuit for binocular motion integration in larval zebrafish’, he showed how important the rationale of a study is to understand a biological system.

Taking inspiration from David Marr’s seminal 1982 book Vision, Florian discussed recent work undertaken in his laboratory at Harvard aimed to dissect the neural mechanisms generating adaptive motor responses during whole-field visual motion in zebrafish larvae. According to Marr, in order to fully comprehend a machine (e.g., a brain, a synapse) carrying out an information-processing task, the following three levels of explanation should be addressed: 1) Computational theory, 2) Representation and algorithm, and 3) Hardware implementation. More specifically, one should first understand the goal of a computation and the logic of the process being performed or computed – what the neural system does and why. Secondly, the representation for the input and output of the process and the algorithm by which the transformations or manipulations are performed should be explained – how the computation is performed. Finally, one should find out the type of hardware or machinery in which the algorithm is physically embodied – the neural substrate of the brain in which the process is realised.

These three levels of explanation guided Florian and his team in the discovery of specific brain-wide neural circuits (3rd Level) underlying the effective adjustment of body position and orientation according to whole-field visual shifts in the surrounding environment (1st Level). Using Florian’s words, after having observed the fish larva performing a defined behaviour, the researcher should ‘sit and think with the brain constrains in mind’ to carefully work out what the fish does and why. Then, with the help of modelling and simulation programs, he or she should ‘write down a recipe of instructions’ to describe the algorithm carrying out the input-output transformations. The final experiment, in the form of neural activity recording through whole-brain two-photon calcium imaging, represents a ‘control experiment’ to basically locate and confirm the ‘postulated neural implementation’ of the algorithm in the fish brain.

At the end of the talk, the host of the event, Winnie Wefelmeyer, asked Florian a question selected by the NEUReka! Committee – Where will the neuroscience field be in ten years? During the refreshments held in the MRC Centre for Developmental Neurobiology, Florian answered the question saying that he thinks there will be no new big leaps or paradigm shifts in neuroscience. He is not one of those neuroscientists waiting for a ground-breaking discovery that will revolutionise the field, like the determination of the DNA structure by Watson and Crick in 1953 was for molecular biology. Instead, he thinks that the key principles of neural systems have already been revealed. In his view, we will see ‘baby steps‘ that will gradually push the field forward and lead to a greater, more comprehensive understanding of the brain.

Paride Antinucci

PhD student in Robert Hindges lab
and NEUReka! Committee member

Please follow NEUReka! Seminars at

facebook_icon  twitter_icon

Pictures by Alina Letzel

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s