Cortico-Limbic Coding of Object Navigation
In order to survive, animals are required to learn about threat or safety objects in their environment and tune their behaviour accordingly. This mechanism is called object directed navigation. Previous studies have shown that the lateral entorhinal cortex (LEC) takes part in object directed navigation [1,2,3], it has however not been determined how the information in the LEC about the external environment triggers avoidance or approach responses based on experience. Here, we hypothesize that a dedicated circuit between LEC and amygdala controls spatial object navigation.
Specifically, we suggest that projections from the LEC to the basolateral (BLA) and centrolateral (CEl) amygdala are ideally suited for this purpose. These projections are thought to process information about safety objects via the CEl, whereas threat object information is delivered to the BLA. Neurons in the BLA and CEl are innervating the centromedial amygdala (CEm) which controls certain behaviours of the animal. Specifically, excitation of the latter causes an avoidance behaviour. Projections from the BLA to the CEm are thought to have an excitatory effect on the CEm while projections from the CEl to the CEm have an inhibiting effect on it. Thus, we hypothesize that threat object information and behavior are channelled through the LEC-BLA-CEm circuits, while safe object behavior runs through the LEC-CEl-Cem circuits.
Through a conditioning task, mice were conditioned to avoid a threat object. In this conditioning task, a mouse was placed in an arena with two objects, one of them a safety object and the other a threat object that triggered an electric shock in the mouse whenever it was touched.
During the sessions of the conditioning essay, activity in the relevant brain areas that we hypothesize are involved in the suggested neural circuit was recorded using Ca2+ imaging. This imaging method is used to identify Ca2+ spikes that indicate that action potentials are generated. At the same time, the behaviour and position of the mouse were recorded as well.
Here, we analyse this neuronal activity data to investigate correlations between neuronal activity in the suggested circuits and object related behavior.
With this project we aim to understand which neuronal circuits underly experience dependent behavior towards a threat object. In addition, we speculate that the rate of the Ca2+ spikes in the relevant areas corresponds to the position of the mouse. Furthermore, the tuning of these spatial spike gradients might underly the mouse’s behavior respectively to its distance to a threat object.
 S. S. Deshmukh and J. J. Knierim, ‘Representation of Non-Spatial and Spatial Information in the Lateral Entorhinal Cortex’, Frontiers in Behavioral Neuroscience, vol. 5. Frontiers Media SA, 2011. doi: 10.3389/fnbeh.2011.00069.
 C. E. Connor and J. J. Knierim, ‘Integration of objects and space in perception and memory’, Nature Neuroscience, vol. 20, no. 11. Springer Science and Business Media LLC, pp. 1493–1503, Nov. 2017. doi: 10.1038/nn.4657.  C. Wang et al., ‘Egocentric coding of external items in the lateral entorhinal cortex’, Science, vol. 362, no. 6417. American Association for the Advancement of Science (AAAS), pp. 945–949, Nov. 2018. doi: 10.1126/science.aau4940.