Below are the abstract, introduction, and conclusion of a computer science research paper. Please summarize the main contribution of the work in a single sentence. Your response should include the summary and no additional text.

Paper text:

Place and grid-cells are known to aid navigation in animals and humans.
Together with concept cells, they allow humans to form an internal representation of the external world, namely the concept space.
We investigate the presence of such a space in deep neural networks by plotting the activation profile of its hidden layer neurons.
Although place cell and concept-cell like properties are found, grid-cell like firing patterns are absent thereby indicating a lack of path integration or feature transformation functionality in trained networks.
Overall, we present a plausible inadequacy in current deep learning practices that restrict deep networks from performing analogical reasoning and memory retrieval tasks.
We investigated if simple deep networks possess grid cell-like artificial neurons while memory retrieval in the learned concept space.