<jats:title>The Space in Your Head</jats:title>          <jats:p>            Space,
  and events associated with places and spaces, are represented in the brain by a
  circuitry made of place cells, head direction cells, grid cells, and border cells.
  These cell types form a collective dynamic representation of our position as we
  move through the environment. How this representation is formed has remained a mystery.
  Is it acquired, or are we born with the ability to represent external space (see
  the Perspective by            <jats:bold>              <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink"
  ext-link-type="doi" issue="5985" page="1487" related-article-type="in-this-issue"
  vol="328" xlink:href="10.1126/science.1191527">                <jats:bold>Palmer
  and Lynch</jats:bold>              </jats:related-article>            </jats:bold>            )?            <jats:bold>              Langston              <jats:italic>et
  al.</jats:italic>            </jats:bold>            (p.            <jats:related-article
  xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1576" related-article-type="in-this-issue"
  vol="328" xlink:href="10.1126/science.1188210">1576</jats:related-article>            )
  and            <jats:bold>              Wills              <jats:italic>et al.</jats:italic>            </jats:bold>            (p.            <jats:related-article
  xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1573" related-article-type="in-this-issue"
  vol="328" xlink:href="10.1126/science.1188224">1573</jats:related-article>            )
  investigated the early development of spatial activity in the hippocampal formation
  and the entorhinal cortex of rat pups when they first began to explore their environment.
  Rudiments of place cells, head direction cells, and grid cells already existed when
  the pups made their first movements out of the nest. A neural representation of
  external space at this early time points to strong innate components for perception
  of space. These findings provide experimental support for Kant's 200-year-old concept
  of space as an a priori faculty of the mind.          </jats:p>
