www.astralcodexten.com/p/next-token-predictor-is-an-ais-job

The post describes “entorhinal cells” as being “in the hippocampus.” But the entorhinal cortex is a distinct cortical region in the medial temporal lobe that serves as a major interface/gateway to the hippocampus; it is not the hippocampus itself. In particular, the spatial-navigation neurons most associated with toroidal/manifold descriptions—**grid cells**—are classically described as being in the **medial entorhinal cortex (MEC)**, not in the hippocampus. Multiple neuroscience references describe grid cells as being found in the entorhinal cortex and explain that the entorhinal cortex relays information to the hippocampus. So while the entorhinal cortex is tightly connected with the hippocampus (and sometimes discussed within the broader “entorhinal–hippocampal system”), it is inaccurate to say entorhinal cells are *in the hippocampus*.