Biology subjects

Kaefer, K.

Publications and source records attributed to Kaefer, K..

3 recordsLinked to original sources

bioRxiv2026

Representational Dynamics in the Hippocampus and Medial Prefrontal Cortex during Learning and Task Mastery

While the medial prefrontal cortex (mPFC) interacts with the hippocampus to support learning and consolidation, how its neural representations evolve remains unclear. We recorded population activity from CA1 and the mPFC as rats trained on radial maze tasks over weeks. Low-dimensional mPFC manifolds generated using UMAP or PCA embeddings initially tracked session progression, showing within-session drift. As animals gained task familiarity, this temporal tracking weakened; mPFC manifolds differentiated specific arms, mirroring hippocampal representations. Arm discriminability was selectively enhanced at locations requiring spatial choices, but weakened when such demands were absent. These findings demonstrate that systems consolidation does not uniformly promote cortical generalization. Instead, the mPFC may slowly refine representations in response to specific task demands to support tailored task schemas.

neuroscience↗

bioRxiv2022

Entorhinal layer 6b subplate neurons govern spatial learning and memory

The mammalian hippocampal formation (HF) plays a key role in several higher brain functions, such as spatial coding, learning and memory. Its simple circuit architecture is often viewed as a "trisynaptic loop", processing input originating from the superficial layers of the entorhinal cortex (EC) in a linear fashion, and sending it back to its deeper layers. Here, we show that contrary to this canonical view, excitatory neurons in the deepest layer of the mouse EC, exhibiting the unique morphology and molecular profile of layer 6b cortical subplate neurons (SPNs), project to all sub-regions comprising the HF, with a preference towards CA3 pyramidal neurons, and receive input from the CA1, thalamus and claustrum. Furthermore, their output is characterized by unique slow-decaying excitatory post-synaptic currents (EPSCs), capable of driving plateau-like potentials in their target cells. Optogenetic inhibition of the EC-6b pathway markedly affects spatial coding in CA1 pyramidal neurons, while cell ablation impairs not only acquisition of new spatial memories, but also degradation of previously acquired ones. Our results provide the first evidence of a functional role for the cortical layer 6b neurons in the adult brain and elucidate a critical novel element determining cortico-hippocampal activity patterns.

neuroscience↗

bioRxiv2021

The generalized spatial representation in the prefrontal cortex is inherited from the hippocampus

Hippocampal and neocortical neural activity is modulated by the position of the individual in space. While hippocampal neurons provide the basis for a spatial map, prefrontal cortical neurons generalize over environmental features. Whether these generalized representations result from a bidirectional interaction with, or are mainly derived from hippocampal spatial representations is not known. By examining simultaneously recorded hippocampal and medial prefrontal neurons, we observed that prefrontal spatial representations show a delayed coherence with hippocampal ones. We also identified subpopulations of cells in the hippocampus and medial prefrontal cortex that formed functional cross-area couplings; these resembled the optimal connections predicted by a probabilistic model of spatial information transfer and generalization. Moreover, cross-area couplings were strongest and had the shortest delay preceding spatial decision-making. Our results suggest that generalized spatial coding in the medial prefrontal cortex is inherited from spatial representations in the hippocampus, and that the routing of information can change dynamically with behavioral demands.

neuroscience↗