DOI: 10.5061/dryad.73n5tb309
title: Adult-born granule cells improve stimulus encoding and discrimination in the dentate gyrus

description: Heterogeneity plays an important role in diversifying neural responses to
 support brain function. Adult neurogenesis provides the dentate gyrus with
 a heterogeneous population of granule cells (GCs) that were born and
 developed their properties at different times. Immature GCs have distinct
 intrinsic and synaptic properties than mature GCs and are needed for
 correct encoding and discrimination in spatial tasks. How immature GCs
 enhance the encoding of information to support these functions is not well
 understood. Here, we record the responses to fluctuating current
 injections of GCs of different ages to study how they encode stimuli.
 Immature GCs produce unreliable responses compared to mature GCs,
 exhibiting imprecise spike timings across repeated stimulation. We use a
 statistical model to describe the stimulus-response transformation
 performed by GCs of different ages. We fit this model to the data and
 obtain parameters that capture GCs encoding properties. Parameter values
 from this fit reflect the maturational differences of the population and
 indicate that immature GCs perform a differential encoding of stimuli. To
 study how this age heterogeneity influences encoding by a population, we
 perform stimulus decoding using populations that contain GCs of different
 ages. We find that, despite their individual unreliability, immature GCs
 enhance the fidelity of the signal encoded by the population and improve
 the discrimination of similar time dependent stimuli. Thus, the observed
 heterogeneity confers the population with enhanced encoding capabilities.
description: <strong>Electrophysiological
 Recordings</strong> The
 dataset contains electrophysiological recordings from neurons of the mouse
 dentate gyrus. Recorded immature
 neurons were visually identified by fluorescence. GCs used between 28 and
 30 days post injection were labeled as 4w and GCs used between 34 and 36
 days post injection were labeled as 5w. The mature population encompassed
 unlabeled neurons localized in the outer third of the granule cell layer.
 Whole-cell current-clamp recordings were performed using microelectrodes
 (4–6 MΩ) filled with a potassium gluconate internal solution (in mM): 120
 potassium gluconate, 4 MgCl2, 10 HEPES buffer, 0.1 EGTA, 5NaCl, 20KCl,
 4ATP-tris, 0.3 GTP-tris, and 10 phosphocreatine (pH = 7.3; 290 mOsm).
 Excitatory and inhibitory synaptic transmission were blocked
 pharmacologically with kynurenic acid (Sigma-Aldrich Cat K3375) and
 picrotoxin (Sigma-Aldrich Cat P1675). Recordings were obtained using
 Multiclamp 700B amplifiers (Molecular Devices), digitized using Digidata
 1550 (Axon instruments), and acquired at 10 kHz onto a personal computer
 using the pClamp10 software (Molecular Devices). Before starting every
 protocol of stimulation, the resting membrane potential was kept at around
 -70 mV by passing a holding current. Passive properties were measured by
 injecting a small hyperpolarizing current step. Current step amplitude was
 adapted to each neuron and resulted in a negative membrane potential
 deviation of 1-4 mV.
description: <strong>File type and
 access</strong> Raw data
 files are in the Axon Binary File format (ABF) which allows the storage of
 binary experimental data. It is the format type used by the pCLAMP suite
 of data acquisition and analysis programs, but is also supported by
 AxoTape and AxoScope software. Any software that opens ABF files can be
 used to access the data, for example the open source Python package pyABF
 available at https://swharden.com/pyabf/.