Synaptic basis of feature selectivity in hippocampal neurons
Abstract
A central question in neuroscience is how synaptic plasticity shapes the feature selectivity of neurons in behaving animals. Hippocampal CA1 pyramidal neurons display one of the most striking forms of feature selectivity by forming spatially and contextually selective receptive fields called place fields, which serve as a model for studying the synaptic basis of learning and memory. Various forms of synaptic plasticity have been proposed as cellular substrates for the emergence of place fields. However, despite decades of work, our understanding of how synaptic plasticity underlies place field formation and memory encoding remains limited, largely due to a shortage of tools and technical challenges associated with the visualization of synaptic plasticity at single-neuron resolution in awake-behaving animals. To address this, we developed an all-optical approach to monitor the spatiotemporal tuning and synaptic weight changes of dendritic spines, before and after the induction of a place field in single CA1 pyramidal neurons during spatial navigation. We identified a temporally asymmetric synaptic plasticity kernel resulting from bidirectional modifications of synaptic weights around the induction of a place field. Surprisingly, our work uncovered compartment-specific differences in the magnitude and temporal expression of synaptic plasticity between basal and oblique dendrites. Our results provide the first experimental evidence linking synaptic plasticity to the rapid emergence of spatial selectivity in hippocampal neurons, a critical prerequisite for episodic memory.
README: Synaptic basis of feature selectivity in hippocampal neurons
https://doi.org/10.5061/dryad.66t1g1k9r
Description of the data and file structure
Processed spine data for both experimental (with opsin) and control (without opsin) groups.
Description of column headers:
- region: Dendritic compartment recorded (o, oblique; b, basal)
- scan_roi: Unique identifier of branch (o3, oblique branch #3)
- group_label: Name of structure imaged (spine)
- roi_label: Identity of each spine on imaged branch (s1, spine#1; s2, spine#2)
- field_count: Unique identifier of glutamate place field number at each spine
- field_start and field_stop: Start and stop location of glutamate place field (normalized 0-100)
- time_difference: Amount of time elapsed between arrival of glutamate input and onset of place field stimulation (seconds)
- initial_w: Initial spine weight (a.u.)
- reward_location: Location of water rewards in the environment (normalized 0-100)
- final_w: Final spine weight (a.u.)
- delta_w: Change in spine weight (final-initial) (a.u.)
- field_center: Center of glutamate place field (normalized 0-100)
- zscore_initial_w: Z-scored initial spine weight
- log2fc: Change in spine weight on a Log2 scale
- modulation_index: Ratio of change in spine weight
- experiment: Unique identifier of mouse and experiment number
- percent_pf_strength: Change in somatic jRGECO1a calcium tuning curves inside induction zone before and after place field induction (%)
- log2_pf_strength: Change in somatic jRGECO1a calcium tuning curves inside induction zone before and after place field induction on a Log2 scale
- reward1_loc and reward2_loc: Location of water rewards (normalized 0-1)
- led_center_loc: Center location of LED stimulation (normalized 0-1)
- led_onset_loc: Start location of LED stimulation (normalized 0-1)
- dist_rwd1_led_onset and dist_rwd2_led_onset: Distance between rewards and LED onset (normalized 0-1)
- post_somatic_avgtc_peak_loc = Peak of somatic jRGECO1a calcium tuning curve after place field induction (normalized 0-1)
- dist_led_onset_postsomapeak = Distance between LED onset and the peak of the somatic jRGECO1a calcium tuning curve after place field induction (normalized 0-1)
- led_onset_rwd_shortest_distance = Shortest distance between LED onset and reward location
- abs_deltaw = Absolute value of change in synaptic weights
Code/Software
Python 2.7 and Python 3.7 are required to run all analysis codes.