Standard Oddball Stimulus with Jittered Intervals

Overview

The Standard Oddball Stimulus with Jittered Intervals is an enhanced version of the standard oddball paradigm that introduces predetermined but variable inter-stimulus intervals.

Stimulus Structure

Duration Mismatch Analysis

The figure above shows a comprehensive analysis of the jittered intervals protocol:

  1. Block Structure Timeline: Displays the temporal organization including:
  2. Jitter Oddball Blocks: Periods with variable inter-stimulus intervals
  3. Jitter Control Blocks: Control periods for comparison

  4. RF Mapping Blocks: Spatial tuning phases

  5. Grating Orientations Over Time: Shows the sequence of stimulus orientations with temporal jitter

  6. Oddball Events Distribution: Highlights when timing violations occur, demonstrating the jittered presentation schedule

This analysis reveals how temporal unpredictability is introduced while maintaining the core oddball paradigm structure.

Script Location

The stimulus script is located at: - /code/stimulus-control/src/Standard_oddball_slap2_jitter_random.bonsai

Hardware Requirements

  • SLAP2 imaging system
  • Behavior device with encoder/wheel for tracking animal movement
  • Digital outputs (DO2) for synchronization with recording equipment

Stimulus Parameters

Basic Parameters

  • Display Type: Drifting gratings
  • Spatial Frequency: 0.04 cycles per degree
  • Temporal Frequency: 2 Hz (standard)
  • Contrast: 1.0 (full contrast)
  • Size: 360° (full-field gratings)
  • Stimulus Duration: 343 ms (fixed)
  • Inter-stimulus Intervals: Four predefined values (0.343s, 1s, 1.5s, 2s)

Configurable Parameters

The script contains several externalized parameters that can be adjusted: - NbBaselineGrating: Number of standard gratings (default: 20) - NbMismatchPerCondition: Number of repetitions for each deviant condition (default: 1) - NbReceptiveFieldRepeats: Number of repetitions for receptive field mapping (default: 1)

Experimental Design

1. Orientation Tuning Component with Jittered Intervals

This experiment includes presentation of 16 different orientations (0°, 22.5°, 45°, etc.) with a systematic jitter implementation:

  • Each orientation is paired with each of the four possible inter-stimulus intervals (0.343s, 1s, 1.5s, 2s)
  • This creates 64 unique orientation-delay pairs (16 orientations × 4 delays)
  • The entire set of these pairs is randomized using a permutation algorithm
  • This ensures each orientation is shown at each possible delay, but the sequence is unpredictable

The jitter is not randomly chosen at runtime; instead, each orientation appears four times in the randomized sequence, each time with a different predefined delay.

2. Standard-Oddball Paradigm

The core of the experiment consists of:

  • Standard Stimulus: 0° orientation grating with 2 Hz temporal frequency (repeated ~20 times)
  • Deviant Stimuli:
    • Orientation deviants: 45° and 90° oriented gratings
    • Temporal frequency deviant: 0 Hz (stationary grating at 0° orientation)
    • Contrast deviant: 0 contrast (blank screen) with 2 Hz temporal frequency

The jittered intervals break the rhythmic presentation pattern found in the standard oddball paradigm, which helps isolate responses to stimulus features from responses to stimulus timing.

3. Receptive Field Mapping

The experiment includes a mapping component with smaller gratings (20° diameter) presented at locations defined in receptive_field.csv. These specialized mapping gratings have: - Higher spatial frequency (0.08 cpd) - Higher temporal frequency (4 Hz) - Higher contrast (0.8) - Shorter duration (250 ms) - No inter-stimulus interval (0 ms delay)

Data Collection

The script logs all stimulus parameters and timing information to CSV files: - orientations_logger.csv: Contains timing of stimulus events - vstimLog.csv: Records the detailed parameters of each stimulus presentation, including the specific delay used for each stimulus

Animal running data is collected via an encoder on Port 2 of the behavior device.

Synchronization

  • TTL pulses (100ms) are generated at stimulus onset via DO2 output
  • SLAP2 recording is automatically started and stopped during the experiment

Running the Experiment

  1. Start the Bonsai workflow
  2. Press the spacebar to begin the experiment
  3. The experiment can be terminated with the End key

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