Protocol for implementing medial forebrain bundle stimulation as a reward for perceptual tasks in mice

Abstract

Training mice to perform perceptual tasks is a vital part of integrative neuroscience. Replacing classical rewards like water with medial forebrain bundle (MFB) stimulation allows experimenters to avoid deprivation and obtain higher trial numbers per session. Here, we provide a protocol for implementing MFB-based reward in mice. We describe steps for MFB electrode implantation, efficacy testing, and stimulation calibration. After these steps, MFB reward can be used to facilitate sensory discrimination task training and enable nuanced characterization of psychophysical abilities. For complete details on the use and execution of this protocol, please refer to Verdier et al. (2022).¹.

Keywords: Behavior; Model Organisms; Neuroscience.

Graphical abstract

Figure 1

Experimental setup for head-fixed behavior (A) Circuit diagram for licking detection. (B) Main components of the setup for performing head-fixed training with lick as report behavior.

Figure 2

Step by step guide to MFB implantation (A–S) Key steps of the MFB implantation surgery as referenced in the main text.

Figure 4

Experimental setup for cotton assay and head-fixed behavior (A) Interaction time with the cotton swab strongly increased in all mice, except those with non-functional MFB stimulation. (Wilcoxon signed rank test, pval = 4.3E-4, zval: -3.51, n = 16; error bars are quartiles). (B) Licking rates during the initial free-lick phase for mice with functional (blue, n = 8) and non-functional (red, n = 2) MFB stimulation. (error bars are +/- sem) (C) Example calibration curves for four mice with sigmoid fit are shown in red. The arrow indicates the voltage used for learning (Rsquared goodness of fit for a sigmoid function).

Figure 3

Experimental setup for cotton assay (A) Schematic of the cotton assay. Interaction time with a cotton pellet is measured for 5 min without and then with 3V MFB stimulation every time the mouse was in contact with the cotton swab. (B) Setup for performing cotton assay.