Enhancement of Motor Cortical Gamma Oscillations and Sniffing Activity by Medial Forebrain Bundle Stimulation Precedes Locomotion

Abstract

The medial forebrain bundle (MFB) is a white matter pathway that traverses through mesolimbic structures and includes dopaminergic neural fibers ascending from the ventral tegmental area (VTA). Since dopaminergic signals represent hedonic responses, electrical stimulation of the MFB in animals has been used as a neural reward for operant and spatial tasks. MFB stimulation strongly motivates animals to rapidly learn to perform a variety of behavioral tasks to obtain a reward. Although the MFB is known to connect various brain regions and MFB stimulation dynamically modulates animal behavior, how central and peripheral functions are affected by MFB stimulation per se is poorly understood. To address this question, we simultaneously recorded electrocorticograms (ECoGs) in the primary motor cortex (M1), primary somatosensory cortex (S1), and olfactory bulb (OB) of behaving rats while electrically stimulating the MFB. We found that MFB stimulation increased the locomotor activity of rats. Spectral analysis confirmed that immediately after MFB stimulation, sniffing activity was facilitated and the power of gamma oscillations in the M1 was increased. After sniffing activity and motor cortical gamma oscillations were facilitated, animals started to move. These results provide insight into the importance of sniffing activity and cortical gamma oscillations for motor execution and learning facilitated by MFB stimulation.

Non-invasive stimulation of the human striatum disrupts reinforcement learning of motor skills

“…Such disruption was frequency-and reinforcement-specific: learning was not altered with striatal tTIS20Hz in the presence of reinforcement, or when striatal tTIS80Hz was delivered in the absence of reinforcement. The rationale to stimulate at high gamma frequency was based on previous work showing reinforcement-related modulation of gamma oscillations in the striatum [19][20][21]24,26,74,79 and in the frontal cortex [79][80][81][82] . Several neuronal mechanisms may contribute to the detrimental effect of tTIS80Hz on reinforcement motor learning.…”

Physiological paradigm for assessing reward prediction and extinction using cortical direct current potential responses in rats

“…Because we recorded DC potentials from the cortex contralateral to MFB stimulation due to technical interference issues related to electrode placement, we have to carefully consider potential neurotransmission delays, complexity, and laterality. Unilateral MFB stimulation has been used as a method to induce reward in animals, and EEG recordings from the contralateral side of the stimulating electrode have been used in previous studies 45 . Additionally, the issue of latent inhibition of AEPs due to the random repetition of two tones should be noted.…”

“…The parameters utilized for the a priori power analysis for ANOVA with G*Power included an effect size of 0.3333 (partial η 2 of 0.1), α error probability of 0.05, power (1 − α error probability) of 0.8, correlation among repeated measures of 0.5, and nonsphericity correction ε of 1. The minimum necessary sample size for the present experiment was estimated based on previous research 25 , 45 . To strengthen the interpretability of our research results, Bayesian repeated measures ANOVAs were conducted using JASP (version 0.18.3, https://jasp-stats.org/ ).…”

Chronic morphine exposure and maternal separation induce impairments in cognition and locomotor activity of male adolescent rats

“…It has been proven that stimulation of the rat medial forebrain bundle facilitates sniffing, increases gamma waves only in the primary motor cortex (M1), and thereafter stimulates locomotion, motor execution, and learning (Yoshimoto et al, 2022). This locomotor activity and the spatial associative process might be mediated by dopamine D1 receptors (Tran et al, 2005).…”