Human large-scale oscillatory brain activity during an operant shaping procedure

Abstract

The present study aimed at examining the oscillatory brain-electric correlates of human operant learning using high-density electroencephalography (EEG). Induced gamma-band activity (GBA) was studied using a fixed-interval reinforcement schedule with a variable limited hold period, which was decreased depending on response accuracy. Thus, participants' behavior was shaped during the course of the learning session. After each response, numbers indicating the money value of that response served as reinforcing stimuli. Random reinforcement and self-paced button pressing without reinforcement were added as control conditions. GBA around 40 Hz was enhanced at posterior electrodes in response to visual feedback stimuli during shaping and random reward compared to the self-paced pressing condition where no visual feedback was provided. Furthermore, shaping was associated with a pronounced left frontal lower gamma (20-30 Hz) increase in response to feedback stimuli, whereas this pattern was not observed in the random reinforcement and self-paced pressing conditions. The present findings are in line with the notion that macroscopic high-frequency dynamics of neuronal cell assemblies may be regarded as a mechanism involved in learning and memory formation. Theme: Neural basis of behaviorTopic: Learning and memory: systems and functions

Neuronal Mechanisms of Repetition Priming in Occipitotemporal Cortex: Spatiotemporal Evidence from Functional Magnetic Resonance Imaging and Electroencephalography

“…Analogous effects were observed in induced GBRs and phase locking among electrode sites. fMRI (R. and previous gamma-band findings during perceptual memory formation (Miltner et al, 1999;Keil et al, 2001b) suggest that these repetition-related increases might reflect encoding-related processes (i.e., the formation of new cell assemblies representing previously unfamiliar stimuli). This argument gains support from a previous repetition priming study using familiar and unfamiliar pictorial material, which showed a similar pattern of results (Gruber and Müller, 2005).…”

Direct Instrumental Conditioning of Neural Activity Using Functional Magnetic Resonance Imaging-Derived Reward Feedback

“…Our goal in this study was to show that by using a reward schedule based on behavioral shaping we could train subjects to increase the level of their neural responses in a specific brain region over time. Shaping schedules constantly adjust the threshold required to earn reward, based on subjects' previous performance, thus ensuring that subjects are in a state of constant learning (Keil et al, 2001). Our procedure succeeded not only in increasing activity over time but also in selectively increasing and decreasing activities in the specific ROIs, whereas activities in other regions recruited by this task remained stable.…”

Autism and Abnormal Development of Brain Connectivity: Figure 1.

“…Brock et al (2002) proposed that underconnectivity between separate functional brain regions in autism might be reflected in a lack of EEG synchrony in the gamma band (30 -80 Hz). In normal subjects, gamma activity is modulated by a variety of integrative processes, including feature binding (TallonBaudry et al, 1998), top-down feature selection (Hermann and Mecklinger, 2001), attention (Müller et al, 2000), face processing (Keil et al, 1999;Rodriguez et al, 1999), emotional arousal (Keil et al, 2001), and memory rehearsal (Tallon-Baudry et al, 1998. We are in the process of testing Brock's hypothesis using a delayed match-to-sample task, and preliminary data suggest abnormality of gamma activity over frontal cortex and visual processing areas during both stimulus encoding and memory rehearsal.…”