Electrophysiological Activity from the Eye Muscles, Cerebellum and Cerebrum During Reflexive (Classical Pavlovian) Versus Voluntary (Ivanov-Smolensky) Eye-Blink Conditioning

Fig. 1. A Axial and coronal views of the experimental montage (grey electrodes) consisting of infra-ocular (IO1, IO2), central (C3’, C4’) and cerebellar (CB3, CB4) electrodes used to record EOG/EMG, EEG and ECeG, respectively. The infra-ocular montage consisted of active (A) and reference (R) electrodes positioned slightly lateral and beneath the eyes. EEG recordings from over frontal eye fields were made 2 cm anterior to the conventional C3 and C4 locations. ECeG recordings were made lateral (6 cm) to the midline CBz location, which is situated 5% below the Iz level. EEG and ECeG recordings were referenced to linked earlobes (A1, A2). B The recording epoch demonstrating the stimulus onsets (CS, US1, US2, an implied third stimulus US3) and segmentation used for analysis (refer to Table 1 for abbreviations). The single subject data shown is taken from the CB4 electrode. Note differing durations of the segments, shorter around the time of the expected response to the US

Fig. 2. The sequence for experiments 1 (reflexive) and 2 (voluntary) including the preceding baseline block (BLB) of eleven CS alone trials (CS (BL)). For both experiments, six learning blocks were carried out (LB1-6) with each consisting of eleven trials (T1–T9: CS+US trials, T10: CS alone (CS (LRN)) and T11: US alone). For experiment one, an extinction block (EB; grey box) was recorded after learning and consisted of eleven CS alone trials (CS (EXT)). For experiment two, two blocks were recorded after learning. A voluntary blink block (VB, black box) in which subjects were instructed to blink when the US would have occurred (CS (BLK)) and an equivalent extinction block to experiment one in which subjects were instructed to not blink (CS (BLK SUPPR))

Fig. 3. Grand unrectified means for the right-sided infra-ocular (A, B; IO2), central (C, D; C4’) and cerebellar electrodes (E, F; CB4) for each of the five trial types for experiment 1 (reflexive conditioning; left column) and experiment 2 (voluntary timed eye blinks; right column). For experiment 1, the infra-ocular electrodes show large EMG/EOG potentials (blink UR) which are diminished upon the second US stimulus in US alone and CS+US trial types. Central electrodes show auditory evoked potentials (AEP) in all CS onset trial types with vestibular evoked potentials (VsEPs) after the US taps. Cerebellar electrodes show a presumed climbing-fibre response (CFR) following both US onsets and subsequent pause-burst activity. For experiment 2, the infra-ocular electrodes demonstrated large timed blink responses which often peaked close to the US onsets whereas voluntary blinks during CS alone trials were infrequent and peaked later. For the central electrodes, auditory evoked potentials (AEP) were present in all CS onset trial types, similar to experiment 1. Pre-movement potentials (CNVs) were present in the CS+US and CS alone during learning trial types. Findings for the cerebellar…

Fig. 4. Marginal means using RMS averaging of sequential segments, for the effects of ‘segment’ and the interaction of ‘segment’ and ‘trial type’ cerebellar electrodes for experiment 1 (A, C; left column) and experiment 2 (B, D; right column). Overall, similar patterns were seen for both movement tasks. Note that the segment durations are not constant

Fig. 5. Scaleograms for the infra-ocular EMG/EOG (A, B; IO2), central EEG (E, F; C4’) and cerebellar ECeG (G, H; CB4) for experiment 1 (reflexive conditioning) and experiment 2 (voluntary conditioning) for the CS+US trial type. C3’-CB4 EEG-ECeG coherograms (C, D) are illustrated for comparison and were similar to the corresponding C4’-CB3 coherograms

Fig. 6. VHF power for the infra-ocular (A, B), central (E, F) and cerebellar electrodes (G, H) and CS+US trial types for experiment 1 (reflexive conditioning) and experiment 2 (voluntary conditioning). VHF power shown reflects the averages between the right and left sides for EMG/EOG, EEG and ECeG graphs. VHF EEG-ECeG coherence bands are also illustrated for comparison (C, D) and are the average coherence of C3’-CB4 and C4’-CB3 comparisons. The CFR peaks (6G-H) relate to the USs and not the CRs. v-CR-related pause-bursting is present in experiment 2 (6H). Red lines reflect the onset of the v-CRs, whereas green lines reflect the peak EMG/EOG CR