Awareness is essential for differential delay eyeblink conditioning with soft-tone but not loud-tone conditioned stimuli

The role of awareness in differential delay eyeblink conditioning （DEC） remains controversial. Here, we investigated the involvement of awareness in differential DEC with a soft or a loud tone as the conditioned stimulus （CS）. In the experiment, 36 participants were trained in differential DEC with a soft tone （60 dB） or a loud tone （85 dB） as the CS, paired with a corneal air-puff as the unconditioned stimulus （US）. After conditioning, awareness of the relationship between assessed with a 17-item the CS and the US was true/false questionnaire. Interestingly, during differential DEC with a soft-tone CS, a higher proportion of differential conditioned responses （CRs） was evident in participants who were aware than those who were unaware. In contrast, when a loud tone was used as the CS, the proportion of differential CRs of the aware participants did not differ significantly from those who were unaware over any of the blocks of 20 trials. In unaware participants, the percentage of differential CRs with a loud-tone CS was significantly higher than that with a soft-tone CS; however in participants classified as aware, the percentage of differential CRs with a loud-tone CS did not differ significantly from that with a soft-tone CS. The present findings suggest that awareness is critical for differential DEC when the delay task is rendered more difficult.

Establishment of Visual Fear Conditioning in Long-evans Rats

The neural mechanisms underlying visual information transmission and coding are currently attracting the attention of neuroscience and brain-like computing scholars.The subcortical visual pathway is known to affect fear emotion regulation via the amygdala;however an experimental paradigm for visual fear cognition training remains undefined.In this study,Long-Evans(LE)rats were used to develop an experimental training paradigm for visual cognition-associated fear conditioning based on the Pavlovian conditioning reflex.Simple images were shown on a unilateral screen(conditioned stimulus)were combined with electric foot shocks(unconditioned stimulus).We designed training paradigms and set up an estimated index using the rate of successful active escape.The training results were analyzed using a two-way ANOVA,and curve fitting was used to analyze the influence of decision time between the conditioned stimulus(CS)and unconditioned stimulus(US)on choice behavior.While neither the CS nor US had a significant effect on visual fear association training in LE rats,the decision time duration(CS-US)did have an impact on training.The method described here is most effective in establishing visual fear associations in rats when the(CS-UC)=10 s.This study describes a new experimental training paradigm for fear conditioning using visual stimuli and a quantitative evaluation standard according to the training mode of visual stimulation graphics.Moreover,it is an efficient paradigm for future study on visual information-processing mechanisms in the subcortical visual pathway during fear conditioning.