Conscious perception and the modulatory role of dopamine: no effect of the dopamine D2 agonist cabergoline on visual masking, the attentional blink, and probabilistic discrimination

Abstract

Rationale. Conscious perception is thought to depend on global amplification of sensory input. In recent years, striatal dopamine has been proposed to be involved in gating information and conscious access, due to its modulatory influence on thalamocortical connectivity.Objectives. Since much of the evidence that implicates striatal dopamine is correlational, we conducted a double-blind crossover pharmacological study in which we administered cabergoline -a dopamine D2 agonist -and placebo to 30 healthy participants. Under both conditions, we subjected participants to several well-established experimental consciousperception paradigms, such as backward masking and the attentional blink task.Results. We found no evidence in support of an effect of cabergoline on conscious perception: key behavioral and event-related potential (ERP) findings associated with each of these tasks were unaffected by cabergoline. Conclusions.Our results cast doubt on a causal role for dopamine in visual perception. It remains an open possibility that dopamine has causal effects in other tasks, perhaps where perceptual uncertainty is more prominent.

Conscious perception and the role of the basal ganglia: preliminary findings from a deep brain stimulation study

“…As shown in Fig. 7, we replicated previous reports showing that the target-evoked P3 ERP components are affected by the duration of target-mask SOA despite our small sample size (Boonstra et al, 2020; Del Cul et al, 2007). Specifically, the target-evoked P3 was virtually absent for the 16-ms SOA, in which targets were typically not seen, but present in all other SOA trials.…”

“…Specifically, the target-evoked P3 was virtually absent for the 16-ms SOA, in which targets were typically not seen, but present in all other SOA trials. While the amplitude of the P3 did not further scale with longer target-mask SOAs, as in our previous study (Boonstra et al, 2020), P3 latency seemed to scale with SOA. This could potentially be explained by a more pronounced preceding N2 in longer SOA trials (see Fig.…”

“…It is notable in this respect that fMRI studies consistently show differences in BOLD activity in the striatum between consciously perceived and unconscious stimuli using backward masking tasks (Bisenius et al 2015). Another repeated finding is a relationship between striatal D2 receptor binding and performance on conscious perception tasks (Bisenius et al, 2015; Slagter et al, 2010, 2012; Van Opstal et al, 2014; but see Boonstra et al, 2020). Most of these studies employ neuroimaging, and thereby lack temporal precision and/or a direct measure of BG activity.…”

Conscious self-monitoring: from molecule to culture

“…D1 receptors occur abundantly in medial prefrontal and limbic structures (Hall et al, 1994), which are key components of the paralimbic network causal in generation of conscious experience as described above. In contrast, Boonstra et al (Boonstra et al, 2020) used cabergoline, which is another dopamine agonist acting principally on on D2 receptors in basal ganglia. As would be expected, stimulation with cabergoline failed to elicit responses reflecting conscious experiences like visual masking and probalistic discrimination.…”