Significant differences between standard and deviant deflections with respect to deviant probability.

*<p>p-values are FDR corrected for multiple comparisons.</p

MMN-like activity displayed as difference waveforms for two deviant probabilities.

<p>Difference calculated as deviant minus standard potential displayed for four electrodes. Potentials were elicited using an oddball paradigm with deviant probability 0.1 (black curve) and 0.2 (grey curve). Black bar on the x-axis shows the stimulus duration. Below each graph FDR-corrected p-values are shown.</p

Oddball deviant compared to the equiprobable control condition.

<p>Oddball deviant (red curve), control “deviant” (black curve) and oddball standard (blue curve) potentials were elicited with either 0.1 deviant probability (diagrams on the left side) or 0.2 deviant probability (diagrams on the right side). Data is derived from 6 rats. The posterior electrodes on the left and right hemisphere as well as anterior electrodes on the left and right hemisphere were pooled for displaying the results and statistical calculation. Black bar on the x-axis shows stimulus duration. Below each graph FDR-corrected p-values are shown. The black curve displays the differences between oddball deviants and control deviants whereas the blue curve displays significant differences between oddball standard and control deviant.</p

Significant differences between the deviant in the control condition and the deviant in the oddball condition and differences between control deviant and the standards in the oddball condition.

*<p>p-values are FDR corrected for multiple comparisons.</p

This figure represents behavioral results in terms of reaction times for depleting dopamine in three regions: the superior colliculus encoding sensory salience (as in previous figure), the motor cortex encoding proprioception (middle column) and the premotor cortex encoding affordance (right column).

<p>These results are shown using the same format as in previous figure and illustrate the qualitatively different effects of dopamine depletion in different parts of the brain (or model). The lower panels indicate the implicit projections, from the substantia nigra or ventral tegmental area, have been selectively depleted (where a red cross highlights the forward prediction errors affected). The key thing to take from these simulations is that reducing the precision of prediction errors on sensory salience induces bradykinesia and perseveration; whereas the equivalent reduction in proprioceptive affordance causes bradykinesia without perseveration. Finally, compromising the precision of changes in affordance increases perseveration and decreases bradykinesia.</p

This figure provides a schematic overview of the message passing scheme implied by <b>Equation 3</b>.

<p>In this scheme, neurons are divided into prediction (black) and prediction error (red) units that pass messages to each other, within and between hierarchical levels. Superficial pyramidal cells (red) send forward prediction errors to deep pyramidal cells (black), which reciprocate with predictions that are conveyed by (polysynaptic) backward extrinsic connections. This process continues until the amplitude of prediction error has been minimized and the predictions are optimized in a Bayesian sense. The prediction errors are the (precision weighted) difference between conditional expectations encoded at any level and top down or lateral predictions. Note that there are prediction errors at every level of the hierarchy, for both hidden states and hidden causes (and sensory states and the lowest level). The synaptic infrastructure proposed to mediate this comparison and subsequent modulation is shown in the lower panel, in terms of a doubly-innervated synapse <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002327#pcbi.1002327-Kubota1" target="_blank">[84]</a> that is gated by dopamine (cyan). Here, dopamine is delivered by <i>en passant</i> synaptic boutons and postsynaptic D1 receptors have been located on a dendritic spine expressing asymmetric (excitatory) and symmetric (inhibitory) synaptic connections. This represents the synaptic arrangements indicated by the cyan arrows in the upper panel.</p

This figure presents the behavioral results from the simulations under different levels of dopamine.

<p>The upper panel shows the reaction times for each trial or cue as a function of cue order (over 10 cues). The reaction time was measured as the time from cue onset to the time that the pointing location fell within a small distance of the target location. The equivalent results for accuracy are shown in the lower panel in terms of the (inverse) average distance from the pointing location to the target location for each trial. The colored lines correspond to different levels of simulated dopamine; with red lines indicating the lowest level and yellow lines the highest. The key things to note here are: (i) the reaction time costs of unpredictable (first five), relative to predictable trials (first five), shown by the yellow line and (ii) the increase in amplitude and duration of switching costs as dopamine is depleted (colored lines); modeled here in terms of the precision of prediction errors on visual salience.</p