Fig. 8: Possible circuitry underlying the relationship between pattern selectivity and choice probability.

a A two-stage model of component- and pattern-direction selectivity and the potential influence of top-down feedback on choice-related activity in MT. Here, pattern direction selectivity (PDS - “P”) at the MT stage arises through: (i) broad sampling over direction selective inputs consistent with a particular pattern velocity, and (ii) strong tuned suppression. MT stage component direction selective (CDS) cells (“C”) sample narrowly over input directions and lack strong tuned suppression.Untuned suppression confers gain control in both populations. Colored arrows represent units’ preferred direction. Only a subset of V1-MT connections and a single pattern- and component-direction selective unit are illustrated for clarity. In the case of a feedforward (FF) interpretation of our results, the broader input tuning and strong tuned suppression in PDS cells (highlighted in red) generates a larger difference in activity in response to patterns with multiple motions. This population drives upstream decision circuits and biases perception in our segmentation task. Conversely, in the feedback (FB) case, perceptual decisions are generated in upstream circuits by both sensory evidence and cognitive biases and a greater influence of top-down FB on PDS cells (thicker line) generates the choice signal. b Illustration of an alternative model of CDS and PDS units. Here, PDS signals in MT arise via not only direct V1 input but also via indirect inputs from a V1-V2-MT pathway. The model indirect pathway is configured to confer selectivity for texture boundaries (plaid overlap regions). MT stage CDS cells perform a weighted sum on direct and indirect inputs and send outputs to PDS units. PDS tuning arises via competitive inhibition. Again, only those connections necessary to sketch the basic model architecture are shown. Here, distinct FF mechanisms from those posited in a could be responsible for driving greater variability in PDS cell plaid responses, which would, again, drive biases in decision circuits. Alternatively, greater CP in PDS cells could still be the result of a bias in the strength or efficacy of FB connections to PDS cells. There is evidence supporting both two- and three-stage models of MT PDS and FF and FB explanations for CP.