High Quality but Limited Quantity Perceptual Evidence Produces Neural Accumulation in Frontal and Parietal Cortex

Abstract

Goal-directed perceptual decisions involve the analysis of sensory inputs, the extraction and accumulation of evidence, and the commitment to a choice. Previous neuroimaging studies of perceptual decision making have identified activity related to accumulation in parietal, inferior temporal, and frontal regions. However, such effects may be related to factors other than the integration of evidence over time, such as changes in the quantity of stimulus input and in attentional demands leading up to a decision. The current study tested an accumulation account using 2 manipulations. First, to test whether patterns of accumulation can be explained by changes in the quantity of sensory information, objects were revealed with a high quality but consistent quantity of evidence throughout the trial. Imaging analysis revealed patterns of accumulation in frontal and parietal regions but not in inferior temporal regions. This result supports a framework in which evidence is processed in sensory cortex and integrated over time in higher order cortical areas. Second, to test whether accumulation signals are driven by attentional demands, task difficulty was increased on some trials. This manipulation did not affect the nature of accumulating functional magnetic resonance imaging signals, indicating that accumulating signals are not necessarily driven by changes in attentional demand.

Functional Heterogeneity in Posterior Parietal Cortex Across Attention and Episodic Memory Retrieval

“…Guerin andMiller 2011). This interpretation is supported by prior research suggesting that IPS activity during perceptual decisions in humans (Ploran et al 2007;Heekeren et al 2008;Tosoni et al 2008;Kayser et al 2010;Ploran et al 2011, cf. Ho et al 2009Guerin and Miller 2011) and lateral intraparietal activity in nonhuman primates Newsome 1996, 2001;Schall 2003;Kiani et al 2008;Kiani and Shadlen 2009) is associated with the accumulation of evidence to guide perceptual decision making.…”

Predicting Perceptual Decision Biases from Early Brain Activity

“…When discriminability is very low, medial parietal regions, as well as medial prefrontal regions, may become informative about decision outcomes, because the recent choice history might prime the decision system and magnify choice-related preexisting activity. Consistent with this hypothesis, areas in prefrontal cortex and posterior parietal cortex (Heekeren et al, 2004;Philiastides et al, 2011;Ploran et al, 2011), predominantly in monkey parietal area LIP, have been linked theoretically to diffusive information accumulation (Shadlen and Newsome, 2001;Mazurek et al, 2003;Gold and Shadlen, 2007), decision confidence (Kiani and Shadlen, 2009), as well as to the representation of generic categorical associations (Fitzgerald et al, 2011). Our EEGdecoding approach lacks the spatial resolution to identify the sources of information encoding precisely.…”

The neural representation of sensorimotor transformations in a human perceptual decision making network

“…In humans, a number of studies have identified a frontoparietal network involved in processes during perceptual decisions, including sensory processing, attentional control, evidence accumulation, and motor planning (Heekeren et al, 2008; Kayser et al., 2010a,b;Liu and Pleskac, 2011;Ploran et al, 2007Ploran et al, , 2011Rowe et al, 2010;Ho et al, 2009;Tosoni et al, 2008). Previously we demonstrated that for subjects performing a dot motion discrimination task, this network displays a blood oxygen level-dependent (BOLD) response that varies inversely with motion coherence (Kayser et al, 2010a).…”