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As we gather noisy sensory information from the environment, prior knowledge about the likely cause(s) of sensory input can be leveraged to facilitate perceptual judgments. Here, we investigated the computational and neural manifestation of cued expectations in human subjects as they performed a probabilistic face/house discrimination task in which face and house stimuli were preceded by informative or neutral cues. Drift-diffusion modeling of behavioral data showed that cued expectations biased both the baseline (pre-sensory) and drift-rate (post-sensory) of evidence accumulation. By employing a catch-trial functional MRI design we were able to isolate neural signatures of expectation during pre- and post-sensory stages of decision processing in face- and house-selective areas of inferior temporal cortex (ITC). Cue-evoked timecourses were modulated by cues in a manner consistent with a pre-sensory prediction signal that scaled with probability. Sensory-evoked timecourses resembled a prediction-error signal, greater in magnitude for surprising than expected stimuli. Individual differences in baseline and drift-rate biases showed a clear mapping onto pre- and post-sensory fMRI activity in ITC. These findings highlight the specificity of perceptual expectations and provide new insight into the convergence of top-down and bottom-up signals in ITC and their distinct interactions prior to and during sensory processing.

In humans, the anterior insula (aI) has been the topic of considerable research and ascribed a vast number of functional properties by way of neuroimaging and lesion studies. Here, we argue that the aI, at least in part, plays a role in domain-general attentional control and highlight studies (Dosenbach et al. 2006 ; Dosenbach et al. 2007 ) supporting this view. Additionally, we discuss a study (Ploran et al. 2007 ) that implicates aI in processes related to the capture of focal attention. Task-level control and focal attention may or may not reflect information processing supported by a single functional area (within the aI). Therefore, we apply a novel technique (Cohen et al. 2008 ) that utilizes resting state functional connectivity MRI (rs-fcMRI) to determine whether separable regions exist within the aI. rs-fcMRI mapping suggests that the ventral portion of the aI is distinguishable from more dorsal/anterior regions, which are themselves distinct from more posterior parts of the aI. When these regions are applied to functional MRI (fMRI) data, the ventral and dorsal/anterior regions support processes potentially related to both task-level control and focal attention, whereas the more posterior aI regions did not. These findings suggest that there exists some functional heterogeneity within aI that may subserve related but distinct types of higher-order cognitive processing.

Neural correlates of remembering were examined using event-related functional MRI (fMRI) in 20 young adults. A recognition paradigm based on the remember/know (RK) procedure was used to separately classify studied items that were correctly identified and accompanied by a conscious recollection of details about the study episode from studied items that were correctly identified in the absence of conscious recollection. To facilitate exploration of the basis of remember decisions, studied items were paired with pictures and sounds to encourage retrieval of specific content during scanned testing. Analyses using a priori regions of interest indicated that remembering recruited both regions that associate with the perception and/or decision that information is old and regions that associate preferentially with visual content, while knowing recruited regions associated with oldness, but did not recruit visual content regions. Exploratory analyses further indicated a functional dissociation across regions of parietal cortex that may aid to reconcile several divergent results in the literature. Lateral parietal regions responded preferentially to remember decisions, while a slightly medial region responded robustly to both remember and know decisions. Taken collectively, these results suggest that remembering and knowing associate with common processes supporting a perception and/or the decision that information is old. Remembering additionally recruits regions specific to retrieved content, which may participate to convey the vividness typical of recollective experience.

A fundamental question in human memory is how the brain represents sensory-specific information during the process of retrieval. One hypothesis is that regions of sensory cortex are reactivated during retrieval of sensory-specific information (1-3). Here we report findings from a study in which subjects learned a set of picture and sound items and were then given a recall test during which they vividly remembered the items while imaged by using event-related functional MRI. Regions of visual and auditory cortex were activated differentially during retrieval of pictures and sounds, respectively. Furthermore, the regions activated during the recall test comprised a subset of those activated during a separate perception task in which subjects actually viewed pictures and heard sounds. Regions activated during the recall test were found to be represented more in late than in early visual and auditory cortex. Therefore, results indicate that retrieval of vivid visual and auditory information can be associated with a reactivation of some of the same sensory regions that were activated during perception of those items.

During a perceptual decision, neuronal activity can change as a function of time-integrated evidence. Such neurons may serve as decision variables, signaling a choice when activity reaches a boundary. Because the signals occur on a millisecond timescale, translating to human decision-making using functional neuroimaging has been challenging. Previous neuroimaging work in humans has identified patterns of neural activity consistent with an accumulation account. However, the degree to which the accumulating neuroimaging signals reflect specific sources of perceptual evidence is unknown. Using an extended face/house discrimination task in conjunction with cognitive modeling, we tested whether accumulation signals, as measured using functional magnetic resonance imaging (fMRI), are stimulus-specific. Accumulation signals were defined as a change in the slope of the rising edge of activation corresponding with response time (RT), with higher slopes associated with faster RTs. Consistent with an accumulation account, fMRI activity in face- and house-selective regions in the inferior temporal cortex increased at a rate proportional to decision time in favor of the preferred stimulus. This finding indicates that stimulus-specific regions perform an evidence integrative function during goal-directed behavior and that different sources of evidence accumulate separately. We also assessed the decision-related function of other regions throughout the brain and found that several regions were consistent with classifications from prior work, suggesting a degree of domain generality in decision processing. Taken together, these results provide support for an integration-to-boundary decision mechanism and highlight possible roles of both domain-specific and domain-general regions in decision evidence evaluation. •Stimulus-selective inferotemporal regions accumulate perceptual evidence•Different sources of evidence integrate separately in a content-specific manner•Accumulation in stimulus-selective regions reflects diffusion model drift-rate.•Time-extended fMRI tasks prove useful to investigate time-sensitive effects.

Optimal memory retrieval depends not only on the fidelity of stored information, but also on the attentional state of the subject. Factors such as mental preparedness to engage in stimulus processing can facilitate or hinder memory retrieval. The current study used functional magnetic resonance imaging (fMRI) to distinguish preparatory brain activity before episodic and semantic retrieval tasks from activity associated with retrieval itself. A catch-trial imaging paradigm permitted separation of neural responses to preparatory task cues and memory probes. Episodic and semantic task preparation engaged a common set of brain regions, including the bilateral intraparietal sulcus (IPS), left fusiform gyrus (FG), and the pre-supplementary motor area (pre-SMA). In the subsequent retrieval phase, the left IPS was among a set of frontoparietal regions that responded differently to old and new stimuli. In contrast, the right IPS responded to preparatory cues with little modulation during memory retrieval. The findings support a strong left-lateralization of retrieval success effects in left parietal cortex, and further indicate that left IPS performs operations that are common to both task preparation and memory retrieval. Such operations may be related to attentional control, monitoring of stimulus relevance, or retrieval.

Remembering draws on a diverse array of cognitive processes to construct a representation that is experienced as a copy of the original past. The results of brain-imaging, neuropsychological and physiological studies indicate that distinct neocortical regions might interact with medial temporal lobe structures to reinstate a memory. Frontal regions mediate the strategic retrieval attempt and monitor its outcome, with dissociated frontal regions making functionally separate contributions to retrieval. Parietal and frontal regions might supply a signal that information is old during the process of retrieval, allowing us to perceive that reconstructed representations are memories, rather than the products of new stimuli in the environment. Domain-specific cortical regions are reactivated during vivid remembering and contribute to the contents of a memory. Here, we describe how these regions interact to orchestrate an act of remembering.

Episodic memory retrieval involves multiple component processes, including those that occur when information is correctly remembered (retrieval success). The present study employed rapid-presentation event-related functional MRI that allowed different trial types with short intertrial intervals to be sorted such that the hemodynamic response associated with retrieval success could be extracted. Specifically, in an old/new episodic recognition task, hit trials (correctly recognized old items) and correct rejection trials (correctly rejected new items) were directly compared. The comparison revealed a mostly left-lateralized set of brain regions. Differential activation was most robust in left lateral parietal cortex and medial parietal cortex. Additional regions of differential activation included left anterior prefrontal cortex at or near Brodmann area 10, anterior insula, thalamus, anterior cingulate cortex, frontal cortex along inferior frontal gyrus, premotor cortex, and presupplementary motor area. These results suggest that left frontal and parietal regions modulate activity based on the successful retrieval of information from episodic memory. We discuss these findings in the context of several recent investigations that provide converging results as well as prior studies that have failed to detect these changes.

Successful memory retrieval depends not only on memory fidelity but also on the mental preparedness on the part of the subject. ERP studies of recognition memory have identified two topographically distinct ERP components, the FN400 old/new effect and the late posterior component (LPC) old/new effect, commonly associated with familiarity and recollection, respectively. Here we used a task-switching paradigm to examine the extent to which adoption of a retrieval task-set influences FN400 and LPC old/new effects, in light of the presumption that recollection, as a control process, relies on the adoption of a retrieval task-set, but that familiarity-based retrieval does not. Behavioral accuracy indicated that source memory (experiment 2), but not item recognition (experiment 1), improved with task-set adoption. ERP data demonstrated a larger LPC on stay trials when a task-set had been adopted even with a simple recognition memory judgment. We conclude that adopting a retrieval task-set impacts recollection memory but not familiarity. These data indicate that attentional state immediately prior to retrieval can influence objective measures of recollection memory. ► Using a task-switching paradigm we examined the impact of preparation on retrieval. ► The FN400, typically associated with familiarity was uninfluenced by preparation. ► The LPC, typically associated with recollection increased with preparation. ► Source memory, but not item recognition showed significant switch costs. ► Results suggest familiarity and recollection are differently impacted by preparation.

The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with subsequent memory. These opposing results suggest that repetition-related neural attenuation for subsequent hits and misses may be driven by different factors. In order to investigate the factors that affect the degree of neural attenuation, we varied perceptual similarity between repetitions in a scanned encoding phase that was followed by a subsequent memory test outside the scanner. We demonstrated that the degree of neural attenuation in the object processing regions depends on the interaction between perceptual similarity across repeated presentations and the quality their encodings. Specifically, the same areas that decreased neural signal for repetitions of same exemplars that were subsequently recognized with confidence that the repetitions were identical showed a decrease in neural signal for different-exemplar misses but not for the corresponding subsequently recognized hits. Our results imply that repetition-related neural attenuation should be related to the more efficient processing of perceptual properties of the stimuli only if subjects are able to subsequently remember the stimuli. Otherwise, the cause of attenuation may be in the failure to encode the stimuli on the second presentation as shown by the pattern of neural attenuation for the different-exemplar misses. ► Behavioral priming does not depend on subsequent memory. ► Neural attenuation depends on perceptual similarity and the quality of encoding. ► Neural attenuation can be caused by poor encoding on the second presentation. ► Hippocampal activation varies in priming task as a function of subsequent memory.