Our use of tools is situated in different contexts. Prior evidence suggests that diverse regions within the ventral and dorsal streams represent information supporting common tool use. However, given the flexibility of object concepts, these regions may be tuned to different types of information when generating novel or uncommon uses of tools. To investigate this, we collected fMRI data from participants who reported common or uncommon tool uses in response to visually presented familiar objects. We performed a pattern dissimilarity analysis in which we correlated cortical patterns with behavioral measures of visual, action, and category information. The results showed that evoked cortical patterns within the dorsal tool use network reflected action and visual information to a greater extent in the uncommon use group, whereas evoked neural patterns within the ventral tool use network reflected categorical information more strongly in the common use group. These results reveal the flexibility of cortical representations of tool use and the situated nature of cortical representations more generally.

Successful language comprehension requires one to correctly match symbols in an utterance to referents in the world, but the rampant ambiguity present in that mapping poses a challenge. Sometimes the ambiguity lies in which of two (or more) types of things in the world are under discussion (i.e., lexical ambiguity); however, even a word with a single sense can have an ambiguous referent. This ambiguity occurs when an object can exist in multiple states. Here, we consider two cases in which the presence of multiple object states may render a single-sense word ambiguous. In the first case, one must disambiguate between two states of a single object token in a short discourse. In the second case, the discourse establishes two different tokens of the object category. Both cases involve multiple object states: These states are mutually exclusive in the first case, whereas in the second case, these states can logically exist at the same time. We use fMRI to contrast same-token and different-token discourses, using responses in left posterior ventrolateral prefrontal cortex (pVLPFC) as an indicator of conflict. Because the left pVLPFC is sensitive to competition between multiple, incompatible representations, we predicted that state ambiguity should engender conflict only when those states are mutually exclusive. Indeed, we find evidence of conflict in same-token, but not different-token, discourses. Our data support a theory of left pVLPFC function in which general conflict resolution mechanisms are engaged to select between multiple incompatible representations that arise in many kinds of ambiguity present in language.

A central concern in the study of learning and decision-making is the identification of neural signals associated with the values of choice alternatives. An important factor in understanding the neural correlates of value is the representation of the object itself, separate from the act of choosing. Is it the case that the representation of an object within visual areas will change if it is associated with a particular value? We used fMRI adaptation to measure the neural similarity of a set of novel objects before and after participants learned to associate monetary values with the objects. We used a range of both positive and negative values to allow us to distinguish effects of behavioral salience (i.e., large vs. small values) from effects of valence (i.e., positive vs. negative values). During the scanning session, participants made a perceptual judgment unrelated to value. Crucially, the similarity of the visual features of any pair of objects did not predict the similarity of their value, so we could distinguish adaptation effects due to each dimension of similarity. Within early visual areas, we found that value similarity modulated the neural response to the objects after training. These results show that an abstract dimension, in this case, monetary value, modulates neural response to an object in visual areas of the brain even when attention is diverted.

Many features can describe a concept, but only some features define a concept in that they enable discrimination of items that are instances of a concept from (similar) items that are not. We refer to this property of some features as feature diagnosticity. Previous work has described the behavioral effects of feature diagnosticity, but there has been little work on explaining why and how these effects arise. In this study, we aimed to understand the impact of feature diagnosticity on concept representations across two complementary experiments. In Experiment 1, we manipulated the diagnosticity of one feature, color, for a set of novel objects that human participants learned over the course of 1 week. We report behavioral and neural evidence that diagnostic features are likely to be automatically recruited during remembering. Specifically, individuals activated color-selective regions of ventral temporal cortex (specifically, left fusiform gyrus and left inferior temporal gyrus) when thinking about the novel objects, although color information was never explicitly probed during the task. Moreover, multiple behavioral and neural measures of the effects of feature diagnosticity were correlated across participants. In Experiment 2, we examined relative color association in familiar object categories, which varied in feature diagnosticity (fruits and vegetables, household items). Taken together, these results offer novel insights into the neural mechanisms underlying concept representations by demonstrating that automatic recruitment of diagnostic information gives rise to behavioral effects of feature diagnosticity.

Neuroimaging tests of sensorimotor theories of semantic memory hinge on the extent to which similar activation patterns are observed during perception and retrieval of objects or object properties. The present study was motivated by the hypothesis that some of the seeming discrepancies across studies reflect flexibility in the systems responsible for conceptual and perceptual processing of color. Specifically, we test the hypothesis that retrieval of color knowledge can be influenced by both context (a task variable) and individual differences in cognitive style (a subject variable). In Experiment 1, we provide fMRI evidence for differential activity during color knowledge retrieval by having subjects perform a verbal task, in which context encouraged subjects to retrieve more- or less-detailed information about the colors of named common objects in a blocked experimental design. In the left fusiform, we found more activity during retrieval of more- versus less-detailed color knowledge. We also assessed preference for verbal or visual cognitive style, finding that brain activity in the left lingual gyrus significantly correlated with preference for a visual cognitive style. We replicated many of these effects in Experiment 2, in which stimuli were presented more quickly, in a random order, and in the auditory modality. This illustration of some of the factors that can influence color knowledge retrieval leads to the conclusion that tests of conceptual and perceptual overlap must consider variation in both of these processes.

Interference from previously learned information, known as proactive interference (PI), limits our memory retrieval abilities. Previous studies of PI resolution have focused on the role of short-term familiarity, or recency, in causing PI. In the present study, we investigated the impact of long-term stimulus familiarity on PI resolution processes. In two behavioral experiments and one event-related fMRI experiment, long-term familiarity was manipulated through the use of famous and nonfamous stimuli, and short-term familiarity was manipulated through the use of recent and nonrecent probe items in an item recognition task. The right middle frontal gyrus demonstrated greater sensitivity to famous stimuli, suggesting that long-term stimulus familiarity plays a role in influencing PI resolution processes. Further examination of the effect of long-term stimulus familiarity on PI resolution revealed a larger behavioral interference effect for famous stimuli, but only under speeded response conditions. Thus, models of memory retrieval—and of the cognitive control mechanisms that guide retrieval processes—should consider the impact of and interactions among sources of familiarity on multiple time scales.

Cognitive neuroscientists habitually deny that functional neuroimaging can furnish causal information about the relationship between brain events and behavior. However, imaging studies do provide causal information about those relationships—although not causal certainty. Although popular portrayals of functional neuroimaging tend to attribute too much inferential power to the technique, we should restrain ourselves from ascribing it too little.

For over a century, a link between left prefrontal cortex and language processing has been accepted, yet the precise characterization of this link remains elusive. Recent advances in both the study of sentence processing and the neuroscientific study of frontal lobe function suggest an intriguing possibility: The demands to resolve competition between incompatible characterizations of a linguistic stimulus may recruit top–down cognitive control processes mediated by prefrontal cortex. We use functional magnetic resonance imaging to test the hypothesis that individuals use shared prefrontal neural circuitry during two very different tasks—color identification under Stroop conflict and sentence comprehension under conditions of syntactic ambiguity—both of which putatively rely on cognitive control processes. We report the first demonstration of within-subject overlap in neural responses to syntactic and nonsyntactic conflict. These findings serve to clarify the role of Broca's area in, and the neural and psychological organization of, the language processing system.

Debates about the function of the prefrontal cortex are as old as the field of neuropsychology—often dated to Paul Broca's seminal work. Theories of the functional organization of the prefrontal cortex can be roughly divided into those that describe organization by process and those that describe organization by material. Recent studies of the function of the posterior, left inferior frontal gyrus (pLIFG) have yielded two quite different interpretations: One hypothesis holds that the pLIFG plays a domain-specific role in phonological processing, whereas another hypothesis describes a more general function of the pLIFG in cognitive control. In the current study, we distinguish effects of increasing cognitive control demands from effects of phonological processing. The results support the hypothesized role for the pLIFG in cognitive control, and more task-specific roles for posterior areas in phonology and semantics. Thus, these results suggest an alternative explanation of previously reported phonology-specific effects in the pLIFG.

A number of theories about the evolution of language posit a close (and perhaps causal) relationship between tool use and speech. Consistent with this idea, neuroimaging studies have found that tool knowledge retrieval activates not only a region of the left premotor cortex involved in hand action, but also an adjacent region that is typically described as a language center. We examined whether this pattern of activation is best described as the result of a single process, related to both action and language, or the result of two independent processes. We identified two distinct neural components that jointly contribute to this response: a posterior region centered in the premotor cortex, which responds to motor knowledge retrieval, and an anterior region centered in the left frontal operculum, which responds to lexical competition. Crucial to the interpretation of the premotor response, individual variation in motor experience was highly correlated with the magnitude of the response in the premotor cortex, but not in the prefrontal cortex.

Retrieval of conceptual information from action pictures causes greater activation than from object pictures bilaterally in human motion areas (MT/MST) and nearby temporal regions. By contrast, retrieval of conceptual information from action words causes greater activation in left middle and superior temporal gyri, anterior and dorsal to the MT/MST. We performed two fMRI experiments to replicate and extend these findings regarding action words. In the first experiment, subjects performed conceptual judgments of action and object words under conditions that stressed visual semantic information. Under these conditions, action words again activated posterior temporal regions close to, but not identical with, the MT/MST. In the second experiment, we included conceptual judgments of manipulable object words in addition to judgments of action and animal words. Both action and manipulable object judgments caused greater activity than animal judgments in the posterior middle temporal gyrus. Both of these experiments support the hypothesis that middle temporal gyrus activation is related to accessing conceptual information about motion attributes, rather than alternative accounts on the basis of lexical or grammatical factors. Furthermore, these experiments provide additional support for the notion of a concrete to abstract gradient of motion representations with the lateral occipito-temporal cortex, extending anterior and dorsal from the MT/MST towards the peri-sylvian cortex.

Humans and animals use information obtained from different viewpoints to form representations of the spatial structure of the world. We used functional magnetic resonance imaging (fMRI) adaptation to investigate the neural basis of this learning process and to show how the concomitant representations vary across individuals as a function of navigational ability. In particular, we examined the effect of repeating viewpoint and/ or place information over both short (within-trial) and long (across-scan) intervals on the neural response in scene processing regions. Short-term fMRI adaptation effects in the parahippocampal cortex were initially highly viewpoint-specific but became less so over time. Long-term fMRI repetition effects included a significant viewpoint-invariant component. When individual differences in navigational ability were considered, a significant correlation between the strength of these effects and self-reported navigational competence was observed. In particular, good navigators encoded representations that differed between new and old views and new and old places, whereas bad navigators did not. These results suggest that cortical scene representations evolve over time to become more viewpoint-invariant and that the quality of these representations directly impacts navigational ability.

Research on the functional organization of the lateral prefrontal cortex (PFC) in working memory continues to be fairly equivocal between two major frameworks: organization-by-process or organization-by-material. Although there is fairly strong evidence for organization-by-process models from event-related fMRI studies, some investigators argue that the nature of the stimulus material better defines the functional organization of the lateral PFC, particularly in more ventral regions (BA 47/45/44). Specifically, the anterior region of the ventrolateral PFC (BA 47/45) is hypothesized to subserve semantic processing while the posterior region (BA 44) may subserve phonological processing. In the current event-related fMRI study, we directly compared process-related versus material-related organizational principles in a verbal working memory task. Subjects performed a modified delayed response task in which they (1) retained a list of five words or five nonwords during the delay period (“maintenance”), or (2) performed a semantic (size reordering) or phonological (alphabetical reordering) task on the word or nonword lists, respectively (“manipulation”). We did not find evidence during the delay period of our task to support claims of anterior-posterior specializations in the ventrolateral PFC for semantic versus phonological processing. Subjects did, however, display greater neuronal activity during the delay period of manipulation trials than maintenance trials in both the dorsolateral PFC and posterior ventrolateral regions. These data are more consistent with the process model of the organization of lateral PFC in verbal working memory.

Lesion and neuroimaging studies suggest the amygdala is important in the perception and production of negative emotion; however, the effects of emotion regulation on the amygdalar response to negative stimuli remain unknown. Using event-related fMRI, we tested the hypothesis that voluntary modulation of negative emotion is associated with changes in neural activity within the amygdala. Negative and neutral pictures were presented with instructions to either “maintain” the emotional response or “passively view” the picture without regulating the emotion. Each picture presentation was followed by a delay, after which subjects indicated how they currently felt via a response keypad. Consistent with previous reports, greater signal change was observed in the amygdala during the presentation of negative compared to neutral pictures. No significant effect of instruction was found during the picture presentation component of the trial. However, a prolonged increase in signal change was observed in the amygdala when subjects maintained the negative emotional response during the delay following negative picture offset. This increase in amygdalar signal due to the active maintenance of negative emotion was significantly correlated with subjects' self-reported dispositional levels of negative affect. These results suggest that consciously evoked cognitive mechanisms that alter the emotional response of the subject operate, at least in part, by altering the degree of neural activity within the amygdala.