Biomedical subjects

William M Kelley

Publications and source records attributed to William M Kelley.

11 recordsLinked to original sources

PubMed2006

Anterior cingulate cortex responds differentially to expectancy violation and social rejection.

This study investigated human anterior cingulate cortex (ACC) involvement during a task that dissociated expectancy violation from social rejection. Across two studies, participants underwent functional magnetic resonance imaging while making social judgments and receiving fictitious feedback that was either positive or negative and consistent or inconsistent with their expectations. The results demonstrate that the dorsal ACC is sensitive to expectancy violations, whereas the ventral ACC is differentially responsive to social feedback.

Emotions↗

PubMed2006

Dissociable medial temporal lobe contributions to social memory.

Medial temporal lobe structures such as the hippocampus have been shown to play a critical role in mnemonic processes, with additional recruitment of the amygdala when memories contain emotional content. Thus far, studies that have examined the relationship between amygdala activity and memory have typically relied on emotional content of the kind that is rarely encountered in day-to-day interactions. The present event-related functional magnetic resonance imaging study investigates whether amygdala activity supports emotional memory during the more subtle social interactions that punctuate everyday life. Across four training sessions, subjects learned common first names for unfamiliar faces in the presence or absence of additional contextual information that was positive, negative, and neutral in valence (e.g., "Emily helps the homeless," "Bob is a deadbeat dad," "Eric likes carrots"). During scanning, subjects performed a yes/no recognition memory test on studied and novel faces. Results revealed a functional dissociation within the medial temporal lobe. Whereas a region within the right hippocampus responded strongly to all faces that had been paired with a description, regardless of its valence, activity in the right amygdala was uniquely sensitive to faces that had been previously associated with emotional descriptions (negative and positive > neutral). This pattern of activity in the amygdala was preserved even when the emotional contexts associated with faces could not be explicitly retrieved, suggesting a role for the amygdala in providing a nonspecific arousal indicator in response to viewing individuals with emotionally colored pasts.

Adolescent↗

PubMed2005

Reductions in neural activity underlie behavioral components of repetition priming.

Repetition priming is a nonconscious form of memory that is accompanied by reductions in neural activity when an experience is repeated. To date, however, there is no direct evidence that these neural reductions underlie the behavioral advantage afforded to repeated material. Here we demonstrate a causal linkage between neural and behavioral priming in humans. fMRI (functional magnetic resonance imaging) was used in combination with transcranial magnetic stimulation (TMS) to target and disrupt activity in the left frontal cortex during repeated classification of objects. Left-frontal TMS disrupted both the neural and behavioral markers of priming. Neural priming in early sensory regions was unaffected by left-frontal TMS--a finding that provides evidence for separable conceptual and perceptual components of priming.

Adult↗

PubMed2005

Musical imagery: sound of silence activates auditory cortex.

Auditory imagery occurs when one mentally rehearses telephone numbers or has a song 'on the brain'--it is the subjective experience of hearing in the absence of auditory stimulation, and is useful for investigating aspects of human cognition. Here we use functional magnetic resonance imaging to identify and characterize the neural substrates that support unprompted auditory imagery and find that auditory and visual imagery seem to obey similar basic neural principles.

Acoustic Stimulation↗

PubMed2005

Lipopolysaccharide-binding protein modulates acetaminophen-induced liver injury in mice.

Acetaminophen toxicity is the most common cause of acute liver failure in the United States and Europe. Although much is known about the metabolism of acetaminophen, many questions remain regarding the pathogenesis of liver injury. In this study, we examined the role of lipopolysaccharide-binding protein (LBP), a protein important in mediating cellular response to lipopolysaccharides, by using LBP wild-type and knockout (KO) mice. We found that LBP KO mice were protected from acetaminophen-induced hepatotoxicity. At 350 mg/kg of acetaminophen, LBP KO mice had significantly less liver injury and necrosis than wild-type mice. Repletion studies in LBP KO mice using an LBP-adenoviral construct resulted in significantly more hepatic injury and necrosis after acetaminophen exposure compared with mice receiving the control adenoviral construct. In conclusion, LBP KO mice are protected from toxicity with a decrease in hepatic necrosis following acetaminophen challenge. This suggests a novel role for LBP in modulating acetaminophen-induced liver injury. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/O270-9139/suppmat/index.html).

Acetaminophen↗

PubMed2004

Medial prefrontal activity predicts memory for self.

The ability to remember the past depends on cognitive operations that are recruited when information is initially encountered. In the current experiment, we investigated neural processes that subserve the memorability of a fundamental class of social information: self-knowledge. Participants evaluated the extent to which a series of personality characteristics were self-descriptive. Brain activation was measured using event-related functional magnetic resonance imaging (fMRI) and contrasted based on: (i) whether each word was later remembered or forgotten; and (ii) whether or not each item was judged to be self-relevant. Results revealed that activity in medial prefrontal cortex predicted both subsequent memory performance and judgements of self-relevance. These findings extend current understanding of the nature and functioning of human memory.

Adult↗

PubMed2004

Neural correlates of humor detection and appreciation.

Humor is a uniquely human quality whose neural substrates remain enigmatic. The present report combined dynamic, real-life content and event-related functional magnetic resonance imaging (fMRI) to dissociate humor detection ("getting the joke") from humor appreciation (the affective experience of mirth). During scanning, subjects viewed full-length episodes of the television sitcoms Seinfeld or The Simpsons. Brain activity time-locked to humor detection moments revealed increases in left inferior frontal and posterior temporal cortices, whereas brain activity time-locked to moments of humor appreciation revealed increases in bilateral regions of insular cortex and the amygdala. These findings provide evidence that humor depends critically upon extant neural systems important for resolving incongruities (humor detection) and for the expression of affect (humor appreciation).

Adult↗

PubMed2003

Neural correlates of thought suppression.

The present report used functional magnetic resonance imaging (fMRI) to examine the neural correlates of thought suppression. Subjects were imaged while alternately (i) attempting to suppress a particular thought, (ii) attempting to suppress all thoughts, or (iii) thinking freely about any thought. Suppression of a particular thought, when compared to the free-thought control condition, revealed greater activation in the anterior cingulate. When the task of suppressing all conscious thoughts was compared to free-thought, a more distributed network of brain regions, including the anterior cingulate and the insula, was activated. These findings are consistent with previous research on cognitive control and may provide potential insights into psychological disorders involving recurring, intrusive thoughts.

Adult↗

PubMed2003

Out of contact, out of mind: the distributed nature of the self.

A truly remarkable aspect of human existence is the unitary sense of self that exists across time and place. Understanding the nature of self-what it is and what it does-has challenged scholars since antiquity. How can empirical research measure what it is to have a sense of self? We propose that the sense of self may emerge from the functions of a left hemisphere "interpreter". First, we examine evidence for the existence of self-processing mechanisms in the intact brain, from behavioral and functional neuroimaging research. The available evidence suggests that the sense of self is widely distributed throughout the brain. Second, we discuss these findings in relation to what is known about higher cognitive functions in humans who have undergone a surgical procedure to sever the connection between the two cerebral hemispheres. Split-brain research has facilitated an understanding of the way in which each cerebral hemisphere independently processes information. Research in this area has shown that each cerebral hemisphere features distinct information-processing capabilities. This cognitive asymmetry is reflected in the notion of a left hemisphere interpreter module which, we have argued, generates a unitary sense of consciousness even in the disconnected brain. This chapter describes how this interpreter may also give rise to a unified sense of self.

Brain↗

PubMed2002

Mike or me? Self-recognition in a split-brain patient.

A split-brain patient (epileptic individual whose corpus callosum had been severed to minimize the spread of seizure activity) was asked to recognize morphed facial stimuli--presented separately to each hemisphere--as either himself or a familiar other. Both hemispheres were capable of face recognition, but the left hemisphere showed a recognition bias for self and the right hemisphere a bias for familiar others. These findings suggest a possible dissociation between self-recognition and more generalized face processing within the human brain.

Cerebral Cortex↗

PubMedDate not supplied

Separable routes to human memory formation: dissociating task and material contributions in the prefrontal cortex.

The present study used fMRI to investigate functional dissociations across frontal regions during incidental memory formation. Subjects were imaged while encoding materials with differential access to phonological codes (nonfamous faces and nameable famous faces) under task conditions that encouraged elaborate (deep) or superficial (shallow) encoding strategies. Results revealed a functional dissociation between dorsal posterior regions of the prefrontal cortex (BA 6/44) that were sensitive to material type (famous vs. nonfamous), irrespective of the encoding task, and ventral anterior regions of the prefrontal cortex (BA 45/47) that were uniquely sensitive to task demands (deep vs. shallow), regardless of material type. Further, subjects realized a memorial advantage to the extent that they recruited these dissociable frontal regions. These results demonstrate a posterior/anterior dichotomy in the frontal cortex that underlies separable code-based routes to human memory formation.

Adolescent↗