Biomedical subjects

Christopher I Wright

Publications and source records attributed to Christopher I Wright.

At least 19 recordsLinked to original sources

PubMed2007

Neuroanatomical correlates of personality in the elderly.

Extraversion and neuroticism are two important and frequently studied dimensions of human personality. They describe individual differences in emotional responding that are quite stable across the adult lifespan. Neuroimaging research has begun to provide evidence that neuroticism and extraversion have specific neuroanatomical correlates within the cerebral cortex and amygdala of young adults. However, these brain areas undergo alterations in size with aging, which may influence the nature of these personality factor-brain structure associations in the elderly. One study in the elderly demonstrated associations between perisylvian cortex structure and measures of self transcendence [Kaasinen, V., Maguire, R.P., Kurki, T., Bruck, A., Rinne, J.O., 2005. Mapping brain structure and personality in late adulthood. NeuroImage 24, 315-322], but the neuroanatomical correlates of extraversion and neuroticism, or other measures of the Five Factor Model of personality have not been explored. The purpose of the present study was to investigate the structural correlates of neuroticism and extraversion in healthy elderly subjects (n=29) using neuroanatomic measures of the cerebral cortex and amygdala. We observed that the thickness of specific lateral prefrontal cortex (PFC) regions, but not amygdala volume, correlates with measures of extraversion and neuroticism. The results suggest differences in the regional neuroanatomic correlates of specific personality traits with aging. We speculate that this relates to the influences of age-related structural changes in the PFC.

Aged↗

PubMed2007

Recall of fear extinction in humans activates the ventromedial prefrontal cortex and hippocampus in concert.

BACKGROUND: Extinction of conditioned fear is thought to form a new safety memory that is expressed in the context in which the extinction learning took place. Rodent studies implicate the ventromedial prefrontal cortex (vmPFC) and hippocampus in extinction recall and its modulation by context, respectively. The aim of the present study is to investigate the mediating anatomy of extinction recall in healthy humans. METHODS: We used event-related functional magnetic resonance imaging (fMRI) and a 2-day fear conditioning and extinction protocol with skin conductance response as the index of conditioned responses. RESULTS: During extinction recall, we found significant activations in vmPFC and hippocampus in response to the extinguished versus an unextinguished stimulus. Activation in these brain regions was positively correlated with the magnitude of extinction memory. Functional connectivity analysis revealed significant positive correlation between vmPFC and hippocampal activation during extinction recall. CONCLUSIONS: These results support the involvement of the human hippocampus as well as vmPFC in the recall of extinction memory. Furthermore, this provides a paradigm for future investigations of fronto-temporal function during extinction recall in psychiatric disorders such as posttraumatic stress disorder.

Adult↗

PubMed2006

Functional magnetic resonance imaging study of regional brain activation during implicit sequence learning in obsessive-compulsive disorder.

BACKGROUND: Corticostriatal circuitry has been implicated in the pathophysiology of obsessive-compulsive disorder (OCD). The serial reaction time (SRT) task, a paradigm that tests implicit sequence learning, has been used with imaging to probe striatal function. Initial studies have indicated that OCD patients exhibit deficient striatal activation and aberrant hippocampal recruitment compared with healthy control (HC) subjects. Here, we used the SRT and functional magnetic resonance imaging (fMRI) to replicate prior results in a larger sample and to test for relationships between regional activation and OCD symptom dimensions. METHODS: Using SPM99, fMRI-SRT data from 12 OCD and 12 matched HC subjects were analyzed. Symptom dimensions followed a four-factor model scored on a 0- to 10-point scale. RESULTS: For the implicit learning versus random contrast, group by condition interactions revealed aberrant recruitment within the hippocampus as well as orbitofrontal cortex (OCD > HC) but no striatal group differences. However, an inverse correlation was found between striatal activation and specific symptom factors. CONCLUSIONS: These results replicate previous smaller studies showing aberrant hippocampal recruitment in OCD during SRT performance. Although findings of deficient striatal activation in OCD were not replicated, correlation results suggest that this inconsistency may be attributable to differences among OCD symptom dimensions.

Adult↗

PubMed2006

Neuroanatomical correlates of extraversion and neuroticism.

Introversion/extraversion and neuroticism are 2 important and frequently studied dimensions of human personality. These dimensions describe individual differences in emotional responding across a range of situations and may contribute to a predisposition for psychiatric disorders. Recent neuroimaging research has begun to provide evidence that neuroticism and introversion/extraversion have specific functional and structural neural correlates. Previous studies in healthy adults have reported an association between neuroticism, introversion/extraversion, and the activity of the prefrontal cortex and amygdala. Studies of individuals with psychopathological states have also indicated that anatomic variations in these brain areas may relate to extraversion and neuroticism. The purpose of the present study was to examine selected structural correlates of neuroticism and extraversion in healthy subjects (n = 28) using neuroanatomic measures of the cerebral cortex and amygdala. We observed that the thickness of specific prefrontal cortex regions correlates with measures of extraversion and neuroticism. In contrast, no such correlations were observed for the volume of the amygdala. The results suggest that specific aspects of regional prefrontal anatomy are associated with specific personality traits.

Adult↗

PubMed2006

False recognition of emotional word lists in aging and Alzheimer disease.

OBJECTIVE: To examine 3 different aspects of the emotional memory effect in aging and Alzheimer disease (AD): item-specific recollection, gist memory, and recognition response bias. METHOD: Younger adults, older adults, and patients with AD performed a false recognition memory test in which participants were tested on "lure" items that were not seen at study, but were semantically related to the study items. Participants were tested on 5 emotional and 5 non-emotional lists. RESULTS: In addition to finding an increase in true recognition for emotional versus non-emotional items in healthy younger and older adults but not in patients with AD, and confirming that emotional items led younger adults to shift their response bias to a more liberal one, 3 novel findings were observed. First, the emotional effect on response bias was also observed in healthy older adults. Second, the opposite emotional effect on response bias was observed in patients with AD. Third, emotional items did not lead to an improvement in item-specific recollection or gist memory. CONCLUSIONS: Although healthy older adults show the normal amygdala-modulated criterion shift for emotional items-influencing their subjective feeling that information has been previously encountered, the amygdala pathology present in early AD may disrupt this influence.

Adolescent↗

PubMed2005

Increased medial temporal lobe activation during the passive viewing of emotional and neutral facial expressions in schizophrenia.

INTRODUCTION: Patients with schizophrenia show deficits in facial affect and facial identity recognition and exhibit structural and neurophysiological abnormalities in brain regions known to mediate these processes. Functional neuroimaging studies of neural responses to emotional facial expressions in schizophrenia have reported both increases and decreases in medial temporal lobe (MTL) activity in schizophrenia. Some of this variability may be related to the tasks performed and the baseline conditions used. Here we tested whether MTL responses to human faces in schizophrenia are abnormal when unconstrained by a cognitive task and measured relative to a low-level baseline (fixation) condition. METHODS: 15 patients with schizophrenia and 16 healthy control subjects underwent functional magnetic resonance imaging (fMRI) while passively viewing human faces displaying fearful, happy, and neutral emotional expressions. RESULTS: Relative to control subjects, the patients demonstrated (1) significantly greater activation of the left hippocampus while viewing all three facial expressions and (2) increased right amygdala activation during the initial presentation of fearful and neutral facial expressions. CONCLUSIONS: In schizophrenia, hippocampal and amygdala activity is elevated during the passive viewing of human faces.

Adult↗

PubMed2005

Brain correlates of negative and positive visuospatial priming in adults.

A balance of inhibitory and facilitatory mechanisms is essential for efficient and goal-directed behaviors. These mechanisms may go awry in several neuropsychiatric disorders characterized by uncontrolled, repetitive behaviors. The visuospatial priming paradigm is a well-established probe of inhibition and facilitation that has been used to demonstrate behavioral deficits in patients with Tourette syndrome and obsessive-compulsive disorder. However, the brain correlates of this visuospatial priming paradigm are not yet well established. In the present study, we used a visuospatial priming paradigm and event-related functional MRI, to probe inhibitory and facilitatory brain mechanisms in healthy adult women. When subjects performed the negative priming (i.e., inhibitory) task, several regions of the prefrontal cortex were selectively activated relative to the neutral condition. Non-overlapping regions of the prefrontal cortex were deactivated in the positive priming condition. These results support the notion that the prefrontal cortex is involved in both inhibitory and facilitatory processing and demonstrate that this visuospatial priming task shares brain correlates with other positive and negative priming tasks. In conjunction with functional MRI, this visuospatial priming task may be useful for studying the pathophysiology of neuropsychiatric disorders in which deficient inhibitory processing or excessive facilitation is a feature.

Adolescent↗

PubMed2005

Age-differential patterns of brain activation during perception of angry faces.

Functional magnetic resonance imaging (fMRI) was used to study age-related differences in the neural circuitry involved in perception of negative facial affect. During scanning, 24 younger and 22 older adults viewed blocks of angry and neutral faces. The fMRI data analysis of the angry versus neutral faces contrast demonstrated greater activation in younger versus older individuals in the right amygdala/hippocampus region, whereas older adults demonstrated greater activation in the right anterior-ventral insula cortex. Hence, normal aging seems to affect specific nodes in the neural network involved in processing negative emotional face information. This age-related change from more subcortical to more cortical involvement could reflect functional compensation within the neural system involved in perception of facial affect, or the fact that older adults process emotional information in a different manner than do young adults.

Adult↗

PubMed2005

Differential amygdala habituation to neutral faces in young and elderly adults.

Habituation is a highly adaptive property of the nervous system, which allows for the allocation of attention and other cognitive resources to more imperative environmental events. The amygdala is an important site of habituation in humans, but no studies to date have examined the effects of aging on amygdala habituation. Given the amygdala's role in evaluating the salience of a stimulus and initiating behavioral responses, the potential importance of amygdala habituation in aging may be far-reaching. Therefore, we assessed for differences in habituation in the amygdalae of healthy young and elderly adults during repeated presentations of neutral human faces using functional magnetic resonance imaging (fMRI). In addition, we evaluated the relationship between amygdala volume and habituation, to examine the effects of atrophy. Eighteen healthy young controls and 18 healthy elderly subjects were scanned with fMRI during viewing of repeatedly presented neutral human face stimuli. Significant fMRI signal decrement was observed across all subjects for early versus late face presentations. Analysis of group, condition, and hemisphere revealed a significant three-way interaction, with right greater than left habituation in the young, but left greater than right amygdala habituation in the elderly. Volumetric and correlational analyses demonstrated that amygdala volume is associated with habituation in the right, but not left, hemisphere. We conclude that, in healthy elderly adults, the amygdala retains its adaptive habituation response, but speculate that intrinsic changes in amygdala anatomy during aging may modulate its laterality.

Adult↗

PubMed2005

Brain correlates of negative visuospatial priming in healthy children.

Inhibitory mechanisms that begin to develop in childhood are essential for efficient and goal-directed behaviors. These inhibitory mechanisms may go awry in several childhood-onset neuropsychiatric disorders, such as Tourette syndrome, obsessive-compulsive disorder and attention deficit hyperactivity disorder. Negative visuospatial priming is a well-established behavioral probe of inhibition that has been used to demonstrate deficits in children with neuropsychiatric disorders of inhibition, but the brain correlates of negative visuospatial priming have not previously been well delineated. In the present study, we use a visuospatial priming paradigm and event-related functional magnetic resonance imaging (fMRI) to probe inhibitory brain mechanisms in healthy children. When subjects performed the control (i.e. neutral) motor task, a network of cortical and subcortical sensorimotor regions was activated. In contrast, during performance of the negative priming (i.e. inhibitory) task, several regions of the prefrontal cortex were selectively engaged. These results support the notion that the prefrontal cortex is involved in inhibitory processing in healthy children and demonstrate that negative visuospatial priming shares brain correlates with other inhibitory tasks. In conjunction with fMRI, the visuospatial priming task described in the current study may be useful for studying the pathophysiology of childhood-onset neuropsychiatric disorders characterized by deficient inhibitory processing.

Adolescent↗

PubMed2005

Sustained activation of the hippocampus in response to fearful faces in schizophrenia.

BACKGROUND: In healthy individuals, the activity of the medial temporal lobe habituates rapidly with the repeated presentation of a stimulus. Using functional magnetic resonance imaging (fMRI), we tested the hypothesis that habituation of the medial temporal lobe is reduced in schizophrenia. METHODS: During fMRI scanning, fearful and happy faces were presented repeatedly to healthy control subjects (n =16) and patients with schizophrenia (n =18). Habituation of medial temporal lobe structures was measured by comparing the hemodynamic response occurring during the early and late portions of the presentation of each face. RESULTS: Control subjects demonstrated significant medial temporal lobe habituation to fearful but not to happy faces. In contrast, patients with schizophrenia did not demonstrate medial temporal lobe habituation in response to fearful or happy faces. In a direct, between-group comparison, right hippocampal habituation to fearful faces was significantly greater in control subjects than in the schizophrenia patients. Also, there were no significant differences between the patients and control subjects in the early medial temporal lobe response to fearful faces, suggesting that attenuated hippocampal habituation in schizophrenia is not associated with a reduction in initial activation. CONCLUSIONS: These findings suggest that there is abnormal modulation of hippocampal responses to fearful faces in schizophrenia.

Adult↗

PubMed2005

Novel fearful faces activate the amygdala in healthy young and elderly adults.

Activation of the amygdala to emotionally valenced stimuli, and particularly to fearful faces, has been widely demonstrated in healthy young adults. However, recent studies assessing amygdala responses to fearful emotional faces in the normal elderly have not shown similar results. The reason for this is uncertain, but it may relate to life-span developmental changes in processing emotional stimuli or structural alterations in the amygdala with aging. In order to examine whether the amygdala could be activated in the elderly, we developed a paradigm designed to engage the amygdala on several levels. Based on recent imaging work indicating that novelty and stimulus change activates the amygdala, we assessed amygdala responses in young and elderly adults to novel fearful faces (versus familiar neutral ones). We demonstrate a robust activation in both groups, indicating that the amygdala remains responsive in aging. This activation did not differ between the two groups when we examined regions of interest in the amygdala based on functional or structural criteria. However, there were significantly greater activations in the inferior temporal cortex in the young versus elderly subjects.

Adult↗

PubMed2005

A functional magnetic resonance imaging study of amygdala and medial prefrontal cortex responses to overtly presented fearful faces in posttraumatic stress disorder.

BACKGROUND: Previous functional neuroimaging studies have demonstrated exaggerated amygdala responses and diminished medial prefrontal cortex responses during the symptomatic state in posttraumatic stress disorder (PTSD). OBJECTIVES: To determine whether these abnormalities also occur in response to overtly presented affective stimuli unrelated to trauma; to examine the functional relationship between the amygdala and medial prefrontal cortex and their relationship to PTSD symptom severity in response to these stimuli; and to determine whether responsivity of these regions habituates normally across repeated stimulus presentations in PTSD. DESIGN: Case-control study. SETTING: Academic medical center. PARTICIPANTS: Volunteer sample of 13 men with PTSD (PTSD group) and 13 trauma-exposed men without PTSD (control group). MAIN OUTCOME MEASURES: We used functional magnetic resonance imaging (fMRI) to study blood oxygenation level-dependent signal during the presentation of emotional facial expressions. RESULTS: The PTSD group exhibited exaggerated amygdala responses and diminished medial prefrontal cortex responses to fearful vs happy facial expressions. In addition, in the PTSD group, blood oxygenation level-dependent signal changes in the amygdala were negatively correlated with signal changes in the medial prefrontal cortex, and symptom severity was negatively related to blood oxygenation level-dependent signal changes in the medial prefrontal cortex. Finally, relative to the control group, the PTSD group tended to exhibit diminished habituation of fearful vs happy responses in the right amygdala across functional runs, although this effect did not exceed our a priori statistical threshold. CONCLUSIONS: These results provide evidence for exaggerated amygdala responsivity, diminished medial prefrontal cortex responsivity, and a reciprocal relationship between these 2 regions during passive viewing of overtly presented affective stimuli unrelated to trauma in PTSD.

Amygdala↗

PubMed2004

Amygdala responses to human faces in obsessive-compulsive disorder.

BACKGROUND: To assess the amygdala response to emotional faces in obsessive-compulsive disorder (OCD) using functional magnetic resonance imaging (fMRI). METHODS: Ten subjects with current OCD and 10 healthy control subjects underwent fMRI, during which they viewed pictures of fearful, happy, and neutral human faces, as well as a fixation cross. RESULTS: Across both groups, there was significant activation in left and right amygdala for the fearful versus neutral faces contrast. Data extracted from these functionally defined regions of interest indicated that OCD subjects exhibited a weaker response than control subjects bilaterally across all face conditions versus fixation. No group-by-face condition interactions were observed. CONCLUSIONS: Contrary to findings in other anxiety disorders, there was no observed increase in amygdala responsivity to fearful versus neutral human faces in OCD as compared with healthy control subjects. Moreover, across all face conditions, amygdala responsivity was attenuated in OCD subjects relative to control subjects. Therefore, the present findings are consistent with abnormal amygdala function in OCD and are of a character that may distinguish OCD from other anxiety disorders.

Adult↗

PubMed2004

A magnetic resonance imaging study of cortical thickness in animal phobia.

BACKGROUND: Despite the high prevalence of specific phobia (SP), its neural substrates remain undetermined. Although an initial series of functional neuroimaging studies have implicated paralimbic and sensory cortical regions in the pathophysiology of SP, to date contemporary morphometric neuroimaging methods have not been applied to test specific hypotheses regarding structural abnormalities. METHODS: Morphometric magnetic resonance imaging (MRI) methods were used to measure regional cortical thickness in 10 subjects with SP (animal type) and 20 healthy comparison (HC) subjects. RESULTS: Consistent with a priori hypotheses, between-group differences in cortical thickness were found within paralimbic and sensory cortical regions. Specifically, in comparison with the HC group, the SP group exhibited increased cortical thickness in bilateral insular, bilateral pregenual anterior cingulate, and bilateral posterior cingulate cortex as well as left visual cortical regions. CONCLUSIONS: Taken together, these structural findings parallel results from initial functional imaging studies that implicate paralimbic and sensory cortical regions in the mediating anatomy of SP symptoms. Further research will be necessary to replicate these findings and to determine their specificity as well as their pathophysiologic significance.

Adult↗

PubMed2004

Sex-differential brain activation during exposure to female and male faces.

Sex-discriminating facial features are examples of visual information involved in guiding social behavior. We used functional magnetic resonance imaging (fMRI) to assess brain responses in face-relevant brain areas in men and women during exposure to neutral male and female faces. An increased fMRI signal was found in the left amygdala and adjacent anterior temporal regions in men, but not in women, during exposure to faces of the opposite versus the same sex. These data indicate that the relationship between the sex of the subject and the sex of the face affects activity in the inferior temporal lobe. The sex-differential nature of this activation pattern may reflect sex differences in cognitive style and attentional processes when confronting faces of the opposite sex.

Adult↗

PubMed2004

Functional magnetic resonance imaging evidence for a lack of striatal dysfunction during implicit sequence learning in individuals with animal phobia.

OBJECTIVE: This study investigated the neural substrates of implicit sequence learning in subjects with and without small animal phobia, in a follow-up to analogous studies of obsessive-compulsive disorder (OCD). METHOD: Ten subjects with specific phobia and 10 healthy comparison subjects were studied by using a serial reaction time task paradigm and functional magnetic resonance imaging. RESULTS: A main effect of condition (implicit sequence learning versus random sequence) was observed across diagnostic groups in the right striatum, as well as in other regions. In the striatum, the a priori region of interest, there were no significant effects of diagnosis or the interaction of diagnosis and condition. CONCLUSIONS: Brain activation in the striatum of subjects with specific phobia does not significantly differ from that of normal comparison subjects during implicit sequence learning. This suggests different pathophysiological mechanisms for specific phobia in contrast to OCD, in which deficient striatal recruitment has been reproducibly found with this paradigm. This approach offers promise for demonstrating diagnostic specificity across different neuropsychiatric disorders based on the presence or absence of deficient striatal activation.

Adult↗

PubMed2004

Enhanced occipital and anterior cingulate activation in men but not in women during exposure to angry and fearful male faces.

Blood-oxygenation-level-dependent signal was measured with functional magnetic resonance imaging in 24 healthy young subjects (12 men and 12 women) during viewing of angry, fearful, and neutral male and female face pictures. Exposure to angry male as opposed to angry female faces activated the visual cortex and the anterior cingulate gyrus significantly more in men than in women. A similar sex-differential brain activation pattern was present during exposure to fearful but not neutral faces. Previous behavioral studies indicate enhanced physiological arousal in men but not in women during exposure to angry male asopposed to female faces, and brain imaging studies have shown that the occipital cortex and the anterior cingulate gyrus are influenced by activity in the autonomic nervous system as well as by visualattention. Hence, we suggest that the elevated occipital and anterior cingulate activation in men during confrontation with other angry and fearful males may reflect enhanced vigilance in a potentially dangerous situation.

Adult↗