Amy Garrett

Posterior cingulate cortex activation by emotional words: fMRI evidence from a valence decision task

Functional imaging studies consistently find that emotional stimuli activate the posterior cingulate cortex, a region that appears to have memory‐related functions. However, prior imaging studies have not controlled for non‐emotional stimulus features that might activate this region by engaging memory processes unrelated to emotion. This study examined whether emotional words activated the posterior cingulate cortex when these potentially confounding factors were controlled. Sixty‐four pleasant and 64 unpleasant words were matched with neutral words on non‐emotional features known to influence memory. Eight subjects underwent block‐designed functional magnetic resonance imaging scans while evaluating the valence of these words. The posterior cingulate cortex was significantly activated bilaterally during both unpleasant and pleasant compared to neutral words. The strongest activation peak with both unpleasant and pleasant words was observed in the left subgenual cingulate cortex. Anteromedial orbital and left inferior and middle frontal cortices were also activated by both pleasant and unpleasant words. Right amygdala and auditory cortex were activated only by unpleasant words, while left frontal pole was activated only by pleasant words. The results show that activation of the posterior cingulate cortex by emotional stimuli cannot be attributed to the memory‐enhancing effects of non‐emotional stimulus features. The findings are consistent with the suggestion that this region may mediate interactions of emotional and memory‐related processes. The results also extend prior findings that evaluating emotional words consistently activates the subgenual cingulate cortex, and suggest a means of probing this region in patients with mood disorders. Hum. Brain Mapping 18:30–41, 2003.

REMEMBERING FAMILIAR PEOPLE: THE POSTERIOR CINGULATE CORTEX AND AUTOBIOGRAPHICAL MEMORY RETRIEVAL

Most functional imaging studies of memory retrieval investigate memory for standardized laboratory stimuli. However, naturally acquired autobiographical memories differ from memories of standardized stimuli in important ways. Neuroimaging studies of natural memories may reveal distinctive patterns of brain activation and may have particular value in assessing clinical disorders of memory. This study used functional magnetic resonance imaging to investigate brain activation during successful retrieval of autobiographical memories elicited by name-cued recall of family members and friends. The caudal part of the left posterior cingulate cortex was the most strongly activated region and was significantly activated in all eight subjects studied. Most subjects also showed significant activation of the left anterior orbitomedial, anterior middle frontal, precuneus, cuneus, and posterior inferior parietal cortices, and the right posterior cingulate and motor cortices.Our findings are consistent with prior studies showing posterior cingulate cortex activation during autobiographical memory retrieval. This region is also consistently activated during retrieval of standardized memory stimuli when experimental designs emphasizing successful retrieval are employed. Our results support the hypothesis that the posterior cingulate cortex plays an important role in successful memory retrieval. The posterior cingulate cortex has strong reciprocal connections with entorhinal and parahippocampal cortices. Studies of early Alzheimers disease, temporal lobectomy, and hypoxic amnesia show that hypometabolism of the posterior cingulate cortex is an early and prominent indicator of pathology in these patients. Our findings suggest that autobiographical memory retrieval tasks could be used to probe the functional status of the posterior cingulate cortex in patients with early Alzheimers disease or at risk for that condition.

Effects of medication on neuroimaging findings in bipolar disorder: an updated review.

Hafeman DM, Chang KD, Garrett AS, Sanders EM, Phillips ML. Effects of medication on neuroimaging findings in bipolar disorder: an updated review. 
Bipolar Disord 2012: 14: 375–410.

Aberrant brain activation during a response inhibition task in adolescent eating disorder subtypes.

OBJECTIVE Behavioral and personality characteristics associated with excessive inhibition and disinhibition are observed in patients with eating disorders, but neural correlates of inhibitory control have not been examined in adolescents with these disorders. METHOD Thirteen female adolescents with binge eating and purging behaviors (i.e., bulimia nervosa or anorexia nervosa, binge eating/purging type);14 with anorexia nervosa, restricting type; and 13 healthy comparison subjects performed a rapid, jittered event-related go/no-go task. Functional magnetic resonance images were collected using a 3 Tesla GE scanner and a spiral pulse sequence. A whole-brain three-group analysis of variance in SPM5 was used to identify significant activation associated with the main effect of group for the comparison of correct no-go versus go trials. The mean activation in these clusters was extracted for further comparisons in SPSS. RESULTS The binge eating/purging group showed significantly greater activation than the healthy comparison group in the bilateral precentral gyri, anterior cingulate cortex, and middle and superior temporal gyri as well as greater activation relative to both comparison and restricting type anorexia subjects in the hypothalamus and right dorsolateral prefrontal cortex. Within-group analysis found that only the restricting type anorexia group showed a positive correlation between the percent correct on no-go trials and activation in posterior visual and inferior parietal cortex regions. CONCLUSIONS The present study provides preliminary evidence that during adolescence, eating disorder subtypes may be distinguishable in terms of neural correlates of inhibitory control. This distinction is consistent with differences in behavioral impulsivity in these patient groups.

Women with hypoactive sexual desire disorder compared to normal females: a functional magnetic resonance imaging study.

Lack of sexual interest is the most common sexual complaint among women. However, factors affecting sexual desire in women have rarely been studied. While the role of the brain in integrating the sensory, attentional, motivational, and motor aspects of sexual response is commonly acknowledged as important, little is known about specific patterns of brain activation and sexual interest or response, particularly among women. We compared 20 females with no history of sexual dysfunction (NHSD) to 16 women with hypoactive sexual desire disorder (HSDD) in a functional magnetic resonance imaging (fMRI) study that included assessment of subjective sexual arousal, peripheral sexual response using a vaginal photoplethysmograph (VPP), as well as brain activation across three time points. Video stimuli included erotic, sports, and relaxing segments. Subjective arousal to erotic stimuli was significantly greater in NHSD participants compared with HSDD. In the erotic-sports contrast, NHSD women showed significantly greater activation in the bilateral entorhinal cortex than HSDD women. In the same contrast, HSDD females demonstrated higher activation than NHSD females in the medial frontal gyrus (Brodmann area (BA) 10), right inferior frontal gyrus (BA 47) and bilateral putamen. There were no between group differences in VPP-correlated brain activation and peripheral sexual response was not significantly associated with either subjective sexual response or brain activation patterns. Findings were consistent across the three experimental sessions. The results suggest differences between women with NHSD and HSDD in encoding arousing stimuli, retrieval of past erotic experiences, or both. The findings of greater activation in BA 10 and BA 47 among women with HSDD suggest that this group allocated significantly more attention to monitoring and/or evaluating their responses than NHSD participants, which may interfere with normal sexual response.

Reduced Hippocampal Activity in Youth with Posttraumatic Stress Symptoms: An fMRI Study

OBJECTIVE Youth who experience interpersonal trauma and have posttraumatic stress symptoms (PTSS) develop cognitive deficits that impact their development. Our goal is to investigate the function of the hippocampus in adolescents with PTSS during a memory processing task. METHODS Twenty-seven adolescents between the ages of 10-17 years (16 with PTSS and 11 healthy controls) encoded and retrieved visually presented nouns (Verbal Declarative Memory Task) while undergoing fMRI scanning. RESULTS The PTSS group demonstrated reduced activation of the right hippocampus during the retrieval component of the task. Further, severity of symptoms of avoidance and numbing correlated with reduced left hippocampal activation during retrieval. CONCLUSIONS Decreased activity of the hippocampus during a verbal memory task may be a neurofunctional marker of PTSS in youth with history of interpersonal trauma. The results of this study may facilitate the development of focused treatments and may be of utility when assessing treatment outcome for PTSS.

Anomalous brain activation during face and gaze processing in Williams syndrome.

Objective: To investigate the discrete neural systems that underlie relatively preserved face processing skills in Williams syndrome (WS). Methods: The authors compared face and eye-gaze direction processing abilities in 11 clinically and genetically diagnosed WS subjects with 11 healthy age- and sex-matched controls, using functional MRI (fMRI). Results: Compared to controls, WS subjects showed a strong trend toward being less accurate in determining the direction of gaze and had significantly longer response latencies. Significant increases in activation were observed in the right fusiform gyrus (FuG) and several frontal and temporal regions for the WS group. By comparison, controls showed activation in the bilateral FuG, occipital, and temporal lobes. Between-group analysis showed WS subjects to have more extensive activation in the right inferior, superior, and medial frontal gyri, anterior cingulate, and several subcortical regions encompassing the anterior thalamus and caudate. Conversely, controls had greater activation in the primary and secondary visual cortices. Conclusion: The observed patterns of activation in WS subjects suggest a preservation of neural functioning within frontal and temporal regions, presumably resulting from task difficulty or compensatory mechanisms. Persons with WS may possess impairments in visual cortical regions, possibly disrupting global-coherence and visuospatial aspects of face and gaze processing.

Amygdala and hippocampal volumes in Turner syndrome: A high-resolution MRI study of X-monosomy

Turner syndrome (TS) results from partial or complete X-monosomy and is characterized by deficits in visuospatial functioning as well as social cognition and memory. Neuroimaging studies have demonstrated volumetric differences in the parietal region of females with TS compared to controls. The present study examined amygdala and hippocampus morphology in an attempt to further understand the neural correlates of psychosocial and memory functioning in TS. Thirty females with TS age 7.6-33.3 years (mean = 14.7 +/- 6.4) and 29 age-matched controls (mean age = 14.8 +/- 5.9; range = 6.4-32.7) were scanned using high resolution MRI. Volumetric analyses of the MRI scans included whole brain segmentation and manual delineation of the amygdala and hippocampus. Compared to controls, participants with TS demonstrated significantly larger left amygdala gray matter volumes, irrespective of total cerebral tissue and age. Participants with TS also showed disproportionately reduced right hippocampal volumes, involving both gray and white matter. Amygdala and hippocampal volumes appear to be impacted by X-monosomy. Aberrant morphology in these regions may be related to the social cognition and memory deficits often experienced by individuals with TS. Further investigations of changes in medial temporal morphology associated with TS are warranted.

Separating subjective emotion from the perception of emotion-inducing stimuli: An fMRI study

fMRI was used to dissociate neural responses temporally associated with the subjective experience of emotion from those associated with the perception of emotion-inducing stimuli in order to better define the emotion-related functions of the amygdala, lateral orbital frontal cortex (OFC), and hippocampus. Subjects viewed aversive pictures followed by an extended post-stimulus period of sustained subjective emotion. Brain regions showing activation paralleling the period of sustained subjective emotion were distinguished from those showing activation limited to the period of aversive picture presentation. Behavioral results showed that subjective ratings of emotion remained elevated for 20 s after offset of the aversive pictures. fMRI results showed that viewing aversive pictures activated the amygdala, lateral OFC, and hippocampus. Subjective emotion (present both during and after aversive pictures) was temporally associated with activation in the right lateral OFC and left hippocampus but not the amygdala. Ratings of subjective emotion were correlated with activation in the right lateral OFC and left hippocampus. The results support direct amygdala involvement in emotion perception but suggest that amygdala activation is not temporally associated with subjective emotion that occurs after the offset of emotion-related stimuli. The results are consistent with a general role for the lateral OFC in monitoring or reflecting on internal experience and show that hippocampal activation is sustained during a period of subjective emotion, possibly related to enhanced memory encoding for the aversive pictures.

Time course of the subjective emotional response to aversive pictures: relevance to fMRI studies

Using functional magnetic resonance imaging (fMRI) to study brain activity related to the experience of emotion presents unique challenges to neuroscientists. One important consideration arises when an experimentally induced subjective emotional response persists after the end of the emotional stimulation epoch. In this case, brain activity related to the emotional response may continue during the subsequent control or comparison epoch. The comparison epoch of the experiment may then contain a lingering emotional response. This study was conducted to better understand the time course of the subjective emotional response to intensely aversive pictures, with the goal of applying this knowledge to the design and analysis of fMRI studies of emotion. A total of 18 women in two separate experiments were shown a series of aversive, neutral and scrambled pictures presented in alternating block designs. Subjects rated the intensity of their negative feelings every 4 s while viewing the pictures. Results indicate that the subjective emotional response persists well after the end of the emotional stimulation epoch. Following a 16-s block of aversive pictures, an average of an additional 16 s elapsed before self-reported negative feelings showed a 74-80% decline. These data suggest that fMRI studies of emotion should consider the time course of the subjective response to emotionally laden stimuli.