Shaky scaffolding: Age differences in cerebellar activation revealed through activation likelihood estimation meta-analysis.

Cognitive neuroscience research has provided foundational insights into aging, but has focused primarily on the cerebral cortex. However, the cerebellum is subject to the effects of aging. Given the importance of this structure in the performance of motor and cognitive tasks, cerebellar differences stand to provide critical insights into age differences in behavior. However, our understanding of cerebellar functional activation in aging is limited. Thus, we completed a meta-analysis of neuroimaging studies across task domains. Unlike in the cortex where an increase in bilateral activation is seen during cognitive task performance with advanced age, there is less overlap in cerebellar activation across tasks in older adults (OAs) relative to young. Conversely, we see an increase in activation overlap in OAs during motor tasks. We propose that this is due to inputs for comparator processing in the context of control theory (cortical and spinal) that may be differentially impacted in aging. These findings advance our understanding of the aging mind and brain.

Common pathways and communication between the brain and heart: connecting post-traumatic stress disorder and heart failure.

Psychiatric illnesses and cardiovascular disease (CVD) contribute to significant overall morbidity, mortality, and health care costs, and are predicted to reach epidemic proportions with the aging population. Within the Veterans Administration (VA) health care system, psychiatric illnesses such as post-traumatic stress disorder (PTSD) and CVD such as heart failure (HF), are leading causes of hospital admissions, prolonged hospital stays, and resource utilization. Numerous studies have demonstrated associations between PTSD symptoms and CVD endpoints, particularly in the Veteran population. Not only does PTSD increase the risk of HF, but this relationship is bi-directional. Accordingly, a VA-sponsored conference entitled "Cardiovascular Comorbidities in PTSD: The Brain-Heart Consortium" was convened to explore potential relationships and common biological pathways between PTSD and HF. The conference was framed around the hypothesis that specific common systems are dysregulated in both PTSD and HF, resulting in a synergistic acceleration and amplification of both disease processes. The conference was not intended to identify all independent pathways that give rise to PTSD and HF, but rather identify shared systems, pathways, and biological mediators that would be modifiable in both disease processes. The results from this conference identified specific endocrine, autonomic, immune, structural, genetic, and physiological changes that may contribute to shared PTSD-CVD pathophysiology and could represent unique opportunities to develop therapies for both PTSD and HF. Some recommendations from the group for future research opportunities are provided.

Greater Early Posttrauma Activation in the Right Inferior Frontal Gyrus Predicts Recovery From Posttraumatic Stress Disorder Symptoms.

BACKGROUND: Posttraumatic stress disorder (PTSD) has been associated with altered emotion processing and modulation in specific brain regions, i.e., the amygdala, insula, and medial prefrontal and anterior cingulate cortices. Functional alterations in these regions, recorded shortly after trauma exposure, may predict changes in PTSD symptoms. METHODS: Survivors (N = 104) of a traumatic event, predominantly a motor vehicle accident, were included. Functional magnetic resonance imaging was used to assess brain activation 1, 6, and 14 months after trauma exposure (T1, T2, and T3, respectively). Participants performed the Shifted-attention Emotional Appraisal Task, which probes 3 affective processes: implicit emotional processing (of emotional faces), emotion modulation by attention shifting (away from these faces), and emotion modulation by appraisal (of the participants' own emotional response to these faces). We defined regions of interest based on task-related activations, extracted beta weights from these regions of interest, and submitted them to a series of analyses to examine relationships between neural activation and PTSD severity over the 3 time points. RESULTS: At T1, a regression model containing activations in the left dorsolateral prefrontal cortex, bilateral inferior frontal gyrus (IFG), and medial prefrontal cortex during emotion modulation by appraisal significantly predicted change in PTSD symptoms. More specifically, greater right IFG activation at T1 was associated with greater reduction in symptom severity (T1-T3). Exploratory analysis also found that activation of the right IFG increased from T1 to T3. CONCLUSIONS: The results suggest that greater early posttrauma activation during emotion appraisal in the right IFG, a region previously linked to cognitive control in PTSD, predicts recovery from PTSD symptoms.

Fear Extinction Learning in Posttraumatic Stress Disorder.

Impairments in fear extinction processes have been implicated in the genesis and maintenance of debilitating psychopathologies, including Posttraumatic stress disorder (PTSD). PTSD, classified as a trauma- and stressor-related disorder, is characterized by four symptom clusters: intrusive recollections of trauma, avoidance of trauma-related stimuli, alterations in cognition and mood, and hyperarousal. One of the key pathological feature associated with the persistence of these symptoms is impaired fear extinction, as delineated in multiple studies employing Pavlovian fear-conditioning paradigms. These paradigms, comprising fear acquisition, extinction, extinction recall, and fear renewal phases, have illuminated the neurobiological substrates of PTSD. Dysfunctions in the neural circuits that mediate these fear learning and extinction processes can result in failure to extinguish fear responses and retain extinction memory, giving rise to enduring experience of fear and anxiety. The protective avoidance behaviors observed in individuals with PTSD further exacerbate intrusive symptoms and pose challenges to effective treatment strategies. A comprehensive analysis of fear conditioning and extinction processes, along with the underlying neurobiology, could significantly enhance our understanding of PTSD pathophysiology. This chapter delineates the role of fear extinction processes in PTSD, investigates the underlying neurobiological substrates, and underscores the therapeutic implications, while also identifying future research directions.

Reward Processing and Circuit Dysregulation in Posttraumatic Stress Disorder.

Past decades have witnessed substantial progress in understanding of neurobiological mechanisms that contribute to generation of various PTSD symptoms, including intrusive memories, physiological arousal and avoidance of trauma reminders. However, the neurobiology of anhedonia and emotional numbing in PTSD, that have been conceptualized as reward processing deficits - reward wanting (anticipation of reward) and reward liking (satisfaction with reward outcome), respectively, remains largely unexplored. Empirical evidence on reward processing in PTSD is rather limited, and no studies have examined association of reward processing abnormalities and neurocircuitry-based models of PTSD pathophysiology. The manuscript briefly summarizes "state of the science" of both human reward processing, and of PTSD implicated neurocircuitry, as well as empirical evidence of reward processing deficits in PTSD. We then summarize current gaps in the literature and outline key future directions, further illustrating it by the example of two alternative explanations of PTSD pathophysiology potentially affecting reward processing via different neurobiological pathways. Studying reward processing in PTSD will not only advance the understanding of their link, but also could enhance current treatment approaches by specifically targeting anhedonia and emotional symptoms in PTSD patients.

Altered resting-state functional connectivity in adolescents is associated with PTSD symptoms and trauma exposure.

Alterations in resting-state functional connectivity (rsFC) have been demonstrated in Posttraumatic Stress Disorder (PTSD). However, such reports have primarily focused on adult participants, whereas findings in adolescents with PTSD are mixed and not entirely consistent with the adult literature. Here, we examined rsFC in a non-treatment seeking adolescent sample with posttraumatic stress symptoms (PTSS; n = 59) relative to asymptomatic controls (n = 226). We also examined differences between trauma-exposed and non-exposed control subgroups (TEC n = 73 and Non-TEC n = 153) to examine alterations associated with more general trauma exposure. Finally, we compared the PTSS and TEC groups, to confirm that the reported alterations in PTSS were not driven by trauma exposure. Using a seed-based approach, we examined connectivity of default-mode (DMN) and salience (SN) networks, where alterations have been previously reported. Results suggest that PTSS are associated with less within-DMN connectivity and greater SN-DMN connectivity, as well as altered connectivity with attention regions. Trauma exposure is associated with greater within-SN connectivity. Additionally, we report findings from exploratory connectome-based analysis, which demonstrate a number of topological alterations within DMN in the PTSS group. Overall, our findings replicate prior reports of altered rsFC in PTSD and extend them to non-treatment seeking, trauma-exposed adolescents, who did or did not report PTSS. They specifically highlight SN-DMN desegregation, lower within-DMN and greater within-SN connectivity, as well as altered connectivity with attention regions, in trauma-exposed adolescents. Future research is required to confirm that adolescents with diagnosed PTSD have similar/exacerbated connectivity patterns.