Check out some of the papers that were recently published by DMCBH members:

Kiran Soma: An aggressive interaction rapidly increases brain androgens in a male songbird during the non-breeding season

Journal: Journal of Neuroscience 

Aggression is an essential behaviour which affects access to resources in different environmental contexts. During the breeding season, androgens synthesized by the gonads promote aggression for mating and resource guarding purposes. However, aggression also occurs during the non-breeding season without elevated levels of androgen synthesis, potentially due to the synthesis of neurosteroids. The present study examined 11 steroids in the context following a simulated territorial intrusion (STI) in male song sparrows during the breeding and non-breeding seasons. In the breeding season, it had no rapid effect on androgens or estrogens, but in the non-breeding season, STI increased testosterone and androstenedione in several relevant brain regions but not in the blood. Overall, it was observed that rapid, socially modulated changes in brain steroid levels are more prominent during the non-breeding season, suggesting that neurosteroids play a key role in aggression during this time.  


Daniela Palombo: The relationship between environmentally induced emotion and memory for a naturalistic virtual experience 

Journal: Cognition and Emotion 

This study aims to determine how memory is affected by an indirect, environmentally induced emotional state. Participants were randomly assigned to discovery (n = 305) and replication (n = 306) groups and exposed to an ambiguously threatening video depicting the exploration of an abandoned laboratory in first person perspective. Immediately afterwards, participants completed a test of item memory, then a test where they rearranged 14 stimuli into the order that they were encountered in the video. Afterwards, participants indicated how long they believed the video lasted and then completed subjective memory tests. In both samples, a Partial Least Squares Correlation analysis showed that a state of high negative emotion was reliably associated with better memory about the item. However, there was no effect for any temporal memory measures such as order and duration. In conclusion, an environmentally induced state of negative emotion corresponds with enhanced memory about “what” happened, but not necessarily “when” it happened.  


Lara Boyd: Modulation of the Association Between Corticospinal Tract Damage and Outcome After Stroke by White Matter Hyperintensities 

Journal: Neurology

Common motor symptoms occurring after stroke are related to damage to the corticospinal tract (CST), which is normally involved in voluntary motor function. To mediate motor recovery, the brain uses surviving neural pathways to compensate for this damage. White matter hyperintensities (WMH) are the most common form of age-related cerebrovascular damage and reflect damage or lesions within the white matter of the brain. Motor outcomes after stroke can be affected by WMHs due to the potential of preexisting damage in compensatory pathways. The present study tests whether the relationship between post-stroke motor impairment and CST damage is affected by concurrent WMH damage. Greater CST damage and WMH volume was related to more severe motor impairment, and the severity of the WMH affected the relationship between the degree of motor impairment and CST damage. In those with smaller VMH volumes, the relationship was stronger, but in those with moderate-severe VMHs, there was no significant relationship. These findings indicate that WMHs may be an important consideration in building models of stroke recovery in the aging population.  


Fidel Vila-Rodriguez: Effects of repetitive transcranial magnetic stimulation on individual variability of resting-state functional connectivity in major depressive disorder 

Journal: Journal of Psychiatry & Neuroscience  

Past research has indicated that repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex is an effective treatment for major depressive disorder, predicting greater clinical improvement in those with treatment resistant depression. However, the outcomes of the treatment are diverse due to individual variability in brain structure. The present study examined a potential mechanism of action of rTMS on individual variability in resting state functional connectivity before and after treatment. Variability in connectivity was examined in controls and depressed patients and quantified by calculating the mean correlational distance of connectivity maps relative to controls. Patients with major depressive disorder did not show significant differences in baseline variability in connectivity compared with controls. Also, treatment with rTMS was found to increase the individual variability of the right anterior cingulate cortex, indicating a more atypical connectivity pattern. This study provides preliminary evidence that rTMS can alter brain function via individual variability of resting state functional connectivity within the right anterior cingulate and precuneous, but with no significant relation to clinical outcomes.  


Annie Ciernia: Impact of maternal immune activation and sex on placental and fetal brain cytokine and gene expression profiles in a preclinical model of neurodevelopmental disorders

Journal: Journal of Neuroinflammation  

Maternal inflammation during pregnancy is associated with neurodevelopmental disorders in the child such as autism spectrum disorder. However, not much is known about the specific impact of maternal immune activation (MIA) on placental and fetal brain development. The present study aimed to investigate the effects of maternal immune activation by exposing pregnant mice to polyinosinic: polycytidylic acid, which elicits an immune response, and then analyzing the placental and brain tissues of offspring. There was an increased sex-dependent cytokine response in the placenta and fetal brains of male offspring. In addition, MIA offspring exhibit dysregulation of genes relating to synaptic vesicles, neuronal development, adhesion and metabolic processes in fetal brains and placenta. These may contribute to the observed structural and neuronal connectivity issues found in neurodevelopmental disorders. These findings support the hypothesis that MIA contributes to the sex-specific abnormalities in ASD, potentially due to altered neuron development from exposure to inflammatory cytokines.  


Stan Floresco: Perturbations in risk/reward decision making and frontal cortical catecholamine regulation induced by mild traumatic brain injury 

Journal: Behavioural Brain Research  

While the effects of mild traumatic brain injury are usually transient, repetitive mild traumatic brain injury (rmTBI) can result in severe and long-lasting cognitive impairments. The prefrontal cortex (PFC) is frequently affected by brain injury and mediates decision making in situations involving uncertain risk/reward outcomes. The prefrontal cortex is innervated by catecholaminergic fibers containing dopamine and norepinephrine, which modulate PFC-facilitated processes. Abnormalities in catecholamine activity like increased dopamine and norepinephrine can result in impaired cognitive function. The present study examined the effect of rmTBI on risk/reward decision making behavior and catecholamine transmitter regulator proteins. Rats were exposed to sham, single, or multiple cortical impact injuries and assessed for decision making behaviours. Researchers found that mTBI increased risky choice preference and rmTBI increased latencies to make risky choices in males, demonstrating a delay in processing speed. Both males and females exhibited reduced levels of norepinephrine reuptake transport in the orbitofrontal cortex after rmTBI, suggesting that the orbitofrontal cortex is susceptible to catecholamine instability after rmTBI.  


Todd Woodward: Hypoactivation of the language network during auditory imagery contributes to hallucinations in Schizophrenia 

Journal: Psychiatry Research: Neuroimaging 

One of the most common symptoms of schizophrenia is the presence of auditory verbal hallucinations (AVH) – hearing voices in the absence of external stimuli. The present study provides an updated whole-brain network analysis of a previously published study which showed reduced connections between Broca’s and Wernicke’s regions of interest for hallucinations. Researchers found that the language network showed an earlier and shallower response for hallucinating patients in the auditory imagery condition only. This suggests that reduced activation of the language network during internal auditory imagery may contribute to the tendency to hallucinate.  


Lara Boyd, Doris Doudet:  Evaluation of microglia activation related markers following a clinical course of TBS: A non-human primate study 

Journal: PLoS One 

Various forms of repetitive transcranial magnetic stimulation (rTMS) have been evaluated for treating different neuropsychiatric disorders. However, little is known about their effects on glial cells and neuroinflammation. The study used a multimodal imaging approach to assess the effects of a clinical course of theta burst stimulation, a type of rTMS, on markers for microglia activation and tissue injury. Stimulation was delivered to healthy non-human primates 5 times a week over 3-4 weeks. Results indicated that TBS in the healthy brain did not change the expression of markers commonly associated with neuroinflammation and injuries, potentially indicating the absence of a neuroinflammatory response. 


Joanne Matsubara:  Synthesis and Evaluation of a Novel PET Radioligand for Imaging Glutaminyl Cyclase Activity as a Biomarker for Detecting Alzheimer’s Disease 

Journal: ACS Sensors 

Alzheimer’s disease (AD) is the most prevalent cause of dementia, marked by the presence of extracellular amyloid-β protein (Abeta) and intracellular neurofibrillary tangles. These eventually lead to neuronal toxicity and tissue atrophy. Abeta proteins can be truncated at the N-terminal, potentially exposing a glutamic acid residue, allowing cyclization of Abeta by glutaminyl cyclase (QC). Past research has indicated that treatments of transgenic AD mice models with QC inhibitors can diminish plaque formation and improve cognition, suggesting that QC plays a role in the neuropathology of Alzheimer’s. This study describes the design, synthesis and validation of a novel PET radioligand designed to target and image QC. Non-invasive PET imaging showed that the probe is distributed in the brain 5 minutes after intravenous injection, and that AD mice show significantly higher QC activity. This new probe can potentially speed up screening of QC inhibitor treatments, evaluate their efficacy, and improve early detection of AD.