Bianca Voss

Neural correlates of the core facets of empathy in schizophrenia

Empathy is a multidimensional construct composed of several components such as emotion recognition, emotional perspective taking and affective responsiveness. Even though patients with schizophrenia demonstrate deficits in all core components of this basic social ability, the neural underpinnings of these dysfunctions are less clear. Using fMRI, we analyzed data from 15 patients meeting the DSM-IV criteria for schizophrenia and 15 matched healthy volunteers performing three separate paradigms tapping the core components of empathy, i.e. emotion recognition, perspective taking and affective responsiveness. Behavioral data analysis indicated a significant empathic deficit in patients, reflected in worse performance in all three domains. Analysis of functional data revealed hypoactivation in a fronto-temporo-parietal network including the amygdala in patients. Moreover, amygdala activation correlated negatively with severity of negative symptoms. The results suggest that schizophrenia patients not only suffer from a broad range of emotional deficits but also show cortical and subcortical abnormalities, extending previous findings on fronto-temporal cortical dysfunctions. Since empathy is related to psychosocial functioning and hence of high clinical relevance in schizophrenia, a more detailed understanding of the exact nature of these impairments is mandatory.

Muscarinic antagonist effects on executive control of attention

Acetylcholine plays a major role in mediating attention processes. We investigated the muscarinic antagonist effect of scopolamine on functional neuro-anatomy of attention and cognition. We assessed 12 healthy volunteers while performing the Attention Network Task on 0.4 mg scopolamine and placebo in a single-blind randomized trial in a 1.5 T magnetic resonance scanner. Neurocognitive measures included verbal learning, verbal memory, verbal fluency, trail making, digit span, a continuous performance task and a planning task (Tower of London). When compared to placebo, scopolamine increased reaction times for conflicting stimulus processing, together with decreasing brain activation in the anterior cingulate cortex (a brain region involved in conflict processing) suggestive of a muscarinic antagonist effect on executive control of attention. Contrary to the notion of a predominantly right-hemispheric lateralization of cognitive processes associated with orienting attention, scopolamine reduced brain activity in left superior and left middle frontal brain areas. Our neuropsychological test data revealed a selective effect of scopolamine on verbal learning and memory while other cognitive domains, such as planning and working memory, were unaffected. These findings are consistent with muscarinic modulation of dopaminergic neurotransmission in frontal attention networks when processing conflicting information.

Nicotinic antagonist effects on functional attention networks

Cholinergic neurotransmission has been implicated in memory and attention. We investigated the effect of the non-competitive nicotinic antagonist mecamylamine on three components of attention processes (i.e. alerting, orienting and executive control) in 12 healthy male subjects whilst performing the Attention Network Task (ANT) in a magnetic resonance imaging (MRI) scanner. Participants received 15 mg mecamylamine in a single blind and placebo- controlled randomized procedure 90 min prior to obtaining functional MRI data. Our results confirm previous reports of beneficial effects of cueing (alerting and orienting) and detrimental effects of conflict (executive control) on reaction times when performing the ANT. The functional MRI data confirmed distinct neural networks associated with each of the three attention components. Alerting was associated with increased left temporal lobe activation while orienting increased bilateral prefrontal, right precuneus and left caudate activation. Executive control activated anterior cingulate and precuneus. Mecamylamine slowed overall response time and down-regulated brain activation associated with orienting and to some extent brain activation associated with executive control when compared to placebo. These findings are consistent with nicotinic modulation of orienting attention by cueing and executive control when responding to conflicting information. The latter nicotine antagonist effect may be mediated via cholinergic modulation of dopamine neurotransmission in mesolimbic pathways.

Neural correlates of unsuccessful memory performance in MCI

People with mild cognitive impairment (MCI) are at an elevated risk of developing Alzheimer’s disease or other forms of dementia. Although the neural correlates of successful memory performance in MCI have been widely investigated, the neural mechanisms involved in unsuccessful memory performance remain unknown. The current study examines the differences between patients suffering from stable amnestic MCI with multiple deficit syndromes and healthy elderly controls in relation to the neural correlates of both successful and unsuccessful encoding and recognition. Forty-six subjects (27 controls, 19 MCI) from the HelMA (Helmholtz Alliance for Mental Health in an Aging Society) completed a comprehensive neuropsychological test battery and participated in an fMRI experiment for associative face-name memory. In patients, the areas of frontal, parietal, and temporal cortices were less involved during unsuccessful encoding and recognition. A temporary dysfunction of the top-down control of frontal or parietal (or both) areas is likely to result in a non-selective propagation of task-related information to memory.

From provocation to aggression: the neural network

BackgroundIn-vivo observations of neural processes during human aggressive behavior are difficult to obtain, limiting the number of studies in this area. To address this gap, the present study implemented a social reactive aggression paradigm in 29 healthy men, employing non-violent provocation in a two-player game to elicit aggressive behavior in fMRI settings.ResultsParticipants responded more aggressively after high provocation reflected in taking more money from their opponents. Comparing aggression trials after high provocation to those after low provocation revealed activations in neural circuits involved in aggression: the medial prefrontal cortex (mPFC), the orbitofrontal cortex (OFC), the dorsolateral prefrontal cortex (dlPFC), the anterior cingulate cortex (ACC), and the insula. In general, our findings indicate that aggressive behavior activates a complex, widespread brain network, reflecting a cortico-limbic interaction and overlapping with circuits underlying negative emotions and conflicting decision-making. Brain activation during provocation in the OFC was associated with the degree of aggressive behavior in this task.ConclusionTherefore, data suggest there is greater susceptibility for provocation, rather than less inhibition of aggressive tendencies, in individuals with higher aggressive responses. This further supports the hypothesis that reactive aggression can be seen as a consequence of provocation of aggressive emotional responses and parallel evaluative regulatory processes mediated mainly by the insula and prefrontal areas (OFC, mPFC, dlPFC, and ACC) respectively.

Psychological Sequelae After Severe Trauma

Severe trauma can elicit not only a cascade of physiological injuries but also a series of psychological consequences or impairments. These hurts are not necessarily obvious at the time the trauma victims first reach medical facilities (e.g., emergency rooms) but emerge after a certain delay of hours, days, months, years, or decades. As a consequence of severe trauma, acute stress disorder, post-traumatic stress disorder (PTSD) as well as comorbid symptoms of depression and anxiety are of major concern. With prevalence rates of PTSD of about 25 % after a traumatic experience, clinicians need to be aware of the high risk of psychological impairments in addition to physical injuries. Risk factors such as female gender, preexisting psychological conditions, and peritraumatic symptoms of dissociation have to be considered. Specific considerations have to be factored regarding the psychological sequelae of traumatic experiences in children and adolescents. Altogether, an enhanced awareness of clinicians for such complications can support the supply of adequate measures for the patients at risk and may hence be of benefit for the public health system.