Faculty Bibliography

Making decisions when an objectively correct option is not obvious, involves different neurobiological mechanisms than "veridical" decision making. The dorsolateral prefrontal cortex (DLPFC) exhibits a distinct pattern of prefrontal activation in non-veridical cognition, but little is known about the role of underlying neurobiological endophenotypes. A functional polymorphism in the brain-derived neurotrophic factor (BDNF) gene, causing a valine (Val) to methionine (Met) amino acid substitution at codon 66, has been shown to be associated with structural and functional changes in DLPFC and affect veridical decision making. We hypothesized that the BDNF genotype may be related to non-veridical cognition. We explored whether the BDNF Val66Met polymorphism affected preferences in a cognitive task devoid of intrinsically correct or false choice, using the Cognitive Bias Task (CBT). We also studied if manipulating the right DLPFC with rTMS stimulation changes non-veridical preferences. Sixteen healthy adults, including 9 Val/Val and 7 Val/Met subjects, participated in the study. Participants with Val/Met genotype expressed a more context-independent, internally driven choice selection preference. Val/Val subjects' selection was more dependent on the context, driven by the properties of external stimuli. rTMS stimulation enhanced a preexisting bias in choice preferences. In Val/Val subjects, TMS stimulation shifted the non-veridical preference bias towards greater dependence on external context, while in Val/Met subjects the CBT score became more context-independent. Our study showed that BDNF genotype is associated with a bias in non-veridical preferences and that Val/Val and Val/Met subjects respond differently to right DLPFC rTMS stimulation, further enhancing their preexisting selection biases.

We test the emerging hypothesis that prefrontal cortical mechanisms involved in non-veridical decision making do not overlap with those of veridical decision making. Healthy female subjects performed an experimental task assessing free choice, agent-centered decision making (The Cognitive Bias Task) and a veridical control task related to visuospatial working memory (the Moving Spot Task). Transcranial magnetic stimulation (TMS) was applied to the left and right dorsolateral prefrontal cortex (DLPFC) using 1 Hz and 10 Hz (intermittent) rTMS and sham protocols. Both 1 Hz and 10 Hz stimulation of the DLPFC triggered a shift towards a more context-independent, internal representations driven non-veridical selection bias. A significantly reduced preference for choosing objects based on similarity was detected, following both 1 Hz and 10 Hz treatment of the right as well as 1 Hz rTMS of the left DLPFC. 1 Hz rTMS treatment of the right DLPFC also triggered a significant improvement in visuospatial working memory performance on the veridical task. The effects induced by prefrontal TMS mimicked those of posterior lesions, suggesting that prefrontal stimulation influenced neuronal activity in remote cortical regions interconnected with the stimulation site via longitudinal fasciculi.

Abstract The relationship between specific genes and particular diseases in neuropsychiatry is unclear, and newer studies focus on shared domains of neurobiological and cognitive pathology across different disorders. This paper reviews the evidence for an association between schizophrenia and frontotemporal dementia, including symptom similarity, familial co-morbidity, and neuroanatomical changes. Genetic as well as epigenetic findings from both schizophrenia and frontotemporal dementia are also discussed. As a result, we introduce the hypothesis of a shared susceptibility for certain subgroups of schizophrenia and frontotemporal dementia. This common causation may involve the same gene(s) at different stages of life: early in schizophrenia and late in frontotemporal dementia. Additionally, we provide a rationale for future research that should emphasize both genetic and cognitive parallels between certain forms of schizophrenia and frontotemporal dementia in a synergistic, coordinated way, placing both in the context of aberrant lateralization patterns.

Hemispheric asymmetry represents a cardinal feature of cerebral organization, but the nature of structural and functional differences between the hemispheres is far from fully understood. Using Magnetic Resonance Imaging morphometry, we identified several volumetric differences between the two hemispheres of the human brain. Heteromodal inferoparietal and lateral prefrontal cortices are more extensive in the right than left hemisphere, as is visual cortex. Heteromodal mesial and orbital prefrontal and cingulate cortices are more extensive in the left than right hemisphere, as are somatosensory, parts of motor, and auditory cortices. Thus, heteromodal association cortices are more extensively represented on the lateral aspect of the right than in the left hemisphere, and modality-specific cortices are more extensively represented on the lateral aspect of the left than in the right hemisphere. On the mesial aspect heteromodal association cortices are more extensively represented in the left than right hemisphere

Traumatic brain injury (TBI) is a neurological injury that can affect the cognitive, emotional, psychological, and physical functioning of an individual. The clinical neuropsychologist working with TBI patients must take a holistic approach when assessing and treating the patient and consider the patient in total, including premorbid and post-incident factors, to formulate a comprehensive and accurate picture of the patient. This approach will guide the clinician regarding multiple types of treatment the patient may require

OBJECTIVE: Novelty and routinization-related information processing disturbances were examined in adolescent males with ADHD using an oddball paradigm and electrophysiological measurement of theta (4-7Hz) activity. METHODS: Fifty-four unmedicated adolescent males (12-18years) with Attention Deficit Hyperactivity Disorder (ADHD) and matched controls performed an auditory oddball task. Theta activity was sub-averaged, and Fourier Integrals with simultaneous measurement of electrodermal activity (EDA) was used to index response to stimulus novelty and routinization. RESULTS: ADHD participants showed an overall increase in theta activity to both novel and routine stimuli relative to controls. While controls showed increased theta activity in response to novel compared to routine targets across the brain, ADHD participants did not show this novelty-related increase in theta activity in the right anterior/frontal brain. CONCLUSIONS: The findings of this study are consistent with disturbances in theta activity and the brain substrates of novelty relative to routinization-related processing in ADHD. SIGNIFICANCE: These findings show that there are distinct alterations in theta activity related to stimulus novelty and routinization during an auditory oddball task in ADHD, and they highlight the value of using an event-related approach to elucidate the neural substrates of stimulus processing in ADHD