Sheila V. Kusnoor

Extracerebellar role for Cerebellin1: Modulation of dendritic spine density and synapses in striatal medium spiny neurons

Cerebellin1 (Cbln1) is a secreted glycoprotein that was originally isolated from the cerebellum and subsequently found to regulate synaptic development and stability. Cbln1 has a heterogeneous distribution in brain, but the only site in which it has been shown to have central effects is the cerebellar cortex, where loss of Cbln1 causes a reduction in granule cell‐Purkinje cell synapses. Neurons of the thalamic parafascicular nucleus (PF), which provide glutamatergic projections to the striatum, also express high levels of Cbln1. We first examined Cbln1 in thalamostriatal neurons and then determined if cbln1 knockout mice exhibit structural deficits in striatal neurons. Virtually all PF neurons express Cbln1‐immunoreactivity (‐ir). In contrast, only rare Cbln1‐ir neurons are present in the central medial complex, the other thalamic region that projects heavily to the dorsal striatum. In the striatum Cbln1‐ir processes are apposed to medium spiny neuron (MSN) dendrites; ultrastructural studies revealed that Cbln1‐ir axon terminals form axodendritic synapses with MSNs. Tract‐tracing studies found that all PF cells retrogradely labeled from the striatum express Cbln1‐ir. We then examined the dendritic structure of Golgi‐impregnated MSNs in adult cbln1 knockout mice. MSN dendritic spine density was markedly increased in cbln1−/− mice relative to wildtype littermates, but total dendritic length was unchanged. Ultrastructural examination revealed an increase in the density of MSN axospinous synapses in cbln1−/− mice, with no change in postsynaptic density length. Thus, Cbln1 determines the dendritic structure of striatal MSNs, with effects distinct from those seen in the cerebellum. J. Comp. Neurol. 518:2525–2537, 2010.

The Cbln Family of Proteins Interact with Multiple Signaling Pathways

J. Neurochem. (2012) 121, 717–729.

Functional Connectome Analysis of Dopamine Neuron Glutamatergic Connections in Forebrain Regions

In the ventral tegmental area (VTA), a subpopulation of dopamine neurons express vesicular glutamate transporter 2 and make glutamatergic connections to nucleus accumbens (NAc) and olfactory tubercle (OT) neurons. However, their glutamatergic connections across the forebrain have not been explored systematically. To visualize dopamine neuron forebrain projections and to enable photostimulation of their axons independent of transmitter status, we virally transfected VTA neurons with channelrhodopsin-2 fused to enhanced yellow fluorescent protein (ChR2-EYFP) and used DATIREScre mice to restrict expression to dopamine neurons. ChR2-EYFP-expressing neurons almost invariably stained for tyrosine hydroxylase, identifying them as dopaminergic. Dopamine neuron axons visualized by ChR2-EYFP fluorescence projected most densely to the striatum, moderately to the amygdala and entorhinal cortex (ERC), sparsely to prefrontal and cingulate cortices, and rarely to the hippocampus. Guided by ChR2-EYFP fluorescence, we recorded systematically from putative principal neurons in target areas and determined the incidence and strength of glutamatergic connections by activating all dopamine neuron terminals impinging on recorded neurons with wide-field photostimulation. This revealed strong glutamatergic connections in the NAc, OT, and ERC; moderate strength connections in the central amygdala; and weak connections in the cingulate cortex. No glutamatergic connections were found in the dorsal striatum, hippocampus, basolateral amygdala, or prefrontal cortex. These results indicate that VTA dopamine neurons elicit widespread, but regionally distinct, glutamatergic signals in the forebrain and begin to define the dopamine neuron excitatory functional connectome. SIGNIFICANCE STATEMENT Dopamine neurons are important for the control of motivated behavior and are involved in the pathophysiology of several major neuropsychiatric disorders. Recent studies have shown that some ventral midbrain dopamine neurons are capable of glutamate cotransmission. With conditional expression of channelrhodopsin in dopamine neurons, we systematically explored dopamine neuron connections in the forebrain and identified regionally specific dopamine neuron excitatory connections. Establishing that only a subset of forebrain regions receive excitatory connections from dopamine neurons will help to determine the function of dopamine neuron glutamate cotransmission, which likely involves transmission of precise temporal signals and enhancement of the dynamic range of dopamine neuron signals.

Comparison of Cbln1 and Cbln2 Functions using Transgenic and Knockout Mice

J. Neurochem. (2012) 120, 528–540.

Guiding Oncology Patients Through the Maze of Precision Medicine

As the role of genomics in health care grows, patients increasingly require adequate genetic literacy to fully engage in their care. This study investigated a model for delivering consumer-friendly genetic information to improve understanding of precision medicine using health literacy and learning style principles. My Cancer Genome (MCG), a freely available cancer decision support tool, was used as a testbed. MCG content on a melanoma tumor mutation, BRAF V600E, was translated to a 6th-grade reading level, incorporating multiple learning modalities. A total of 90 patients and caregivers were recruited from a melanoma clinic at an academic medical center and randomized to 3 groups. Group A (control) received an exact copy of text from MCG. Group B was given the same content with hyperlinks to videos explaining key genetic concepts, identified and labeled by the team as knowledge pearls. Group C received the translated content with the knowledge pearls embedded. Changes in knowledge were measured through pre and post questionnaires. Group C showed the greatest improvement in knowledge. The study results demonstrate that providing information based on health literacy and learning style principles can improve patients’ understanding of genetic concepts, thus increasing their likelihood of taking an active role in any decision making concerning their health.

The effects of nigrostriatal dopamine depletion on the thalamic parafascicular nucleus

Neuronal loss in Parkinsons disease (PD) is seen in a number of brain regions in addition to the substantia nigra (SN). Among these is the thalamic parafascicular nucleus (PF), which sends glutamatergic projections to the striatum and receives GABAergic inputs from the SN. Recent data suggest that lesions of nigrostriatal dopamine axons cause a loss of PF neurons, which has been interpreted to suggest that the PF cell loss seen in PD is secondary to dopamine denervation. However, the extent of a PF dopamine innervation in the rat is unclear, and it is possible that PF cell loss in parkinsonism is independent of nigrostriatal dopamine degeneration. We characterized the dopamine innervation of the PF in the rat and determined if 6-hydroxydopamine SN lesions cause PF neuron degeneration. Dual-label immunohistochemistry revealed that almost all tyrosine hydroxylase-immunoreactive (TH-ir) axons in the PF also expressed dopamine-beta-hydroxylase and were therefore noradrenergic or adrenergic. Moreover, an antibody directed against dopamine revealed only very rare PF dopaminergic axons. Retrograde-tract tracing-immunohistochemistry did not uncover an innervation of the PF from midbrain dopamine neurons. Nigrostriatal dopamine neuron lesions did not elicit degeneration of PF cells, as reflected by a lack of FluoroJade C staining. Similarly, neither unilateral 6-OHDA lesions of nigrostriatal axons nor the dorsal noradrenergic bundle decreased the number of PF neurons or the number of PF neurons retrogradely-labeled from the striatum. These data suggest that the loss of thalamostriatal PF neurons in Parkinsons Disease is a primary event rather than secondary to nigrostriatal dopamine degeneration.

Is the loss of thalamostriatal neurons protective in parkinsonism

Neuronal loss in Parkinsons disease (PD) is more widespread than originally thought. Among the extrastriatal sites in which significant loss of neurons has been reported is the centremedian-parafascicular (CM-PF) complex of the thalamus, which provides one of the three major afferent sources to the striatum. The functional significance of CM-PF loss in PD is unclear. Interestingly, several recent small trials have suggested that deep brain stimulation of the CM-PF improves motor function in PD. We discuss the possible transsynaptic determination of CM-PF loss secondary to nigrostriatal dopamine degeneration, and suggest that expression of the glycoprotein cerebellin1 (Cbln1) in CM-PF neurons may play an important role in striatal synaptic remodeling in parkinsonism.

Institute of Medicine Measures of Social and Behavioral Determinants of Health: A Feasibility Study

INTRODUCTION Social and behavioral factors are known to affect health but are not routinely assessed in medical practice. To date, no studies have assessed a parsimonious panel of measures of social and behavioral determinants of health (SBDs). This study evaluated the panel of SBD measures recommended by the Institute of Medicine and examined the effect of question order. METHODS Adults, aged ≥18 years, were recruited using ResearchMatch.org for this randomized, parallel design study conducted in 2015 (data analyzed in 2015-2016). Three versions of the SBD measures, sharing the same items but in different orders of presentation (Versions 1-3), were developed. Randomized to six groups, participants completed each version at least 1 week apart (Weeks 1-3). Version order was counterbalanced across each administration and randomization was stratified by gender, race, and age. Main outcomes were effect of question order, completion time, and non-response rates. RESULTS Of 781 participants, 624 (80%) completed the Week 1 questionnaire; median completion time for answering all SBD questions was 5 minutes, 583/624 participants answered all items, and no statistically significant differences associated with question order were observed when comparing responses across all versions. No significant differences in responses within assignment groups over time were found, with the exception of the stress measure for Group 5 (p=0.036). CONCLUSION Question order did not significantly impact participant responses. Time to complete the questionnaire was brief, and non-response rate was low. Findings support the feasibility of using the Institute of Medicine-recommended questionnaire to capture SBDs.

Internet-Based Assessment of Oncology Health Care Professional Learning Style and Optimization of Materials for Web-Based Learning: Controlled Trial With Concealed Allocation

Background Precision medicine has resulted in increasing complexity in the treatment of cancer. Web-based educational materials can help address the needs of oncology health care professionals seeking to understand up-to-date treatment strategies. Objective This study aimed to assess learning styles of oncology health care professionals and to determine whether learning style-tailored educational materials lead to enhanced learning. Methods In all, 21,465 oncology health care professionals were invited by email to participate in the fully automated, parallel group study. Enrollment and follow-up occurred between July 13 and September 7, 2015. Self-enrolled participants took a learning style survey and were assigned to the intervention or control arm using concealed alternating allocation. Participants in the intervention group viewed educational materials consistent with their preferences for learning (reading, listening, and/or watching); participants in the control group viewed educational materials typical of the My Cancer Genome website. Educational materials covered the topic of treatment of metastatic estrogen receptor-positive (ER+) breast cancer using cyclin-dependent kinases 4/6 (CDK4/6) inhibitors. Participant knowledge was assessed immediately before (pretest), immediately after (posttest), and 2 weeks after (follow-up test) review of the educational materials. Study statisticians were blinded to group assignment. Results A total of 751 participants enrolled in the study. Of these, 367 (48.9%) were allocated to the intervention arm and 384 (51.1%) were allocated to the control arm. Of those allocated to the intervention arm, 256 (69.8%) completed all assessments. Of those allocated to the control arm, 296 (77.1%) completed all assessments. An additional 12 participants were deemed ineligible and one withdrew. Of the 552 participants, 438 (79.3%) self-identified as multimodal learners. The intervention arm showed greater improvement in posttest score compared to the control group (0.4 points or 4.0% more improvement on average; P=.004) and a higher follow-up test score than the control group (0.3 points or 3.3% more improvement on average; P=.02). Conclusions Although the study demonstrated more learning with learning style-tailored educational materials, the magnitude of increased learning and the largely multimodal learning styles preferred by the study participants lead us to conclude that future content-creation efforts should focus on multimodal educational materials rather than learning style-tailored content.

National Academy of Medicine Social and Behavioral Measures: Associations With Self-Reported Health

INTRODUCTION Social and behavioral factors play important roles in physical and mental health; however, they are not routinely assessed in the healthcare system. A brief panel of measures of social and behavioral determinants of health (SBDs) were recommended in a National Academy of Medicine report for use in electronic health records. Initial testing of the panel established feasibility of use and robustness of the measures. This study evaluates their convergent and divergent validity in relation to self-reported physical and mental health and social desirability bias. METHODS Adults, aged ≥18 years, were recruited through Qualtrics online panel survey platform in 2015 (data analyzed in 2015-2016). Participants completed the (1) panel of SBD measures; (2) 12-Item Short Form Health Survey to assess associations with global physical and mental health; and (3) Marlowe-Crowne Social Desirability Scale short form to assess whether social desirability influenced associations between SBD measures and self-reported health. RESULTS The sample included 513 participants (mean age, 47.9 [SD=14.2] years; 65.5% female). Several SBD domain measures were associated with physical and mental health. Adjusting for age, poorer physical and mental health were observed among participants reporting higher levels of financial resource strain, stress, depression, physical inactivity, current tobacco use, and a positive score for intimate partner violence. These associations remained significant after adjustment for social desirability bias. CONCLUSIONS SBD domains were associated with global measures of physical and mental health and were not impacted by social desirability bias. The panel of SBD measures should now be tested in clinical settings.