Comparison of unitary synaptic currents generated by indirect and direct pathway neurons of the mouse striatum.

Two subtypes of striatal spiny projection neurons, iSPNs and dSPNs, whose axons form the "indirect" and "direct" pathways of the basal ganglia, respectively, both make synaptic connections in the external globus pallidus (GPe) but are usually found to have different effects on behavior. Activation of the terminal fields of iSPNs or dSPNs generated compound currents in almost all GPe neurons. To determine whether iSPNs and dSPNs have the same or different effects on pallidal neurons, we studied the unitary synaptic currents generated in GPe neurons by action potentials in single striatal neurons. We used optogenetic excitation to elicit repetitive firing in a small number of nearby SPNs, producing sparse barrages of inhibitory postsynaptic currents (IPSCs) in GPe neurons. From these barrages, we isolated sequences of IPSCs with similar time courses and amplitudes, which presumably arose from the same SPN. There was no difference between the amplitudes of unitary IPSCs generated by the indirect and direct pathways. Most unitary IPSCs were small, but a subset from each pathway were much larger. To determine the effects of these unitary synaptic currents on the action potential firing of GPe neurons, we drove SPNs to fire as before and recorded the membrane potential of GPe neurons. Large unitary potentials from iSPNs and dSPNs perturbed the spike timing of GPe neurons in a similar way. Most SPN-GPe neuron pairs are weakly connected, but a subset of pairs in both pathways are strongly connected.NEW & NOTEWORTHY This is the first study to record the synaptic currents generated by single identified direct or indirect pathway striatal neurons on single pallidal neurons. Each GPe neuron receives synaptic inputs from both pathways. Most striatal neurons generate small synaptic currents that become influential when occurring together, but a few are powerful enough to be individually influential.

Propagation of Oscillations in the Indirect Pathway of the Basal Ganglia.

Oscillatory signals propagate in the basal ganglia from prototypic neurons in the external globus pallidus (GPe) to their target neurons in the substantia nigra pars reticulata (SNr), internal pallidal segment, and subthalamic nucleus. Neurons in the GPe fire spontaneously, so oscillatory input signals can be encoded as changes in timing of action potentials within an ongoing spike train. When GPe neurons were driven by an oscillatory current in male and female mice, these spike-timing changes produced spike-oscillation coherence over a range of frequencies extending at least to 100 Hz. Using the known kinetics of the GPe→SNr synapse, we calculated the postsynaptic currents that would be generated in SNr neurons from the recorded GPe spike trains. The ongoing synaptic barrage from spontaneous firing, frequency-dependent short-term depression, and stochastic fluctuations at the synapse embed the input oscillation into a noisy sequence of synaptic currents in the SNr. The oscillatory component of the resulting synaptic current must compete with the noisy spontaneous synaptic barrage for control of postsynaptic SNr neurons, which have their own frequency-dependent sensitivities. Despite this, SNr neurons subjected to synaptic conductance changes generated from recorded GPe neuron firing patterns also became coherent with oscillations over a broad range of frequencies. The presynaptic, synaptic, and postsynaptic frequency sensitivities were all dependent on the firing rates of presynaptic and postsynaptic neurons. Firing rate changes, often assumed to be the propagating signal in these circuits, do not encode most oscillation frequencies, but instead determine which signal frequencies propagate effectively and which are suppressed.SIGNIFICANCE STATEMENT Oscillations are present in all the basal ganglia nuclei, include a range of frequencies, and change over the course of learning and behavior. Exaggerated oscillations are a hallmark of basal ganglia pathologies, and each has a specific frequency range. Because of its position as a hub in the basal ganglia circuitry, the globus pallidus is a candidate origin for oscillations propagating between nuclei. We imposed low-amplitude oscillations on individual globus pallidus neurons at specific frequencies and measured the coherence between the oscillation and firing as a function of frequency. We then used these responses to measure the effectiveness of oscillatory propagation to other basal ganglia nuclei. Propagation was effective for oscillation frequencies as high as 100 Hz.

SK and Kv4 Channels Limit Spike Timing Perturbations in Pacemaking Dopamine Neurons.

Midbrain dopamine (DA) neurons are among the best characterized pacemaker neurons, having intrinsic, rhythmic firing activity even in the absence of synaptic input. However, the mechanisms of DA neuron pacemaking have not been systematically related to how these cells respond to synaptic input. The input-output properties of pacemaking neurons can be characterized by the phase-resetting curve (PRC), which describes the sensitivity of interspike interval (ISI) length to inputs arriving at different phases of the firing cycle. Here we determined PRCs of putative DA neurons in the substantia nigra pars compacta in brain slices from male and female mice using gramicidin-perforated current-clamp recordings with electrical noise stimuli applied through the patch pipette. On average, and compared with nearby putative GABA neurons, DA neurons showed a low, nearly constant level of sensitivity across most of the ISI, but individual cells had PRCs showing relatively greater sensitivity at early or late phases. Pharmacological experiments showed that DA neuron PRCs are shaped by small-conductance calcium-activated potassium and Kv4 channels, which limit input sensitivity across early and late phases of the ISI. Our results establish the PRC as a tractable experimental measurement of individual DA neuron input-output relationships and identify two of the major ionic conductances that limit perturbations to rhythmic firing. These findings have applications in modeling and for identifying biophysical changes in response to disease or environmental manipulations.

Spontaneous Activity of the Local GABAergic Synaptic Network Causes Irregular Neuronal Firing in the External Globus Pallidus.

Autonomously firing GABAergic neurons in the external globus pallidus (GPe) form a local synaptic network. In slices, most GPe neurons receive a continuous inhibitory synaptic barrage from 1 or 2 presynaptic GPe neurons. We measured the barrage's effect on the firing rate and regularity of GPe neurons in male and female mice using perforated patch recordings. Silencing the firing of parvalbumin-positive (PV+) GPe neurons by activating genetically expressed Archaerhodopsin current increased the firing rate and regularity of PV- neurons. In contrast, silencing Npas1+ GPe neurons with Archaerhodopsin had insignificant effects on Npas1- neuron firing. Blocking spontaneous GABAergic synaptic input with gabazine reproduced the effects of silencing PV+ neuron firing on the firing rate and regularity of Npas1+ neurons and had similar effects on PV+ neuron firing. To simulate the barrage, we constructed conductance waveforms for dynamic clamp based on experimentally measured inhibitory postsynaptic conductance trains from 1 or 2 unitary local connections. The resulting inhibition replicated the effect on firing seen in the intact active network in the slice. We then increased the number of unitary inputs to match estimates of local network connectivity in vivo As few as 5 unitary inputs produced large increases in firing irregularity. The firing rate was also reduced initially, but PV+ neurons exhibited a slow spike-frequency adaptation that partially restored the rate despite sustained inhibition. We conclude that the irregular firing pattern of GPe neurons in vivo is largely due to the ongoing local inhibitory synaptic barrage produced by the spontaneous firing of other GPe neurons.SIGNIFICANCE STATEMENT Functional roles of local axon collaterals in the external globus pallidus (GPe) have remained elusive because of difficulty in isolating local inhibition from other GABAergic inputs in vivo, and in preserving the autonomous firing of GPe neurons and detecting their spontaneous local inputs in slices. We used perforated patch recordings to detect spontaneous local inputs during rhythmic firing. We found that the autonomous firing of single presynaptic GPe neurons produces inhibitory synaptic barrages that significantly alter the firing regularity of other GPe neurons. Our findings suggest that, although GPe neurons receive input from only a few other GPe neurons, each local connection has a large impact on their firing.

Periodic unitary synaptic currents in the mouse globus pallidus during spontaneous firing in slices.

Neurons in the external globus pallidus (GPe) are autonomous pacemakers, but their spontaneous firing is continually perturbed by synaptic input. Because GPe neurons fire rhythmically in slices, spontaneous inhibitory synaptic currents (IPSCs) should be evident there. We identified periodic series of IPSCs in slices, each corresponding to unitary synaptic currents from one presynaptic cell. Optogenetic stimulation of the striatal indirect pathway axons caused a pause and temporal resetting of the periodic input, confirming that it arose from local neurons subject to striatal inhibition. We determined the firing statistics of the presynaptic neurons from the unitary IPSC statistics and estimated their frequencies, peak amplitudes, and reliabilities. To determine what types of GPe neurons received the spontaneous inhibition, we recorded from genetically labeled parvalbumin (PV) and Npas1-expressing neurons. Both cell types received periodic spontaneous IPSCs with similar frequencies. Optogenetic inhibition of PV neurons reduced the spontaneous IPSC rate in almost all neurons with active unitary inputs, whereas inhibition of Npas1 neurons rarely affected the spontaneous IPSC rate in any neurons. These results suggest that PV neurons provided most of the active unitary inputs to both cell types. Optogenetic pulse stimulation of PV neurons at light levels that can activate cut axons yielded an estimate of connectivity in the fully connected network. The local network is a powerful source of inhibition to both PV and Npas1 neurons, which contributes to irregular firing and may influence the responses to external synaptic inputs.NEW & NOTEWORTHY Brain circuits are often quiet in slices. In the globus pallidus, network activity continues because of the neurons' rhythmic autonomous firing. In this study, synaptic currents generated by the network barrage were measured in single neurons. Unitary synaptic currents arising from single presynaptic neurons were identified by their unique periodicity. Periodic synaptic currents were large and reliable, even at the cell's natural firing rates, but arose from a small number of other globus pallidus neurons.

Assessing working memory capacity through picture span and feature binding with visual-graphic symbols during a visual search task with typical children and adults.

This study investigated developmental memory capacity through picture span and feature binding. Participants included third grade students and college age adults with typical development. Picture span was used to assess working memory capacity when participants were asked to identify, locate, and sequence common visual-graphic symbols from experimental grid displays. Feature binding was assessed to evaluate how symbols, locations and sequences are bound together in working memory. The features assessed included symbol recall, location recall, symbol location binding, symbol sequence binding, and location sequence binding. All participants were shown a sequence of visual-graphic symbols on 4 by 4 stimulus grid displays. Participants were then asked to remember symbols amidst distractor symbols and place them in the correct location on a response grid, using the correct sequence. Results revealed expected developmental differences between third graders and adults on picture span. Significant differences between third graders and adults were also obtained for symbol sequence and location sequence binding. Performance for both groups on the sequence binding features were marginal (i.e., 30% of third graders and 60% of adults binding symbol sequence; 27% of third graders and 52% of adults binding location sequence). These results convey the influence of picture span and feature binding on working memory capacity. Implications are discussed in relation to theoretical models on working memory and compensatory strategies to increase feature binding with target and contextual memory.

Framing and source effects on White college students' reactions to racial inequity information.

OBJECTIVES: This study addressed: (a) Do professors' race/ethnicity and the race-related inequity information they present influence students' evaluations of the professors, acknowledgment of racial inequity, or motivation to respond without prejudice (MRWP)? (b) Do collective guilt and students' evaluations of professors mediate these relationships? METHOD: White American undergraduate students (N = 614, 66.3% females, 64.7% first year, mean age of 19.3 years [age SD = 1.5]) completed an anonymous online survey. Students imagined they were taking a racial diversity course with either a Black or a White male professor who presented either White privilege or Black disadvantage statements. Participants then completed surveys that assessed their evaluations of the professor, collective guilt, beliefs regarding racial inequity, and MRWP. RESULTS: Students evaluated White professors as having lower expertise, learning conduciveness, and warmth/intelligence but rated Black professors as more biased. Consistent with the inequality-framing model, intergroup sensitivity effect (ISE), and findings from prejudice confrontation research, White professors induced greater acknowledgment of racial inequity when they discussed White privilege rather than Black disadvantage. But, Black professors induced more external MRWP when they presented White privilege rather than Black disadvantage. Students' perceptions of the professors' warmth/intelligence determined the effectiveness of the inequity message while perceptions of the professors' expertise, judgmental, and conduciveness to learning determined students' concerns about appearing prejudiced. CONCLUSIONS: The presenters' race/ethnicity and how they frame racial inequity information affect students' evaluation of the presenters, the message effectiveness, and students' external MRWP. (PsycINFO Database Record

Promoting Fitness and Safety in Elementary Students: A Randomized Control Study of the Michigan Model for Health.

BACKGROUND: In elementary grades, comprehensive health education curricula have demonstrated effectiveness in addressing singular health issues. The Michigan Model for Health (MMH) was implemented and evaluated to determine its impact on nutrition, physical fitness, and safety knowledge and skills. METHODS: Schools (N = 52) were randomly assigned to intervention and control conditions. Participants received MMH with 24 lessons in grade 4 and 28 more lessons in grade 5 including material focusing on nutrition, physical fitness, and safety attitudes and skills. The 40-minute lessons were taught by the classroom teacher who received curriculum training and provided feedback on implementation fidelity. Self-report survey data were collected from the fourth-grade students (N = 1983) prior to the intervention, immediately after the intervention, and 6 weeks after the intervention, with the same data collection schedule repeated in fifth grade. Analysis of the scales was conducted using a mixed-model approach. RESULTS: Students who received the curriculum had better nutrition, physical activity, and safety skills than the control-group students. Intervention students also reported higher consumption of fruits; however, no difference was reported for other types of food consumption. CONCLUSION: The effectiveness of the MMH in promoting fitness and safety supports the call for integrated strategies that begin in elementary grades, target multiple risk behaviors, and result in practical and financial benefits to schools.

Virtual TeamSTEPPS(®) Simulations Produce Teamwork Attitude Changes Among Health Professions Students.

BACKGROUND: The majority of the estimated 400,000 or more patient deaths per year in the United States are from preventable medical errors due to poor communication. Team training programs have been established to teach teamwork skills to health professions students. However, it is often challenging to provide this training at a physical site. A brief intervention using a virtual learning environment with TeamSTEPPS(®)-based scenarios is described. METHOD: Using a pretest-posttest design, the effects on teamwork attitudes in 109 health professional students from two institutions and multiple disciplines were measured using the TeamSTEPPS Teamwork Attitudes questionnaire. RESULTS: Participants showed significant attitude changes in the categories of leadership, situation monitoring, mutual support, and communication (p ⩽ .05), with significance in four of the six indicator attitudes in the communication section at the p ⩽ .001 level. CONCLUSION: These findings indicate the potential impact that virtual learning experiences may have on teamwork attitudes in learners across professions on multiple campuses.

Promoting mental health and preventing substance abuse and violence in elementary students: a randomized control study of the Michigan Model for Health.

BACKGROUND: In elementary grades, comprehensive health education curricula mostly have demonstrated effectiveness in addressing singular health issues. The Michigan Model for Health (MMH) was implemented and evaluated to determine its impact on multiple health issues, including social and emotional skills, prosocial behavior, and drug use and aggression. METHODS: Schools (N = 52) were randomly assigned to intervention and control conditions. Participants received 24 lessons in grade 4 (over 12 weeks) and 28 more lessons in grade 5 (over 14 weeks), including material focusing on social and emotional health, interpersonal communication, social pressure resistance skills, drug use prevention, and conflict resolution skills. The 40-minute lessons were taught by the classroom or health teacher who received curriculum training and provided feedback on implementation fidelity. Self-report survey data were collected from the fourth-grade students (n = 2512) prior to the intervention, immediately after the intervention, and 6 weeks after the intervention, with the same data collection schedule repeated in fifth grade. RESULTS: Students who received the curriculum had better interpersonal communication skills, social and emotional skills, and drug refusal skills than the control group students. Intervention students also reported lower intentions to use alcohol and tobacco, less alcohol and tobacco use initiated during the study and in the past 30 days, and reduced levels of aggression. CONCLUSION: The effectiveness of the MMH in promoting mental health and preventing drug use and aggression supports the call for integrated strategies that begin in elementary grades, target multiple risk behaviors, and result in practical and financial benefits to schools.

The future of financing for long-term care: the Own Your Future campaign.

The purpose of this study was to examine the outreach effort and impact of a joint federal-state campaign, Own Your Future, promoting awareness and planning for long-term care (LTC) in the state of Washington. The study applied survey methodology to evaluate the extent of campaign dissemination, evidence of its impact on LTC planning behaviors, and barriers to purchasing private LTC insurance. A total of 3,198 survey responses from a randomly selected community sample and a Washington State employee sample (ages 51 to 71) were analyzed. Results indicated that the impact of the campaign was limited, both with respect to awareness of the campaign itself and to initiation of LTC planning behaviors. Quantitative data revealed a high prevalence of health-related problems (e.g., obesity, diabetes), inadequate knowledge of basic LTC-related information (e.g., cost, payers), and negative attitudes toward purchasing LTC insurance among respondents. Qualitative analyses suggested that respondents perceived significant problems related to affordability and accountability within the current LTC insurance industry. These possible barriers to the purchase of LTC insurance suggest targets to be addressed by policy makers seeking to find ways to offset the public costs of LTC.

Attitudes toward older adults: a reexamination of two major scales.

Two studies were conducted to reexamine the psychometric properties of two major scales measuring attitudes toward older adults. The Kogan Attitudes Toward Old People Scale (Kogan OP Scale; Kogan, 1961b) was administered to a sample of 512 college students in Study One. The refined version (Polizzi & Millikin, 2002) of the Aging Semantic Differential (ASD; Rosencranz & McNeivin, 1969) using an attitudinal target, older adults, was evaluated in Study Two with a sample of 785 college students. Overall, the refined ASD using a nongender and age-specific attitudinal target, older adults, was found to be more psychometrically promising than the Kogan OP Scale. Much refinement is needed for the Kogan OP Scale because of a major flaw associated with OP+ and OP subscales. The refined ASD using older adults as the attitudinal target is a potentially practical tool in gerontological and geriatric fields with future clarification of its factor structure. Strengths and shortcomings of these scales are discussed based on psychometric features. Implications for future studies are discussed.

Direct care workers' recommendations for training and continuing education.

Training of direct care workers (DCWs) varies depending upon the setting in which they work and the state in which they are trained. Evidence points to the importance of adequate training as critical to DCW job satisfaction and reduction in turnover. Several approaches have been taken to enhance the training of DCWs with the objective that as job satisfaction increases, the quality of care provided to consumers will also be enhanced. Based on a sample of 644 DCWs across the nursing home, assisted living, and home health settings, we share DCWs' perceptions and recommendations for better training and continuing education.

Developing and testing a satisfaction survey for nursing home residents: the Ohio Experience.

Input from consumers has become an important part of quality improvement in long-term care and for consumer decision-making. This paper documents the development of the Ohio Nursing Home Resident Satisfaction Survey (ONHRSS) through a partnership of state government, research, and industry experts. The instrument was tested and refined through two waves of data--a pretest phase and later with statewide data. Exploratory and confirmatory analyses with statewide data identified eight primary factors along with an underlying, secondary Global Satisfaction factor. Reliability of the domains ranged from .69 to .95. Recommendations for further refinement and testing of the instrument are discussed along with policy and practice implications.