Many Paths to the Same Goal: Balancing Exploration and Exploitation during Probabilistic Route Planning.

During self-guided behaviors, animals identify constraints of the problems they face and adaptively employ appropriate strategies (Marsh, 2002). In the case of foraging, animals must balance sensory-guided exploration of an environment with memory-guided exploitation of known resource locations. Here, we show that animals adaptively shift cognitive resources between sensory and memory systems during foraging to optimize route planning under uncertainty. We demonstrate this using a new, laboratory-based discovery method to define the strategies used to solve a difficult route optimization scenario, the probabilistic "traveling salesman" problem (Raman and Gill, 2017; Fuentes et al., 2018; Mukherjee et al., 2019). Using this system, we precisely manipulated the strength of prior information as well as the complexity of the problem. We find that rats are capable of efficiently solving this route-planning problem, even under conditions with unreliable prior information and a large space of possible solutions. Through analysis of animals' trajectories, we show that they shift the balance between exploiting known locations and searching for new locations of rewards based on the predictability of reward locations. When compared with a Bayesian search, we found that animal performance is consistent with an approach that adaptively allocates cognitive resources between sensory processing and memory, enhancing sensory acuity and reducing memory load under conditions in which prior information is unreliable. Our findings establish new approaches to understand neural substrates of natural behavior as well as the rational development of biologically inspired approaches for complex real-world optimization.

Small-Diameter Implants: A 7-Year Retrospective Study.

Oral implantology has become a major discipline within the field of dentistry. Small or mini dental implants have demonstrated success in the retention of removable and fixed prostheses. Small-diameter implants (SDI) and mini-diameter implants (MDI) describe a group of implants that demonstrate a diameter less than 3 mm. This retrospective study reports on 335 SDI placed during a 7-year period. All implants were placed in healed sites (>6 months) and loaded immediately or after waiting 3 months. A total of 321 implants were restored and functional within the study's time interval. A total of 14 implants failed, resulting in a 96.1% implant success rate. Treatment plan considerations should include prosthetic design, specific arch, and immediate load. Overall, SDI can be utilized as an alternative implant treatment option for patients with atrophic bone, compromised medical histories and financial constraints.

The relationship between sleep and drug use characteristics in participants with cocaine or methamphetamine use disorders.

The goal of this project was to evaluate the relationship between self-reported sleep habits, daytime sleepiness, and drug use variables in individuals with cocaine and methamphetamine (METH) use disorders. Participants with a cocaine or meth use disorder completed questionnaires, including the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and a demographic/drug use form. Participants with a cocaine (N=51) or meth use disorder (N=85) were separated into those with either high or low sleep deficits. In participants with a cocaine use disorder, ANOVA revealed significantly higher ESS scores among those defined as "poor sleepers" (with a PSQI score >5) when compared to those defined as "good sleepers" (with a PSQI score ≤5). In addition, poor sleepers reported using cocaine for more days out of the past 30 when compared to good sleepers. Interestingly, good sleepers reported using more grams of cocaine/day compared to poor sleepers. In participants with a METH use disorder, ANOVA revealed significantly higher ESS scores among poor sleepers when compared to good sleepers. Finally, individuals with a METH use disorder that endorsed elevated daytime sleepiness also had significantly higher PSQI scores when compared to those with normal daytime sleepiness. The results indicate that drug use variables, such as recent and daily use, may affect sleep quality and daytime sleepiness in individuals with stimulant use disorders; however, further investigations (i.e. in cocaine and METH users that do not meet criteria for a cocaine or METH use disorder) must be conducted in order to provide more conclusive evidence of the impact these usage variables may have on these sleep characteristics.

Treatment of congenitally missing maxillary lateral incisors: an interdisciplinary approach.

Dentists have several treatment options when restoring patients with congenitally missing maxillary lateral incisors. Endosseous implant therapy combined with orthodontics can achieve predictable outcomes while meeting patient expectations. This case report exhibits an interdisciplinary approach involving orthodontics, implant surgery, and prosthodontics to resolve this common dental concern.

Acute modafinil exposure reduces daytime sleepiness in abstinent methamphetamine-dependent volunteers.

The purpose of this study was to evaluate the effects of acute, oral modafinil (200 mg) exposure on daytime sleepiness in methamphetamine (Meth)-dependent individuals. Eighteen Meth-dependent subjects were enrolled in a 7-d inpatient study and were administered placebo or modafinil on day 6 and the counter-condition on day 7 (randomized) of the protocol. Subjects completed several subjective daily assessments (such as the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Beck Depression Inventory and visual analogue scale) throughout the protocol as well as objective assessments on days 5-7, when the Multiple Sleep Latency Test was performed. The results of the current study suggest that short-term abstinence from Meth is associated with increased daytime sleepiness and that a single dose of 200 mg modafinil reduces daytime somnolence in this population. In addition, a positive correlation was found between subjective reporting of the likelihood of taking a nap and craving and desire for Meth, as well as the likelihood of using Meth and whether Meth would make the participant feel better. The results of this study should be considered when investigating candidate medications for Meth-dependence, especially in those individuals who attribute their Meth use to overcoming deficits resulting from sleep abnormalities.

Acute, low-dose methamphetamine administration improves attention/information processing speed and working memory in methamphetamine-dependent individuals displaying poorer cognitive performance at baseline.

Abstinent methamphetamine (Meth) dependent individuals demonstrate poorer performance on tests sensitive to attention/information processing speed, learning and memory, and working memory when compared to non-Meth dependent individuals. The poorer performance on these tests may contribute to the morbidity associated with Meth-dependence. In light of this, we sought to determine the effects of acute, low-dose Meth administration on attention, working memory, and verbal learning and memory in 19 non-treatment seeking, Meth-dependent individuals. Participants were predominantly male (89%), Caucasian (63%), and cigarette smokers (63%). Following a four day, drug-free washout period, participants were given a single-blind intravenous infusion of saline, followed the next day by 30 mg of Meth. A battery of neurocognitive tasks was administered before and after each infusion, and performance on measures of accuracy and reaction time were compared between conditions. While acute Meth exposure did not affect test performance for the entire sample, participants who demonstrated relatively poor performance on these tests at baseline, identified using a median split on each test, showed significant improvement on measures of attention/information processing speed and working memory when administered Meth. Improved performance was seen on the following measures of working memory: choice reaction time task (p≤0.04), a 1-back task (p≤0.01), and a 2-back task (p≤0.04). In addition, those participants demonstrating high neurocognitive performance at baseline experienced similar or decreased performance following Meth exposure. These findings suggest that acute administration of Meth may temporarily improve Meth-associated neurocognitive performance in those individuals experiencing lower cognitive performance at baseline. As a result, stimulants may serve as a successful treatment for improving cognitive functioning in those Meth-dependent individuals experiencing neurocognitive impairment.

Small diameter implants: specific indications and considerations for the posterior mandible: a case report.

The field of implant dentistry continues to grow globally as clinicians embrace the evolution of various endosseous implant technologies and the array of enhanced surgical and prosthetic products. The utilization of small diameter implants in limited osseous regions increases patients' ability to choose implants as a viable restorative option. Although small diameter implants have been indicated in the incisor region for the maxilla and mandible primarily, their usage should be considered in select posterior regions. These 2 case reports demonstrate the incorporation of small diameter implants to replace missing mandibular posterior teeth.

Socket grafting: a predictable technique for site preservation.

The demand for dental implants continues to rise worldwide, requiring clinicians to consider the incorporation of bone preservation procedures into their dental practice. Socket grafting offers a predictable, simple way to conserve the buccolingual and mesiodistal dimensions of the future implant site. Careful bone management and the use of various bone-grafting materials must be part of the practice of every implantologist. In this case report, the authors present a fundamental technique for socket grafting and 3 cases of site preservation with subsequent implant placement and restoration. Emphasis is placed on the evidence-based rationale for this procedure, the clinical technique, and the various grafting materials that can be employed by the clinician.

The use of laser-welded titanium framework technology: a case report for the totally edentulous patient.

Laser-welded technology has become a viable alternative to the conventional lost wax-casting technique in the field of implant dentistry. Studies have demonstrated the predictable nature of laser-welded titanium frameworks for endosseous implants in the partial and totally edentulous patient. A standardized impression and fabrication procedure is required for an accurate and predictable superstructure. More long-term studies are needed for more widespread acceptance and usage by dental practitioners.

Occlusal principles and clinical applications for endosseous implants.

Endosseous implant dentistry has become a predictable clinical modality. The role of the restorative dentist is to minimize overload to the crestal bone by utilizing implant occlusal principles. The prosthetic stages of treatment should follow a disciplined sequence. This article reviews occlusal principles and clinical applications for long-term success of endosseous implants.