All optical modulation in vertically coupled indium tin oxide ring resonator employing epsilon near zero state

We present an innovative approach to achieve all-optical modulation within an ITO-based vertically coupled ring resonator. This method leverages the material's enhanced nonlinear response in the near-infrared wavelengths, particularly within the epsilon-near-zero (ENZ) state. To enhance the interaction between light and the material while minimizing scattering losses, our approach employs an ITO-based vertically connected ring resonator. The vertical arrangement eliminates the need for etching fine gaps to separate the ring and bus waveguide. The novel waveguide design addresses the necessity of high sensitivity, non-linear effects and compact size opening the possibilities for all-optical signal processing. This unique resonator structure effectively facilitates the coupling of a high-intensity pump wavelength into the ITO-based micro-ring resonator. Consequently, this optical pumping induces electron heating within the ITO material, leading to a significant increase in its nonlinear optical properties. This, in turn, results in a noteworthy alteration of ITO's refractive index, specifically in the unity order, thereby modifying the complex effective index of the optical beam propagating at 1550 nm. Our experimental findings demonstrate an impressive extinction ratio of 18 dB for a 30 µm long device, which highlights the efficiency of our approach in achieving all-optical modulation through the optical pumping of an ITO-based vertically coupled ring resonator. The proposed all-optical modulator has outperformed as compared to conventional waveguide-based modulators in terms of extinction ratio and footprint. This novel technique holds immense potential for advancing high-speed data communication systems in the future. As the demand for advanced processing capabilities, such as artificial intelligence, continues to grow, all-optical modulation emerges as a groundbreaking technology poised to revolutionize the next generation of computing and communication systems.

Does Liposuction for Lymphedema Worsen Lymphatic Injury?

Liposuction for treatment of lymphedema is an effective and time-tested treatment. However, as there is a fear regarding further lymphatic damage caused by liposuction, we objectively compared lymphatic function pre- and post-liposuction. All patients with solid-predominant lymphedema who were treated during the study period of June 2014 and November 2018 were included. Patients were assessed using patient-reported baselines/outcomes, lymphedema- specific quality of life scale (LYMQOL), limb circumference/volume measurements, and indocyanine green lymphography (ICGL) preoperatively and at predefined postoperative time intervals. Fifty-seven limbs from 41 patients were included. Mean lipoaspirate volumes were 2035 mL, 5385 mL, and 3106 mL for the arm, thigh, and leg, respectively with a mean adipose fraction of the lipoaspirate of 71%. All patients underwent redundant skin excision with the "flying squirrel" technique. The mean follow-up was 10.7 months (range 3 - 48 months) with a mean limb volume reduction of 32.2% and all patients reporting satisfactory relief of symptoms. All showed statistically significant improvement in LYMQOL in symptoms, appearance, and function. On ICGL, none showed worsened lymphatic drainage, rather, all showed improved lymph drainage. Furthermore, the improved lymph drainage was found to be progressive during the study period in all patients. Our study results demonstrate that treating extremity lymphedema with liposuction does not worsen lymphatic function and in fact, paradoxically, it induces progressive improvement in lymph drainage.

Early detection of Pseudomonas aeruginosa and Escherichia coli. using zinc tetraphenylporphyrin

The sensory characteristics of food are considerably effected by the metabolic processes of various micro-organisms in the food stored in the field or at ambient temperature. Also, this microbial contamination can pose serious health hazards to public health. Chemical analysis of the complex mixture of volatiles produced during bacterial growth and investigation methods of these microorganisms presents a big challenge. There remains major unmet need to shorten and improve detection methods. Therefore, early detection of the microorganisms will open many frontiers for quality control in the foodstuffs industry. Accordingly, the aim of this study was to assess the feasibility and performance of chemoreceptive sensors for the rapid detection of bacterial pathogens, specifically Pseudomonas aeruginosa and Escherichia coli.

In Uv/vis study, zinc tetraphenyl porphyrin solutions (in DMF) was tested with various volatile compounds, such as propanal, hexanal and heptanal which are commonly found to be released during the growth of bacteria. These sensors were used to detect the bacterial odours of two pathogenic species (E.coli and P.aeruginosa) during their growth cycle at 4 °C and ambient temperature.

Hypochromic shifts in Uv/vis and hydrogen bonding in FT-IR studies confirmed the interaction between the volatiles and porphyrin. The porphyrin used detected the presence of microorganisms after 12 hrs incubation and showed more sensitivity for volatiles released during aerobic activity P. aeruginosa as compared to E. coli at 4 °C and ambient temperature.

Zinc tetraphenyl porphyrin based chemoreceptive membranes has been proved successful for the detection of P. aeruginosa. Hence, the present study proves wide scope of improvement over current laboratory techniques for the detection of pathogens in terms of speed, ease of use, and cost.

Key messages

The developed technique allows rapid detection of spoiled food. Chemoreceptive property of porphyrin has been exploited for the early detection of bacteria.

Probing the Electronic Structure of Hybrid Perovskites in the Orientationally Disordered Cubic Phase

Hybrid organic-inorganic lead halide perovskites are projected as new generation photovoltaic and optoelectronic materials with improved efficiencies. However, their electronic structure so far remains poorly understood, particularly in the orientationally disordered cubic phase. We performed electronic structure investigations using angle-resolved photoemission spectroscopy on two prototypical samples (MAPbBr₃ and MAPbCl₃) in their cubic phase, and the results are compared with the calculations within two theoretical models where MA⁺ is orientationally (1) disordered (MA⁺ ion is replaced by spherically symmetric Cs⁺ ion) and (2) ordered (MA oriented along (100) direction) but keeping the symmetry of the unit cell cubic. Degeneracy of the valence bands and behavior of constant energy contours are consistent with model 1, which supports strongly the disordered nature of the orientation of the MA⁺ ions in the cubic phase. Band structure calculations also reveal that spin-orbit coupling induced Rashba splitting is suppressed by the orientational disorder.

Robotics and ophthalmology: Are we there yet?

Ophthalmology is a field that is now seeing the integration of robotics in its surgical procedures and interventions. Assistance facilitated by robots offers substantial improvements in terms of movement control, tremor cancellation, enhanced visualization, and distance sensing. Robotic technology has only recently been integrated into ophthalmology; hence, the progression is only in its initial stages. Robotic technologies such as da Vinci Surgical System are integrated into the field of ophthalmology and are assisting surgeons in complex eye surgeries. Ophthalmic surgeries require high accuracy and precision to execute tissue manipulation, and some complex ocular surgery may take few hours to complete the procedures that may predispose high-volume ophthalmic surgeons to work-related musculoskeletal disorders. A complete paradigm shift has been achieved in this particular field through the integration of advanced robotic technology, resulting in easier and more efficient procedures. Where robotic technology assists the surgeons and improves the overall quality of care, it also projects several challenges including limited availability, training, and the high cost of the robotic system. Although considerable studies and trials have been conducted for various robotic systems, only a few of them have made it to the commercial stage and ophthalmology, on its own, has a long way to go in robotics technology.

The Interpeduncular Angle: A Practical and Objective Marker for the Detection and Diagnosis of Intracranial Hypotension on Brain MRI

BACKGROUND AND PURPOSE

Classic findings of intracranial hypotension on MR imaging, such as brain stem slumping, can be variably present and, at times, subjective, potentially making the diagnosis difficult. We hypothesize that the angle between the cerebral peduncles correlates with the volume of interpeduncular cistern fluid and is decreased in cases of intracranial hypotension. We aimed to investigate its use as an objective assessment for intracranial hypotension.

MATERIALS AND METHODS

Brain MRIs of 30 patients with intracranial hypotension and 30 age-matched controls were evaluated by 2 fellowship-trained neuroradiologists for classic findings of intracranial hypotension and the interpeduncular angle. Group analysis was performed with a Student t test, and receiver operating characteristic analysis was used to identify an ideal angle threshold to maximize sensitivity and specificity. Interobserver reliability was assessed for classic findings of intracranial hypotension using the Cohen κ value, and the interpeduncular angle, using the intraclass correlation.

RESULTS

The interpeduncular angle had excellent interobserver reliability (intraclass correlation coefficient value = 0.833) and was significantly lower in the intracranial hypotension group compared with the control group (25.3° versus 56.3°; P < .001). There was significant correlation between the interpeduncular angle and the presence of brain stem slumping (P < .001) and in cases with ≥3 classic features of intracranial hypotension (P = .01). With a threshold of 40.5°, sensitivity and specificity were 80% and 96.7%, respectively.

CONCLUSIONS

The interpeduncular angle is a sensitive and specific measure of intracranial hypotension and is a reliably reproducible parameter on routine clinical MR imaging.

Evaluation of effectiveness of Mass Vaccination Campaign against Peste des petits ruminants in Chhattisgarh state, India

The study evaluated the effectiveness of 'Mass Vaccination Campaign (MVC)' implemented against the contagious transboundary OIE notified Peste des petits ruminants (PPR) in sheep and goats on the lines of 'pulse polio campaign' for humans in Chhattisgarh state, India. The effectiveness was evaluated on the axes of adequacy, financial viability under with and without MVC through differencing under various scenarios and options and programme impact from a farmer's perspective. The adequacy evaluation revealed that the reported outbreaks, diagnosed and death cases declined under PPR-MVC inconsonance with increased vaccination coverage. Furthermore, the seroconversion increased during post PPR-MVC implies elevated immunity levels in the sheep and goat population. The estimated mean mortality loss was USD 45.2 and USD 16.5 per animal in goats and sheep, respectively, whereas the treatment and opportunity cost of labour was USD 1.9 and USD 2.5 per animal respectively. Under the low PPR incidence scenario, benefit: cost ratio, net present value and internal rate of return were 4.9:1, 48.9 million USD and 146.6%, whereas it was 12.4:1,142.7 million USD and 430.4% and 13.5:1,156.7 million USD and 430.4% under medium and high incidence scenarios. Furthermore, the option of vaccinating 100% risk population during the first year followed by 30% during subsequent years to cover naïve population will maximize benefits than 100% coverage every year; nevertheless, benefits outweighs cost manifolds in both of these options. The farmers had a positive opinion on the overall services provided under PPR-MVC and the results provide the empirical evidence on effectiveness of 'mass vaccination' for its replication in other states of India or countries with similar socio-economic and rearing environments.

Role of HAMP Genetic Variants on Pathophysiology of Iron Deficiency Anemia

Hepcidin is a 25-amino acid peptide hormone produced by hepatocytes and plays a key role in body iron metabolism. Hepcidin deficiency is the cause of iron overload in hereditary hemochromatosis, iron-loading anemia, and its excess is associated with anemia of inflammation, chronic disease and iron deficiency anemia (IDA). The aims of this study was to evaluate HAMP gene mutation, namely IVS2 + 1(-G) (c.148-150 + 1del) and Gly71 Asp (c.212G > A (rs104894696) association with iron status in IDA conditions. Our study participants were 500 IDA patients and 550 age and sex-matched healthy controls. Hepcidin, ferritin and CRP analysis was done by ELISA method while ESR analysis was done according to Wintrobe method. CBC analysis was done by auto-analyzer. Two mutations in the HAMP genes were analysed by PCR RFLP method. Among the IDA patients, 7 were heterozygous for Met50del IVS2 + 1(-G) mutation. Nine IDA patients were heterozygous for G71D G-A mutation and homozygous were not identified in both mutations.Controls were showing heterozygous frequency 1.8 and 2.1% of Met50del IVS2 + 1(-G) and G71D G-A mutations respectively. Mutation of HAMP (Met50del IVS2 + 1(-G) and G71D G-A) were clinically associated with IDA and act as modulator of disease.

Zepto-rhexis: A new surgical technique of capsulorhexis using precision nano-pulse technology in difficult cataract cases

Several techniques are used to make a capsulorhexis in white mature cataract cases as needle cystotome, Utrata capsulorhexis forceps, microincision capsulorhexis forceps, femtosecond Laser, etc. Zepto precision nano-pulse capsulotomy device (Mynosys Cellular Devices; Fremont, CA, USA) is Food and Drug Administration approved, a disposable capsulotomy device that uses low-energy pulses to create a precise central capsulorhexis, independent of pupil size, corneal clarity, or lens density. In this article, the authors report their experience of performing anterior circular curvilinear capsulorhexis with Zepto precision nano-pulse capsulotomy device in challenging cataract cases done at our center. The Zepto handpiece device was inserted through 2.8 mm clear corneal incision. Results of our study in 3 cataract cases (intumescent cataract, morgagnian cataract, and cataract with small pupil) revealed that the precision pulse capsulotomy technology mechanically and simultaneously cleaves all 360° of the apposed capsule of without cauterizing it, creating CCC of 5.2 mm size.

Comparative assessment of (18) F-Mefway as a serotonin 5-HT1A receptor PET imaging agent across species: Rodents, nonhuman primates, and humans

We have developed (18) F-trans-Mefway ((18) F-Mefway) for positron emission tomography (PET) imaging studies of serotonin 5-HT1A receptors which are implicated in various brain functions. Translation of imaging the 5-HT1A receptor in animal models to humans will facilitate an understanding of the role of the receptor in human brain disorders. We report comparative brain distribution of (18) F-Mefway in normal mice, rats, monkeys, and healthy human volunteers. Mefway was found to be very selective, with subnanomolar affinity for the 5-HT1A receptor. Affinities of >55 nM were found for all other human-cloned receptor subtypes tested. Mefway was found to be a poor substrate (>30 μM) for the multidrug resistance 1 protein, suggesting low likelihood of brain uptake being affected by P-glycoprotein. Cerebellum was used as a reference region in all imaging studies across all species due to the low levels of (18) F-Mefway binding. Consistent binding of (18) F-Mefway in cortical regions, hippocampus, and raphe was observed across all species. (18) F-Mefway in the human brain regions correlated with the known postmortem distribution of 5-HT1A receptors. Quantitation of raphe was affected by the resolution of the PET scanners in rodents, whereas monkeys and humans showed a raphe to cerebellum ratio of approximately 3. (18) F-Mefway appears to be an effective 5-HT1A receptor imaging agent in all models, including humans. (18) F-Mefway therefore may be used to quantify 5-HT1A receptor distribution in brain regions for the study of various CNS disorders. J. Comp. Neurol. 524:1457-1471, 2016. © 2015 Wiley Periodicals, Inc.

Synthesis, spectroscopic, thermal and antimicrobial studies of neodymium(III) and samarium(III) complexes derived from tetradentate ligands containing N and S donor atoms

Trivalent lanthanide complexes of the type [Ln(L)Cl(H2O)2] (where Ln=Nd(III) or Sm(III) and LH2=Schiff bases derived by the condensation of 3-(phenyl/substitutedphenyl)-4-amino-5-mercapto-1,2,4-triazole with diacetyl/benzil) have been synthesized by the reactions of anhydrous lanthanide(III) chloride with Schiff bases in methanol. The structures of the complexes have been proposed on the basis of elemental analysis, electrical conductance, magnetic moment, spectroscopic measurements (IR, 1H, 13C NMR and UV-vis spectra) and X-ray diffraction studies. The spectral data reveal that the Schiff base ligands behave as dibasic tetradentate chelating agents having coordination sites at two thiol sulfur atoms and two azomethine nitrogen atoms. The presence of coordinated water in metal complexes was confirmed by thermal and IR data of the complexes. All the Schiff bases and their metal complexes have also been screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus and antifungal activities against Aspergillus niger, Curvularia pallescens and Colletotrichum capsici.

Investigation of thermoelectric properties of half-metallic Co₂MnGe by using first principles calculations

By combining the electronic structures obtained from first principles calculations with Boltzmann transport theory we have investigated the electronic, magnetic and transport properties of the Co2MnGe Heusler compound. The density of state plots, dispersion curves and the total energy of paramagnetic and ferromagnetic (FM) phases clearly show the half-metallic FM ground state for the compound, with an indirect band gap of about 400 meV in the minority spin channel. It has an integer value of the magnetic moment equal to 5 μ(B). In the FM phase a very large value (∼ 550 µV K(-1)) of the Seebeck coefficient (S) is obtained for down-spin electrons due to the existence of an almost flat conduction band along X in the Γ direction. The two-current model has been used to find the total S and the obtained value is about 10 µV K(-1). The calculated values of the Seebeck coefficient, resistivity and electronic thermal conductivity show nice agreement with the experimental results.

Multimodality imaging probe for positron emission tomography and fluorescence imaging studies

Our goal is to develop multimodality imaging agents for use in cell tracking studies by positron emission tomography (PET) and optical imaging (OI). For this purpose, bovine serum albumin (BSA) was complexed with biotin (histologic studies), 5(6)-carboxyfluorescein, succinimidyl ester (FAM SE) (OI studies), and diethylenetriamine pentaacetic acid (DTPA) for chelating gallium 68 (PET studies). For synthesis of BSA-biotin-FAM-DTPA, BSA was coupled to (+)-biotin N-hydroxysuccinimide ester (biotin-NHSI). BSA-biotin was treated with DTPA-anhydride and biotin-BSA-DTPA was reacted with FAM. The biotin-BSA-DTPA-FAM was reacted with gallium chloride 3 to 5 mCi eluted from the generator using 0.1 N HCl and was passed through basic resin (AG 11 A8) and 150 μCi (100 μL, pH 7-8) was incubated with 0.1 mg of FAM conjugate (100 μL) at room temperature for 15 minutes to give 68Ga-BSA-biotin-DTPA-FAM. A shaved C57 black mouse was injected with FAM conjugate (50 μL) at one flank and FAM-68Ga (50 μL, 30 μCi) at the other. Immediately after injection, the mouse was placed in a fluorescence imaging system (Kodak In-Vivo F, Bruker Biospin Co., Woodbridge, CT) and imaged (λex: 465 nm, λem: 535 nm, time: 8 seconds, Xenon Light Source, Kodak). The same mouse was then placed under an Inveon microPET scanner (Siemens Medical Solutions, Knoxville, TN) injected (intravenously) with 25 μCi of 18F and after a half-hour (to allow sufficient bone uptake) was imaged for 30 minutes. Molecular weight determined using matrix-associated laser desorption ionization (MALDI) for the BSA sample was 66,485 Da and for biotin-BSA was 67,116 Da, indicating two biotin moieties per BSA molecule; for biotin-BSA-DTPA was 81,584 Da, indicating an average of 30 DTPA moieties per BSA molecule; and for FAM conjugate was 82,383 Da, indicating an average of 1.7 fluorescent moieties per BSA molecule. Fluorescence imaging clearly showed localization of FAM conjugate and FAM-68Ga at respective flanks of the mouse, whereas only a hot spot at the expected flank (FAM-68Ga injection site) was observed in microPET imaging. Our results suggest that BSA-biotin-DTPA-FAM may function as a multiprobe for PET and fluorescence imaging. Experiments are currently in progress to demonstrate cell tracking using both optical and nuclear imaging.

Impact of integrated nutrient management on tomato yield under farmers field conditions

Field trials were conducted in farmer's field of district Chandauli, Uttar Pradesh, India to assess the impact of integrated nutrient management (INM) on the performance of tomato crop during rabi (2008) and kharif (2009) season. Before conducting trials technological gap between actual and potential productivity were analyzed by interviewing growers to find out the major causes for low yield. Overall gap in use of fertilizers was recorded 64.90 % whereas overall mean gap in technology was 43.83%. On-farm experiments on INM were conducted by applying FYM (10t ha(-1)) + (NPK (150:80:60 kg ha(-1)) followed by dipping seedling roots in 1% Azotobacter solution for 15 min and foliar spray with 20 ppm ferrous ammonium sulphate after 30, 45 and 75 days of transplantation. The plant height, root length, number of primary branches, average fruit weight increased in INM plots as compared to farm practice. The increment in yield was found to be 28.84 and 33.86% during rabi and kharif season respectively. The maximum marketable yield obtained in INM plot during kharif and rabi seasons was 1025 q ha(-1) and 955 q ha(-1) respectively, whereas as farm practice yielded 740 q ha(-1) and 713 q ha(-1) during the same seasons. The percent loss from total production was recorded 8.5 % and 8.8 % in control plot and only 4.9 % and 5.7 % in INM plot during rabi and kharif seasons respectively. The higher fruit weight and lower incidence of disease and pest were observed in INM field in comparison to farm practice. The benefit cost ratio with INM treatment was recorded 4.25 and 4.23 in rabi and kharif season respectively against the benefit cost ratio of 2.98 and 2.82 in control plot during the same respective seasons.

Evaluation of serotonin 5-HT(1A) receptors in rodent models using [¹⁸F]mefway PET

INTRODUCTION

Serotonin 5-HT(1A) receptors have been investigated in various CNS disorders, including epilepsy, mood disorders, and neurodegeneration. [¹⁸F]Mefway (N-{2-[4-(2'-methoxyphenyl)piperazinyl]ethyl}-N-(2-pyridyl)-N-(cis/trans-4'-[¹⁸F]fluoromethylcyclohexane)-carboxamide) has been developed as a suitable positron emission tomography (PET) imaging agent for these receptors. We have now evaluated the suitability of [¹⁸F]trans-mefway in rat and mouse models using PET and computerized tomography (CT) imaging and corroborated with ex vivo and in vitro autoradiographic studies.

METHODS

Normal Sprague-Dawley rats and Balb/C mice were used for PET/CT imaging using intravenously injected [¹⁸F]trans-mefway. Brain PET data were coregistered with rat and mouse magnetic resonance imaging template and regional distribution of radioactivity was quantitated. Selected animals were used for ex vivo autoradiographic studies to confirm regional brain distribution and quantitative measures of binding, using brain region to cerebellum ratios. Binding affinity of trans-mefway and WAY-100635 was measured in rat brain homogenates. Distribution of [¹⁸F]trans-4-fluoromethylcyclohexane carboxylate ([¹⁸F]FMCHA), a major metabolite of [¹⁸F] trans-mefway, was assessed in the rat by PET/CT.

RESULTS

The inhibition constant, K(i) for trans-mefway was 0.84 nM and that for WAY-100635 was 1.07 nM. Rapid brain uptake of [¹⁸F]trans-mefway was observed in all rat brain regions and clearance from cerebellum was fast and was used as a reference region in all studies. Distribution of [¹⁸F]trans-mefway in various brain regions was consistent in PET and in vitro studies. The dorsal raphe was visualized and quantified in the rat PET but identification in the mouse was difficult. The rank order of binding to the various brain regions was hippocampus > frontal cortex > anterior cingulate cortex > lateral septal nuclei > dorsal raphe nuclei.

CONCLUSION

[¹⁸F]trans-Mefway appears to be an effective 5-HT(1A) receptor imaging agent in rodents for studies of various disease models.

Synthesis and evaluation of 3-¹²³I-iodo-5-[2-(S)-3-pyrrolinylmethoxy]-pyridine (niodene) as a potential nicotinic α4β2 receptor imaging agent

Nicotinic acetylcholine receptors (nAChRs) are downregulated in disease conditions such as Alzheimer's and substance abuse. Presently, (123)I-5-IA-85380 is used in human studies and requires over 6h of scanning time, thus increases patient discomfort. We have designed and synthesized 3-iodo-5-[2-(S)-3-pyrrolinylmethoxy]pyridine (niodene) with the aim to have faster binding kinetics compared to (123)I-5-IA-85380, which may reduce scanning time and help in imaging studies. Binding affinity K(i) of niodene for rat brain α4β2 receptors in brain homogenate assays using (3)H-cytisine was 0.27 nM. Niodene, 10nM displaced >95% of (18)F-nifene bound to α4β2 receptors in rat brain slices. By using the iododestannylation method, (123)I-niodene was obtained in high radiochemical purity (>95%) but with low radiochemical yield (<5%) and low specific activity (∼100 Ci/mmol). Autoradiograms show (123)I-niodene localized in the thalamus and cortex, which was displaced by nicotine (thalamus to cerebellum ratio=4; cortex to cerebellum ratio=1.6). Methods of radioiodination need to be further evaluated in order to obtain (123)I-niodene in higher radiochemical yields and higher specific activity of this potentially useful new SPECT imaging agent.

Nicotinic acetylcholine receptors in rat forebrain that bind ¹⁸F-nifene: relating PET imaging, autoradiography, and behavior

Nicotinic acetylcholine receptors (nAChRs) in the brain are important for cognitive function; however, their specific role in relevant brain regions remains unclear. In this study, we used the novel compound ¹⁸F-nifene to examine the distribution of nAChRs in the rat forebrain, and for individual animals related the results to behavioral performance on an auditory-cognitive task. We first show negligible binding of ¹⁸F-nifene in mice lacking the β2 nAChR subunit, consistent with previous findings that ¹⁸F-nifene binds to α4β2* nAChRs. We then examined the distribution of ¹⁸F-nifene in rat using three methods: in vivo PET, ex vivo PET and autoradiography. Generally, ¹⁸F-nifene labeled forebrain regions known to contain nAChRs, and the three methods produced similar relative binding among regions. Importantly, ¹⁸F-nifene also labeled some white matter (myelinated axon) tracts, most prominently in the temporal subcortical region that contains the auditory thalamocortical pathway. Finally, we related ¹⁸F-nifene binding in several forebrain regions to each animal's performance on an auditory-cued, active avoidance task. The strongest correlations with performance after 14 days training were found for ¹⁸F-nifene binding in the temporal subcortical white matter, subiculum, and medial frontal cortex (correlation coefficients, r > 0.8); there was no correlation with binding in the auditory thalamus or auditory cortex. These findings suggest that individual performance is linked to nicotinic functions in specific brain regions, and further support a role for nAChRs in sensory-cognitive function.