Zone Preference in the Visual Water Maze
June 26, 2025
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The history of telescopes is fascinating. The first telescope was invented in the 17th century. Note that it was spectacle-maker Hans Lippershey, who was credited as the inventor of the first refractor telescope, and Galileo Galilei, who pointed the telescope towards the skies. Early refractor telescopes, however, suffered from chromatic aberration, so in 1668 Sir Isaac Newton replaced the primary lens with a mirror, solving the problem of chromatic aberration and creating the so-called Newtonian reflecting telescope. Half a century later, John Hadley improved the design of reflecting telescopes and started using parabolic mirrors that displayed little spherical aberration or distortion.
Now reflecting telescopes are highly popular among amateur astronomers and nature lovers. Optics industry leaders, such as Celestron, Orion, and Meade, manufacture excellent units suitable for both terrestrial and astronomical use and offer users the unique opportunity to explore the mysteries of the universe. Additionally, powerful and computerized telescopes with advanced optics and large mechanical structures enhance the study of distant celestial objects, such as nebulae, novae, and asteroids, by their emission or reflection of electromagnetic radiation (e.g., radio, infrared, and gamma-ray units)
Telescopes are fascinating instruments in the field of science. Yet, choosing a telescope can be a daunting endeavor, especially for amateur astronomers. We should note there are three main types of optical microscopes available on the market: 1) refracting telescopes that use lenses to bring light to a focal point; 2) reflecting telescopes that use mirrors; 3) catadioptric telescopes that are equipped with both mirrors and lenses.
Additionally, there are three major aspects buyers should consider before purchasing a reflecting unit:
Requirements: One of the main factors that should determine purchasing choices is user requirements: users should decide what objects they want to see (e.g., deep-sky or bright objects) and where they’ll be viewing them (e.g., light-polluted areas or rural regions).
Reflecting telescopes, in particular, are ideal for both astronomical and terrestrial use. As explained above, reflectors employ mirrors instead of lenses to focus light onto a focal point. As wavelengths reflect off the mirrors in the same way, reflecting telescopes do not suffer from optical problems, such as chromatic aberration. Note that a secondary mirror can be employed to focus the light onto the eyepiece, which is often positioned near the front of the tube. Reflectors are ideal for viewing deep-sky objects such as nebulae and galaxies, as well as observing bright celestial objects like planets.
Specifications: Aperture, magnification, and focal length are all factors to consider when buying a reflecting telescope. Note that aperture is defined as the diameter of the telescope’s main optical part (lenses or mirrors) through which light passes. A bigger aperture is ideal for viewing deep-sky objects (e.g., galaxies, nebulae, clusters).
Magnification is another essential characteristic to consider. The magnification of a unit can be calculated by dividing the eyepiece focal length by the telescope focal length. For example, if a unit has a 1500 mm focal length and uses an eyepiece of a 10 mm focal length, the magnification produced will be 150X. Note that low powers are ideal for viewing deep-sky objects (e.g., galaxies), while medium-high powers are ideal for observing bright objects (e.g., planets). Too high magnification, however, can lead to blurry images and make telescopes unusable.
Total cost: Before purchasing a reflecting telescope, users should decide on a budget. Aperture, optical quality, and materials used are all essential factors to consider. As mentioned above, the bigger the aperture, the better the image is; telescopes should have an aperture above three inches to be considered usable items. Units with big aperture (above 150 mm) can provide magnificent views of deep-sky objects, such as galaxies, star clusters, and nebulae, while an aperture of 60-80 mm will be enough for viewing bright images, such as the Moon – one of the easiest and most fascinating objects to explore.
Additional features, such as support systems, mounts, focusers, finderscopes, camera adapters, and bags, should also be considered. Note that computerized telescopes can be more costly but more suitable for beginners with little knowledge of the night sky because such units can facilitate celestial alignment, tracking, and observation.
Whether it’s for studying the mysteries of the universe or stargazing with your loved ones, telescopes are worth investing in. Reflecting telescopes, in particular, are preferred tools by many as they are simple to assemble and use. Reflectors also come with a bigger aperture, which makes them ideal for observing deep-sky objects. Based on different characteristics and user reviews, here’s a list of the best reflecting telescopes on the market:
Orion 10134 SkyQuest XT8g Computerized GoTo Dobsonian Telescope is one of the most powerful reflecting telescopes (with an aperture of 203 mm) that can help users conquer the mysteries of the skies. Some of the extra features the unit comes equipped with are a two-inch dual-speed (11:1) Crayford focuser and a fully motorized object location. Note that for fully motorized operations, users should buy 12V power supply, which is sold separately. Orion 10134 skyQuest XT8g Computerized GoTo Dobsonian Telescope also comes with pre-installed GoTo motors and gears, so assembling is pretty straightforward, allowing users to enjoy the beauty of more than 42,000 objects in the skies.
Orion 09007 SpaceProbe 130ST Equatorial Reflector Telescope is a wonderful tool for both beginners and experts. It has a 130 mm parabolic mirror and two 25 mm and 10 mm Sirius Plossl eyepieces. The unit is equipped with an EQ-2 equatorial mount with slow-motion hand controls and a stable tripod with an accessory tray. Moreover, Orion 09007 SpaceProbe 130ST Equatorial Reflector Telescope is light and easy to take out to different stargazing locations.
Celestron 31045 AstroMaster 130EQ Reflector Telescope is a powerful unit that comes with a German equatorial mount, an adjustable steel tripod, two eyepieces (20 mm and 10 mm), and a StarPointer red-dot finderscope. The aperture of the unit is 130 mm, allowing the viewing of both bright and deep-sky celestial objects. Additionally, Celestron 31045 AstroMaster 130EQ Reflector Telescope comes with Starry Night astronomy software with a rich 10,000 celestial objects database, printable maps, and enhanced images.
Celestron 21045 PowerSeeker 114EQ Reflector Telescope is one of the most suitable tools for beginners; the telescope is easy to use and powerful at the same time. The unit comes with two eyepieces (20 mm and 4 mm), a 3X Barlow lens, and a finderscope. Additionally, this Newtonian telescope is equipped with a German equatorial mount with a slow-motion altitude rod to facilitate alignment and viewing. Celestron 21045 PowerSeeker 114EQ Reflector Telescope is simply ideal for navigating the night sky.
Meade Instruments 216006 Polaris 130 EQ Reflector Telescope is a powerful tool equipped with a rack-and-pinion focuser, low (26 mm), medium (9 mm), and high (6.3mm) 1.25-inch magnification eyepieces, and a 2X Barlow lens. Note that the unit has a focal length of 650 mm and a focal ratio of f/5.0. It comes with a German equatorial mount, a steel tripod with a tray, and a red-dot viewfinder, as well as a bonus astronomical software. With a variety of features, Meade Instruments 216006 Polaris 130 EQ Reflector Telescope is suitable for both experts and amateurs.
Sky-Watcher 10″ Collapsible Dobsonian Telescope is a powerful Dobsonian-style Newtonian telescope, with an aperture of 254 mm (10 inches). The unit comes equipped with a two-inch Crayford-style focuser with a 1.25-inch adaptor, 4-element Plossl 25 mm and 10 mm 1.25-inch eyepieces, and an 8×50 RA viewfinder. Thus, Sky-Watcher Collapsible Dobsonian Telescope is a wonderful large-aperture telescope, ideal for viewing dim celestial objects and exploring the starry skies.
Orion 10016 StarBlast 6 Astro Reflector Telescope is a versatile product with an aperture of 150 mm and a magnification of 300X. Its compact tabletop design makes it a great portable telescope with a total weight of 10.7 kg (23.5 lbs). Furthermore, the unit is equipped with two 1.25-inch eyepieces (25 mm and 10 mm), an EZ Finder II aiming device, as well as Starry Night software. Orion 10016 StarBlast 6 Astro Reflector Telescope can reveal the secrets of the night sky to both beginners and seasoned users.
Celestron 21023 Cometron FirstScope Telescope is a portable Dobsonian-style telescope. Note that its spherical mirror provides 76 mm of aperture and sharp views, ideal for viewing both bright celestial objects and deep-sky objects. The unit includes two Kellner eyepieces and a 5×24 finderscope. With its appealing design, Celestron 21023 Cometron FirstScope Telescope is not only a great reflector unit but a beautiful decorative fixture on your bookshelf.
Meade Instruments LightBridge Mini 82 Tabletop Telescope is another portable Dobsonian unit, which is ideal for stargazing and outdoor adventures. This model features an 82 mm aperture, a Dobsonian mount, two eyepieces (9 mm and 26 mm), a 2X Barlow lens, and a red-dot finder. Meade Instruments LightBridge Mini 82 Tabletop Telescope also comes with a software DVD, which makes it ideal for beginners and astronomy lovers.
Orion SpaceProbe II 76 mm Altazimuth Reflector Telescope is an affordable telescope kit with a variety of features. The unit includes a stable altazimuth mount, a tripod, 25 mm and 10 mm Kellner eyepieces (28X and 70X magnification rates, respectively), a red-dot reflex sight, a 1.25-inch focuser. Note that this telescope has a 76 mm aperture, which is large enough for wonderful views of the Moon, the rings of Saturn, the moons orbiting Jupiter, and some bright nebulae. Last but not least, Orion SpaceProbe II 76 mm Altazimuth Reflector Telescopes come with useful MoonMap 260 to help users dive into the secrets of the skies.
From Newtonian models to Dobsonian tools, there’s a wide variety of reflecting telescopes on the market. Reflectors are highly popular as they are simple to assemble and use. As reflecting models use mirrors instead of lenses, they do not suffer from optical problems such as chromatic aberration, which makes them preferred tools by astronomy lovers.
Here we should mention that Cassegrain telescopes are a type of reflecting telescopes that use a combination of a concave and a convex mirror to elongate the focal length of the system. In fact, there are two types of Cassegrain units: symmetrical and asymmetrical telescopes. Cassegrain systems are also used in sophisticated catadioptric systems, including the Schmidt-Cassegrain, Maksutov-Cassegrain, and Klevtsov-Cassegrain, which are ideal for professional and seasoned users.
As stated earlier, Celestron, Meade, Orion, Tasco, Bushnell, iOptron, and Vixen are among the most top-notch companies on the market.
That being said, taking care of telescopes is essential to ensure accurate and long use:
Telescopes are fascinating inventions that facilitate the study of scenery, animals, and celestial objects. Reflecting telescopes, in particular, are popular units that provide enlarged images of objects and structures. Note that the first reflecting telescope was invented in 1668 by Sir Isaac Newton, who replaced the primary lens of the refractor system with a mirror. Half a century later, John Hadley added a parabolic mirror to eliminate possible distortions. Today’s reflecting telescopes do not suffer from problems such as chromatic aberration and can be made quite big, which makes them ideal for viewing dim celestial objects.
Choosing and taking care of a telescope, however, can be challenging. Users should consider three main factors: requirements, specifications, and total costs. Aperture, magnification, and focal length are all essential characteristics. Note that a high aperture is ideal for observing deep-sky objects, such as nebulae and galaxies. Additional accessories, such as focusers, carry bags, and celestial maps, are also essential to facilitate satisfactory viewing of the night sky.
In behavioral neuroscience, the Open Field Test (OFT) remains one of the most widely used assays to evaluate rodent models of affect, cognition, and motivation. It provides a non-invasive framework for examining how animals respond to novelty, stress, and pharmacological or environmental manipulations. Among the test’s core metrics, the percentage of time spent in the center zone offers a uniquely normalized and sensitive measure of an animal’s emotional reactivity and willingness to engage with a potentially risky environment.
This metric is calculated as the proportion of time spent in the central area of the arena—typically the inner 25%—relative to the entire session duration. By normalizing this value, researchers gain a behaviorally informative variable that is resilient to fluctuations in session length or overall movement levels. This makes it especially valuable in comparative analyses, longitudinal monitoring, and cross-model validation.
Unlike raw center duration, which can be affected by trial design inconsistencies, the percentage-based measure enables clearer comparisons across animals, treatments, and conditions. It plays a key role in identifying trait anxiety, avoidance behavior, risk-taking tendencies, and environmental adaptation, making it indispensable in both basic and translational research contexts.
Whereas simple center duration provides absolute time, the percentage-based metric introduces greater interpretability and reproducibility, especially when comparing different animal models, treatment conditions, or experimental setups. It is particularly effective for quantifying avoidance behaviors, risk assessment strategies, and trait anxiety profiles in both acute and longitudinal designs.
This metric reflects the relative amount of time an animal chooses to spend in the open, exposed portion of the arena—typically defined as the inner 25% of a square or circular enclosure. Because rodents innately prefer the periphery (thigmotaxis), time in the center is inversely associated with anxiety-like behavior. As such, this percentage is considered a sensitive, normalized index of:
Critically, because this metric is normalized by session duration, it accommodates variability in activity levels or testing conditions. This makes it especially suitable for comparing across individuals, treatment groups, or timepoints in longitudinal studies.
A high percentage of center time indicates reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance. reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance.
The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity, where animals exhibit persistent avoidance of the center due to heightened emotional reactivity. This metric can also distinguish between acute anxiety responses and enduring trait anxiety, especially in longitudinal or developmental studies. Its normalized nature makes it ideal for comparing across cohorts with variable locomotor profiles, helping researchers detect true affective changes rather than activity-based confounds.
Rodents that spend more time in the center zone typically exhibit broader and more flexible exploration strategies. This behavior reflects not only reduced anxiety but also cognitive engagement and environmental curiosity. High center percentage is associated with robust spatial learning, attentional scanning, and memory encoding functions, supported by coordinated activation in the prefrontal cortex, hippocampus, and basal forebrain. In contrast, reduced center engagement may signal spatial rigidity, attentional narrowing, or cognitive withdrawal, particularly in models of neurodegeneration or aging.
The open field test remains one of the most widely accepted platforms for testing anxiolytic and psychotropic drugs. The percentage of center time reliably increases following administration of anxiolytic agents such as benzodiazepines, SSRIs, and GABA-A receptor agonists. This metric serves as a sensitive and reproducible endpoint in preclinical dose-finding studies, mechanistic pharmacology, and compound screening pipelines. It also aids in differentiating true anxiolytic effects from sedation or motor suppression by integrating with other behavioral parameters like distance traveled and entry count (Prut & Belzung, 2003).
Sex-based differences in emotional regulation often manifest in open field behavior, with female rodents generally exhibiting higher variability in center zone metrics due to hormonal cycling. For example, estrogen has been shown to facilitate exploratory behavior and increase center occupancy, while progesterone and stress-induced corticosterone often reduce it. Studies involving gonadectomy, hormone replacement, or sex-specific genetic knockouts use this metric to quantify the impact of endocrine factors on anxiety and exploratory behavior. As such, it remains a vital tool for dissecting sex-dependent neurobehavioral dynamics.
The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity. Because it is normalized, this metric is especially helpful for distinguishing between genuine avoidance and low general activity.
Environmental Control: Uniformity in environmental conditions is essential. Lighting should be evenly diffused to avoid shadow bias, and noise should be minimized to prevent stress-induced variability. The arena must be cleaned between trials using odor-neutral solutions to eliminate scent trails or pheromone cues that may affect zone preference. Any variation in these conditions can introduce systematic bias in center zone behavior. Use consistent definitions of the center zone (commonly 25% of total area) to allow valid comparisons. Software-based segmentation enhances spatial precision.
Evaluating how center time evolves across the duration of a session—divided into early, middle, and late thirds—provides insight into behavioral transitions and adaptive responses. Animals may begin by avoiding the center, only to gradually increase center time as they habituate to the environment. Conversely, persistently low center time across the session can signal prolonged anxiety, fear generalization, or a trait-like avoidance phenotype.
To validate the significance of center time percentage, it should be examined alongside results from other anxiety-related tests such as the Elevated Plus Maze, Light-Dark Box, or Novelty Suppressed Feeding. Concordance across paradigms supports the reliability of center time as a trait marker, while discordance may indicate task-specific reactivity or behavioral dissociation.
When paired with high-resolution scoring of behavioral events such as rearing, grooming, defecation, or immobility, center time offers a richer view of the animal’s internal state. For example, an animal that spends substantial time in the center while grooming may be coping with mild stress, while another that remains immobile in the periphery may be experiencing more severe anxiety. Microstructure analysis aids in decoding the complexity behind spatial behavior.
Animals naturally vary in their exploratory style. By analyzing percentage of center time across subjects, researchers can identify behavioral subgroups—such as consistently bold individuals who frequently explore the center versus cautious animals that remain along the periphery. These classifications can be used to examine predictors of drug response, resilience to stress, or vulnerability to neuropsychiatric disorders.
In studies with large cohorts or multiple behavioral variables, machine learning techniques such as hierarchical clustering or principal component analysis can incorporate center time percentage to discover novel phenotypic groupings. These data-driven approaches help uncover latent dimensions of behavior that may not be visible through univariate analyses alone.
Total locomotion helps contextualize center time. Low percentage values in animals with minimal movement may reflect sedation or fatigue, while similar values in high-mobility subjects suggest deliberate avoidance. This metric helps distinguish emotional versus motor causes of low center engagement.
This measure indicates how often the animal initiates exploration of the center zone. When combined with percentage of time, it differentiates between frequent but brief visits (indicative of anxiety or impulsivity) versus fewer but sustained center engagements (suggesting comfort and behavioral confidence).
The delay before the first center entry reflects initial threat appraisal. Longer latencies may be associated with heightened fear or low motivation, while shorter latencies are typically linked to exploratory drive or low anxiety.
Time spent hugging the walls offers a spatial counterbalance to center metrics. High thigmotaxis and low center time jointly support an interpretation of strong avoidance behavior. This inverse relationship helps triangulate affective and motivational states.
By expressing center zone activity as a proportion of total trial time, researchers gain a metric that is resistant to session variability and more readily comparable across time, treatment, and model conditions. This normalized measure enhances reproducibility and statistical power, particularly in multi-cohort or cross-laboratory designs.
For experimental designs aimed at assessing anxiety, exploratory strategy, or affective state, the percentage of time spent in the center offers one of the most robust and interpretable measures available in the Open Field Test.
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