Zone Preference in the Visual Water Maze
June 26, 2025
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There are several microbiology techniques and procedures specially developed over the years to study and understand the metabolic processes, genetics, functions, and interaction of microbes with other organisms.[1]
The methodologies mostly involve techniques for culturing, identification, isolation, staining, and engineering these tiny organisms. They also have applications in other areas of biological research, including genetics, plant physiology, evolution, and molecular biology.[1]
Moreover, some of them contribute to better our health, but some cause life-threatening diseases. Others are used in food and beverage production, and to understand all this, we need to study these organisms.
Given the myriad uses of microbiology and its basic techniques, this article presents an overview of the basic microbiological laboratory techniques, how they work and are used in labs.
The microbiology techniques are categorized based on the type of experiments. It includes:[2]
These techniques don’t cover every microbiology technique; however, they are fundamental to all practices performed in microbiology laboratories.
It’s the complete removal of all other microbial forms, including viruses, bacteria, fungus, spores, and other vegetative cells from the surface or the culture media.
Based on the purpose of the sterilization, the method is categorized into two groups:
Disinfection is the process of killing microbes or inhibiting their growth from inanimate objects or surfaces by using physical or chemical agents like phenol, chlorine, alcohol, and heavy metal and their compounds.[2]
It’s the complete elimination of all pathogenic and non-pathogenic microbes from surface tops to reduce contamination. It’s also employed in daily lives to sanitize hands or in restaurants, dairies, and breweries to remove microbes and prevent infection and contamination.
It involves using chlorine-based cleaners, alcohol-based cleaners, formaldehyde, and hydrogen peroxide.[2]
Before introducing the microbial strain to the culture media, the isolation and inoculation techniques are followed.[3]
It’s a basic technique used in microbiology labs to place microbial cultures onto a culture medium. It’s performed using an apparatus, called inoculation loop, made of platinum or nichrome wire with a loop at its one end. It’s mainly used in streaking and culture plate techniques.[3] The small sample picked up and transferred from the culture is known as inoculum.
Isolation is a microbiological technique in which a specific microbial strain is isolated from a mixed culture of microorganisms by culturing the microbes on a selective culture media.[3] However, the procedure must be repeated several times to eliminate contamination by other microbes and achieve a pure culture of the microbial strain, which is then observed in culture plates as discrete/isolated individual colonies.
Microbes are grown in labs on culture media, which supply their nutritional requirements. These requirements vary for different microorganisms, thus a spectrum of culture medium recipes have been developed by scientists to obtain the desired microbial strain.[3]
Now, the common culture techniques used in microbiology labs include:[5]
After the microorganisms are inoculated in plates, the culture plates are sealed from base to lid using adhesive tape to prevent contamination. Then, the plates are kept in the incubator for the required time and temperature for the growth of the organisms. Furthermore, keeping the plates in an inverted position prevents the formation and fall of water droplets into the culture media.[4]
If it’s required to store the microbial samples for later experiments, the following storage techniques are used:
Counting microbial colonies is an essential task in performing a range of experiments. Here are some enumerating techniques:[6]
Pathogen identification is important for several applications. For example, it’s used to know which microbe is involved in contamination and food spoilage, which has useful applications in human lives, and which microorganism caused the particular disease for correct diagnosis and treatment in hospitals.
Microbes are identified by:[5]
Microbiology techniques are required to study microorganisms’ structure, function, metabolism, and genomics. They help understand how microbes work, interact with living organisms, cause diseases, and how they can be applied for human use.
The fundamental microbiology laboratory techniques include aseptic techniques, culturing techniques, enumerating bacteria, and identifying different classes of microorganisms. These techniques form the base of advanced research and experiments performed on microorganisms. The data obtained through these experiments also relate to other branches of biology, including molecular biology, soil science, agriculture, and the evolution of organisms.
The microbial study has helped scientists in many ways, from understanding how life began on earth to the use of microbes to control pollution. Moreover, the efficient use of these microbiological tools provides a deeper understanding of microbial life and the discovery of new species with new mysteries.
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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