Sareesh Naduvil Narayanan

Background: Ontogeny refers to the gradual changes in behaviour and physiological processes that occur across the lifespan of an organism, which are associated with significant changes in sensory, emotional and social systems. Purpose: In this study, the changes that occur in object recognition memory, exploratory activity and anxiety-like behaviour were studied in 6-, 12- and 24-month-old rats as a result of their normal developmental and/or ageing process, with the help of two behavioural testing paradigms, such as the novel object recognition test (NORT) and open field test (OFT). Methods: Animals were randomly assigned to three experimental groups: Group 1: 6-month-old—representing early adulthood, a stage characterised by peak physiological and cognitive function. Group 2: 12-month-old—representing middle-aged, a transitional phase with potential early signs of age-related changes. Group 3: 24-month-old—representing late adulthood and early ageing, a period associated with progressive neurobiological and behavioural alterations. The NORT and OFT were carried out using the Panlab-SMART automated behavioural video tracking system. Results: Results demonstrate that recognition memory was only mildly decreased in middle-aged animals, and remained mostly intact throughout adulthood and in aged animals. Anxiety-like behaviour did not show significant differences across age groups. In contrast, rearing and exploratory activity declined with age, suggesting the behavioural changes are more reflective of exploratory and locomotor behaviours. Stretching and other risk-assessment behaviours did not change as the age progressed. Conclusion: When combined, these results imply that exploratory and locomotor behaviours are more susceptible to ageing, compared to recognition memory and anxiety-like behaviours. The results also highlight the importance of using multiple behavioural assays to holistically unravel emotionality changes across various age groups in rats. Further research is needed to understand better the molecular, cellular and neurobiological mechanisms driving these behavioural trajectories in rats.

Introduction: Handwriting is a complex neuromotor skill that involves cognitive and motor processes. Reports demonstrating the relationship between handwriting speed, handgrip strength, and pinch force are scanty. Knowledge of this will help in managing illnesses that impair motor function, such as developmental or neurological disorders. This study was carried out to determine the handgrip strength, pinch force, and handwriting speed in young adults and to understand the relationship between them. Materials and methods: This cross-sectional study was conducted among 127 students (aged 18–22 years) after obtaining their informed consent. Participants’ demographic data were collected using a questionnaire. Their handgrip strength and pinch force were measured using a hand dynamometer/pinch gauge (JAMAR, USA). The handwriting speed was determined by calculating the words written per minute. Student’s 't' test, one-way ANOVA, and Pearson’s correlation tests were performed for data analysis. Results: The mean handwriting speed of participants was significantly different in males and females. Handgrip strength and pinch force were found to be significantly higher in males compared to females. A significant negative correlation was observed between handwriting speed and handgrip strength and/or pinch force. However, these parameters were not found to be significantly different in different BMI groups. Conclusion: The current study demonstrates that handwriting speed was higher in females than in males, but both grip strength and pinch force were higher in males than in females. The grip strength and pinch force had a negative relationship with handwriting speed but BMI did not influence any of the parameters studied in young adults. These results emphasise the significance of fine motor skills over muscle strength in handwriting effectiveness, stressing the necessity for rehabilitation approaches that prioritise coordination and endurance training instead of just enhancing grip strength.

Background: Tactile stimulation (TS) is a positive experience that mimics maternal licking and grooming in the rat. Since the brain is extremely plastic in early life, TS during this period may modulate normal brain organisation and could enhance cognitive and/or motor abilities. Purpose: This study is designed to evaluate the possible changes in exploratory behaviour, emotionality and learning and memory following repetitive TS during periadolescent period. Methods: Male albino Wistar rats were grouped into control and TS groups. The TS group animals were exposed to repetitive TS (15 min/session), three times/day from postnatal day 28–43. After this, exploratory behaviour, emotionality and object recognition memory were tested using open field (OF), elevated plus maze (EPM) and novel object recognition (NORT) tests by a computerised video-tracking system. Results: TS increased rearing number, rearing rate, total stretching, total stretching duration, stretching rate, mean speed and parallelism index in rats during the OF test. However, total distance travelled, global activity and total zone transitions were comparable in both groups during the OF test. TS significantly increased stretching duration and decreased entries to the closed arm during the EPM test. It slightly increased the percentage of time spent and distance travelled on the open arm in TS group. Total distance travelled, total zone transitions and global activity were comparable in both groups during the EPM test. TS mildly increased recognition index during NORT. Conclusion: Tactile stimulation exposed animals demonstrated increased exploratory, risk assessment and decision-making behaviours on OF test suggesting a possible positive influence of TS on these behaviours. However, TS only mildly influenced emotionality and object recognition memory, and it did not alter general locomotor behaviours in rats.

Background: The constant artificial blue light exposure from electronic gadgets at night raises concerns about its impact on mood and brain functions. This study is designed to evaluate the effect of chronic exposure to artificial blue light from a light-emitting diode (LED) on emotionality, locomotion, novel object recognition memory and hippocampal cytoarchitecture in adolescent rats. Materials and methods: Male albino Wistar rats were exposed to artificial blue light (450 – 495 nm, and 100 Lux) for 14 days from a LED light source. Later, their emotionality, general locomotor behaviours and novel object recognition memory were tested by a computerised behavioural assessment system. After the behavioural assessments animals were euthanized to study the hippocampal cytoarchitecture by Nissl and Golgi-Cox staining. Results: In the open field test, latency to enter the centre zone was significantly increased in blue light exposed animals compared to controls. Total entries to the centre zone and percentage of time spent in the centre zone were slightly reduced in blue light exposed animals. The mean speed of animals in the centre, total zone transitions, and total distance travelled were not different between the two groups. In the elevated plus maze test, entries to the open arm were significantly reduced in blue light exposed animals. Time spent and distance travelled on the open arm were slightly reduced in blue light exposed animals. Entries to the closed arm and time spent in the closed arm were slightly increased but, the distance travelled in the closed arm was significantly reduced in the blue light exposed group. The mean speed of blue light exposed animals on the open arm, closed arm and centre were comparable in the two groups. Rearing duration and total zone transitions were slightly reduced but the total distance travelled was significantly reduced in the light exposed group. Novel object recognition was altered in the light exposed group as indicated by their negative discrimination index values. Hippocampal cornu ammonis-1 (CA1), and cornu ammonis-3 (CA3) regions demonstrated pyknotic cells and CA1 apical dendritic spine density was reduced in blue light exposed rats. Conclusion: Artificial blue light exposure induced anxiety-like behaviours, and significantly altered novel object recognition memory, but only mildly affected the general locomotor behaviours in adolescent rats. Moreover, it induced hippocampal cellular pyknosis and reduced CA1 apical dendritic spine density in blue light exposed adolescent rats.

Since it first appeared, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has had a significant and lasting negative impact on the health and economies of millions of individuals all over the globe. At the level of individual health too, many patients are not recovering fully and experiencing a long-term condition now commonly termed ‘long-COVID’. Long-COVID is a collection of symptoms which must last more than 12 weeks following initial COVID infection, and which cannot be adequately explained by alternate diagnoses. The neurological and psychosocial impact of long-COVID is itself now a global health crisis and therefore preventing, diagnosing, and managing these patients is of paramount importance. This review focuses primarily on: neurological functioning deficits; mental health impacts; long-term mood problems; and associated psychosocial issues, among patients suffering from long-COVID with an eye towards the neurological basis of these symptoms. A concise account of the clinical relevance of the neurological and psychosocial impacts of long-COVID, the effects on long-term morbidity, and varied approaches in managing patients with significant chronic neurological symptoms and conditions was extracted from the literature, analysed and reported. A comprehensive account of plausible pathophysiological mechanisms involved in the development of long-COVID, its management, and future research needs have been discussed.

In this report, a novel teaching methodology, “real-life scenario (RLS) blended teaching” is described and its effectiveness in facilitating inquisitive learning in undergraduate medical students is evaluated. Students exposed to RLS sessions blended with multiple miniassignments, peer discussions, multiple formative assignments, and facilitator feedback sessions performed well in the summative assessments compared with those exposed to RLS sessions and assignments or exposed to traditional teaching alone. Students preferred active teaching-learning techniques over the traditional method.

Emerging viral infections are a ceaseless challenge and remain a global public health concern. The world has not yet come back to normal from the devastating effects of the highly contagious and pathogenic novel coronavirus, or Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Olfactory and taste dysfunction is common in patients infected by the novel coronavirus. In light of the emergence of different coronavirus variants, it is important to update the prevalence and pathophysiology of these side effects. In this review, articles published on the prevalence of olfactory and taste dysfunction from coronavirus disease (COVID-19) and their possible pathophysiologic mechanisms have been reviewed and reported. The modulatory role of different SARS-CoV-2 variants on the chemical senses is then described. The clinical relevance of chemical sense disorder and its long-term morbidity and management is also discussed.

Epigenetic mechanisms, which include DNA methylation, a variety of post-translational modifications of histone proteins (acetylation, phosphorylation, methylation, ubiquitination, sumoylation, serotonylation, dopaminylation), chromatin remodeling enzymes, and long non-coding RNAs, are robust regulators of activity-dependent changes in gene transcription. In the brain, many of these epigenetic modifications have been widely implicated in synaptic plasticity and memory formation. Dysregulation of epigenetic mechanisms has been reported in the aged brain and is associated with or contributes to memory decline across the lifespan. Furthermore, alterations in the epigenome have been reported in neurodegenerative disorders, including Alzheimer’s disease. Here, we review the diverse types of epigenetic modifications and their role in activity- and learning-dependent synaptic plasticity. We then discuss how these mechanisms become dysregulated across the lifespan and contribute to memory loss with age and in Alzheimer’s disease. Collectively, the evidence reviewed here strongly supports a role for diverse epigenetic mechanisms in memory formation, aging, and neurodegeneration in the brain.

Journal of Clinical and Diagnostic Research aims to publish findings of doctors at grass root level and post graduate students, so that all unique medical experiences are recorded in literature.