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Fulltext Effect of different inter-stimulus intervals (ISI) on cortical auditory evoked potential in normal hearing adults: a preliminary finding

‘Afaf Ezzaty Abdul Rahim, Ahmad Aidil Arafat Dzulkarnain

International Journal of Allied Health Sciences, 2018;2(3):459-467.
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The aim of this study was to investigate the effect of different inter-stimulus intervals to the Cortical Auditory Evoked Potential (CAEP) findings in adult participants. Nineteen normal hearing individuals aged between 20 and 24 years old participated in this study. CAEP were measured by presenting 1000 Hz tone burst stimulus at 70dBnHL at three different inter-stimulus intervals (ISI)s of 2000, 909 and 555 ms in randomized order. Results revealed significant changes in the CAEP’s amplitude as a function of ISI with a reduction of P1-N1 amplitude of up to 50%. N2 peak was absent in some subjects using short ISI (555 ms). This study concluded that the use of very short ISI (e.g. 555 ms) may not be appropriate clinically because it can reduce the CAEP wave amplitude
and can cause an absence of peak N2. In contrast, the use of short ISI may be useful for other clinical applications that may benefit from neural habituation and refractoriness, for example to predict the potential future outcome of speech and mental disorders.

Matched MeSH terms: Habituation, Psychophysiologic
Fulltext Design and development of a modified runway model of mouse drug self-administration

Pandy V, Khan Y

Sci Rep, 2016;6:21944.
PMID: 26902717 DOI: 10.1038/srep21944

The present study established a novel mouse model of a runway drug self-administration in our laboratory. The operant runway apparatus consisted of three long runways arranged in a zig-zag manner. The methodology consisted of six distinct phases: habituation, preconditioning, conditioning, post-conditioning, extinction and reinstatement. The effects of saline were compared with escalating doses of either ethanol (0.5-4.0 g/kg, i.p), heroin (5-40 mg/kg, i.p), or nicotine (0.1-0.5mg/kg, i.p) administered in the goal box during the conditioning phase (day 1 to day 5). A significant decrease in the time of trained (conditioned) mice to reach the goal box confirmed the subjects' motivation to seek those drugs on day 6 (expression). The mice were then subjected to non-rewarded extinction trials for 5 days over which run times were significantly increased. After 5 days of abstinence, a priming dose of ethanol or heroin (1/5th of maximum dose used in conditioning) significantly reinstated the drug-seeking behavior. These results suggest that the modified runway model can serve as a powerful behavioral tool for the study of the behavioral and neurobiological bases of drug self-administration and, as such, is appropriate simple but powerful tool for investigating the drug-seeking behavior of laboratory mice.

Matched MeSH terms: Habituation, Psychophysiologic
Bulbar signs in normal population

Lim KS, Hew YC, Lau HK, Lim TS, Tan CT

Can J Neurol Sci, 2009 Jan;36(1):60-4.
PMID: 19294890

BACKGROUND AND OBJECTIVES: There is lack of published data on bulbar signs among the healthy population. This study aims to determine the range of normality of bulbar signs particularly among the elderly.
METHODS: Systemic examination of bulbar signs was carried out according to a predetermined protocol on a cohort of young and elderly healthy subjects.
RESULTS: A total of 206 subjects were recruited in the study, 104 young adults with mean age of 20 years, and 102 elderly with mean age of 73 years. Uvula deviation was seen in 28 (26.9%) young subjects and 22 (21.6%) elderly. Irregular tongue border was seen in 17 subjects, unilateral in 4 subjects. Fourteen (6.8%) subjects had deviation on tongue protrusion. Occasional tremor of tongue on protrusion is common in both young and old. Persistent (severe) tongue tremor on protrusion was seen in 18.6% of the elderly, and 4.8% of the young. None of the subjects had tremor of tongue at rest. In gag reflex, absence of gagging response was common in elderly, seen in two thirds of the subjects on stimulation of the posterior pharyngeal wall. However, all the subjects had uvular movement. Habituation or suppression of gagging response was seen in close to 90% of young males.
CONCLUSION: There is wide range of normality in bulbar signs in normal population, particularly among the elderly.

Matched MeSH terms: Habituation, Psychophysiologic/physiology
Fulltext Ape conservation physiology: fecal glucocorticoid responses in wild Pongo pygmaeus morio following human visitation

Muehlenbein MP, Ancrenaz M, Sakong R, Ambu L, Prall S, Fuller G, et al.

PLoS One, 2012;7(3):e33357.
PMID: 22438916 DOI: 10.1371/journal.pone.0033357

Nature-based tourism can generate important revenue to support conservation of biodiversity. However, constant exposure to tourists and subsequent chronic activation of stress responses can produce pathological effects, including impaired cognition, growth, reproduction, and immunity in the same animals we are interested in protecting. Utilizing fecal samples (N = 53) from 2 wild habituated orangutans (Pongo pygmaeus morio) (in addition to 26 fecal samples from 4 wild unhabituated orangutans) in the Lower Kinabatangan Wildlife Sanctuary of Sabah, Malaysian Borneo, we predicted that i) fecal glucocorticoid metabolite concentrations would be elevated on the day after tourist visitation (indicative of normal stress response to exposure to tourists on the previous day) compared to samples taken before or during tourist visitation in wild, habituated orangutans, and ii) that samples collected from habituated animals would have lower fecal glucocorticoid metabolites than unhabituated animals not used for tourism. Among the habituated animals used for tourism, fecal glucocorticoid metabolite levels were significantly elevated in samples collected the day after tourist visitation (indicative of elevated cortisol production on the previous day during tourist visitation). Fecal glucocorticoid metabolite levels were also lower in the habituated animals compared to their age-matched unhabituated counterparts. We conclude that the habituated animals used for this singular ecotourism project are not chronically stressed, unlike other species/populations with documented permanent alterations in stress responses. Animal temperament, species, the presence of coping/escape mechanisms, social confounders, and variation in amount of tourism may explain differences among previous experiments. Acute alterations in glucocorticoid measures in wildlife exposed to tourism must be interpreted conservatively. While permanently altered stress responses can be detrimental, preliminary results in these wild habituated orangutans suggest that low levels of predictable disturbance can likely result in low physiological impact on these animals.

Matched MeSH terms: Habituation, Psychophysiologic