Stimuli produced by observing responses make rats' ethanol self-administration more resistant to price increases

Rationale. Observing responses bring sensory receptors into contact with environmental stimuli. In the observing-response procedure, periods in which an operant response (e.g. pressing a lever) is reinforced by drug deliveries alternate with periods in which this response is never reinforced (i.e. extinction). These alternating periods of drug availability versus extinction are not signaled. Observing responses (i.e. presses on a second lever) produce brief stimuli signaling whether drug is available or not for responses on the first lever. Little is known about how parameters of the drug reinforcer affect drug-stimulus observing. Objectives. The effects of changes in the unit price (responses/reinforcer magnitude) of self-administered ethanol on rats' observing were examined. Also, the effects of an observing-response-produced ethanol stimulus on ethanol consumption were examined by comparing consumption during signaled and unsignaled periods of ethanol availability. Methods. Rats self-administered oral ethanol in the observing-response procedure. The unit price of ethanol in the observing-response procedure was increased by increasing the response requirement for ethanol across conditions. Results. Observing and response rates on the ethanol lever increased and then decreased with increases in the unit price of ethanol. However, ethanol-lever responding and ethanol consumption during periods when ethanol was available were less sensitive to increases in price when the observing-response-produced ethanol stimulus was present. Conclusions. Observing varies as an orderly function of unit price of a drug reinforcer, and drug stimuli produced by observing responses can make drug consumption less sensitive to increases in price. This procedure may provide an animal model of both attending to drug stimuli and the resultant effects of these stimuli on drug taking. Electronic Publication     

Language representation in a patient with a dominant right hemisphere: fMRI evidence for an intrahemispheric reorganisation

Studies have suggested that congenital left hemispheric (LH) frontal arteriovenous malformations (AVMs) are associated with an early transfer of language to right hemisphere (RH) frontal regions. The question remains whether such anatomofunctional reorganisation is due to RH compensatory abilities or to a general principle of lateral shift. In this study, we used fMRI language paradigms to investigate the case of a patient presenting aphasic symptoms following an haemorrhage due to a right frontal AVM. Prior to surgery, fMRI showed that language processing was confined to the RH, suggesting that language had not shifted during childhood from this congenitally dominant RH to the LH. After surgery, the patient presented severe aphasia that recovered to presurgical level within 70 days. At this time, fMRI showed that language tasks were still not associated with activations in the LH. These results suggest that the principles of early cerebral reorganisation after congenital lesions may differ in the RH and the LH. In addition, they support the idea that efficient restoration of language is achieved if a sufficiently large neuronal network is preserved around the lesion.     

Evaluation of condylar morphology following orthognathic surgery on digital panoramic radiographs. Could methodology influence the range of “normality” in condylar changes?

Objectives:

To evaluate the morphological condylar changes following orthognathic surgery by using a rapid and reliable computational method on panoramic radiographs.

Methods:

Digital panoramic radiographs of 45 patients who underwent bilateral sagittal split osteotomy (alone or associated with a Le Fort I osteotomy) between 2007 and 2010 were analysed. Calculation of the area, perimeter and height of 90 condyles was performed by using a specific computational method. Measurements were taken before surgery (m₁), 1 day after surgery (m₂) and 1 year after surgery (m₃). The evolution of each index was analysed using paired t-tests between measures before and 1 day after surgery (m₁ − m₂) and measures before and 1 year after surgery (m₁ − m₃). The changes in the condylar area, perimeter and height were examined using the Bland and Altman plotting method.

Results:

There were no statistically significant changes in the mean condylar area, perimeter or height between m₁ and m₂ or between m₁ and m₃. The Bland and Altman plots for each index showed that a very limited number of condyles increased or decreased in area, perimeter and/or height outside the boundaries of the measurement error. Given the impossibility for a condyle to increase in size, these results are considered to represent the limits of the computational method used.

Conclusions:

This study demonstrated that there were no significant morphological condylar changes at the 1-year follow-up following surgery and that the range of normality in condylar changes could be influenced by the methodology used.     

Attitudes towards child restrains and seat belts usage in the learned population of Karachi,Pakistan

BACKGROUND:

Motor vehicles crashes (MVCs) are the leading cause of injury related morbidity and mortality in developed countries. Recent evidence proves that properly used child seat belts can dramatically reduce the risk of severe and life-threatening injury from MVCs. There are rarities of thought and inspiration regarding the use of child seat belts in our society and region, therefore we lack of data regarding factors and paucity of usage of child seat belts in motor vehicles. This study aimed to assess the knowledge and attitudes of child seat belt usage among the educated population in Karachi, Pakistan.

METHODS:

Altogether 304 employees were investigated. They were employees of Aga Khan University who were using their cars and having children younger than 10 years old. A cross sectional observational study was designed, and a 36-item questionnaire in English was used to collect data on participants’ demographic details, designation, educational level, economic status, validity of driving license, number of children and cars, availability of adult seat belts and child seat belts along with their functionality, awareness, knowledge and attitude toward its use, and reason of not using these devices. SPSS version 20 for Windows was used to analyze the data and the Chi-square test was used.

RESULTS:

Totally 290 participants were recruited with a response rate of 72% (212). Of 212 participants, 126 (59%) were male. 154 (72.6%) participants had valid driver licenses, and 154 (72.6%) had adult seat belts in their vehicles. Only 32 (15%) reported regular use of adult seat belts. Although 168 (79.2%) participants had some knowledge about child restrains (CRs), only 65 (22%) had CRs in their cars. Eighty-two (38.7%) participants got the knowledge about CRs and seat belts from media. Mothers were more concerned about the use of CRs than fathers. Only 14 (6.6%) parents were found to use both adult and child seat belts all the time. Of the 157 parents who did not us use CRs, 42 considered unnecessary, 35 lacked relevant knowledge. But 15 parents used CR against their children’s wills.

CONCLUSIONS:

The pattern of CR usage among the employees at Aga Khan University, Karachi is dictated by the unavailability of CR, followed by ignorance, inconvenience, and non-acceptance by their children. The important issue of CR has consistently been ignored over the years and it has never gained enough popularity in Pakistan.KEY WORDS: Child restrains, Motor vehicles crash, Injury prevention, Pakistan