PubMed Health⌕ Search

Biomedical subjects

R Gallant

Publications and source records attributed to R Gallant.

5 recordsLinked to original sources
PubMed1999

Role of the dorsomedial hypothalamus in mediating the response to benzodiazepines on trial 2 in the elevated plus-maze test of anxiety.

Trial 2 in the elevated plus-maze provides an animal model of specific phobia (fear of heights). On this trial, rats no longer respond to benzodiazepines. The present experiment examined the role of the dorsomedial hypothalamus in mediating insensitivity to chlordiazepoxide on trial 2. Rats received a 5 min exposure to the maze, undrugged. Forty-eight hours later, rats injected with control infusions into the dorsomedial hypothalamus showed the usual lack of response to chlordiazepoxide (5 mg/kg, i.p.). However, those receiving lidocaine injections (40 micrograms/microliter in a volume of 0.2 microliter) in the dorsomedial hypothalamus (producing functional inactivation), immediately before trial 2, responded with an anxiolytic response to chlordiazepoxide, characterised by an increased percentage of time on the open arms and by an increased number of entries into, and time spent on, the distal portions of the open arms. Since the lidocaine injections were without anxiolytic effects, our results suggest that this region of the hypothalamus regulates the functional state of benzodiazepine receptors in other brain regions.

Animals↗
PubMed1998

Role of the basolateral nucleus of the amygdala in the formation of a phobia.

Specific phobia is an anxiety disorder that does not respond to benzodiazepines. The elevated plus-maze test of anxiety is sensitive to benzodiazepines on trial 1, but during the first 5-min trial the nature of the anxiety generated changes to a specific fear of heights, and, as a result, on trial 2 the rats no longer respond to benzodiazepines. However, rats that received reversible bilateral lesions of the basolateral amygdala (by lidocaine injection) immediately after trial 1 responded with an anxiolytic response to chlordiazepoxide when tested 48 h later on trial 2. Those that received vehicle injections after trial 1 showed the usual lack of response to chlordiazepoxide on trial 2. Thus, the basolateral amygdala plays a crucial role in the consolidation of information that leads to the formation of a specific phobia and subsequent insensitivity to benzodiazepines.

Amygdala↗
PubMed1992

Empirical evidence for assumptions underlying time orientation in undergraduates.

282 undergraduate students between 17 and 68 years of age were asked to list the 5 most significant experiences of their lives, to assign the time zones to these experiences, and to provide estimates of emotional valence corresponding to each significant life experience they listed. Subjects also provided judgements of time perspective on a Life Line. The sample showed a near-past orientation and a positive emotional valence across the experiences reported. However, the first experiences reported were distant past experiences significantly more frequently than expected by chance, while the last experiences in the Experiential Inventory were significantly more often located in the distant future. While this result validates the prevailing assumption of a unidirectional flow of past to future, empirical evidence was also found for the larger magnitude and variability of future as compared with past perspective. This suggests a bidirectional model of time should be invoked to explain the differing character of the opponent temporal processes of recall and anticipation in human experience.

Adolescent↗
PubMed1991

Subjective time estimation and age.

Time seems to accelerate with increasing age. This subjective acceleration or compression may be due to the operation of a linear or a square-root function that relates present age to past age. A subjective magnitude-estimation technique was applied in a questionnaire given to 282 university students to determine which function best fitted the data. The results did not support the hypothesis that subjective time is estimated by either linear or square-root functions. Instead, the results indicate that subjective time is estimated with respect to a stable constant independent of age. These results support the notion that the purely subjective perception of time may serve as a measure of psychological temporal processes that remain stable with age. A linear function of age was, however, significantly related to error in the estimation of test-duration.

Adolescent↗