FEAR POTENTIATED STARTLE: PILOT STUDY 1

Subjects. Subjects were 8 female C57BL/6J mice (Harlan, UK), weighing 15-21 g at arrival (8-9 weeks). The mice were 5 months old at the time of the experiment. The mice were group housed and the environment conditions were controlled and constant (21°C±1°C, humidity at 50%±10%, light period 0700-1900 h). Food and water were available ad libitum.

Apparatus. Conditioning (training sessions) was carried out in two modified Plexiglas chambers (San Diego Instruments), fitted with stainless steel bars, through which shock could be administered. Testing (pre- and posttraining tests) was carried out in cylindrical Plexiglas restrainers (San Diego Instruments). Startle amplitude was defined as the peak voltage (Vmax) that occurred during the first 150 ms after the onset of the startle stimulus.

Procedure. Animals were subjected to three tests, (1) a Pretraining Test, (2) a Training Session, and (3) a Posttraining Test. Each test or training session was preceeded by a 5 min acclimation period when the animal was not be subjected to any stimuli presentations.

1. The Pretraining Test consisted of 10 presentations of 30 s tone and 10 presentations of 30 s tone co-terminating with a 100 dB white noise burst, lasting 50 ms. The stimuli had a fixed ITI (inter-trial interval) of 60 s. The order of presentations was randomised. The Pretest was conducted with the animal enclosed in the restrainer with the electric grid in place (although not active). The pretest was used to establish the "baseline startle" of each animal.
2. The Training Session (Paired) consisted of 10 presentations of tone + shock. The Each paired training trial consisted of a 30 s tone that co-terminated with a 500 ms, 0.3 mA foot shock. The ITI averaged 5 min and ranged from 4 to 6 min. The training sessions were conducted in the modified Plexiglas chambers.
The Training Session (Unpaired) consisted of 9 presentations of a 30 s tone and 9 presentations of a 500 ms, 0.3 mA foot shock. The animals were furthermore presented with a 30 s tone that co-terminated with a 500 ms, 0.3 mA foot shock (a paired trial).The ITI averaged 3 min and ranged from 2 min to 4 min.
3. The Posttraining Test was identical to the pretraining test.

Results.




NOT SIGNIFICANT

 

FEAR POTENTIATED STARTLE: PILOT STUDY 2

Subjects. Subjects were 8 female C57BL/6J mice (Harlan, UK), weighing 15-22 g at arrival (7-8 weeks). The mice were 5 months old at the time of the experiment. The mice were group housed and the environment conditions were controlled and constant (21°C±1°C, humidity at 50%±10%, light period 0700-1900 h). Food and water were available ad libitum.

Apparatus. As in FPS Pilot 1.

Procedure. As in FPS Pilot 1, except that the Pretraining Test consisted of 5 presentations of 30 s tone and 5 presentations of 30 s tone co-terminating with a 100 dB white noise burst, lasting 50 ms. The stimuli had a fixed ITI (inter-trial interval) of 60 s. The posttraining session was identical to the posttraining session in Pilot Study 1.

Results.


NOT SIGNIFICANT




FEAR POTENTIATED STARTLE: PILOT STUDY 3
(DATA SHOWN: PILOT 1 AND 3 COMBINED)

Subjects. Subjects were 12 female C57BL/6J mice (Harlan, UK), weighing 15-22 g at arrival (7-8 weeks). The mice were 5 months old at the time of the experiment. The mice were group housed and the environment conditions were controlled and constant (21°C±1°C, humidity at 50%±10%, light period 0700-1900 h). Food and water were available ad libitum.

Apparatus. As in FPS Pilot 1 (see above).

Procedure. As in FPS Pilot 1 (see above).

Results.


SIGNIFICANT INTERACTION



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