Fear conditioning (TSE)
LSID: http://syli.cz/urn:lsid:public.sylics.com:conventionaltest:6A8D-4B86-B725Materials and Methods
Mice were singly housed on sawdust in standard Makrolon type II cages enriched with cardboard nesting material for at least one week prior to experiments, with water and food ad libitum (7:00/19:00 lights on/off; providing an abrupt phase transition).
Associated Mammalian Phenotype Ontologies (MGI)
- MP:0003106 abnormal fear-related response
- MP:0001469 abnormal contextual conditioning behaviour
- MP:0002062 abnormal associative learning
- MP:0001454 abnormal cued conditioning behaviour
Fear conditioning
Fear conditioning was performed as described before (pubmed 15669102), employing a computerized fear conditioning system (TSE, Bad Homburg, Germany). Mice were trained in a Plexiglas cage (36 x 21 x 20 cm) placed within a constantly illuminated (120-500 lx) dark gray fear conditioning box (context 1). A high-frequency loudspeaker (Conrad, KT-25-DT, Hirschau,Germany) provided constant background noise in the conditioning box (white noise, 68 dB). Context and tone conditioning consisted of exposure to the conditioning context for 180 s followed by 30 s tone exposure used as CS (10 kHz, 75 dB, pulsed 5 Hz). Termination of tone was followed after 15 s by the onset of the US (footshock: 0.7 mA, 2 s, constant current) delivered through a stainless steel floor grid (4 mm diameter, distance 9 mm). Mice were removed from the fear conditioning box 30 s after shock termination. The fear conditioning box was thoroughly cleaned with 70% ethanol before the placement of each mouse. The light in the experimental room was turned off during training. Context-dependent memory was assessed 23 h after conditioning in the fear conditioning box (context 1) for 180 s without tone or US presentation under otherwise identical conditions as during training. Tone-dependent memory was tested in a novel context (context 2) 3 h after context-dependent memory tests. Context 2 was an identically sized Plexiglas cage with a plain floor (no shock grid) in a white surrounding (380-480 lx) outside the fear conditioning box. No background noise was provided and lights in the experimental room were on. In the tone-dependent memory test, a 180-s exposure to a novel context without stimulation (pre-CS phase) was followed by a 180-s period of tone presentation (CS phase). The context 2 box was cleaned with 1% acetic acid in the same way as the fear conditioning box. During training and testing, activity (cm/s) was measured by a photo beam detection system (10 Hz detection rate, resolution of 1.3 x 2.5 cm).
Explanation of phases and trials:
Phase 1, trial 1: Day1, 180-s before onset of tone, used as assessment of general differences in activity
Phase 1, trial 2: Day1, 30-s tone. Typically the activity of mice decreases when they hear the tone, compared to the preceding 180-s
Phase 1, trial 3: Day1, 2-s electrical shock.High levels of activity if they are able to feel the shock.
Phase 1, trial 4: Day1, 30-s post shock period.
Phase 2, trial 1: Day 2 (~24 h after conditioning), 180-s in conditioned context (Context 1, see above).
Phase 3, trial 1: Day 3 (~48 h after conditioning), 180-s in a novel context (Context 2, see above)
Phase 3, trial 2: Day 3 (~48 h after conditioning), 180-s in a novel context (Context 2, see above) with tone presentation.
Parameter information
| Parameter name | Units |
| Distance moved per trial | cm |
| Average velocity per trial | cm/sec |
| Activity per trial | Percent |
| Hyperactivity per trial | Percent |
| Freezing number per trial (2 seconds threshold) | Frequency |
| Change in velocity during post-shock period in context1 | Velocity cm/sec |
| Freezing number per trial (3 seconds threshold) | Frequency |
| Freezing number per trial (4 seconds threshold) | Frequency |
| Freezing number per trial (5 seconds threshold) | Frequency |
| Freezing duration per trial (2 seconds threshold) | Seconds |
| Freezing duration per trial (3 seconds threshold) | Seconds |
| Freezing duration per trial (4 seconds threshold) | Seconds |
| Freezing duration per trial (5 seconds threshold) | Seconds |
| *Change in velocity in response to shock | Velocity (cm/s) |
| *Change in velocity in response to tone, before conditioning | Velocity (cm/s) |
| Change in velocity in response to tone, after conditioning in context2 | Velocity (cm/s) |
| Change in velocity in response to context1, 24h after conditioning in context1 | Velocity (cm/s) |
| Change in velocity in response to context2 (generalized fear) | Velocity (cm/s) |
| Freezing number (baseline - 3 seconds threshold) | Frequency |
| Freezing number (tone in context 2 - 3 seconds threshold) | Frequency |
| Freezing number (in context 1, 24h after conditioning - 3 seconds threshold) | Frequency |
| *Freezing duration (baseline - 3 seconds threshold) | Seconds |
| *Freezing duration (tone in context 2 - 3 seconds threshold) | Seconds |
| *Freezing duration (in context 1, 24h after conditioning - 3 seconds threshold) | Seconds |
| *Freezing duration (context 2 before tone - 3 seconds threshold) | Seconds |
| Freezing number (in context 2 before tone - 3 seconds threshold) | Frequency |