These experiments tested the role of CaV1.2 L-type voltage gated calcium channels in fear-related learning and memory using Pavlovian fear conditioning in CaV1.2 knockout mice. The results showed that deletion of CaV1.2 did not affect fear memory consolidation or generalization to similar contexts. However, deletion of CaV1.2 did disrupt the extinction of learned fear responses, as CaV1.2 knockout mice showed persistent fear compared to wildtype mice. These findings suggest that CaV1.2 plays a specific role in fear extinction rather than consolidation or generalization.

1. Training Test
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C a V 1 .2 K .O . W T
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These CaV1.2 K.O. mice were tested using Pavlovian fear conditioning methods,
yielding interesting conclusions. Deletion of CaV1.2 did not have an effect on memory
consolidation or generalization, but did effect extinction. Taken together, these results
demonstrate that CaV1.2 does not have a role in fear consolidation or generalization,
however, the lack of extinction describes a phenotype of persistent fear in CaV1.2
knockout mice similar to that found in anxiety related disorders such as PTSD. These
results, along with the previous findings provide further evidence for the role of
LVGCCs, and more specifically, the role of CaV1.2 in fear extinction.
Introduction Extinction Results
Generalization Results
Consolidation Results
Acknowledgements
Special thanks to Stephanie Temme for her guidance, support and mentorship
throughout this project.
..
The Role of CaV1.2 in Fear Related Learning and
Memory
Ryan Z. Bell1, Stephanie J. Temme2, Geoffrey G. Murphy1,2,3
Molecular and Behavioral Neuroscience Institute1, Neuroscience Graduate Program2,
Department of Integrative Physiology3, University of Michigan, Ann Arbor, MI
Experimental Setup
L-Type voltage gated calcium channels (LVGCCS) are thought to be involved in the
neuronal basis of learning and memory. There are two major subunits of LVGCCs in the
brain, CaV1.2 and CaV1.3. The specific role of each subunit in fear based memory and
learning is unknown. In order to understand the role of CaV1.2 in fear related learning
and memory, transgenic mice were used in which CaV1.2 was deleted specifically in
neurons. The following experiments test CaV1.2 knock-out mice in various forms of
Pavlovian fear conditioning and indicate CaV1.2 having a specific role in the extinction of
fear related memories.
Generalization Tests
Consolidation Tests
Extinction Tests
Animals were trained using three unsignalled foot shocks (3min pre-period; 0.5mA, 2sec
shocks; each separated by 30sec; 30sec post-shock) per day for two days. On day three,
animals were tested in either the training context, or a similar novel context. On day four,
animals were placed in a different, novel context and assessed as before.
Animals were trained using one unsignalled foot shock (3min pre-period; 0.5mA, 2sec
shock; 1min post-shock) per day for two days. Animals were then extinguished to the
training context through half-hour long context exposures for two days. Twenty-four
hours later, the animals were tested for their fear to the training context for five minutes.
Shock: Animals were trained using one unsignalled foot shock (3min pre-period; 0.5mA,
2sec shock; 1min post-shock) per day for two days. On day three, animals were tested
for their fear of the training context. Fear was assessed through levels of freezing.
Tone: Animals were trained using three co-terminating tone/shock pairings (3min pre-
period; 0.5mA, 2sec shocks; 2.8KHz, 75dB, 10sec tone; 30sec post tone/shock intervals)
per day for two days. On day three the animals were presented with only tone cues
(5 tones: 2.8KHz, 75dB, 10sec tone duration; 30sec post tone interval) and assessed.
Transgenic Mice
CaV1.2 neuronal conditional knock-out animals were generated by breeding mice
heterozygous for the floxed CaV1.2 exon 2 to transgenic mice expressing cre
recombinase regulated by the synapsin 1a promoter. Heterozygous floxed, cre positive
mice were then crossed with heterozygous, cre negative mice to produce cKO and WT
animals. Knock-out and wildtype animals are bred on an F2 129S6/SvEvTac, C57BL/6J
cross.
Training Generalization Tests
or or
A B C
Training TestExtinction
Trained to Shock
Trained to Tone
Training Test
Tone:
Shock:
This work was supported by a grant from the NIA R01 AG028488 to Geoffrey Murphy and
by the National Science Foundation through a graduate research fellowship to Stephanie
Temme.
CaV1.2 deletion does not effect in-session
generalization
CaV1.2 deletion does not effect memory
consolidation
Conclusions
CaV1.2 deletion does not effect in-session extinction,
but does significantly disrupt extinction retention
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G e n e ra liz a tio n T e s t
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S a m e (A )
S im ila r(B )
D iffe re n t(C )
N .S .
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C o n te x t E x tin c tio n
T im e (5 m in u te B in s )
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P o st-E xtin ctio n
P re -E xtin c tio n*