ABSTRACT
Accumulation of c-Fos and Arc proteins in neurons in different regions of the hippocampus after single trial of contextual fear conditioning was studied by using immunohistochemical staining. We found that the dynamics of the c-Fos and Arc expression has a biphasic pattern: the first peak was observed in 15-30 min after learning and the second less pronounced peak in 1-3 h. Induction of Arc occurred earlier than c-Fos and the overall dynamics of the two waves slightly varied in the dentate gyrus and hippocampal CA1 and CA3 fields. The findings open the possibility of mapping the cognitive neural networks of the brain with higher temporal resolution and draw attention to fluctuations of hippocampal activity after a single brief episode of new experience.
Subject(s)
Conditioning, Psychological/physiology , Cytoskeletal Proteins/metabolism , Nerve Tissue Proteins/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Pyramidal Cells/metabolism , Animals , CA1 Region, Hippocampal/cytology , CA3 Region, Hippocampal/cytology , Dentate Gyrus/cytology , Fear/physiology , Male , Mice, Inbred C57BLABSTRACT
Memory consolidation is a term used to describe the process of memory stabilization from labile, easily disrupted state into disruption-resistant long-term form. Protein synthesis inhibitors injected before or immediately after learning episode, produce significant amnesia. However in a limited number of studies the possibility of memory recovery after such pharmacologically-produced amnesia was shown. The aim of present study was to investigate the possibility of memory recovery in single-session fear conditioning paradigm in mice. Mice were injected with protein synthesis inhibitor cycloheximide twenty minutes prior learning to induce amnesia. Twenty four hours after training mice were subjected to reminder shock, similar to one used during training. Amnestic animals have demonstrated complete recovery of cued fear memory to the level of normal animals when tested 24h after reminder presentation. Thus our data indicate that specific type of memory might be restored using nonspecific stimulus as a reminder. Possible mechanisms of memory reparation after PSI injection during learning are discussed.
Subject(s)
Amnesia/chemically induced , Learning , Memory/physiology , Amnesia/physiopathology , Animals , Conditioning, Psychological , Cycloheximide/pharmacology , Cycloheximide/toxicity , Fear/physiology , Humans , Learning/drug effects , Learning/physiology , Memory/drug effects , Mice , Protein Synthesis Inhibitors/pharmacology , Protein Synthesis Inhibitors/toxicity , Time FactorsABSTRACT
We analyzed the expression of transcription factor c-Fos induced by neural activity in the mouse brain after acoustic stimulation. The brain sections of the animals subjected to acoustic stimulation and controls were immunohistochemically stained for c-Fos protein. Statistical parametric mapping (SPM) was used to identify group differences in the acquired images. c-Fos expression was significantly higher in the auditory cortex, amygdala, and hippocampus CA3 area after tone presentation. The proposed combination of SPM with molecular-biological approach to visualization of transcription in the nerve cells makes it possible to identify the collaborative activation of distant brain structures assumed to be the components of united functional systems.
Subject(s)
Acoustic Stimulation , Amygdala/metabolism , Auditory Cortex/metabolism , Hippocampus/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Animals , Brain/metabolism , Brain Mapping , Gene Expression , Male , Mice , Mice, Inbred C57BL , Neurons/metabolism , Proto-Oncogene Proteins c-fos/geneticsABSTRACT
Possible mechanisms of recovery of the memory impaired during consolidation process were investigated. In mice, amnesia was induced by intraperitoneal cycloheximide (100 mg/kg) administration 20 min before exposure to tone signal combined with footshock (2 sec, 0.5 mA). Reminder by the footshock (2 sec, 0.5 mA) 24 h after the learning procedure resulted in recovery of impaired memory in amnestic animals up to the level of control animals. Analysis of c-Fos expression in response to reminder indicated increased number of c-Fos-positive cells in prelimbic cortex in the animals with unaffected memory in comparison with corresponding parameter in amnestic animals. These findings are indicative of impairment in prelimbic cortex activity in experimental amnesia as well as for reminder ability to recover the memory impaired in that way.
Subject(s)
Amnesia/physiopathology , Prefrontal Cortex/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Recovery of Function/physiology , Acoustic Stimulation , Animals , Cycloheximide/administration & dosage , Cycloheximide/toxicity , Electric Stimulation , Immunohistochemistry , Injections, Intraperitoneal , Male , Mice , Mice, Inbred C57BLABSTRACT
We developed a method to detect and superimpose neuronal populations involved in two different episodes of activity in the brain of single animal. This method is based on usage of two transcriptional factors with different accumulation curves, c-Fos and pCREB, as the markers. The overlap of neuronal populations involved in performance of spatial and nonspatial tasks in Morris water maze has been shown to occur at "chance" level.
