The prefrontal cortex (and in particular the left hemisphere) is also involved in the formation of new episodic memories (also known as episodic encoding). Patients with damage to the prefrontal cortex can learn new information, but tend to do so in a disordered fashion. For example, they might show normal recognition of an object they had seen in the past, but fail to recollect when or where it had been viewed (Janowsky et al., 1989). Some researchers believe that the prefrontal cortex helps organize information for more efficient storage, drawing upon its role in executive function. Others believe that the prefrontal cortex underlies semantic strategies which enhance encoding, such as thinking about the meaning the study material or rehearsing it in working memory (Gabrieli et al., 1998).
The hippocampus's role in memory storage
Researchers do not agree about how long episodic memories are stored in the hippocampus. Some researchers believe that episodic memories always rely on the hippocampus. Others believe the hippocampus only stores episodic memories for a short time, after which the memories are consolidated to the neocortex. The latter view is strengthened by recent evidence that neurogenesis in the adult hippocampus may ease the removal of old memories and increase the efficiency of forming new memories (Deisseroth et al 2004).
References & Bibliography
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- Nyberg, L., Cabeza, R., & Tulving, E. (1998). Asymmetric frontal activation during episodic memory: what kind of specificity? Trends in Cognitive Sciences, 2, 419-420.
- Tulving, E., & Markowitsch, H. J. (1998). Episodic and declarative memory: Role of the hippocampus. Hippocampus, 8, 198-204.
- Wheeler, M., Stuss, D. T., & Tulving, E. (1997). Toward a theory of episodic memory: The frontal lobes and autonoetic consciousness. Psychological Bulletin, 121, 331-354.
- Nyberg, L., McIntosh, A. R., Houle, S., Nilsson, L.-G., & Tulving, E. (1996). Activation of medial temporal structures during episodic memory retrieval in individual subjects. Nature, 380, 715-717.
- Nyberg, L., McIntosh, A. R., Cabeza, R., Nilsson, L.-G., Houle, S., Habib, R., & Tulving, E. (1996). Network analysis of PET rCBF data: Ensemble inhibition during episodic memory retrieval. Journal of Neuroscience, 16, 3753-3759.
- Nyberg, L., Tulving, E., Habib, R., Nilsson, L.-G., Kapur, S., Houle, S., Cabeza, R. E. L., & McIntosh, A. R. (1995). Functional brain maps of retrieval mode and recovery of episodic information. NeuroReport, 7, 249-252.
- Tulving, E., Kapur, S., Markowitsch, H. J., Craik, F. I. M., Habib, R., & Houle, S. (1994). Neuroanatomical correlates of retrieval in episodic memory: Auditory sentence recognition. Proceedings of National Academy of Sciences U.S.A. 91, 2012-2015.
- Tulving, E., Kapur, S., Craik, F. I. M., Moscovitsch, M., & Houle, S. (1994) Hemispheric encoding/retrieval asymmetry in episodic memory: Positron emission tomography findings. Proceedings of National Academy of Sciences U.S.A. 91, 2016-2020.
- Tulving, E., Risberg, J., & Ingvar, D. H. (1988). Regional cerebral blood flow and episodic memory retrieval. Bulletin of the Psychonomic Society, 26, 522.