Hippocampus Hijinks: The Impacts of CA1 on Episodic Memory

            In 2017, a team of researchers at Columbia University’s Zuckerman Institute used a mouse model to investigate the biological sources of the severe memory deficit that is often a major symptom of schizophrenia. They focused on the CA1 region of the hippocampus, an area implicated in episodic memory as well as navigation and often showing alterations between normal brains and those of people with schizophrenia. Place cells, which are important for the brain’s internal mapping, navigation system, and spatial aspects of episodic memory, are housed in CA1 and were observed during the experiments using a two-photon microscope. Researchers genetically modified mice to mimic symptoms of schizophrenia and compared them to controls for experimentation. In the study, both groups of mice were placed on treadmills and introduced to different visual, auditory, and olfactory stimuli, to see how well the mice navigated environments, both new and familiar. Both control and experimental groups performed well when navigating a new environment, but the experimental group struggled remembering familiar ones, and found adapting to alterations in familiar environments challenging. The control mice’s place cells were found to fire more intensely as they approached a familiar landmark, and would drop back down in intensity after they moved away from it. The researchers would also move the location of those familiar landmarks, and once the control mice re-learned the new location, the same pattern was observed. Schizophrenia-like mice, however, did not show any alteration in place cell activation when familiar stimuli were moved to another location, showing that they were unable to adapt as well as normally developing mice, giving more insight into how the memory system may be affected by schizophrenia.

           

            This study relates to Dr. Molly Erickson’s talk on the neural mechanisms potentially underlying the memory deficits seen among patients with schizophrenia. Through her research, she has determined that the most likely step of the memory process that is defective in people with schizophrenia is the consolidation of the information, rather than the memory processing or storage itself. While she focused on the alpha and beta bands of the brain and how their responses differ between control patients and patients with schizophrenia, the results of this study could further identify more brain regions implicated in the memory deficits associated with the disorder, as the consolidation of memories may involve multiple regions of the brain.

References:

Erickson MA, Smith D, Albrecht MA, Silverstein S. Alpha-band desynchronization reflects memory-specific processes during visual change detection. Psychophysiology. 2019;00:e13442. https://doi.org/10.1111/psyp.13442

https://www.sciencedaily.com/releases/2017/09/170904120423.htm