Commentary: Stimulation of the Posterior Cingulate Cortex Impairs Episodic Memory Encoding

Neuroimaging experiments implicate the posterior cingulate cortex (PCC) in episodic memory processing, making it a potential target for responsive neuromodulation strategies outside of the hippocampal network. However, causal evidence for the role PCC plays in memory encoding is lacking. In patients undergoing seizure mapping, we investigated functional properties of the PCC using deep brain stimulation (DBS) and stereotactic electroencephalography (stereo EEG). These techniques allow precise targeting of deep cortical structures including the PCC, and simultaneous acquisition of oscillatory recordings from neighboring regions such as the hippocampus. We used a free recall experiment in which PCC was stimulated during item encoding period of half of the study lists, while no stimulation was applied during encoding period of the remaining lists. We evaluated if stimulation affected memory and/or modulated hippocampal activity. Results revealed four main findings. (i) Stimulation during encoding impaired memory for early items on the study lists. (ii) Stimulation increased hippocampal gamma band power. (iii) Stimulation-induced gamma power predicted memory impairment. (iv) Functional connectivity between the hippocampus and PCC predicted the degree of stimulation effect on memory. Our findings offer the first causal evidence implicating the PCC in episodic memory encoding. Importantly, results highlight that stimulation targeted outside of the temporal lobe can modulate hippocampal activity with implications on behavior. Furthermore, a-priori measures of connectivity between brain regions within a functional network can be informative in predicting behavioral effects of stimulation. Our findings have significant implications for developing therapies to treat diseases of memory loss and cognitive impairment using DBS.

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The effect of hippocampal function, volume and connectivity on posterior cingulate cortex functioning during episodic memory fMRI in mild cognitive impairment

European Radiology ◽

10.1007/s00330-017-4768-1 ◽

2017 ◽

Vol 27 (9) ◽

pp. 3716-3724 ◽

Cited By ~ 8

Author(s):

Janne M. Papma ◽

Marion Smits ◽

Marius de Groot ◽

Francesco U. Mattace Raso ◽

Aad van der Lugt ◽

...

Keyword(s):

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Episodic Memory ◽

Cingulate Cortex ◽

Posterior Cingulate Cortex ◽

Hippocampal Function ◽

Posterior Cingulate

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Modulation of Oscillatory Power and Connectivity in the Human Posterior Cingulate Cortex Supports the Encoding and Retrieval of Episodic Memories

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01133 ◽

2017 ◽

Vol 29 (8) ◽

pp. 1415-1432 ◽

Cited By ~ 13

Author(s):

Bradley Lega ◽

James Germi ◽

Michael D. Rugg

Keyword(s):

Episodic Memory ◽

Low Frequency ◽

Cingulate Cortex ◽

Posterior Cingulate Cortex ◽

Gamma Band ◽

Posterior Cingulate ◽

Oscillatory Power ◽

Episodic Memories ◽

Encoding And Retrieval

Existing data from noninvasive studies have led researchers to posit that the posterior cingulate cortex (PCC) supports mnemonic processes: It exhibits degeneration in memory disorders, and fMRI investigations have demonstrated memory-related activation principally during the retrieval of memory items. Despite these data, the role of the PCC in episodic memory has received only limited treatment using the spatial and temporal precision of intracranial EEG, with previous analyses focused on item retrieval. Using data gathered from 21 human participants who underwent stereo-EEG for seizure localization, we characterized oscillatory patterns in the PCC during the encoding and retrieval of episodic memories. We identified a subsequent memory effect during item encoding characterized by increased gamma band oscillatory power and a low-frequency power desynchronization. Fourteen participants had stereotactic electrodes located simultaneously in the hippocampus and PCC, and with these unique data, we describe connectivity changes between these structures that predict successful item encoding and that precede item retrieval. Oscillatory power during retrieval matched the pattern we observed during encoding, with low-frequency (below 15 Hz) desynchronization and a gamma band (especially high gamma, 70–180 Hz) power increase. Encoding is characterized by synchrony between the hippocampus and PCC, centered at 3 Hz, consistent with other observations of properties of this oscillation akin to those for rodent theta activity. We discuss our findings in light of existing theories of episodic memory processing, including the information via desynchronization hypothesis and retrieved context theory, and examine how our data fit with existing theories for the functional role of the PCC. These include a postulated role for the PCC in modulating internally directed attention and for representing or integrating contextual information for memory items.

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Impaired posterior cingulate cortex–parahippocampus connectivity is associated with episodic memory retrieval problems in amnestic mild cognitive impairment

European Journal of Neuroscience ◽

10.1111/ejn.15189 ◽

2021 ◽

Author(s):

Sven Vanneste ◽

Alison Luckey ◽

S. Lauren McLeod ◽

Ian H. Robertson ◽

Wing Ting To

Keyword(s):

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Episodic Memory ◽

Memory Retrieval ◽

Cingulate Cortex ◽

Posterior Cingulate Cortex ◽

Amnestic Mild Cognitive Impairment ◽

Posterior Cingulate

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Are inhibitory and excitatory neurotransmitter levels in the posterior cingulate cortex associated with MS fatigue?

10.26226/morressier.59a3e8b4d462b8028d89445c ◽

2017 ◽

Author(s):

Karen A. Ribbons

Keyword(s):

Cingulate Cortex ◽

Posterior Cingulate Cortex ◽

Excitatory Neurotransmitter ◽

Posterior Cingulate

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Serum Vitamin D and Cingulate Cortex Thickness in Older Adults: Quantitative MRI of the Brain

Current Alzheimer Research ◽

10.2174/1567205016666191113124356 ◽

2019 ◽

Vol 16 (11) ◽

pp. 1063-1071 ◽

Cited By ~ 1

Author(s):

Gonzague Foucault ◽

Guillaume T Duval ◽

Romain Simon ◽

Olivier Beauchet ◽

Mickael Dinomais ◽

...

Keyword(s):

Older Adults ◽

Vitamin D ◽

Brain Mri ◽

Serum Vitamin ◽

Cingulate Cortex ◽

Posterior Cingulate Cortex ◽

Vitamin D Insufficiency ◽

Anterior Cingulate ◽

Posterior Cingulate ◽

Significant Difference

Background: Vitamin D insufficiency is associated with brain changes, and cognitive and mobility declines in older adults. Method: Two hundred and fifteen Caucasian older community-dwellers (mean±SD, 72.1±5.5years; 40% female) received a blood test and brain MRI. The thickness of perigenual anterior cingulate cortex, midcingulate cortex and posterior cingulate cortex was measured using FreeSurfer from T1-weighted MR images. Age, gender, education, BMI, mean arterial pressure, comorbidities, use of vitamin D supplements or anti-vascular drugs, MMSE, GDS, IADL, serum calcium and vitamin B9 concentrations, creatinine clearance were used as covariables. Results: Participants with vitamin D insufficiency (n=80) had thinner total cingulate thickness than the others (24.6±1.9mm versus 25.3±1.4mm, P=0.001); a significant difference found for all 3 regions. Vitamin D insufficiency was cross-sectionally associated with a decreased total cingulate thickness (β=- 0.49, P=0.028). Serum 25OHD concentration correlated positively with the thickness of perigenual anterior (P=0.011), midcingulate (P=0.013) and posterior cingulate cortex (P=0.021). Conclusion: Vitamin D insufficiency was associated with thinner cingulate cortex in the studied sample of older adults. These findings provide insight into the pathophysiology of cognitive and mobility declines in older adults with vitamin D insufficiency.

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