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. 2022 May 12;13:878991. doi: 10.3389/fneur.2022.878991

Table 4.

Main takeaways for the pre-clinical sections and associated clinical relevance.

Coding Physiology Epilepsy
Preclinical Clinical Preclinical Clinical
Rate • Place cells fire when an animal visits a specific place field
• Time cells fire at specific times in a task called time fields and they can be time locked to an external stimulus
• Grid cells provide activity-based maps of speed and direction in a certain environment and fire in different locations in an environment
• Place and grid cells map are part of the greater hippocampal cognitive map
• Inputs from the entorhinal cortex are important for hippocampal rate coding in the formation of the spatial memory and cognitive map
• Selective disruption of the theta rhythm power correlated with spatial component of the non-verbal correlates of episodic-like memory task
• Time cells fire at specific times in a task called time fields and they can be time locked to an external stimulus
• Inputs from the entorhinal cortex are important for hippocampal rate coding in the formation of the spatial memory and cognitive map
• Place cell misfiring
• Loss of accurate spatial navigation
• Lesioning the hippocampus results in loss of spatial memory
• Lesioning the lateral entorhinal cortex impairs the hippocampal rate remapping upon changing the configuration of the environment
• Time and grid cells deficits
• Time cells firing deficits
• Disruption of entorhinal cortex inputs
• Spatial memory deficits
Temporal • The rate of populations of neuronal firing is also modulated in time
• Temporal modulation is manifested as burst firing with bursts occurring at theta frequency in the hippocampus
• Theta modulation is important for phase precession, phase preference and hippocampal replay
• Phase precession is important for information processing.
• Theta-phase precession could be an indication of item-context associations
• Selective disruption of theta coordination across CA1 and the DG correlated with temporal component of the non-verbal correlates of episodic-like memory task
• The rate of populations of neuronal firing is also modulated in time
• Neurons in the hippocampus and entorhinal cortex fire for space and time
• Time cells exhibited theta-phase precession during memory encoding
• Time cells activity correlates with the use of temporal location during retrieval phase of free recall task
• Loss of phase precession
• Temporal modulation deficits
• Item-context association deficits
• Loss of time modulation of neuronal firings
• Theta-phase precession deficits
• Temporal location alteration in free recall task
Population • Neurons are functionally connected into a network
• Population coding increases robustness of network function
• Place cell populations will respond when the animal goes into the field
• Dentate gyrus (DG) and its projection to CA3 underlie the pattern separation process
• Working memory in the prefrontal cortex depends on population coding
• Pattern separation involves posterior occipitotemporal cortex (OTC) and the hippocampus
• Dentate gyrus (DG) and its projection to CA3 underlie the pattern separation process
• Working memory in the prefrontal cortex depends on population coding
• BOLD signal on fMRI decreases during the delay phase of image-sequence matching task in humans
• BOLD signal re-emerge during the image presentation phase of image-sequence matching task
• Working memory information is maintained in the collective synaptic weights of populations of neurons in the PFC.
• Loss of functional connections
• Decreased robustness of network function
• Loss of place cells firing accuracy
• DG aberrant CA3 influences
• Working memory deficits
• Early stage TLE patients experience functional connectivity deficits in the ipsilateral hemisphere and interhemispheric connections
• Patients with generalized epilepsy have an increase in the interhemispheric connectivity but reduced functional connectivity
• Decreased cluster coefficient within the DMN underlies the language impairment in patients with generalized epilepsy without focal brain damage
• Reduced DMN activity suppression can alter the balance between activated and deactivated neural networks and disturb cognitive function
• Hub nodes in TLE patients were mainly located in the limbic and temporal association cortices instead of being evenly distributed between different lobes
• Memory impairments are present in patients who don't show a lesion with MRI