Scene-selective coding by single neurons in the human parahippocampal cortex

Mormann, Florian; Kornblith, Simon; Cerf, Moran; Ison, Matias J.; Kraskov, Alexander; Tran, Michelle; Knieling, Simeon; Quiroga, Rodrigo Quian; Koch, Christof; Fried, Itzhak

doi:10.1073/pnas.1608159113

Cited by 42 publications

(38 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, single object‐vector cells signal the position of the animal relative to any object whereas an ensemble of object‐vector cells may signal the position of the animal relative to a specific spatial configuration of objects. These findings are likely related to findings in humans; a subset of cells in human entorhinal cortex display selectivity to specific scenes filled with landmarks (Mormann et al, ).…”

Section: Entorhinal Cortex Fills Memories With Contentsupporting

confidence: 71%

Episodic memory: Neuronal codes for what, where, and when

2019

View full text Add to dashboard Cite

Episodic memory is defined as the ability to recall events in a spatiotemporal context. Formation of such memories is critically dependent on the hippocampal formation and its inputs from the entorhinal cortex. To be able to support the formation of episodic memories, entorhinal cortex and hippocampal formation should contain a neuronal code that follows several requirements. First, the code should include information about position of the agent (“where”), sequence of events (“when”), and the content of the experience itself (“what”). Second, the code should arise instantly thereby being able to support memory formation of one‐shot experiences. For successful encoding and to avoid interference between memories during recall, variations in location, time, or in content of experience should result in unique ensemble activity. Finally, the code should capture several different resolutions of experience so that the necessary details relevant for future memory‐based predictions will be stored. We review how neuronal codes in entorhinal cortex and hippocampus follow these requirements and argue that during formation of episodic memories entorhinal cortex provides hippocampus with instant information about ongoing experience. Such information originates from (a) spatially modulated neurons in medial entorhinal cortex, including grid cells, which provide a stable and universal positional metric of the environment; (b) a continuously varying signal in lateral entorhinal cortex providing a code for the temporal progression of events; and (c) entorhinal neurons coding the content of experiences exemplified by object‐coding and odor‐selective neurons. During formation of episodic memories, information from these systems are thought to be encoded as unique sequential ensemble activity in hippocampus, thereby encoding associations between the content of an event and its spatial and temporal contexts. Upon exposure to parts of the encoded stimuli, activity in these ensembles can be reinstated, leading to reactivation of the encoded activity pattern and memory recollection.

show abstract

Section: Entorhinal Cortex Fills Memories With Contentsupporting

confidence: 71%

Episodic memory: Neuronal codes for what, where, and when

2019

View full text Add to dashboard Cite

show abstract

“…At the cellular level it would be expected that an evoked response should be accompanied by an overall increase in cellular firing rates. Indeed studies have shown a marked firing rate increase at image onset peaking ~300ms after stimulus onset (Andrillon et al, 2015;Mormann et al, 2017), which is consistent with the latency of the imageonset ERP seen here( Figure 2). Our interpretations regarding the image onset ERP are consistent with a recent study that demonstrated an image-onset response very similar to the response observed here and characterized it as an additive/evoked response based on the amplitude/power and phase changes discussed earlier (Lopour et al, 2013).…”

Section: Evoked Image-onset Responsesupporting

confidence: 89%

Differential generation of saccade, fixation and image onset event-related potentials in the human mesial temporal lobe

Katz

Patel

Talakoub

et al. 2018

Preprint

View full text Add to dashboard Cite

The electrophysiological signatures of encoding and retrieval recorded from mesial temporal lobe (MTL) structures are observed as event related potentials (ERPs) during visual memory tasks. The waveforms of the ERPs associated with the onset of visual stimuli (image-onset) and eye movements (saccades and fixations) provide insights into the mechanisms of their generation. We hypothesized that since eye movements and image-onset (common methods of stimulus presentation when testing memory) provide MTL structures with salient visual information, that perhaps they both engage similar neural mechanisms. To explore this question, we used intracranial electroencephalographic (iEEG) data from the MTLs of 11 patients with medically refractory epilepsy who participated in a visual search task. We sought to characterize electrophysiological responses of MTL structures to saccades, fixations and image onset. We demonstrate that the image-onset response is an evoked/additive response with a lowfrequency power increase and post-stimulus phase clustering. In contrast, ERPs following eye movements appeared to arise from phase resetting of higher frequencies than the image onset ERP. Intriguingly, this reset was associated with saccade onset and not saccade termination (fixation), suggesting it is likely the MTL response to a corollary discharge, rather than a response to visual stimulation -in stark contrast to the image onset response. The distinct mechanistic underpinnings of these two ERP may help guide future development of visual memory tasks.

show abstract

“…The increased prevalence of anchor cells in parahippocampal cortex may provide a cellular explanation for the detrimental effects of parahippocampal lesions on learning virtual mazes that require egocentric navigation 175 strategies (25) and on spatial memory in retinotopic, egocentric frames of reference (26). The increased prevalence of anchor cells in parahippocampal cortex may furthermore explain responses of a subpart of this region (the parahippocampal place area) to spatial scenes observed with functional magnetic resonance imaging (27), intracranial electroencephalography (28), or single-neuron recordings (29), because the presentation of 180 spatial scenes from a first-person perspective may result in parahippocampal anchor-cell activity.…”

Section: Main Textmentioning

confidence: 99%

A neural code for egocentric spatial maps in the human medial temporal lobe

Kunz

Brandt

Reinacher

et al. 2020

Preprint

View full text Add to dashboard Cite

Spatial navigation relies on neural systems that encode spatial information relative to the external world or in relation to the navigating organism. Ever since the proposal of cognitive maps, the neuroscience of spatial navigation has focused on allocentric (world-referenced) neural representations such as place cells. Here, using single-neuron recordings during virtual 30 navigation, we reveal a neural code of egocentric (self-centered) spatial information in the human brain: We describe "anchor cells", which represent egocentric directions towards local "anchor points" distributed across the environmental center and periphery. Anchor-cell activity was abundant in parahippocampal cortex, signaled anchor-point distances, and showed memory modulation. Anchor cells may thus facilitate egocentric navigation 35 strategies, may assist in transforming percepts into allocentric spatial representations, and may underlie the first-person perspective in episodic memories. One Sentence Summary:Anchor cells in the human brain provide the neural basis for a self-centered coordinate 40 system during spatial navigation.3 Main text:Detailed neural representations of space form the neurobiological basis of successful navigation and accurate spatial memory. Traditionally, the neuroscience of spatial navigation has focused on allocentric representations, which encode spatial information in relation to the 45 external world: the place field of a place cell may be located in the "northeast" corner of an environment (1, 2), a head-direction cell may activate whenever navigating "south" (3), and a boundary vector/border cell may respond to a spatial boundary located "west" (4, 5). However, spatial environments are primarily experienced from a first-person, egocentric perspective -requiring neural codes that provide spatial information in relation to the self. 50 Via transformation circuits (6, 7), egocentric representations (8-10) may then be converted into their allocentric counterparts (4, 5, 11) for abstract knowledge and long-term storage (12).Despite abundant behavioral evidence that humans employ egocentric spatial information to accomplish wayfinding (12-15), little is known about the neural basis of egocentric spatial 55 representations in humans. Here, we hypothesized that neurons in human medial temporal lobe (MTL) keep track of the instantaneous relationship between the navigating subject and proximal areas of the environment. Specifically, we targeted the identification of "anchor cells" whose activity encodes the subject's egocentric direction towards local reference points (termed "anchor points"). Such a coding scheme would be instrumental for egocentric 60 navigation, because it provides orientation in relation to the proximal spatial layout.To detect and characterize human anchor cells, we recorded single-neuron activity from the MTL of ten neurosurgical epilepsy patients (table S1), while patients performed an objectlocation memory task in a virtual environment (Fig. 1, A and B). In this task (16), patients learne...

show abstract

Scene-selective coding by single neurons in the human parahippocampal cortex

Cited by 42 publications

References 51 publications

Episodic memory: Neuronal codes for what, where, and when

Episodic memory: Neuronal codes for what, where, and when

Differential generation of saccade, fixation and image onset event-related potentials in the human mesial temporal lobe

A neural code for egocentric spatial maps in the human medial temporal lobe

Contact Info

Product

Resources

About