Concept cells: the building blocks of declarative memory functions

“We also found individual neurons whose activations coded directly for some of these features, e.g. a neuron that was active if and only if the agent’s teammate was holding the flag, reminiscent of concept cells ( 51 ).”

“Due to space constraints, we will not review possible contributions to consciousness of the medial temporal lobe and of the insular cortex (Craig, 2010; Seth et al., 2011; Quiroga, 2012), except for pointing out that consciousness is preserved after bilateral lesions of these areas (Corkin, 2002; Damasio et al.”

“1) The multiunit cluster is formed by the superposition of different spikes, it has a relatively low amplitude and violates the refractory period of single neurons—i.e., spikes appear within less than 2.5 ms (Quian Quiroga, 2012a .”

“These studies identified cells that responded to spe-cific individuals, places, or objects (and to stimuli associated with these concepts) whether the entity was presented as an image, or as a written or spoken word (reviewed in [61,62]).”

“In the extreme case—this is likely to be true for neurons that code for complex feature constellations such as concept cells (e.g., a ‘‘Jennifer Aniston neuron’’ (Quiroga et al., 2005; for a review, see Quiroga, 2012)—synaptic weights and weight ratios are optimally adjusted (Figure 4A).”

“Considering the previous finding that MTL neurons show an invariant representation of concepts (Quian Quiroga et al., 2005), our results of association formation in these neurons suggest conceptual associations.”

“An example of a semantic representation is a Jennifer Aniston neuron, which may respond not only to Jennifer Aniston but also to other actors in the same movie and the places with which they are associated (Quiroga 2012; Rey et al. 2015).”

“Consistent with these discoveries, the hippocampus receives projections from the temporal cortical areas specialized for objects or faces, and neurons responsive for particular individuals were found both in the human medial temporal lobe (Kreiman et al., 2000; Quiroga, 2012) and the monkey hippocampus (Sliwa et al.”

“A uthor M anuscript A uthor M anuscript A uthor M anuscript A uthor M anuscript et al., 2008; Quiroga, 2012, 2019; Quiroga et al., 2005; Rutishauser et al., 2021; Staresina et al., 2019).”

“…greatly increased by the introduction of single-cell recordings in the 1950s, now advanced to high level of sophistication with the identi fi cation of concept cells (Quian Quiroga 2012) and, more recently, by imaging techniques of MEG, PET, fMRI and BOLD (blood oxygen level dependent), and fMRI.”

“Human ‘concept cells’ seem to encode a stable representation of a specific person or landmark, regardless of size or viewing angle 104,105 , providing sparse codes [G] for visually invariant abstractions related to personal events 106 .”

“, Halle Barry with a cat-woman mask and a line drawing of her face) as well as their name (Quiroga, Reddy, Kreiman, Koch, & Fried, 2005; Quiroga, 2012).”

“Concept cell: neurons in the medial temporal lobe of the (human) brain that encode a highly speci fi c abstract concept, such as a person or a building [24,25].”

“simple visual features to formation of conceptual, semantic categories – are IT neurons closer to the local edge detectors found in primary visual areas or to the concept cells recently found in human middle temporal lobe [9–11]? While most literature supports the notion that IT neurons code moderately to highly compl…”

“In fact, the concept neurons that were revealed in the medial temporal lobe for familiar faces and scenes (Quiroga, Reddy, Kreiman, Koch, & Fried, 2005; for review, see Quiroga, 2012) may be the neural manifestation of such view-invariant conceptual representation.”

“For instance, semantic meaning (presumably coded in temporal lobe areas such as the hippocampal formation and the anteromedial temporal lobe [76,77]) needs to be coupled to a specific sensory representation to generate the representation of a meaningful object that can be acted on [63].”

“They classify those neurons, that selectively respond to specific individuals like Jennifer Aniston, as the “Jennifer Aniston neurons” – proposing the idea of “concept cells” in the MTL and their ability to store a single “concept” (Quiroga, 2012; Quiroga et al., 2005).”

“Independent contributions of LFP power and phase to neural representation There is now abundant evidence for stimulus specific single neuron activity in humans (reviewed in [20]).”

“…encoding of a day at the beach is likely to bind together coarse-grained concepts such as ‘beach’ and ‘sea’ along with sensory representations such as the melody of an unfamiliar song or the sight of a particular sandcastle, consistent with the evidence for concept cells in the hippocampus 61 .”

“This hypothesis would also fit well with the report of “concept cells”, coding for individual items though with a very high degree of invariance (even across symbolic and pictorial presentations) in the medial areas of the human anterior temporal cortex (Quiroga, 2012).”

“These data have given rise to the hypothesis that visually selective cells represent semantic memories (Rutishauser, 2019), which in turn are the building blocks of episodic memories (Quiroga, 2012).”

“These studies have established the existence of the so-called concept cells (Quiroga, 2012), which respond to a particular individual (and other complex stimuli) in a distinctly multimodal fashion (i.”

“In the first paragraph of his by-now classic paper describing the properties of microelectrodes, Robinson (1968) states, “Despite this prevalence [of the use of microelectrodes for single-cell recordings] there remains a good deal of mystery about how best to make these electrodes and how to interpret the extracellula…”

“, 2022d), and neurons responsive for particular individuals were found both in the human medial temporal lobe (Kreiman et al., 2000; Quiroga, 2012) and the monkey hippocampus (Sliwa et al.”

“Given the proposed role of the MTL in combining information from different sensory modalities to create a unified percept [17, 18], the timing mechanism given by the theta LFP responses may be critical for synchronizing and combining multisensory information involving different processing times.”

“One of the brain mystery is the well-documented phenomenon of Grandmother Cells and the so-called Concept Cells [43].”

“Indeed, “concept cells” in the human hippocampus that encode social memory can fire selectively not only in response to pictures of a specific person but also in response to other sensory modality cues such as the pronounced or written name of that person [51].”

“The so-called concept neurons in the medial temporal lobe (MTL), measured by intracranial electrodes for clinical reasons, show selectivity to individual faces (Quiroga 2012).”

“One contemporary idea is that the diverse elements that make up an episode are coded by the simultaneous activity of a set of these concept neurons 11,12 or by expanding the selectivity of existing concept neurons 13 .”

“Consistent with these assumptions, it has been reported that the concept cell assemblies in the medial temporal lobe encode semantic associations in a sparse manner (Quiroga, 2012; De Falco et al., 2016).”

“Contrasting with the graded responses in neocortex [4–6, 9–11, 13–15, 18], which may be useful for recognition in order to detect changes in the environment, we can postulate that the degree of visual invariance shown by MTL neurons leads to a high degree of conceptualization and abstraction that is the basis of our m…”

“Episodic memory relies on the fast formation of associations (Eichenbaum, 2004; Quian Quiroga, 2012; Wallenstein et al., 1998); for example, the memory of seeing a celebrity in the subway involves making a link between these concepts.”

“First, the iEEG recordingswere conducted in patients with epilepsy whichmakes it difficult to exclude the possibility that pathological changes in the hippocampus or medicationrelated effects could have contributed to the results (though see Quiroga (2012).”

“…may be most prominent in the absence of locomotion, only because at rest only one spatial location is directly experienced, in effect controlling for space (Gelbard-Sagiv, Mukamel, Harel, Malach, & Fried, 2008; MacDonald et al., 2013; Quiroga, 2012; Quiroga et al., 2005; Takahashi et al., 2009b).”

“With these recordings, we have found Concept Cells responding to specific concepts [15,16].”

“The stimulus identity cells in the model are reminiscent of concept cells found in the human hippocampus [39].”

“Several studies of the human MTL have demonstrated the existence of “concept cells” 36 .”

“Most existing spike sorting methods operate either manually or semi-automatically (Lewicki 1998, Einevoll et al 2012, Marre et al 2012, Quiroga 2012).”

“These studies used electrophysiology (Chan et al., 2011; Naci, Taylor, Cusack, & Tyler, 2012; see also Quiroga, 2012), MEG (Marinkovic et al., 2003; van Ackeren, Schneider, Müsch, & Rueschemeyer, 2014; Clarke, Devereux, Randall, & Tyler, 2015), and TMS (Jackson et al., 2015).”

“Notably, this approach has identified neurons that respond selectively to the presentation of a photo of a particular person or landmark (20, 21).”

“These neurons are notable for several reasons, including their putative role in memory functions ( 12 ) and potential uniqueness to humans ( 13 ).”

“For example, it is known that individual concept cells can specifically encode an abstract representation 17 or that neural populations can sparsely encode specific stimulus features 5,16 but less is known about HFOs.”

“Nowadays, the subacute implantation of intracranial electrodes for an extended period allows continuous monitoring of the electrical activity in areas where the epileptic focus is presumed to be potentially located.”

“Concept cells in the hippocampus are in fact assumed to form the building blocks of episodic memories (Quiroga, 2012).”

“…a spatial view or location associated with that person, the sound of the person ’ s voice, and the name of the person (Quian Quiroga et al., 2005; Quian Quiroga, 2012; Fried et al., 2014; Ison et al., 2015; Rey et al., 2015; De Falco et al., 2016; Rutishauser, 2019; Gastaldi et al., E.T. Rolls…”

“…amygdala, entorhinal cortex) have the longest time delay to peak response and are more selective compared to parahippocampal and inferotemporal areas (Mormann et al., 2008; Quiroga, 2012), implicating the mesial temporal lobe structures at the top of this cognitive processing hierarchy.”

“Single-unit studies revealed the importance of the time of firing with respect to hippocampal theta phase for memory processes (49) and their tuning to abstract representations irrespective of perceptual modalities (i.e., so-called “ concept cells ” ) (50).”

“locations and people) in the real world appears to provide the ideal ‘building blocks’ [32] for event engrams (Figure 1b).”

“Concept cells can also fire to the spoken or written name of the same person (Quian Quiroga, 2012).”

“From the continuous wide-band data, spike detection and sorting were carried out using ''Wave_Clus,'' an adaptive and stochastic clustering algorithm (Quian Quiroga et al., 2004).”

“These structures have been linked with high-level aspects of visual perception (Mundy et al. 2013, Murray et al. 2007), mental imagery (Zeidman & Maguire 2016), and high-level visual-object representation (Kravitz et al. 2013, Murray et al. 2007, Quiroga 2012).”

“QuirogaR (2012).”

“In some ways this parallels Waydo, Kraskov, Quian Quiroga, Fried, and Koch (2006) analysis of the single-cell recording data collected by Quian Quiroga, Reddy, Kreiman, Koch, and Fried (2005).”

“Coming back to the question from above on localization versus antilocalization of brain functions [242], Quian Quiroga [182] promoted the idea of a compromise which is, however, inclined towards the direction of a close localization of function.”

“Neuroscientist 24, 582– 608. doi: 10.1177/1073858418769554 . ey, H.G., Gori, B., Chaure, F.J., Collavini, S., Blenkmann, A.O., Seoane, P., Seoane, E., Kochen, S., Quian Quiroga, R., 2020.”

“Semantic representations in hippocampus may facilitate reasoning about high-level item properties, such as conceptual categories (Mack et al., 2016) and social status (Tavares et al., 2015), while also serving as building blocks for representing new memories (Quiroga, 2012).”