Distributed Representation of Visual Objects by Single Neurons in the Human Brain

Valdez, André B.; Papesh, Megan H.; Treiman, David M.; Smith, Kris A.; Goldinger, Stephen D.; Steinmetz, Peter

doi:10.1523/jneurosci.1958-14.2015

Cited by 22 publications

(27 citation statements)

References 58 publications

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“…In studies of semantic memory, single neurons in the medial temporal lobe have been identified that respond reliably to repeated presentations of a known place or landmark, such as the Eiffel Tower (20,24,25). Similarly, in studies of episodic memory (16)(17)(18), single neurons in the medial temporal lobe have been identified that respond reliably to repeated presentations of items drawn from a general stimulus class (e.g., novel items).…”

Section: Discussionmentioning

confidence: 99%

Coding of episodic memory in the human hippocampus

Wixted

Goldinger

Squire

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Neurocomputational models have long posited that episodic memories in the human hippocampus are represented by sparse, stimulus-specific neural codes. A concomitant proposal is that when sparse-distributed neural assemblies become active, they suppress the activity of competing neurons (neural sharpening). We investigated episodic memory coding in the hippocampus and amygdala by measuring single-neuron responses from 20 epilepsy patients (12 female) undergoing intracranial monitoring while they completed a continuous recognition memory task. In the left hippocampus, the distribution of single-neuron activity indicated that only a small fraction of neurons exhibited strong responding to a given repeated word and that each repeated word elicited strong responding in a different small fraction of neurons. This finding reflects sparse distributed coding. The remaining large fraction of neurons exhibited a concurrent reduction in firing rates relative to novel words. The observed pattern accords with longstanding predictions that have previously received scant support from single-cell recordings from human hippocampus.

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Section: Discussionmentioning

confidence: 99%

Coding of episodic memory in the human hippocampus

Wixted

Goldinger

Squire

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…The second scenario described here therefore seems most realistic. Of note, a recent study reported a more distributed code for representation of visual stimuli in the human hippocampus (22). This study, however, used a less conservative response criterion, thus trading response selectivity for sensitivity, and contained no comparison with PHC representations.…”

Section: Discussionmentioning

confidence: 99%

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

Mormann

Kornblith

Cerf

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Imaging, electrophysiological, and lesion studies have shown a relationship between the parahippocampal cortex (PHC) and the processing of spatial scenes. Our present knowledge of PHC, however, is restricted to the macroscopic properties and dynamics of bulk tissue; the behavior and selectivity of single parahippocampal neurons remains largely unknown. In this study, we analyzed responses from 630 parahippocampal neurons in 24 neurosurgical patients during visual stimulus presentation. We found a spatially clustered subpopulation of sceneselective units with an associated event-related field potential. These units form a population code that is more distributed for scenes than for other stimulus categories, and less sparse than elsewhere in the medial temporal lobe. Our electrophysiological findings provide insight into how individual units give rise to the population response observed with functional imaging in the parahippocampal place area.electrophysiology | single units | scene selectivity | population code

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“…Only neurons with well-isolated single unit activity were included in analyses. Our analysis here parallels that we recently used to examine object encoding (Valdez et al, 2015 ). We created a nested set of generalized linear models (McCullagh and Nelder, 1989 ) in R (R Development Core Team, 2009 ) testing firing rate as a function of stimulus affect for each neuron in each experiment ( n = 936).…”

Section: Discussionmentioning

confidence: 65%

“…This spike-sorting technique has been previously used in multiple publications (Steinmetz et al, 2013 ; Valdez et al, 2013 , 2015 ; Wixted et al, 2014 ). In our experience, this technique (Valdez et al, 2013 ) produces results comparable to prior reports in other laboratories (Viskontas et al, 2007 ) in terms of recorded waveform shapes, inter-spike intervals, and firing rates (also see Wild et al, 2012 regarding variability in spike sorting depending on the particular waveforms shapes being detected).…”

Section: Methodsmentioning

confidence: 99%

Gender differences in human single neuron responses to male emotional faces

Newhoff

Treiman

Smith

et al. 2015

Front. Hum. Neurosci.

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Well-documented differences in the psychology and behavior of men and women have spurred extensive exploration of gender's role within the brain, particularly regarding emotional processing. While neuroanatomical studies clearly show differences between the sexes, the functional effects of these differences are less understood. Neuroimaging studies have shown inconsistent locations and magnitudes of gender differences in brain hemodynamic responses to emotion. To better understand the neurophysiology of these gender differences, we analyzed recordings of single neuron activity in the human brain as subjects of both genders viewed emotional expressions. This study included recordings of single-neuron activity of 14 (6 male) epileptic patients in four brain areas: amygdala (236 neurons), hippocampus (n = 270), anterior cingulate cortex (n = 256), and ventromedial prefrontal cortex (n = 174). Neural activity was recorded while participants viewed a series of avatar male faces portraying positive, negative or neutral expressions. Significant gender differences were found in the left amygdala, where 23% (n = 15∕66) of neurons in men were significantly affected by facial emotion, vs. 8% (n = 6∕76) of neurons in women. A Fisher's exact test comparing the two ratios found a highly significant difference between the two (p < 0.01). These results show specific differences between genders at the single-neuron level in the human amygdala. These differences may reflect gender-based distinctions in evolved capacities for emotional processing and also demonstrate the importance of including subject gender as an independent factor in future studies of emotional processing by single neurons in the human amygdala.

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Distributed Representation of Visual Objects by Single Neurons in the Human Brain

Cited by 22 publications

References 58 publications

Coding of episodic memory in the human hippocampus

Coding of episodic memory in the human hippocampus

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

Gender differences in human single neuron responses to male emotional faces

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