scholarly journals Fast Readout of Object Identity from Macaque Inferior Temporal Cortex

Science ◽  
2005 ◽  
Vol 310 (5749) ◽  
pp. 863-866 ◽  
Author(s):  
Chou P. Hung ◽  
Gabriel Kreiman ◽  
Tomaso Poggio ◽  
James J. DiCarlo
Keyword(s):  
Neural Coding ◽  
Temporal Cortex ◽  
Population Level ◽  
Inferior Temporal Cortex ◽  
Object Identity ◽  
Neuronal Populations ◽  
Novel Objects ◽  
Coarse Information ◽  
Short Time

Understanding the brain computations leading to object recognition requires quantitative characterization of the information represented in inferior temporal (IT) cortex. We used a biologically plausible, classifier-based readout technique to investigate the neural coding of selectivity and invariance at the IT population level. The activity of small neuronal populations (∼100 randomly selected cells) over very short time intervals (as small as 12.5 milliseconds) contained unexpectedly accurate and robust information about both object “identity” and “category.” This information generalized over a range of object positions and scales, even for novel objects. Coarse information about position and scale could also be read out from the same population.

scholarly journals Unsupervised changes in core object recognition behavior are predicted by neural plasticity in inferior temporal cortex

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Xiaoxuan Jia ◽  
Ha Hong ◽  
Jim DiCarlo
Keyword(s):  
Object Recognition ◽  
Neural Plasticity ◽  
Time Course ◽  
Human Performance ◽  
Temporal Cortex ◽  
Neural Representation ◽  
Temporal Contiguity ◽  
Inferior Temporal Cortex ◽  
Object Identity ◽  
Visual Stream

Temporal continuity of object identity is a feature of natural visual input, and is potentially exploited -- in an unsupervised manner -- by the ventral visual stream to build the neural representation in inferior temporal (IT) cortex. Here we investigated whether plasticity of individual IT neurons underlies human core-object-recognition behavioral changes induced with unsupervised visual experience. We built a single-neuron plasticity model combined with a previously established IT population-to-recognition-behavior linking model to predict human learning effects. We found that our model, after constrained by neurophysiological data, largely predicted the mean direction, magnitude and time course of human performance changes. We also found a previously unreported dependency of the observed human performance change on the initial task difficulty. This result adds support to the hypothesis that tolerant core object recognition in human and non-human primates is instructed -- at least in part -- by naturally occurring unsupervised temporal contiguity experience.

scholarly journals Effect of Adaptation on Object Representation Accuracy in Macaque Inferior Temporal Cortex

2013 ◽  
Vol 25 (5) ◽  
pp. 777-789 ◽  
Author(s):  
Dzmitry A. Kaliukhovich ◽  
Wouter De Baene ◽  
Rufin Vogels
Keyword(s):  
Object Representation ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Efficient Coding ◽  
Neuronal Populations ◽  
Cross Adaptation ◽  
Functional Consequences ◽  
The Difference ◽  
Induced Changes ◽  
Familiar Stimuli

Stimulus repetition produces a decrease of the response in many cortical areas and different modalities. This adaptation is highly prominent in macaque inferior temporal (IT) neurons. Here we ask how these repetition-induced changes in IT responses affect the accuracy by which IT neurons encode objects. This question bears on the functional consequences of adaptation, which are still unclear. We recorded the responses of single IT neurons to sequences of familiar shapes, each shown for 300 msec with an ISI of the same duration. The difference in shape between the two successively presented stimuli,that is, adapter and test, varied parametrically. The discriminability of the test stimuli was reduced for repeated compared with nonrepeated stimuli. In some conditions for which adapter and test shapes differed, the cross-adaptation resulted in an enhanced discriminability. These single cell results were confirmed in a second experiment in which we recorded multiunit spiking activity using a laminar microelectrode in macaque IT. Two familiar stimuli were presented successively for 500 msec each and separated with an ISI of the same duration. Trials consisted either of a repetition of the same stimulus or of their alternation. Small neuronal populations showed decreased classification accuracy for repeated compared with nonrepeated test stimuli, but classification was enhanced for the test compared with adapter stimuli when the test stimulus differed from recently seen stimuli. These findings suggest that short-term, stimulus-specific adaptation in IT supports efficient coding of stimuli that differ from recently seen ones while impairing the coding of repeated stimuli.

scholarly journals Ramp-shaped neural tuning supports graded population-level representation of the object-to-scene continuum

2022 ◽  
Author(s):  
Jeongho Park ◽  
Emilie Josephs ◽  
Talia Konkle
Keyword(s):  
Spatial Scale ◽  
Neural Coding ◽  
Large Scale ◽  
Temporal Cortex ◽  
Population Level ◽  
Linear Representation ◽  
Small Region ◽  
Indoor Environments ◽  
Brain Responses ◽  
Class Room

We can easily perceive the spatial scale depicted in a picture, regardless of whether it is a small space (e.g., a close-up view of a chair) or a much larger space (e.g., an entire class room). How does the human visual system encode this continuous dimension? Here, we investigated the underlying neural coding of depicted spatial scale, by examining the voxel tuning and topographic organization of brain responses. We created naturalistic yet carefully-controlled stimuli by constructing virtual indoor environments, and rendered a series of snapshots to smoothly sample between a close-up view of the central object and far-scale view of the full environment (object-to-scene continuum). Human brain responses were measured to each position using functional magnetic resonance imaging. We did not find evidence for a smooth topographic mapping for the object-to-scene continuum on the cortex. Instead, we observed large swaths of cortex with opposing ramp-shaped profiles, with highest responses to one end of the object-to-scene continuum or the other, and a small region showing a weak tuning to intermediate scale views. Importantly, when we considered the multi-voxel patterns of the entire ventral occipito-temporal cortex, we found smooth and linear representation of the object-to-scene continuum. Thus, our results together suggest that depicted spatial scale is coded parametrically in large-scale population codes across the entire ventral occipito-temporal cortex.

scholarly journals Novel objects with causal schemas elicit selective responses in tool- and hand-selective lateral occipito-temporal cortex

2021 ◽  
Author(s):  
Anna Leshinskaya ◽  
Mira Bajaj ◽  
Sharon L. Thompson-Schill
Keyword(s):  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Essential Property ◽  
Neural Responses ◽  
Still Images ◽  
Event Sequences ◽  
Environmental Event ◽  
Parahippocampal Cortex ◽  
Novel Objects ◽  
Human Participants

Tool-selective lateral occipito-temporal cortex (LOTC) responds preferentially to images of tools (hammers, brushes) relative to non-tool objects (clocks, shoes). What drives these responses? Tools have elongated shapes and are more likely to have motor associations, but another essential property is that they exert causal effects on the environment. We tested whether LOTC would respond to novel objects associated with a tool-canonical schema in which their actions cause other events. To do so, we taught male and female human participants about novel objects embedded in animated event sequences, which varied in the temporal order of their events. Causer objects moved prior to the appearance of an environmental event (e.g., stars) while Reactor objects moved after an identical event; objects were matched on shape and motor association. During fMRI, participants viewed still images of these novel objects. We localized tool-selective LOTC and non-tool-selective parahippocampal cortex (PHC) by contrasting neural responses to images of familiar tools and non-tools. We found that LOTC responded more to Causers than Reactors; this effect was absent and weaker in right PHC. We also localized responses to images of hands, which elicit overlapping responses with tools. Across inferior temporal cortex, voxels’ tool and hand selectivity positively predicted a preferential response to Causers, and non-tool selectivity negatively so. We conclude that a causal schema typical of tools is sufficient to drive LOTC, and more generally, that preferential responses to domains across the temporal lobe may reflect the relational event structures typical of those domains.

scholarly journals Unsupervised changes in core object recognition behavior are predicted by neural plasticity in inferior temporal cortex

2020 ◽  
Author(s):  
Xiaoxuan Jia ◽  
Ha Hong ◽  
James J. DiCarlo
Keyword(s):  
Object Recognition ◽  
Neural Plasticity ◽  
Time Course ◽  
Human Performance ◽  
Temporal Cortex ◽  
Neural Representation ◽  
Temporal Contiguity ◽  
Inferior Temporal Cortex ◽  
Object Identity ◽  
Visual Stream

AbstractTemporal continuity of object identity is a feature of natural visual input, and is potentially exploited -- in an unsupervised manner -- by the ventral visual stream to build the neural representation in inferior temporal (IT) cortex and IT-dependent core object recognition behavior. Here we investigated whether plasticity of individual IT neurons underlies human behavioral changes induced with unsupervised visual experience by building a single-neuron plasticity model combined with a previously established IT population-to-recognition-behavior linking model to predict human learning effects. We found that our model quite accurately predicted the mean direction, magnitude and time course of human performance changes. We also found a previously unreported dependency of the observed human performance change on the initial task difficulty. This result adds support to the hypothesis that tolerant core object recognition in human and non-human primates is instructed -- at least in part -- by naturally occurring unsupervised temporal contiguity experience.

scholarly journals Category-specific representational patterns in left inferior frontal and temporal cortex reflect similarities and differences in the sensorimotor and distributional properties of concepts

2021 ◽  
Author(s):  
Francesca Carota ◽  
Nikolaus Kriegeskorte ◽  
Hamed Nili ◽  
Friedemann Pulvermüller
Keyword(s):  
Activity Patterns ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Angular Gyrus ◽  
Activation Patterns ◽  
Neuronal Populations ◽  
Distributional Information ◽  
Motor Information ◽  
Category Discrimination ◽  
Sensorimotor Knowledge

AbstractNeuronal populations code similar concepts by similar activity patterns across the human brain’s networks supporting language comprehension. However, it is unclear to what extent such meaning-to-symbol mapping reflects statistical distributions of symbol meanings in language use, as quantified by word co-occurrence frequencies, or, rather, experiential information thought to be necessary for grounding symbols in sensorimotor knowledge. Here we asked whether integrating distributional semantics with human judgments of grounded sensorimotor semantics better approximates the representational similarity of conceptual categories in the brain, as compared with each of these methods used separately. We examined the similarity structure of activation patterns elicited by action- and object-related concepts using multivariate representational similarity analysis (RSA) of fMRI data. The results suggested that a semantic vector integrating both sensorimotor and distributional information yields best category discrimination on the cognitive-linguistic level, and explains the corresponding activation patterns in left posterior inferior temporal cortex. In turn, semantic vectors based on detailed visual and motor information uncovered category-specific similarity patterns in fusiform and angular gyrus for object-related concepts, and in motor cortex, left inferior frontal cortex (BA 44), and supramarginal gyrus for action-related concepts.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

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