scholarly journals Stimulus repetition reduces stimulus encoding by small neuronal populations in macaque inferior temporal cortex

2012 ◽  
Vol 6 ◽  
Author(s):  
Vogels Rufin
Keyword(s):  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Stimulus Repetition ◽  
Neuronal Populations

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 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 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.

Organization of local horizontal functional interactions between neurons in the inferior temporal cortex of macaque monkeys

2014 ◽  
Vol 111 (12) ◽  
pp. 2589-2602 ◽  
Author(s):  
Hiroshi Tamura ◽  
Yoshiya Mori ◽  
Hidekazu Kaneko
Keyword(s):  
Neuronal Activity ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Visual Object ◽  
Detailed Knowledge ◽  
Visual Response ◽  
Stimulus Preference ◽  
Macaque Monkeys ◽  
Functional Interactions ◽  
Cross Correlation Analysis

Detailed knowledge of neuronal circuitry is necessary for understanding the mechanisms underlying information processing in the brain. We investigated the organization of horizontal functional interactions in the inferior temporal cortex of macaque monkeys, which plays important roles in visual object recognition. Neuronal activity was recorded from the inferior temporal cortex using an array of eight tetrodes, with spatial separation between paired neurons up to 1.4 mm. We evaluated functional interactions on a time scale of milliseconds using cross-correlation analysis of neuronal activity of the paired neurons. Visual response properties of neurons were evaluated using responses to a set of 100 visual stimuli. Adjacent neuron pairs tended to show strong functional interactions compared with more distant neuron pairs, and neurons with similar stimulus preferences tended to show stronger functional interactions than neurons with different stimulus preferences. Thus horizontal functional interactions in the inferior temporal cortex appear to be organized according to both cortical distances and similarity in stimulus preference between neurons. Furthermore, the relationship between strength of functional interactions and similarity in stimulus preference observed in distant neuron pairs was more prominent than in adjacent pairs. The results suggest that functional circuitry is specifically organized, depending on the horizontal distances between neurons. Such specificity endows each circuit with unique functions.

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