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 Object Representation in Inferior Temporal Cortex Is Organized Hierarchically in a Mosaic-Like Structure

2013 ◽  
Vol 33 (42) ◽  
pp. 16642-16656 ◽  
Author(s):  
T. Sato ◽  
G. Uchida ◽  
M. D. Lescroart ◽  
J. Kitazono ◽  
M. Okada ◽  
...  
Keyword(s):  
Object Representation ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex

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.

Tuning and spontaneous spike time synchrony share a common structure in macaque inferior temporal cortex

2014 ◽  
Vol 112 (4) ◽  
pp. 856-869 ◽  
Author(s):  
Chia-pei Lin (林佳霈) ◽  
Yueh-peng Chen (陳嶽鵬) ◽  
Chou P. Hung (洪洲伯)
Keyword(s):  
Spatial Structure ◽  
Object Representation ◽  
Visual Stimulation ◽  
Temporal Cortex ◽  
Electrode Array ◽  
Separation Distance ◽  
Spike Timing ◽  
Inferior Temporal Cortex ◽  
Spike Time ◽  
Common Structure

Investigating the relationship between tuning and spike timing is necessary to understand how neuronal populations in anterior visual cortex process complex stimuli. Are tuning and spontaneous spike time synchrony linked by a common spatial structure (do some cells covary more strongly, even in the absence of visual stimulation?), and what is the object coding capability of this structure? Here, we recorded from spiking populations in macaque inferior temporal (IT) cortex under neurolept anesthesia. We report that, although most nearby IT neurons are weakly correlated, neurons with more similar tuning are also more synchronized during spontaneous activity. This link between tuning and synchrony was not simply due to cell separation distance. Instead, it expands on previous reports that neurons along an IT penetration are tuned to similar but slightly different features. This constraint on possible population firing rate patterns was consistent across stimulus sets, including animate vs. inanimate object categories. A classifier trained on this structure was able to generalize category “read-out” to untrained objects using only a few dimensions (a few patterns of site weightings per electrode array). We suggest that tuning and spike synchrony are linked by a common spatial structure that is highly efficient for object representation.

Learning Increases Stimulus Salience in Anterior Inferior Temporal Cortex of the Macaque

2001 ◽  
Vol 86 (1) ◽  
pp. 290-303 ◽  
Author(s):  
Bharathi Jagadeesh ◽  
Leonardo Chelazzi ◽  
Mortimer Mishkin ◽  
Robert Desimone
Keyword(s):  
Working Memory ◽  
Temporal Cortex ◽  
Poor Response ◽  
Neural Representation ◽  
Inferior Temporal Cortex ◽  
Neuronal Responses ◽  
Recording Session ◽  
Baseline Activity ◽  
Incorrect Stimulus ◽  
The Difference

With experience, an object can become behaviorally relevant and thereby quickly attract our interest when presented in a visual scene. A likely site of these learning effects is anterior inferior temporal (aIT) cortex, where neurons are thought to participate in the filtering of irrelevant information out of complex visual displays. We trained monkeys to saccade consistently to one of two pictures in an array, in return for a reward. The array was constructed by pairing two stimuli, one of which elicited a good response from the cell when presented alone (“good” stimulus) and the other of which elicited a poor response (“poor” stimulus). The activity of aIT cells was recorded while monkeys learned to saccade to either the good or poor stimulus in the array. We found that neuronal responses to the array were greater (before the saccade occurred) when training reinforced a saccade to the good stimulus than when training reinforced a saccade to the poor stimulus. This difference was not present on incorrect trials, i.e., when saccades to the incorrect stimulus were made. Thus the difference in activity was correlated with performance. The response difference grew over the course of the recording session, in parallel with the improvement in performance. The response difference was not preceded by a difference in the baseline activity of the cells, unlike what was found in studies of cued visual search and working memory in aIT cortex. Furthermore, we found similar effects in a version of the task in which any of 10 possible pairs of stimuli, prelearned before the recording session, could appear on a given trial, thereby precluding a working memory strategy. The results suggest that increasing the behavioral significance of a stimulus through training alters the neural representation of that stimulus in aIT cortex. As a result, neurons responding to features of the relevant stimulus may suppress neurons responding to features of irrelevant 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.

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