scholarly journals Dynamic Population Coding of Category Information in Inferior Temporal and Prefrontal Cortex

2008 ◽  
Vol 100 (3) ◽  
pp. 1407-1419 ◽  
Author(s):  
Ethan M. Meyers ◽  
David J. Freedman ◽  
Gabriel Kreiman ◽  
Earl K. Miller ◽  
Tomaso Poggio
Keyword(s):  
Prefrontal Cortex ◽  
Visual Information ◽  
Activity Patterns ◽  
Temporal Cortex ◽  
Relevant Information ◽  
Population Coding ◽  
Inferior Temporal Cortex ◽  
Category Information ◽  
Almost All ◽  
Dynamic Population

Most electrophysiology studies analyze the activity of each neuron separately. While such studies have given much insight into properties of the visual system, they have also potentially overlooked important aspects of information coded in changing patterns of activity that are distributed over larger populations of neurons. In this work, we apply a population decoding method to better estimate what information is available in neuronal ensembles and how this information is coded in dynamic patterns of neural activity in data recorded from inferior temporal cortex (ITC) and prefrontal cortex (PFC) as macaque monkeys engaged in a delayed match-to-category task. Analyses of activity patterns in ITC and PFC revealed that both areas contain “abstract” category information (i.e., category information that is not directly correlated with properties of the stimuli); however, in general, PFC has more task-relevant information, and ITC has more detailed visual information. Analyses examining how information coded in these areas show that almost all category information is available in a small fraction of the neurons in the population. Most remarkably, our results also show that category information is coded by a nonstationary pattern of activity that changes over the course of a trial with individual neurons containing information on much shorter time scales than the population as a whole.

scholarly journals The Effect of Spatial Frequency on the Visual Category Representation in the Macaque Inferior Temporal Cortex

2021 ◽  
Author(s):  
Esmaeil Farhang ◽  
Ramin Toosi ◽  
Behnam Karami ◽  
Roxana Koushki ◽  
Ehsan Rezayat ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Visual Processing ◽  
Visual Information ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Category Representation ◽  
Neural Basis ◽  
Shape Information ◽  
Category Information ◽  
The Impact

ABSTRACTTo expand our knowledge about the object recognition, it is critical to understand the role of spatial frequency (SF) in an object representation that occurs in the inferior temporal (IT) cortex at the final stage of processing the visual information across the ventral visual pathway. Object categories are being recognized hierarchically in at least three levels of abstraction: superordinate (e.g., animal), mid-level (e.g., human face), and subordinate (e.g., face identity). Psychophysical studies have shown rapid access to mid-level category information and low SF (LSF) contents. Although the hierarchical representation of categories has been shown to exist inside the IT cortex, the impact of SF on the multi-level category processing is poorly understood. To gain a deeper understanding of the neural basis of the interaction between SF and category representations at multiple levels, we examined the neural responses within the IT cortex of macaque monkeys viewing several SF-filtered objects. Each stimulus could be either intact or bandpass filtered into either the LSF (coarse shape information) or high SF (HSF) (fine shape information) bands. We found that in both High- and Low-SF contents, the advantage of mid-level representation has not been violated. This evidence suggests that mid-level category boundary maps are strongly represented in the IT cortex and remain unaffected with respect to any changes in the frequency content of stimuli. Our observations indicate the necessity of the HSF content for the superordinate category representation inside the IT cortex. In addition, our findings reveal that the representation of global category information is more dependent on the HSF than the LSF content. Furthermore, the lack of subordinate representation in both LSF and HSF filtered stimuli compared to the intact stimuli provide strong evidence that all SF contents are necessary for fine category visual processing.

scholarly journals Preparatory Activity in Posterior Temporal Cortex Causally Contributes to Object Detection in Scenes

2015 ◽  
Vol 27 (11) ◽  
pp. 2117-2125 ◽  
Author(s):  
Reshanne R. Reeder ◽  
Francesca Perini ◽  
Marius V. Peelen
Keyword(s):  
Visual Cortex ◽  
Object Detection ◽  
Activity Patterns ◽  
Temporal Cortex ◽  
Relevant Information ◽  
Visual Selective Attention ◽  
Object Categories ◽  
Preparatory Attention ◽  
Preparatory Activity ◽  
Early Visual Cortex

Theories of visual selective attention propose that top–down preparatory attention signals mediate the selection of task-relevant information in cluttered scenes. Neuroimaging and electrophysiology studies have provided correlative evidence for this hypothesis, finding increased activity in target-selective neural populations in visual cortex in the period between a search cue and target onset. In this study, we used online TMS to test whether preparatory neural activity in visual cortex is causally involved in naturalistic object detection. In two experiments, participants detected the presence of object categories (cars, people) in a diverse set of photographs of real-world scenes. TMS was applied over a region in posterior temporal cortex identified by fMRI as carrying category-specific preparatory activity patterns. Results showed that TMS applied over posterior temporal cortex before scene onset (−200 and −100 msec) impaired the detection of object categories in subsequently presented scenes, relative to vertex and early visual cortex stimulation. This effect was specific to category level detection and was related to the type of attentional template participants adopted, with the strongest effects observed in participants adopting category level templates. These results provide evidence for a causal role of preparatory attention in mediating the detection of objects in cluttered daily-life environments.

Top-Down Signal of Retrieved Information From Prefrontal to Inferior Temporal Cortices

2007 ◽  
Vol 98 (4) ◽  
pp. 1965-1974 ◽  
Author(s):  
Masato Inoue ◽  
Akichika Mikami
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Critical Area ◽  
Retrieval Process ◽  
Multiple Objects ◽  
Top Down ◽  
Ventrolateral Prefrontal Cortex

We compared neuronal activities in the ventrolateral prefrontal cortex (VLPFC) and the inferior temporal cortex (IT) during the retrieval of an object from the working memory. About one third of IT neurons showed color- and target-selective (CT) or target-selective (T) response during the color cue period of the serial probe reproduction (SPR) task. These object-selective (CT and T) responses in IT could be correlated with the retrieval process of an object from the memorized multiple objects because no objects were presented during this period. However, proportion of CT and T responses was smaller in IT than in VLPFC, where two thirds of neurons showed object-selective response. In addition, object-selective response started earlier in VLPFC than in IT. These results suggest that VLPFC retrieves particular object information from the working memory and sends the retrieved object information to IT. The fact that the responses in the error trials did not decrease in IT suggests that IT is not a critical area for the retrieval process from the working memory.

scholarly journals Comparison of Primate Prefrontal and Premotor Cortex Neuronal Activity during Visual Categorization

2011 ◽  
Vol 23 (11) ◽  
pp. 3355-3365 ◽  
Author(s):  
Jason A. Cromer ◽  
Jefferson E. Roy ◽  
Timothy J. Buschman ◽  
Earl K. Miller
Keyword(s):  
Premotor Cortex ◽  
Temporal Cortex ◽  
Motor Planning ◽  
Brain Regions ◽  
Inferior Temporal Cortex ◽  
Decision Variable ◽  
Final Decision ◽  
Visual Categorization ◽  
Category Information ◽  
Cognitive Problem

Previous work has shown that neurons in the PFC show selectivity for learned categorical groupings. In contrast, brain regions lower in the visual hierarchy, such as inferior temporal cortex, do not seem to favor category information over information about physical appearance. However, the role of premotor cortex (PMC) in categorization has not been studied, despite evidence that PMC is strongly engaged by well-learned tasks and reflects learned rules. Here, we directly compare PFC neurons with PMC neurons during visual categorization. Unlike PFC neurons, relatively few PMC neurons distinguished between categories of visual images during a delayed match-to-category task. However, despite the lack of category information in the PMC, more than half of the neurons in both PFC and PMC reflected whether the category of a test image did or did not match the category of a sample image (i.e., had match information). Thus, PFC neurons represented all variables required to solve the cognitive problem, whereas PMC neurons instead represented only the final decision variable that drove the appropriate motor action required to obtain a reward. This dichotomy fits well with PFC's hypothesized role in learning arbitrary information and directing behavior as well as the PMC's role in motor planning.

A Comparison of Abstract Rules in the Prefrontal Cortex, Premotor Cortex, Inferior Temporal Cortex, and Striatum

2006 ◽  
Vol 18 (6) ◽  
pp. 974-989 ◽  
Author(s):  
Rahmat Muhammad ◽  
Jonathan D. Wallis ◽  
Earl K. Miller
Keyword(s):  
Prefrontal Cortex ◽  
Neural Activity ◽  
Premotor Cortex ◽  
Temporal Cortex ◽  
Dorsal Striatum ◽  
Behavioral Responses ◽  
Inferior Temporal Cortex ◽  
Perceptual Information ◽  
Lateral Prefrontal Cortex

The ability to use abstract rules or principles allows behavior to generalize from specific circumstances. We have previously shown that such rules are encoded in the lateral prefrontal cortex (PFC) and premotor cortex (PMC). Here, we extend these investigations to two other areas directly connected with the PFC and the PMC, the inferior temporal cortex (ITC) and the dorsal striatum (STR). Monkeys were trained to use two abstract rules: “same” or “different”. They had to either hold or release a lever, depending on whether two successively presented pictures were the same or different, and depending on which rule was in effect. The rules and the behavioral responses were reflected most strongly and, on average, tended to be earlier in the PMC followed by the PFC and then the STR; few neurons in the ITC reflected the rules or the actions. By contrast, perceptual information (the identity of the pictures used as sample and test stimuli) was encoded more strongly and earlier in the ITC, followed by the PFC; they had weak, if any, effects on neural activity in the PMC and STR. These findings are discussed in the context of the anatomy and posited functions of these areas.

scholarly journals Attention enhances category representations across the brain with strengthened residual correlations to ventral temporal cortex

2021 ◽  
Author(s):  
Arielle S Keller ◽  
Akshay V Jagadeesh ◽  
Lior Bugatus ◽  
Leanne M Williams ◽  
Kalanit Grill-Spector
Keyword(s):  
Selective Attention ◽  
Temporal Cortex ◽  
Relevant Information ◽  
Cortical Region ◽  
Visual Responses ◽  
Attention Task ◽  
Category Information ◽  
Ventral Temporal Cortex ◽  
Residual Correlations ◽  
The Brain

How does attention enhance neural representations of goal-relevant stimuli while suppressing representations of ignored stimuli across regions of the brain? While prior studies have shown that attention enhances visual responses, we lack a cohesive understanding of how selective attention modulates visual representations across the brain. Here, we used functional magnetic resonance imaging (fMRI) while participants performed a selective attention task on superimposed stimuli from multiple categories and used a data-driven approach to test how attention affects both decodability of category information and residual correlations (after regressing out stimulus-driven variance) with category-selective regions of ventral temporal cortex (VTC). Our data reveal three main findings. First, when two objects are simultaneously viewed, the category of the attended object can be decoded more readily than the category of the ignored object, with the greatest attentional enhancements observed in occipital and temporal lobes. Second, after accounting for the response to the stimulus, the correlation in the residual brain activity between a cortical region and a category-selective region of VTC was elevated when that region's preferred category was attended vs. ignored, and more so in the right occipital, parietal, and frontal cortices. Third, we found that the stronger the residual correlations between a given region of cortex and VTC, the better visual category information could be decoded from that region. These findings suggest that heightened residual correlations by selective attention may reflect the sharing of information between sensory regions and higher-order cortical regions to provide attentional enhancement of goal-relevant information.

Ventral Prefrontal Cortex

2021 ◽  
pp. 236-284
Author(s):  
Richard E. Passingham
Keyword(s):  
Prefrontal Cortex ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Long Term Memory ◽  
Frontal Eye Field ◽  
Visual Inputs ◽  
Superior Temporal Cortex ◽  
Eye Field ◽  
Ventral Prefrontal Cortex

The ventral prefrontal cortex learns to associate objects, faces, and vocalizations, and its connectional fingerprint explains why it alone can do so. It receives visual inputs from the inferior temporal cortex and auditory ones from the superior temporal cortex. It combines these inputs with those from the orbital prefrontal (PF) cortex so as to specify the goal that is currently desirable. This is then transformed into the target of search via connections with the frontal eye field and the target for manual retrieval via connections with the premotor areas. The ventral PF cortex can also learn to form associations between objects, for example by linking them into categories. These can be retrieved from long-term memory via connections with the hippocampus.

scholarly journals Learning to Recognize Visual Objects With Microstimulation in Inferior Temporal Cortex

2008 ◽  
Vol 100 (1) ◽  
pp. 197-211 ◽  
Author(s):  
Keisuke Kawasaki ◽  
David L. Sheinberg
Keyword(s):  
Activity Patterns ◽  
Visual Learning ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Classification Learning ◽  
Critical Question ◽  
Direct Stimulation ◽  
Visual Classification ◽  
Association Learning ◽  
New Associations

The malleability of object representations by experience is essential for adaptive behavior. It has been hypothesized that neurons in inferior temporal cortex (IT) in monkeys are pivotal in visual association learning, evidenced by experiments revealing changes in neural selectivity following visual learning, as well as by lesion studies, wherein functional inactivation of IT impairs learning. A critical question remaining to be answered is whether IT neuronal activity is sufficient for learning. To address this question directly, we conducted experiments combining visual classification learning with microstimulation in IT. We assessed the effects of IT microstimulation during learning in cases where the stimulation was exclusively informative, conditionally informative, and informative but not necessary for the classification task. The results show that localized microstimulation in IT can be used to establish visual classification learning, and the same stimulation applied during learning can predictably bias judgments on subsequent recognition. The effect of induced activity can be explained neither by direct stimulation-motor association nor by simple detection of cortical stimulation. We also found that the learning effects are specific to IT stimulation as they are not observed by microstimulation in an adjacent auditory area. Our results add the evidence that the differential activity in IT during visual association learning is sufficient for establishing new associations. The results suggest that experimentally manipulated activity patterns within IT can be effectively combined with ongoing visually induced activity during the formation of new associations.

Temporal encoding of two-dimensional patterns by single units in primate primary visual cortex. II. Information transmission

1990 ◽  
Vol 64 (2) ◽  
pp. 370-380 ◽  
Author(s):  
B. J. Richmond ◽  
L. M. Optican
Keyword(s):  
Cortical Neurons ◽  
Activity Patterns ◽  
Temporal Cortex ◽  
Principal Component ◽  
Response Strength ◽  
Inferior Temporal Cortex ◽  
Temporal Code ◽  
Response Code ◽  
Stimulus Response ◽  
Black And White

1. Previously, we studied how picture information was processed by neurons in inferior temporal cortex. We found that responses varying in both response strength and temporal waveform carried information about briefly flashed stationary black-and-white patterns. Now, we have applied that same paradigm to the study of striate cortical neurons. 2. In this approach the responses to a set of basic black and white pictures were quantified through use of a set of basic waveforms, the principal components (extracted from all the responses of each neuron). We found that the first principal component, which corresponds to the response strength, and others, which correspond to different basic temporal activity patterns, were significantly related to the stimuli, i.e., the stimulus drove both the response strength and its temporal pattern. 3. Our previous study had shown that, when information theory was used to quantify the stimulus-response relation, inferior temporal neurons convey over twice as much information in a response code that includes temporal modulation as in a response code that includes only the response strength. This study shows that striate cortical neurons also carry twice as much information in a temporal code as in a response strength code. Thus single visual neurons at both ends of a cortical processing chain for visual pattern use a multidimensional temporal code to carry stimulus-related information. 4. These results support our multiplex-filter hypothesis, which states that single visual system neurons can be regarded as several simultaneously active parallel channels, each of which conveys independent information about the stimulus.

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