1631 Non-linear interactions of two different visual stimuli in the receptive fields of monkey's inferior temporal cortex

1993 ◽  
Vol 18 ◽  
pp. S185
Author(s):  
Takayuki Sato
Keyword(s):  
Visual Stimuli ◽  
Temporal Cortex ◽  
Receptive Fields ◽  
Inferior Temporal Cortex ◽  
Non Linear ◽  
Linear Interactions

scholarly journals Within and between hemifields generalization of repetition suppression in inferior temporal cortex.

2020 ◽  
Author(s):  
Francesco Fabbrini ◽  
Rufin Vogels
Keyword(s):  
Test Stimulus ◽  
Common Property ◽  
Temporal Cortex ◽  
Receptive Fields ◽  
Selective Adaptation ◽  
Inferior Temporal Cortex ◽  
Repetition Suppression ◽  
Repetition Trial ◽  
End Stage ◽  
Spatial Locations

The decrease in response with stimulus repetition is a common property observed in many sensory brain areas. This repetition suppression (RS) is ubiquitous in neurons of macaque inferior temporal (IT) cortex, the end-stage of the ventral visual pathway. The neural mechanisms of RS in IT are still unclear, and one possibility is that it is inherited from areas upstream to IT that show also RS. Since neurons in IT have larger receptive fields compared to earlier visual areas, we examined the inheritance hypothesis by presenting adapter and test stimuli at widely different spatial locations along both vertical and horizontal meridians, and across hemifields. RS was present for distances between adapter and test stimuli up to 22°, and when the two stimuli were presented in different hemifields. Also, we examined the position tolerance of the stimulus selectivity of adaptation by comparing the responses to a test stimulus following the same (repetition trial) or a different adapter (alternation trial) at a different position than the test stimulus. Stimulus-selective adaptation was still present and consistently stronger in the later phase of the response for distances up to 18°. Finally, we observed stimulus-selective adaptation in repetition trials even without a measurable excitatory response to the adapter stimulus. To accommodate these and previous data, we propose that at least part of the stimulus-selective adaptation in IT is based on short-term plasticity mechanisms within IT and/or reflects top-down activity from areas downstream to IT.

Response properties of neurons in temporal cortical visual areas of infant monkeys

1993 ◽  
Vol 70 (3) ◽  
pp. 1115-1136 ◽  
Author(s):  
H. R. Rodman ◽  
S. P. Scalaidhe ◽  
C. G. Gross
Keyword(s):  
Nitrous Oxide ◽  
Temporal Cortex ◽  
Receptive Fields ◽  
Stimulus Presentation ◽  
Pattern Perception ◽  
Inferior Temporal Cortex ◽  
Field Size ◽  
Visual Response ◽  
Control Adult ◽  
Oxide Anesthesia

1. Inferior temporal cortex (IT) is a "high-order" region of primate temporal visual cortex implicated in visual pattern perception and recognition. To gain some insight into the development of this area, we compared the properties of single neurons in IT in infant monkeys ranging from 5 wk to 7 mo of age with those of neurons in IT in adult animals. Both anesthetized and awake behaving paradigms were used. 2. In immobilized infant monkeys under nitrous oxide anesthesia, the incidence of visually responsive cells was markedly less than in adult monkeys studied under similar conditions. In infants 4-7 mo of age, only half of IT neurons studied were visually responsive, compared with > 80% in adult monkeys. In monkeys < 4 mo old, even fewer (< 10%) could be visually driven. "Habituation" of IT cells to repeated stimulus presentation appeared more pronounced in infant monkeys under nitrous oxide anesthesia than in adult animals. 3. IT cells in the anesthetized infant monkeys that did respond showed receptive field properties similar to those of responsive adult IT neurons studied under similar conditions. Two thirds of the receptive fields plotted in the anesthetized 4 to 7-mo-old group were bilateral, and median field size did not differ between the infants and comparable adult groups, being approximately 20 degrees on a side in each case. 4. In contrast to the results obtained under anesthesia, most IT cells in alert infant monkeys 5 wk-7 mo of age (80%) were responsive to visual stimuli, and this incidence of visually responsive IT neurons did not differ from that obtained in awake adult macaques. However, response magnitude, measured as spikes per second above baseline rate, was significantly lower in the infant alert sample than in the adult control (5.2 vs. 12.6 spikes/s, mean +/- SE, deviation from spontaneous rate, respectively). 5. In addition to having lower magnitudes of visual response, IT cells in the awake infants also tended to have longer and more variable latencies. The overall mean for the infant cells was 196 ms, compared with an overall mean of 140 ms for IT neurons in the alert control adult. 6. Although the magnitude of response of neurons in alert infant IT cortex was lower overall, the incidence and features of stimulus selectivity shown by alert infant IT neurons were strikingly similar to those of IT cells of both anesthetized and unanesthetized adult monkeys.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Large-scale hyperparameter search for predicting human brain responses in the Algonauts challenge

2019 ◽  
Author(s):  
Kamila M. Jozwik ◽  
Michael Lee ◽  
Tiago Marques ◽  
Martin Schrimpf ◽  
Pouya Bashivan
Keyword(s):  
Large Scale ◽  
Visual Stimuli ◽  
Temporal Cortex ◽  
Image Features ◽  
Inferior Temporal Cortex ◽  
Network Architectures ◽  
Image Preprocessing ◽  
Neural Representations ◽  
Brain Responses ◽  
Early Visual Cortex

Image features computed by specific convolutional artificial neural networks (ANNs) can be used to make state-of-the-art predictions of primate ventral stream responses to visual stimuli.However, in addition to selecting the specific ANN and layer that is used, the modeler makes other choices in preprocessing the stimulus image and generating brain predictions from ANN features. The effect of these choices on brain predictivity is currently underexplored.Here, we directly evaluated many of these choices by performing a grid search over network architectures, layers, image preprocessing strategies, feature pooling mechanisms, and the use of dimensionality reduction. Our goal was to identify model configurations that produce responses to visual stimuli that are most similar to the human neural representations, as measured by human fMRI and MEG responses. In total, we evaluated more than 140,338 model configurations. We found that specific configurations of CORnet-S best predicted fMRI responses in early visual cortex, and CORnet-R and SqueezeNet models best predicted fMRI responses in inferior temporal cortex. We found specific configurations of VGG-16 and CORnet-S models that best predicted the MEG responses.We also observed that downsizing input images to ~50-75% of the input tensor size lead to better performing models compared to no downsizing (the default choice in most brain models for vision). Taken together, we present evidence that brain predictivity is sensitive not only to which ANN architecture and layer is used, but choices in image preprocessing and feature postprocessing, and these choices should be further explored.

scholarly journals The Receptive Fields of Inferior Temporal Cortex Neurons in Natural Scenes

2003 ◽  
Vol 23 (1) ◽  
pp. 339-348 ◽  
Author(s):  
Edmund T. Rolls ◽  
Nicholas C. Aggelopoulos ◽  
Fashan Zheng
Keyword(s):  
Temporal Cortex ◽  
Receptive Fields ◽  
Inferior Temporal Cortex ◽  
Natural Scenes

Neural ensemble coding in inferior temporal cortex

1994 ◽  
Vol 71 (6) ◽  
pp. 2325-2337 ◽  
Author(s):  
P. M. Gochin ◽  
M. Colombo ◽  
G. A. Dorfman ◽  
G. L. Gerstein ◽  
C. G. Gross
Keyword(s):  
Time Scale ◽  
Visual Stimuli ◽  
Temporal Cortex ◽  
Population Characteristics ◽  
Basis Set ◽  
Inferior Temporal Cortex ◽  
Stimulus Discrimination ◽  
Linear Discriminant ◽  
Neural Ensemble ◽  
Discrimination Capacity

1. Isolated, single-neuron extracellular potentials were recorded sequentially in area TE of the inferior temporal cortex (IT) of two macaque monkeys (n = 58 and n = 41 neurons). Data were obtained while the animals were performing a paired-associate task. The task utilized five stimuli and eight stimulus pairings (4 correct and 4 incorrect). Data were evaluated as average spike rate during experimental epochs of 100 or 400 ms. Single-unit and population characteristics were measured using a form of linear discriminant analysis and information theoretic measures. To evaluate the significance of covariance on population code measures, additional data consisting of simultaneous recordings from < or = 8 isolated neurons (n = 37) were obtained from a third macaque monkey that was passively viewing visual stimuli. 2. On average, 43% of IT neurons were activated by any of the stimuli used (60% if those inhibited also are included). Yet the neurons were rather unique in the relative magnitude of their responses to each stimulus in the test set. These results suggest that information may be represented in IT by the pattern of activity across neurons and that the representation is not sparsely coded. It is further suggested that the representation scheme may have similarities to DNA or computer codes wherein a coding element is not a local parametric descriptor. This is a departure from the V1 representation, which appears to be both local and parametric. It is also different from theories of IT representation that suggest a constructive basis set or “alphabet”. From this view, determination of stimulus discrimination capacity in IT should be evaluated by measures of population activity patterns. 3. Evaluation of small groups of simultaneously recorded neurons obtained during a fixation task suggests that little information about visual stimuli is conveyed by covariance of activity in IT when a 100-ms time scale is used as in this study. This finding is consistent with a prior report, by Gochin et al., which used a 1-ms time scale and failed to find neural activity coherence or oscillations dependent on stimuli. 4. Population-stimulus-discrimination capacity measures were influenced by the number of neurons and to some extent the number and type of stimuli. 5. Information conveyed by individual neurons (mutual information) averaged 0.26 bits. The distribution of information values was unimodal and is therefore more consistent with a distributed than a local coding scheme.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Object Perception in Natural Scenes: Encoding by Inferior Temporal Cortex Simultaneously Recorded Neurons

2005 ◽  
Vol 93 (3) ◽  
pp. 1342-1357 ◽  
Author(s):  
Nikolaos C. Aggelopoulos ◽  
Leonardo Franco ◽  
Edmund T. Rolls
Keyword(s):  
Alternative Hypothesis ◽  
Temporal Cortex ◽  
Receptive Fields ◽  
Object Perception ◽  
Spike Timing ◽  
Inferior Temporal Cortex ◽  
Natural Scenes ◽  
Small Contribution ◽  
Complex Scene ◽  
Information Encoding

The firing of inferior temporal cortex neurons is tuned to objects and faces, and in a complex scene, their receptive fields are reduced to become similar to the size of an object being fixated. These two properties may underlie how objects in scenes are encoded. An alternative hypothesis suggests that visual perception requires the binding of features of the visual target through spike synchrony in a neuronal assembly. To examine possible contributions of firing synchrony of inferior temporal neurons, we made simultaneous recordings of the activity of several neurons while macaques performed a visual discrimination task. The stimuli were presented in either plain or complex backgrounds. The encoding of information of neurons was analyzed using a decoding algorithm. Ninety-four percent to 99% of the total information was available in the firing rate spike counts, and the contribution of spike timing calculated as stimulus-dependent synchronization (SDS) added only 1–6% of information to the total that was independent of the spike counts in the complex background. Similar results were obtained in the plain background. The quantitatively small contribution of spike timing to the overall information available in spike patterns suggests that information encoding about which stimulus was shown by inferior temporal neurons is achieved mainly by rate coding. Furthermore, it was shown that there was little redundancy (6%) between the information provided by the spike counts of the simultaneously recorded neurons, making spike counts an efficient population code with a high encoding capacity.

Visual properties of neurons in area V4 of the macaque: sensitivity to stimulus form

1987 ◽  
Vol 57 (3) ◽  
pp. 835-868 ◽  
Author(s):  
R. Desimone ◽  
S. J. Schein
Keyword(s):  
Receptive Field ◽  
Temporal Cortex ◽  
Receptive Fields ◽  
Inferior Temporal Cortex ◽  
Field Size ◽  
Lower Visual Field ◽  
Stimulus Form ◽  
Area V4 ◽  
Prestriate Cortex ◽  
Length Width

Area V4, a visuotopically organized area in prestriate cortex of the macaque, is the major source of visual input to the inferior temporal cortex, known to be crucial for object recognition. To examine the selectivity of cells in V4 for stimulus form, we quantitatively measured the responses of 322 cells to bars varying in length, width, orientation, and polarity of contrast, and sinusoidal gratings varying in spatial frequency, phase, orientation, and overall size. All of the cells recorded in V4 were located on the lower portion of the prelunate gyrus. Receptive fields were located almost exclusively within the representation of the central 5 degrees of the lower visual field, and receptive field size, in linear dimension, was 4-7 times greater than that in the corresponding representation of striate cortex (V1). Nearly all receptive fields consisted of overlapping dark and light zones, like “classic” complex fields in V1, but the relative strengths of the dark and light zones often differed. A few cells responded exclusively to light or dark stimuli. Many cells in V4 were selective for stimulus orientation, and a few were selective for direction of motion as well. Although the median orientation bandwidth of the orientation-selective cells (52 degrees) was wider than that reported for oriented cells in V1, approximately 8% of the oriented cells had bandwidths of less than 30 degrees, which is nearly as narrow as the most narrowly tuned cells in V1. The proportion of cells selective for direction of motion (13%) was not markedly different from that reported in V1. The large majority of V4 cells were tuned to the length and width of bars, and the “shape” of the optimal bar varied from cell to cell, as has been reported for cells in the dorsolateral visual area (DL) of the owl monkey, a possible homologue of V4 in the macaque. Preferred lengths and widths varied independently from approximately 0.05 to 6 degrees, with the smallest preferred bars about the size of the smallest receptive fields in V1 and the largest preferred bars larger than any fields in V1. The relationship between the size of the optimal bar and the size of the receptive field varied from cell to cell. Some cells, for example, responded best to bars much narrower or shorter than the field, whereas other cells responded best to bars that filled (but did not extend beyond) the excitatory field in the length, width, or both dimensions.(ABSTRACT TRUNCATED AT 400 WORDS)

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