Enhancement of Object Representations in Primate Perirhinal Cortex During a Visual Working-Memory Task

2007 ◽  
Vol 97 (2) ◽  
pp. 1298-1310 ◽  
Author(s):  
Sidney R. Lehky ◽  
Keiji Tanaka
Keyword(s):  
Brain Area ◽  
Memory Task ◽  
Perirhinal Cortex ◽  
The Other ◽  
Object Representations ◽  
Repetition Effects ◽  
Object Memory ◽  
Stimulus Response ◽  
Cortex Area ◽  
Area Te

We compared single-cell activities in perirhinal cortex (PRh) as well as adjacent visual cortex (area TE) across two tasks. One task required the monkey to identify any stimulus repetition within a sequence of object stimuli. In the other task, the same stimuli were presented, but the monkey didn’t have to remember them. PRh responses during the object-memory task were elevated relative to those during the second task. In TE, on the other hand, there were no significant task-related differences in responses. We did not observe task-related differences related to repetition effects in either brain area. The onset of the enhanced signal in PRh during the object-memory task occurred with a latency of 80 ms after the onset of the stimulus response, suggesting that it was the result of top-down feedback.

scholarly journals A Simple Method to Avoid Brain Shift during Neuronavigation: Technical Note

2020 ◽  
Author(s):  
Jair Leopoldo Raso
Keyword(s):  
Dura Mater ◽  
Brain Area ◽  
Conventional Technique ◽  
Technical Note ◽  
Cortical Surface ◽  
Brain Shift ◽  
Simple Method ◽  
Cortex Area ◽  
Neuronavigation System ◽  
The Brain

Abstract Introduction The precise identification of anatomical structures and lesions in the brain is the main objective of neuronavigation systems. Brain shift, displacement of the brain after opening the cisterns and draining cerebrospinal fluid, is one of the limitations of such systems. Objective To describe a simple method to avoid brain shift in craniotomies for subcortical lesions. Method We used the surgical technique hereby described in five patients with subcortical neoplasms. We performed the neuronavigation-guided craniotomies with the conventional technique. After opening the dura and exposing the cortical surface, we placed two or three arachnoid anchoring sutures to the dura mater, close to the edges of the exposed cortical surface. We placed these anchoring sutures under microscopy, using a 6–0 mononylon wire. With this technique, the cortex surface was kept close to the dura mater, minimizing its displacement during the approach to the subcortical lesion. In these five cases we operated, the cortical surface remained close to the dura, anchored by the arachnoid sutures. All the lesions were located with a good correlation between the handpiece tip inserted in the desired brain area and the display on the navigation system. Conclusion Arachnoid anchoring sutures to the dura mater on the edges of the cortex area exposed by craniotomy constitute a simple method to minimize brain displacement (brain-shift) in craniotomies for subcortical injuries, optimizing the use of the neuronavigation system.

scholarly journals Using fMR-adaptation to track complex object representations in perirhinal cortex

2013 ◽  
Vol 4 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Rachael D. Rubin ◽  
Samantha A. Chesney ◽  
Neal J. Cohen ◽  
Brian D. Gonsalves
Keyword(s):  
Perirhinal Cortex ◽  
Complex Object ◽  
Object Representations

The Effect of Implicit Racial Bias on Recognition of Other-Race Faces

2021 ◽  
Author(s):  
Tobiasz Trawinski ◽  
Araz Aslanian ◽  
Olivia S. Cheung
Keyword(s):  
Face Recognition ◽  
Racial Bias ◽  
Recognition Performance ◽  
Implicit Bias ◽  
Memory Task ◽  
The Other ◽  
Extensive Experience ◽  
Ability Test ◽  
Implicit Racial Bias ◽  
Recognition Ability

Previous research has established a possible link between recognition performance, individuation experience, and implicit racial bias of other-race faces. However, it remains unclear how implicit racial bias might influence other-race face processing in observers with relatively extensive experience with the other race. Here we examined how recognition of other-race faces might be modulated by observers’ implicit racial bias, in addition to the effects of experience and face recognition ability. Caucasian participants in a culturally diverse city completed a memory task for Asian and Caucasian faces, an implicit association test, an experience questionnaire towards Asians and Caucasians, and a face recognition ability test. Overall, participants showed significantly better recognition performance for other- than own-race faces. More importantly, recognition performance for other-race faces was positively predicted by increased face recognition ability, experience with Asians, and negatively predicted by increased positive bias towards Asians, which was modulated by an interaction between face recognition ability and implicit bias, with the effect of implicit bias observed predominantly in observers with high face recognition ability. Moreover, significant differences were observed among the positions of the first two fixations when participants learned the other-race faces, with the first fixation modulated by the effect of experience and the second fixation modulated by the interaction between implicit bias and face recognition ability. Taken together, these findings suggest the complexity in understanding the perceptual and socio-cognitive influences on the other-race effect, and that observers with high face recognition ability may more likely evaluate racial features involuntarily when recognizing other-race faces.

Depressed Responsiveness To Adrenaline In Platelets From Apparently Normal Human Donors – A Familial Trait

1981 ◽  
Author(s):  
M C Scrutton ◽  
K R Bruckdorfer ◽  
R A Hutton
Keyword(s):  
Adenylate Cyclase ◽  
Platelet Function ◽  
Divalent Cation ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
The Other ◽  
Stimulus Response ◽  
A 23187 ◽  
Phospholipid Classes ◽  
Normal Human

Decreased responsiveness to adrenaline has been observed in 5 out of approximately 150 apparently normal unrelated human donors. In 4 donors, familial studies have shown that this trait is inherited. Three of the donors, as well as their affected relatives, exhibit depressed responsiveness to collagen and vasopressin but normal responsiveness to ADP and thrombin in association with the decreased responsiveness to adrenaline. The other two affected donors exhibit normal responsiveness to most other agonists although in one instance depression of responsiveness to vasopressin and absence of a secretory response to ADP may be associated with the decreased adrenaline response.Normal responsiveness can be restored in all instances either by incubating the platelet-rich plasma at 20°C or by addition at 37°C of a low concentration of the divalent cation ionophore, A-23187. No such effect results from addition of an adenylate cyclase inhibitor. All affected platelets have normal ATP and ADP contents, cholesterol to phospholipid ratios, and composition of the phospholipid classes. Mixing experiments demonstrate the absence of a circulating inhibitor of platelet function and suggest that the defect resides in the platelets. We conclude that depressed responsiveness of human platelets to adrenaline may result from a defect in Ca2+ mobilisation to the cytosol. The observed selectivity in the agonists affected may indicate that the stimulus-response coupling pathways converge at the level of an increase in cytosolic Ca2+ concentration.

Nicotinic receptor activation in perirhinal cortex and hippocampus enhances object memory in rats

2012 ◽  
Vol 62 (5-6) ◽  
pp. 2096-2105 ◽  
Author(s):  
Ashley M. Melichercik ◽  
Kevin S. Elliott ◽  
Cristina Bianchi ◽  
Sarah M. Ernst ◽  
Boyer D. Winters
Keyword(s):  
Nicotinic Receptor ◽  
Perirhinal Cortex ◽  
Receptor Activation ◽  
Object Memory

scholarly journals Effects of stimulus features and instruction on response coding, selection, and inhibition: Evidence from repetition effects under task switching

2008 ◽  
Vol 61 (10) ◽  
pp. 1573-1600 ◽  
Author(s):  
Michel D. Druey ◽  
Ronald Hübner
Keyword(s):  
Task Switching ◽  
Response Selection ◽  
Middle Finger ◽  
Task Switch ◽  
Negative Effects ◽  
Repetition Effects ◽  
Stimulus Response ◽  
Stimulus Features ◽  
Feature Overlap ◽  
Response Coding

The coding of stimuli and responses is crucial for human behaviour. Here, we focused primarily on the response codes (or response categories). As a method, we applied a combined dual-task and task-switch paradigm with a fixed task-to-hand mapping. Usually, negative effects (i.e., costs) are observed for response category repetitions under task switching. However, in several previous studies it has been proposed that such repetition effects do not occur, if the stimulus categories (e.g., “odd” if digits have to be classified according to their parity feature) are unequivocally mapped to specific responses. Our aim was to test this hypothesis. In the present experiments, we were able to distinguish between three different types of possible response codes. The results show that the participants generally code their responses according to abstract response features (left/right, or index/middle finger). Moreover, the spatial codes were preferred over the finger-type codes even if the instructions stressed the latter. This preference, though, seemed to result from a stimulus–response feature overlap, so that the spatial response categories were primed by the respective stimulus features. If there was no such overlap, the instructions determined which type of response code was involved in response selection and inhibition.

Asymmetric Interactions in the Processing of the Visual Dimensions of Position, Width, and Contrast of Bar Stimuli

Perception ◽  
1992 ◽  
Vol 21 (3) ◽  
pp. 297-312 ◽  
Author(s):  
Sima Shechter ◽  
Shaul Hochstein
Keyword(s):  
Cortical Neuron ◽  
Single Stimulus ◽  
The Other ◽  
One Dimension ◽  
Repetition Effects ◽  
Other Hand ◽  
Different Dimensions ◽  
Asymmetric Interactions ◽  
Interaction Phenomena ◽  
Random Variation

The processing of different dimensions of a single stimulus may be either integral or separable. Dimensions are called integral if correlated variation of one improves discrimination on the basis of the other and random variation of one interferes with discrimination on the basis of the other. For separable dimensions on the other hand, subjects can attend to one dimension and disregard variations in the other. These discrimination tests were used to find the interactions between the processing of the visual dimensions of position, width, and contrast of a light bar stimulus. The relations between these dimensions were found to be asymmetric-judgments of position and width are independent of contrast variations, but variations in these dimensions influence contrast discriminations. Furthermore, position variations influence width judgements more than vice versa. The data were analyzed for repetition effects, and it was found that this model is not sufficient to explain all the interaction phenomena. The asymmetries found may be related to the different ways these dimensions are mapped onto cortical neuron responses.

scholarly journals Animacy and real world size shape object representations in the human medial temporal lobes

2018 ◽  
Author(s):  
Anna Blumenthal ◽  
Bobby Stojanoski ◽  
Chris Martin ◽  
Rhodri Cusack ◽  
Stefan Köhler
Keyword(s):  
Recognition Memory ◽  
Real World ◽  
Medial Temporal Lobe ◽  
Memory Task ◽  
Functional Differentiation ◽  
Object Representations ◽  
Neural Basis ◽  
Visual Stream ◽  
Ventral Visual Stream ◽  
Domain Level

ABSTRACTIdentifying what an object is, and whether an object has been encountered before, is a crucial aspect of human behavior. Despite this importance, we do not have a complete understanding of the neural basis of these abilities. Investigations into the neural organization of human object representations have revealed category specific organization in the ventral visual stream in perceptual tasks. Interestingly, these categories fall within broader domains of organization, with distinctions between animate, inanimate large, and inanimate small objects. While there is some evidence for category specific effects in the medial temporal lobe (MTL), it is currently unclear whether domain level organization is also present across these structures. To this end, we used fMRI with a continuous recognition memory task. Stimuli were images of objects from several different categories, which were either animate or inanimate, or large or small within the inanimate domain. We employed representational similarity analysis (RSA) to test the hypothesis that object-evoked responses in MTL structures during recognition-memory judgments also show evidence for domain-level organization along both dimensions. Our data support this hypothesis. Specifically, object representations were shaped by either animacy, real-world size, or both, in perirhinal and parahippocampal cortex, as well as the hippocampus. While sensitivity to these dimensions differed when structures when probed individually, hinting at interesting links to functional differentiation, similarities in organization across MTL structures were more prominent overall. These results argue for continuity in the organization of object representations in the ventral visual stream and the MTL.

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