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Sanjay Kumar

Oxford Brookes University, Psychology, Faculty Member

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Robert Lickliter

Florida International University

University of Kansas

Harvard University

Nicola Jane Holt

University of the West of England

Kansas State University

Pennsylvania State University

New York University

Universidade Federal do Rio Grande do Sul

Tomasz Komendzinski

Nicolaus Copernicus University

Maro G Machizawa

Hiroshima University

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Papers by Sanjay Kumar

The cauldron of the ethical review process in human participant research

by Sanjay Kumar and Michael Pilling

Cortex, 2015

Visual speech recognition using wavelet transform and moment based features

International Conference on Informatics in Control, Automation and Robotics, 2006

Fixed Frequency Reuse for LTE-Advanced Systems in Local Area Scenarios

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009

LTE-Advanced systems, which aim to provide high data rate wireless services, have received world-... more LTE-Advanced systems, which aim to provide high data rate wireless services, have received world-wide researching interests nowadays. In this paper, the performance of fixed frequency reuse with different reuse factors is studied in LTE-Advanced systems. Performance is measured in terms of both average cell throughput and cell edge user throughput. It is found that a properly chosen reuse factor with respect to cell size (which leads to different level of inter-cell interference), can offer up to 30% gain in average cell throughput and much higher gain for cell-edge user throughput in Local Area (LA). This high gain from frequency reuse makes it attractive for future LTE-Advanced systems.

Biomarkers inducing changes due to microwave exposure effect on rat brain

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

Animals were exposed for 2 ha day for 45 days at 0.21 mW/cm2 power density SAR (0.038 W/Kg). Afte... more

Mu rhythm desynchronization reveals motoric influences of hand action on object recognition

by Sanjay Kumar and Sanjay Kumar

We examined the effect of hand grip on object recognition by studying the modulation of the mu rh... more We examined the effect of hand grip on object recognition by studying the modulation of the mu rhythm when participants made object decisions to objects and non-objects shown with congruent or incongruent hand-grip actions. Despite the grip responses being irrelevant to the task, mu rhythm activity on the scalp over motor and pre-motor cortex was sensitive to the congruency of the hand grip – in particular the event related desynchronization of the mu rhythm was more pronounced for familiar objects grasped with an appropriate grip than for objects given an inappropriate grasp. Also the power of mu activity correlated with RTs to congruently gripped objects. The results suggest that familiar motor responses evoked by the appropriateness of a hand grip facilitate recognition responses to objects.

Terahertz wave generation by the upper hybrid wave

Physics of Plasmas, 2011

This paper investigates the excitation of terahertz radiation (in the form of a magnetosonic wave... more This paper investigates the excitation of terahertz radiation (in the form of a magnetosonic wave) by the interaction of the upper hybrid (pump) wave and the extraordinary wave (laser). The ponderomotive force due to the nonlinear interaction between the pump wave and the extraordinary wave (laser) generates a nonlinear current at the difference frequency. If the appropriate phase matching conditions

Effect of zeta potential on retention and drainage of secondary fibres

Colloids and Surfaces A-physicochemical and Engineering Aspects, 2005

The experiments have been carried out in the laboratory to investigate the interactions among neg... more The experiments have been carried out in the laboratory to investigate the interactions among negatively charged fibres, fines and positively charged polymer particles on two different papermaking slurries of old corrugated containers (OCC) pulp and mixed office waste (MOW) paper pulp. The effects of different wet-end chemicals such as polyacrylamide, polyamide amine and polyethylene amine on fibre surface chemistry have

Dynamics of the reaction He + H 2 + → HeH + + H on the Aguado-Paniagua surface

Chemical Physics Letters, 1998

Collinear reaction probabilities, and differential and integral cross sections for the reaction H... more Collinear reaction probabilities, and differential and integral cross sections for the reaction He + H+2 → HeH++ H in three dimensions have been computed using a new analytic fit of the ab initio potential-energy values for the system and compared with those obtained using an earlier reported fit and also with the available experimental results. While the results on the

Platelet mechanosensing of substrate stiffness during clot formation mediates adhesion, spreading, and activation

Proceedings of the National Academy of Sciences, 2014

As platelets aggregate and activate at the site of vascular injury to stem bleeding, they are sub... more As platelets aggregate and activate at the site of vascular injury to stem bleeding, they are subjected to a myriad of biochemical and biophysical signals and cues. As clot formation ensues, platelets interact with polymerizing fibrin scaffolds, exposing platelets to a large range of mechanical microenvironments. Here, we show for the first time (to our knowledge) that platelets, which are anucleate cellular fragments, sense microenvironmental mechanical properties, such as substrate stiffness, and transduce those cues into differential biological signals. Specifically, as platelets mechanosense the stiffness of the underlying fibrin/fibrinogen substrate, increasing substrate stiffness leads to increased platelet adhesion and spreading. Importantly, adhesion on stiffer substrates also leads to higher levels of platelet activation, as measured by integrin αIIbβ3 activation, α-granule secretion, and procoagulant activity. Mechanistically, we determined that Rac1 and actomyosin activity mediate substrate stiffness-dependent platelet adhesion, spreading, and activation to different degrees. This capability of platelets to mechanosense microenvironmental cues in a growing thrombus or hemostatic plug and then mechanotransduce those cues into differential levels of platelet adhesion, spreading, and activation provides biophysical insight into the underlying mechanisms of platelet aggregation and platelet activation heterogeneity during thrombus formation.

EMG Based Voice Recognition

Proceedings of the 2004 Intelligent Sensors, Sensor Networks and Information Processing Conference, 2004., 2004

Besides its clinical applications, various researchers have shown that EMG can be utilised in are... more

Photoluminescent, wide-bandgap a-SiC:H alloy films deposited by Cat-CVD using acetylene

Thin Solid Films, 2001

Hydrogenated amorphous siliconycarbon films (a-Si-C:H) are deposited from a silane and acetylene ... more Hydrogenated amorphous siliconycarbon films (a-Si-C:H) are deposited from a silane and acetylene gas mixture by the catalytic chemical vapour deposition (Cat-CVD) technique. It is observed that under certain conditions of total gas pressure and filament temperature (T ), the optical bandgap varies non-linearly with the acetylene to silane (C H ySiH ) ratio, having a maximum F 2 2 4 value of 3.6 eV for a C H ySiH ratio G0.8. However, the deposition rate drastically reduces with an increase in acetylene 2 2 4 fraction. FTIR spectra indicate that the total hydrogen content is lower compared to samples deposited by PECVD using similar gas mixtures, with hydrogen being preferentially attached to carbon rather than silicon atoms. The photoluminescence (PL) spectra of these films show PL in the visible spectral region at room temperature. The films with larger bandgap ()2.5 eV) exhibit PL at room temperature, with the emission having peak energy in the range 2.0-2.3 eV.

Criticality of SAWs on n-Simplex Lattices

Abstract—We have studied self-avoiding walks (SAWs) on a family of n- simplex lattice. Using reno... more Abstract—We have studied self-avoiding walks (SAWs) on a family of n- simplex lattice. Using renormalization group technique, we have calculated the critical exponents for,and,-simplex lattices exactly. These exponents are in very good agreement with a closed relation proposed by Kumar and Singh [1]. We also discuss the issues related with upper critical dimension- ality of the fractal lattices. Keywords—SAW, Fractal lattice, Criticality, Renormalization Group. RACTALS have played a key role in understanding the var-

Widespread cognitive impairment in psychogenic anterograde amnesia

Psychiatry and Clinical Neurosciences, 2007

A 34-year-old man without a past history of any psychiatric or neurological disorder developed se... more A 34-year-old man without a past history of any psychiatric or neurological disorder developed severe anterograde amnesia following a psychological trauma. Initial assessment of neuropsychological functions 3 months after the psychological trauma indicated severe memory deficits for acquiring new information in both verbal and visual modalities with widespread cognitive deficits in attention, executive functions, and intellectual ability. Importantly, working and remote memory were intact. The case illustrates that psychogenic anterograde amnesia might be associated with a wider range of cognitive deficits. Possible neurobiological explanations are discussed to explain large cognitive impairments associated with anterograde psychogenic amnesia.

Response to “Comment on ‘Terahertz wave generation by upper hybrid wave’” [Phys. Plasmas 18, 074701 (2011)]

Physics of Plasmas, 2011

The comment by Stenflo and Brodin mentions two points in our recently published paper [M. Singh, ... more

Effects of molecular crowding on stretching of polymers in poor solvent

Physical Review E, 2009

We consider a linear polymer chain in a disordered environment modeled by percolation clusters on... more We consider a linear polymer chain in a disordered environment modeled by percolation clusters on a square lattice. The disordered environment is meant to roughly represent molecular crowding as seen in cells. The model may be viewed as the simplest representation of biopolymers in a cell. We show the existence of intermediate states during stretching arising as a consequence of molecular crowding. In the constant distance ensemble the force-extension curves exhibit oscillations. We observe the emergence of two or more peaks in the probability distribution curves signaling the coexistence of different states and indicating that the transition is discontinuous unlike what is observed in the absence of molecular crowding.

Stretching of a single-stranded DNA: Evidence for structural transition

Physical Review E, 2009

Recent experiments have shown that the force-extension (F-x) curve for single-stranded DNA (ssDNA... more Recent experiments have shown that the force-extension (F-x) curve for single-stranded DNA (ssDNA) consisting only of adenine [poly(dA)] is significantly different from thymine [poly(dT)]. Here, we show that the base stacking interaction is not sufficient to describe the F-x curves as seen in the experiments. A reduction in the reaction co-ordinate arising from the formation of helix at low forces and an increase in the distance between consecutive phosphates of unstacked bases in the stretched state at high force in the proposed model, qualitatively reproduces the experimentally observed features. The multi-step plateau in the F-x curve is a signature of structural change in ssDNA.

Statistical mechanics of stretching of biopolymers

Journal of Statistical Mechanics: Theory and Experiment, 2011

We developed a simple model of polymers on a triangular lattice to study the force-induced transi... more We developed a simple model of polymers on a triangular lattice to study the force-induced transitions related to biopolymers. Using an exact enumeration technique, we calculate various thermodynamic quantities associated with it. We show here, by including different parameters, e.g. bending and paring interactions in the model system, that one can understand the qualitative differences in the force-extension curves exhibited by different biopolymers. Our study also shows that the solvent plays an important role in the unfolding of proteins.

Reduction of Functional Brain Connectivity in Mild Traumatic Brain Injury during Working Memory

Journal of Neurotrauma, 2009

Working memory deficits are present in patients with mild traumatic brain injury (MTBI). Function... more Working memory deficits are present in patients with mild traumatic brain injury (MTBI). Functional connectivity of different brain regions is required for adequate working memory. Brain injury is associated with disrupted connectivity due to microscopic axonal damage. In this investigation, we sought to investigate functional brain connectivity during working memory in MTBI patients. A sample of 30 MTBI patients and 30 age-, education-, and gender-matched normal controls were studied. Working memory was assessed with the Sternberg's verbal and visuo-spatial working memory tasks. Electro-encephalography (EEG) was recorded from 128 channels while subjects performed working memory tasks and during eyes closed resting condition. EEG coherence was computed in theta; lower and upper alpha; and lower and upper beta frequency bands during the encoding, retention, and retrieval stages of working memory as well as during eyes-closed rest. We found that the MTBI patients had impaired verbal and visuo-spatial working memory. The different stages of working memory were associated with poor intrahemispheric coherence in long-range (fronto-parietal) and mid-range (fronto-temporal and temporo-parietal) regions as well as poor interhemispheric coherence in the frontal and temporal regions in the MTBI patients. The deficit in coherence was present in theta, alpha, and beta frequency bands. However, the MTBI and the control group had comparable coherence values in intra-and inter-hemispheric regions during eyes closed rest. We suggest that the inter-and intra-hemispheric functional connectivity is impaired in MTBI during working memory performance.

Electrophysiological Evidence of Semantic Interference in Visual Search

Journal of Cognitive Neuroscience, 2010

Visual evoked responses were monitored while participants searched for a target (e.g., bird) in a... more Visual evoked responses were monitored while participants searched for a target (e.g., bird) in a four-object display that could include a semantically related distractor (e.g., fish). The occurrence of both the target and the semantically related distractor modulated the N2pc response to the search display: The N2pc amplitude was more pronounced when the target and the distractor appeared in the same visual field, and it was less pronounced when the target and the distractor were in opposite fields, relative to when the distractor was absent. Earlier components (P1, N1) did not show any differences in activity across the different distractor conditions. The data suggest that semantic distractors influence early stages of selecting stimuli in multielement displays.

The Neural Selection and Integration of Actions and Objects: An fMRI Study

by Sanjay Kumar and Goubran M

Journal of Cognitive Neuroscience, 2012

■ There is considerable evidence that there are anatomically and functionally distinct pathways f... more ■ There is considerable evidence that there are anatomically and functionally distinct pathways for action and object recognition. However, little is known about how information about action and objects is integrated. This study provides fMRI evidence for task-based selection of brain regions associated with action and object processing, and on how the congruency between the action and the object modulates neural response. Participants viewed videos of objects used in congruent or incongruent actions and attended either to the action or the object in a one-back procedure. Attending to the action led to increased responses in a fronto-parietal action-associated network. Attending to the object activated regions within a fronto-inferior temporal network. Stronger responses for congruent action-object clips occurred in bilateral parietal, inferior temporal, and putamen. Distinct cortical and thalamic regions were modulated by congruency in the different tasks. The results suggest that (i) selective attention to action and object information is mediated through separate networks, (ii) object-action congruency evokes responses in action planning regions, and (iii) the selective activation of nuclei within the thalamus provides a mechanism to integrate task goals in relation to the congruency of the perceptual information presented to the observer. ■

The cauldron of the ethical review process in human participant research

by Sanjay Kumar and Michael Pilling

Cortex, 2015

Visual speech recognition using wavelet transform and moment based features

International Conference on Informatics in Control, Automation and Robotics, 2006

Fixed Frequency Reuse for LTE-Advanced Systems in Local Area Scenarios

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009

LTE-Advanced systems, which aim to provide high data rate wireless services, have received world-... more LTE-Advanced systems, which aim to provide high data rate wireless services, have received world-wide researching interests nowadays. In this paper, the performance of fixed frequency reuse with different reuse factors is studied in LTE-Advanced systems. Performance is measured in terms of both average cell throughput and cell edge user throughput. It is found that a properly chosen reuse factor with respect to cell size (which leads to different level of inter-cell interference), can offer up to 30% gain in average cell throughput and much higher gain for cell-edge user throughput in Local Area (LA). This high gain from frequency reuse makes it attractive for future LTE-Advanced systems.

Biomarkers inducing changes due to microwave exposure effect on rat brain

2011 XXXth URSI General Assembly and Scientific Symposium, 2011

Animals were exposed for 2 ha day for 45 days at 0.21 mW/cm2 power density SAR (0.038 W/Kg). Afte... more

Mu rhythm desynchronization reveals motoric influences of hand action on object recognition

by Sanjay Kumar and Sanjay Kumar

We examined the effect of hand grip on object recognition by studying the modulation of the mu rh... more We examined the effect of hand grip on object recognition by studying the modulation of the mu rhythm when participants made object decisions to objects and non-objects shown with congruent or incongruent hand-grip actions. Despite the grip responses being irrelevant to the task, mu rhythm activity on the scalp over motor and pre-motor cortex was sensitive to the congruency of the hand grip – in particular the event related desynchronization of the mu rhythm was more pronounced for familiar objects grasped with an appropriate grip than for objects given an inappropriate grasp. Also the power of mu activity correlated with RTs to congruently gripped objects. The results suggest that familiar motor responses evoked by the appropriateness of a hand grip facilitate recognition responses to objects.

Terahertz wave generation by the upper hybrid wave

Physics of Plasmas, 2011

This paper investigates the excitation of terahertz radiation (in the form of a magnetosonic wave... more This paper investigates the excitation of terahertz radiation (in the form of a magnetosonic wave) by the interaction of the upper hybrid (pump) wave and the extraordinary wave (laser). The ponderomotive force due to the nonlinear interaction between the pump wave and the extraordinary wave (laser) generates a nonlinear current at the difference frequency. If the appropriate phase matching conditions

Effect of zeta potential on retention and drainage of secondary fibres

Colloids and Surfaces A-physicochemical and Engineering Aspects, 2005

The experiments have been carried out in the laboratory to investigate the interactions among neg... more The experiments have been carried out in the laboratory to investigate the interactions among negatively charged fibres, fines and positively charged polymer particles on two different papermaking slurries of old corrugated containers (OCC) pulp and mixed office waste (MOW) paper pulp. The effects of different wet-end chemicals such as polyacrylamide, polyamide amine and polyethylene amine on fibre surface chemistry have

Dynamics of the reaction He + H 2 + → HeH + + H on the Aguado-Paniagua surface

Chemical Physics Letters, 1998

Collinear reaction probabilities, and differential and integral cross sections for the reaction H... more Collinear reaction probabilities, and differential and integral cross sections for the reaction He + H+2 → HeH++ H in three dimensions have been computed using a new analytic fit of the ab initio potential-energy values for the system and compared with those obtained using an earlier reported fit and also with the available experimental results. While the results on the

Platelet mechanosensing of substrate stiffness during clot formation mediates adhesion, spreading, and activation

Proceedings of the National Academy of Sciences, 2014

As platelets aggregate and activate at the site of vascular injury to stem bleeding, they are sub... more As platelets aggregate and activate at the site of vascular injury to stem bleeding, they are subjected to a myriad of biochemical and biophysical signals and cues. As clot formation ensues, platelets interact with polymerizing fibrin scaffolds, exposing platelets to a large range of mechanical microenvironments. Here, we show for the first time (to our knowledge) that platelets, which are anucleate cellular fragments, sense microenvironmental mechanical properties, such as substrate stiffness, and transduce those cues into differential biological signals. Specifically, as platelets mechanosense the stiffness of the underlying fibrin/fibrinogen substrate, increasing substrate stiffness leads to increased platelet adhesion and spreading. Importantly, adhesion on stiffer substrates also leads to higher levels of platelet activation, as measured by integrin αIIbβ3 activation, α-granule secretion, and procoagulant activity. Mechanistically, we determined that Rac1 and actomyosin activity mediate substrate stiffness-dependent platelet adhesion, spreading, and activation to different degrees. This capability of platelets to mechanosense microenvironmental cues in a growing thrombus or hemostatic plug and then mechanotransduce those cues into differential levels of platelet adhesion, spreading, and activation provides biophysical insight into the underlying mechanisms of platelet aggregation and platelet activation heterogeneity during thrombus formation.

EMG Based Voice Recognition

Proceedings of the 2004 Intelligent Sensors, Sensor Networks and Information Processing Conference, 2004., 2004

Besides its clinical applications, various researchers have shown that EMG can be utilised in are... more

Photoluminescent, wide-bandgap a-SiC:H alloy films deposited by Cat-CVD using acetylene

Thin Solid Films, 2001

Hydrogenated amorphous siliconycarbon films (a-Si-C:H) are deposited from a silane and acetylene ... more Hydrogenated amorphous siliconycarbon films (a-Si-C:H) are deposited from a silane and acetylene gas mixture by the catalytic chemical vapour deposition (Cat-CVD) technique. It is observed that under certain conditions of total gas pressure and filament temperature (T ), the optical bandgap varies non-linearly with the acetylene to silane (C H ySiH ) ratio, having a maximum F 2 2 4 value of 3.6 eV for a C H ySiH ratio G0.8. However, the deposition rate drastically reduces with an increase in acetylene 2 2 4 fraction. FTIR spectra indicate that the total hydrogen content is lower compared to samples deposited by PECVD using similar gas mixtures, with hydrogen being preferentially attached to carbon rather than silicon atoms. The photoluminescence (PL) spectra of these films show PL in the visible spectral region at room temperature. The films with larger bandgap ()2.5 eV) exhibit PL at room temperature, with the emission having peak energy in the range 2.0-2.3 eV.

Criticality of SAWs on n-Simplex Lattices

Abstract—We have studied self-avoiding walks (SAWs) on a family of n- simplex lattice. Using reno... more Abstract—We have studied self-avoiding walks (SAWs) on a family of n- simplex lattice. Using renormalization group technique, we have calculated the critical exponents for,and,-simplex lattices exactly. These exponents are in very good agreement with a closed relation proposed by Kumar and Singh [1]. We also discuss the issues related with upper critical dimension- ality of the fractal lattices. Keywords—SAW, Fractal lattice, Criticality, Renormalization Group. RACTALS have played a key role in understanding the var-

Widespread cognitive impairment in psychogenic anterograde amnesia

Psychiatry and Clinical Neurosciences, 2007

A 34-year-old man without a past history of any psychiatric or neurological disorder developed se... more A 34-year-old man without a past history of any psychiatric or neurological disorder developed severe anterograde amnesia following a psychological trauma. Initial assessment of neuropsychological functions 3 months after the psychological trauma indicated severe memory deficits for acquiring new information in both verbal and visual modalities with widespread cognitive deficits in attention, executive functions, and intellectual ability. Importantly, working and remote memory were intact. The case illustrates that psychogenic anterograde amnesia might be associated with a wider range of cognitive deficits. Possible neurobiological explanations are discussed to explain large cognitive impairments associated with anterograde psychogenic amnesia.

Response to “Comment on ‘Terahertz wave generation by upper hybrid wave’” [Phys. Plasmas 18, 074701 (2011)]

Physics of Plasmas, 2011

The comment by Stenflo and Brodin mentions two points in our recently published paper [M. Singh, ... more

Effects of molecular crowding on stretching of polymers in poor solvent

Physical Review E, 2009

We consider a linear polymer chain in a disordered environment modeled by percolation clusters on... more We consider a linear polymer chain in a disordered environment modeled by percolation clusters on a square lattice. The disordered environment is meant to roughly represent molecular crowding as seen in cells. The model may be viewed as the simplest representation of biopolymers in a cell. We show the existence of intermediate states during stretching arising as a consequence of molecular crowding. In the constant distance ensemble the force-extension curves exhibit oscillations. We observe the emergence of two or more peaks in the probability distribution curves signaling the coexistence of different states and indicating that the transition is discontinuous unlike what is observed in the absence of molecular crowding.

Stretching of a single-stranded DNA: Evidence for structural transition

Physical Review E, 2009

Recent experiments have shown that the force-extension (F-x) curve for single-stranded DNA (ssDNA... more Recent experiments have shown that the force-extension (F-x) curve for single-stranded DNA (ssDNA) consisting only of adenine [poly(dA)] is significantly different from thymine [poly(dT)]. Here, we show that the base stacking interaction is not sufficient to describe the F-x curves as seen in the experiments. A reduction in the reaction co-ordinate arising from the formation of helix at low forces and an increase in the distance between consecutive phosphates of unstacked bases in the stretched state at high force in the proposed model, qualitatively reproduces the experimentally observed features. The multi-step plateau in the F-x curve is a signature of structural change in ssDNA.

Statistical mechanics of stretching of biopolymers

Journal of Statistical Mechanics: Theory and Experiment, 2011

We developed a simple model of polymers on a triangular lattice to study the force-induced transi... more We developed a simple model of polymers on a triangular lattice to study the force-induced transitions related to biopolymers. Using an exact enumeration technique, we calculate various thermodynamic quantities associated with it. We show here, by including different parameters, e.g. bending and paring interactions in the model system, that one can understand the qualitative differences in the force-extension curves exhibited by different biopolymers. Our study also shows that the solvent plays an important role in the unfolding of proteins.

Reduction of Functional Brain Connectivity in Mild Traumatic Brain Injury during Working Memory

Journal of Neurotrauma, 2009

Working memory deficits are present in patients with mild traumatic brain injury (MTBI). Function... more Working memory deficits are present in patients with mild traumatic brain injury (MTBI). Functional connectivity of different brain regions is required for adequate working memory. Brain injury is associated with disrupted connectivity due to microscopic axonal damage. In this investigation, we sought to investigate functional brain connectivity during working memory in MTBI patients. A sample of 30 MTBI patients and 30 age-, education-, and gender-matched normal controls were studied. Working memory was assessed with the Sternberg's verbal and visuo-spatial working memory tasks. Electro-encephalography (EEG) was recorded from 128 channels while subjects performed working memory tasks and during eyes closed resting condition. EEG coherence was computed in theta; lower and upper alpha; and lower and upper beta frequency bands during the encoding, retention, and retrieval stages of working memory as well as during eyes-closed rest. We found that the MTBI patients had impaired verbal and visuo-spatial working memory. The different stages of working memory were associated with poor intrahemispheric coherence in long-range (fronto-parietal) and mid-range (fronto-temporal and temporo-parietal) regions as well as poor interhemispheric coherence in the frontal and temporal regions in the MTBI patients. The deficit in coherence was present in theta, alpha, and beta frequency bands. However, the MTBI and the control group had comparable coherence values in intra-and inter-hemispheric regions during eyes closed rest. We suggest that the inter-and intra-hemispheric functional connectivity is impaired in MTBI during working memory performance.

Electrophysiological Evidence of Semantic Interference in Visual Search

Journal of Cognitive Neuroscience, 2010

Visual evoked responses were monitored while participants searched for a target (e.g., bird) in a... more Visual evoked responses were monitored while participants searched for a target (e.g., bird) in a four-object display that could include a semantically related distractor (e.g., fish). The occurrence of both the target and the semantically related distractor modulated the N2pc response to the search display: The N2pc amplitude was more pronounced when the target and the distractor appeared in the same visual field, and it was less pronounced when the target and the distractor were in opposite fields, relative to when the distractor was absent. Earlier components (P1, N1) did not show any differences in activity across the different distractor conditions. The data suggest that semantic distractors influence early stages of selecting stimuli in multielement displays.

The Neural Selection and Integration of Actions and Objects: An fMRI Study

by Sanjay Kumar and Goubran M

Journal of Cognitive Neuroscience, 2012

■ There is considerable evidence that there are anatomically and functionally distinct pathways f... more ■ There is considerable evidence that there are anatomically and functionally distinct pathways for action and object recognition. However, little is known about how information about action and objects is integrated. This study provides fMRI evidence for task-based selection of brain regions associated with action and object processing, and on how the congruency between the action and the object modulates neural response. Participants viewed videos of objects used in congruent or incongruent actions and attended either to the action or the object in a one-back procedure. Attending to the action led to increased responses in a fronto-parietal action-associated network. Attending to the object activated regions within a fronto-inferior temporal network. Stronger responses for congruent action-object clips occurred in bilateral parietal, inferior temporal, and putamen. Distinct cortical and thalamic regions were modulated by congruency in the different tasks. The results suggest that (i) selective attention to action and object information is mediated through separate networks, (ii) object-action congruency evokes responses in action planning regions, and (iii) the selective activation of nuclei within the thalamus provides a mechanism to integrate task goals in relation to the congruency of the perceptual information presented to the observer. ■