The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Gregory C Deangelis - One of the best experts on this subject based on the ideXlab platform.
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diverse spatial reference frames of vestibular signals in parietal cortex
Neuron, 2013Co-Authors: Xiaodong Chen, Gregory C Deangelis, Dora E AngelakiAbstract:Summary Reference frames are important for understanding how sensory cues from different modalities are coordinated to guide behavior, and the parietal cortex is critical to these functions. We compare reference frames of vestibular self-motion signals in the ventral intraparietal Area (VIP), parietoinsular vestibular cortex (PIVC), and dorsal medial superior Temporal Area (MSTd). Vestibular heading tuning in VIP is invariant to changes in both eye and head positions, indicating a body (or world)-centered reference frame. Vestibular signals in PIVC have reference frames that are intermediate between head and body centered. In contrast, MSTd neurons show reference frames between head and eye centered but not body centered. Eye and head position gain fields were strongest in MSTd and weakest in PIVC. Our findings reveal distinct spatial reference frames for representing vestibular signals and pose new challenges for understanding the respective roles of these Areas in potentially diverse vestibular functions.
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causal links between dorsal medial superior Temporal Area neurons and multisensory heading perception
The Journal of Neuroscience, 2012Co-Authors: Gregory C Deangelis, Dora E AngelakiAbstract:The dorsal medial superior Temporal Area (MSTd) in the extrastriate visual cortex is thought to play an important role in heading perception because neurons in this Area are tuned to both optic flow and vestibular signals. MSTd neurons also show significant correlations with perceptual judgments during a fine heading direction discrimination task. To test for a causal link with heading perception, we used microstimulation and reversible inactivation techniques to artificially perturb MSTd activity while monitoring behavioral performance. Electrical microstimulation significantly biased monkeys' heading percepts based on optic flow, but did not significantly impact vestibular heading judgments. The latter result may be due to the fact that vestibular heading preferences in MSTd are more weakly clustered than visual preferences and multiunit tuning for vestibular stimuli is weak. Reversible chemical inactivation, however, increased behavioral thresholds when heading judgments were based on either optic flow or vestibular cues, although the magnitude of the effects was substantially stronger for optic flow. Behavioral deficits in a combined visual/vestibular stimulus condition were intermediate between the single-cue effects. Despite deficits in discrimination thresholds, animals were able to combine visual and vestibular cues near optimally, even after large bilateral muscimol injections into MSTd. Simulations show that the overall pattern of results following inactivation is consistent with a mixture of contributions from MSTd and other Areas with vestibular-dominant tuning for heading. Our results support a causal link between MSTd neurons and multisensory heading perception but suggest that other multisensory brain Areas also contribute.
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perceptual learning reduces interneuronal correlations in macaque visual cortex
Neuron, 2011Co-Authors: Sheng Liu, Gregory C Deangelis, Christopher R Fetsch, Yun Yang, Sam Fok, Adhira Sunkara, Dora E AngelakiAbstract:SUMMARY Responses of neurons in early visual cortex change little with training and appear insufficient to account for perceptual learning. Behavioral performance, however, relies on population activity, and the accuracy of a population code is constrained by correlated noise among neurons. We tested whether training changes interneuronal correlations in the dorsal medial superior Temporal Area, which is involved in multisensory heading perception. Pairs of single units were recorded simultaneously in two groups of subjects: animals trained extensively in a heading discrimination task, and ‘‘naive’’ animals that performed a passive fixation task. Correlated noisewassignificantly weakerintrained versusnaive animals, which might be expected to improve coding efficiency. However, we show that the observed uniform reduction in noise correlations leads to little change in population coding efficiency when all neurons are decoded. Thus, global changes in correlated noise among sensory neurons may be insufficient to account for perceptual learning.
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a neural representation of depth from motion parallax in macaque visual cortex
Nature, 2008Co-Authors: Jacob W Nadler, Gregory C Deangelis, Dora E AngelakiAbstract:Depth perception in humans and other animals can be based on binocular vision, in which the brain compares images from each eye. We can also judge depth with one eye, but how the brain processes the many different cues available for monocular perception of depth is not known. A possible explanation for one cue has now been found. The neurons in the middle Temporal Area of the brain, as well as representing retinal motion, can combine visual information and physical movement to extract depth information from motion parallax, a powerful depth cue that we experience when viewing the scenery from the window of a moving train — objects on the horizon move slowly while the scene close to the train flashes by. It is shown that in addition to the well-documented representation of retinal motion, primate Area middle Temporal Area neurons are sensitive to the relative depth of stimuli defined by motion parallax. Motion parallax is a powerful depth cue that arises when the observer is moving due to near and far objects moving across the retina at different speeds. Perception of depth is a fundamental challenge for the visual system, particularly for observers moving through their environment. The brain makes use of multiple visual cues to reconstruct the three-dimensional structure of a scene. One potent cue, motion parallax, frequently arises during translation of the observer because the images of objects at different distances move across the retina with different velocities. Human psychophysical studies have demonstrated that motion parallax can be a powerful depth cue1,2,3,4,5, and motion parallax seems to be heavily exploited by animal species that lack highly developed binocular vision6,7,8. However, little is known about the neural mechanisms that underlie this capacity. Here we show, by using a virtual-reality system to translate macaque monkeys (Macaca mulatta) while they viewed motion parallax displays that simulated objects at different depths, that many neurons in the middle Temporal Area (Area MT) signal the sign of depth (near versus far) from motion parallax in the absence of other depth cues. To achieve this, neurons must combine visual motion with extra-retinal (non-visual) signals related to the animal’s movement. Our findings suggest a new neural substrate for depth perception and demonstrate a robust interaction of visual and non-visual cues in Area MT. Combined with previous studies that implicate Area MT in depth perception based on binocular disparities9,10,11,12, our results suggest that Area MT contains a more general representation of three-dimensional space that makes use of multiple cues.
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spatial reference frames of visual vestibular and multimodal heading signals in the dorsal subdivision of the medial superior Temporal Area
The Journal of Neuroscience, 2007Co-Authors: Christopher R Fetsch, Gregory C Deangelis, Sentao Wang, Dora E AngelakiAbstract:Heading perception is a complex task that generally requires the integration of visual and vestibular cues. This sensory integration is complicated by the fact that these two modalities encode motion in distinct spatial reference frames (visual, eye-centered; vestibular, head-centered). Visual and vestibular heading signals converge in the primate dorsal subdivision of the medial superior Temporal Area (MSTd), a region thought to contribute to heading perception, but the reference frames of these signals remain unknown. We measured the heading tuning of MSTd neurons by presenting optic flow (visual condition), inertial motion (vestibular condition), or a congruent combination of both cues (combined condition). Static eye position was varied from trial to trial to determine the reference frame of tuning (eye-centered, head-centered, or intermediate). We found that tuning for optic flow was predominantly eye-centered, whereas tuning for inertial motion was intermediate but closer to head-centered. Reference frames in the two unimodal conditions were rarely matched in single neurons and uncorrelated across the population. Notably, reference frames in the combined condition varied as a function of the relative strength and spatial congruency of visual and vestibular tuning. This represents the first investigation of spatial reference frames in a naturalistic, multimodal condition in which cues may be integrated to improve perceptual performance. Our results compare favorably with the predictions of a recent neural network model that uses a recurrent architecture to perform optimal cue integration, suggesting that the brain could use a similar computational strategy to integrate sensory signals expressed in distinct frames of reference.
Chang Liu - One of the best experts on this subject based on the ideXlab platform.
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transcranial direct current stimulation of the frontal parietal Temporal Area attenuates smoking behavior
Journal of Psychiatric Research, 2014Co-Authors: Zhiqiang Meng, Chang LiuAbstract:Many brain regions are involved in smoking addiction (e.g. insula, ventral tegmental Area, prefrontal cortex and hippocampus), and the manipulation of the activity of these brain regions can show a modification of smoking behavior. Low current transcranial direct current stimulation (tDCS) is a noninvasive way to manipulate cortical excitability, and thus brain function and associated behaviors. In this study, we examined the effects of inhibiting the frontal-parietal-Temporal association Area (FPT) on attention bias to smoking-related cues and smoking behavior in tobacco users. This inhibition is induced by cathodal tDCS stimulation. We tested three stimulation conditions: 1) bilateral cathodal over both sides of FPT; 2) cathodal over right FPT; and 3) sham-tDCS. Visual attention bias to smoking-related cues was evaluated using an eye tracking system. The measurement for smoking behavior was the number of daily cigarettes consumed before and after tDCS treatment. We found that, after bilateral cathodal stimulation of the FPT Area, while the attention to smoking-related cues showed a decreased trend, the effects were not significantly different from sham stimulation. The daily cigarette consumption was reduced to a significant level. These effects were not seen under single cathodal tDCS or sham-tDCS. Our results show that low current tDCS of FPT Area attenuates smoking cue-related attention and smoking behavior. This non-invasive brain stimulation technique, targeted at FPT Areas, might be a promising method for treating smoking behavior.
Dora E Angelaki - One of the best experts on this subject based on the ideXlab platform.
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diverse spatial reference frames of vestibular signals in parietal cortex
Neuron, 2013Co-Authors: Xiaodong Chen, Gregory C Deangelis, Dora E AngelakiAbstract:Summary Reference frames are important for understanding how sensory cues from different modalities are coordinated to guide behavior, and the parietal cortex is critical to these functions. We compare reference frames of vestibular self-motion signals in the ventral intraparietal Area (VIP), parietoinsular vestibular cortex (PIVC), and dorsal medial superior Temporal Area (MSTd). Vestibular heading tuning in VIP is invariant to changes in both eye and head positions, indicating a body (or world)-centered reference frame. Vestibular signals in PIVC have reference frames that are intermediate between head and body centered. In contrast, MSTd neurons show reference frames between head and eye centered but not body centered. Eye and head position gain fields were strongest in MSTd and weakest in PIVC. Our findings reveal distinct spatial reference frames for representing vestibular signals and pose new challenges for understanding the respective roles of these Areas in potentially diverse vestibular functions.
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causal links between dorsal medial superior Temporal Area neurons and multisensory heading perception
The Journal of Neuroscience, 2012Co-Authors: Gregory C Deangelis, Dora E AngelakiAbstract:The dorsal medial superior Temporal Area (MSTd) in the extrastriate visual cortex is thought to play an important role in heading perception because neurons in this Area are tuned to both optic flow and vestibular signals. MSTd neurons also show significant correlations with perceptual judgments during a fine heading direction discrimination task. To test for a causal link with heading perception, we used microstimulation and reversible inactivation techniques to artificially perturb MSTd activity while monitoring behavioral performance. Electrical microstimulation significantly biased monkeys' heading percepts based on optic flow, but did not significantly impact vestibular heading judgments. The latter result may be due to the fact that vestibular heading preferences in MSTd are more weakly clustered than visual preferences and multiunit tuning for vestibular stimuli is weak. Reversible chemical inactivation, however, increased behavioral thresholds when heading judgments were based on either optic flow or vestibular cues, although the magnitude of the effects was substantially stronger for optic flow. Behavioral deficits in a combined visual/vestibular stimulus condition were intermediate between the single-cue effects. Despite deficits in discrimination thresholds, animals were able to combine visual and vestibular cues near optimally, even after large bilateral muscimol injections into MSTd. Simulations show that the overall pattern of results following inactivation is consistent with a mixture of contributions from MSTd and other Areas with vestibular-dominant tuning for heading. Our results support a causal link between MSTd neurons and multisensory heading perception but suggest that other multisensory brain Areas also contribute.
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perceptual learning reduces interneuronal correlations in macaque visual cortex
Neuron, 2011Co-Authors: Sheng Liu, Gregory C Deangelis, Christopher R Fetsch, Yun Yang, Sam Fok, Adhira Sunkara, Dora E AngelakiAbstract:SUMMARY Responses of neurons in early visual cortex change little with training and appear insufficient to account for perceptual learning. Behavioral performance, however, relies on population activity, and the accuracy of a population code is constrained by correlated noise among neurons. We tested whether training changes interneuronal correlations in the dorsal medial superior Temporal Area, which is involved in multisensory heading perception. Pairs of single units were recorded simultaneously in two groups of subjects: animals trained extensively in a heading discrimination task, and ‘‘naive’’ animals that performed a passive fixation task. Correlated noisewassignificantly weakerintrained versusnaive animals, which might be expected to improve coding efficiency. However, we show that the observed uniform reduction in noise correlations leads to little change in population coding efficiency when all neurons are decoded. Thus, global changes in correlated noise among sensory neurons may be insufficient to account for perceptual learning.
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a neural representation of depth from motion parallax in macaque visual cortex
Nature, 2008Co-Authors: Jacob W Nadler, Gregory C Deangelis, Dora E AngelakiAbstract:Depth perception in humans and other animals can be based on binocular vision, in which the brain compares images from each eye. We can also judge depth with one eye, but how the brain processes the many different cues available for monocular perception of depth is not known. A possible explanation for one cue has now been found. The neurons in the middle Temporal Area of the brain, as well as representing retinal motion, can combine visual information and physical movement to extract depth information from motion parallax, a powerful depth cue that we experience when viewing the scenery from the window of a moving train — objects on the horizon move slowly while the scene close to the train flashes by. It is shown that in addition to the well-documented representation of retinal motion, primate Area middle Temporal Area neurons are sensitive to the relative depth of stimuli defined by motion parallax. Motion parallax is a powerful depth cue that arises when the observer is moving due to near and far objects moving across the retina at different speeds. Perception of depth is a fundamental challenge for the visual system, particularly for observers moving through their environment. The brain makes use of multiple visual cues to reconstruct the three-dimensional structure of a scene. One potent cue, motion parallax, frequently arises during translation of the observer because the images of objects at different distances move across the retina with different velocities. Human psychophysical studies have demonstrated that motion parallax can be a powerful depth cue1,2,3,4,5, and motion parallax seems to be heavily exploited by animal species that lack highly developed binocular vision6,7,8. However, little is known about the neural mechanisms that underlie this capacity. Here we show, by using a virtual-reality system to translate macaque monkeys (Macaca mulatta) while they viewed motion parallax displays that simulated objects at different depths, that many neurons in the middle Temporal Area (Area MT) signal the sign of depth (near versus far) from motion parallax in the absence of other depth cues. To achieve this, neurons must combine visual motion with extra-retinal (non-visual) signals related to the animal’s movement. Our findings suggest a new neural substrate for depth perception and demonstrate a robust interaction of visual and non-visual cues in Area MT. Combined with previous studies that implicate Area MT in depth perception based on binocular disparities9,10,11,12, our results suggest that Area MT contains a more general representation of three-dimensional space that makes use of multiple cues.
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spatial reference frames of visual vestibular and multimodal heading signals in the dorsal subdivision of the medial superior Temporal Area
The Journal of Neuroscience, 2007Co-Authors: Christopher R Fetsch, Gregory C Deangelis, Sentao Wang, Dora E AngelakiAbstract:Heading perception is a complex task that generally requires the integration of visual and vestibular cues. This sensory integration is complicated by the fact that these two modalities encode motion in distinct spatial reference frames (visual, eye-centered; vestibular, head-centered). Visual and vestibular heading signals converge in the primate dorsal subdivision of the medial superior Temporal Area (MSTd), a region thought to contribute to heading perception, but the reference frames of these signals remain unknown. We measured the heading tuning of MSTd neurons by presenting optic flow (visual condition), inertial motion (vestibular condition), or a congruent combination of both cues (combined condition). Static eye position was varied from trial to trial to determine the reference frame of tuning (eye-centered, head-centered, or intermediate). We found that tuning for optic flow was predominantly eye-centered, whereas tuning for inertial motion was intermediate but closer to head-centered. Reference frames in the two unimodal conditions were rarely matched in single neurons and uncorrelated across the population. Notably, reference frames in the combined condition varied as a function of the relative strength and spatial congruency of visual and vestibular tuning. This represents the first investigation of spatial reference frames in a naturalistic, multimodal condition in which cues may be integrated to improve perceptual performance. Our results compare favorably with the predictions of a recent neural network model that uses a recurrent architecture to perform optimal cue integration, suggesting that the brain could use a similar computational strategy to integrate sensory signals expressed in distinct frames of reference.
Klauspeter Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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Visual response properties of neurons in cortical Areas MT and MST projecting to the dorsolateral pontine nucleus or the nucleus of the optic tract in macaque monkeys.
The European journal of neuroscience, 2009Co-Authors: Klauspeter Hoffmann, Frank Bremmer, Claudia DistlerAbstract:Neurons in cortical medial Temporal Area (MT) and medial superior Temporal Area (MST) projecting to the dorsolateral pontine nucleus (DLPN) and/or to the nucleus of the optic tract and dorsal terminal nucleus (NOT-DTN) were identified by antidromic electrical stimulation in five macaque monkeys. Neurons projecting to either target were located in close proximity to each other, and in all subregions of MT and MST sampled. Only a small percentage of the antidromically identified projection neurons (4.4%) sent branches to both the NOT-DTN and the DLPN. Antidromic latencies of neurons projecting to the NOT-DTN (0.9-6 ms, median 2.1 ms) and to the DLPN (0.8-5 ms, median 2.0 ms) did not differ significantly. Visual response properties of the neurons antidromically activated from either site did not differ significantly from those of cells that were not so activated. On the population level only neurons activated from the NOT-DTN had a clear preference for ipsiversive stimulus movement, whereas the neurons activated from the DLPN and neurons not antidromically activated from either target had no common directional preference. These results are discussed in terms of specification of cortico-subcortical connections and with regard to pathways underlying slow eye movements in different visuomotor behaviours.
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cortical projections to the nucleus of the optic tract and dorsal terminal nucleus and to the dorsolateral pontine nucleus in macaques a dual retrograde tracing study
The Journal of Comparative Neurology, 2002Co-Authors: Claudia Distler, Michael J Mustari, Klauspeter HoffmannAbstract:The nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT-DTN) along with the dorsolateral pontine nucleus (DLPN) have been shown to play a role in controlling slow eye movements and in maintaining stable vision during head movements. Both nuclei are known to receive cortical input from striate and extrastriate cortex. To determine to what degree this cortical input arises from the same Areas and potentially from the same individual neurons, we placed different retrograde tracers into the NOT-DTN and the DLPN. In the ipsilateral cortical hemisphere the two projections mainly overlapped in the posterior part of the superior Temporal sulcus (STS) comprising the middle Temporal Area (MT), the middle superior Temporal Area (MST), and the visual Area in the fundus of the STS (FST) and the surrounding cortex. In these Areas, neurons projecting to the NOT-DTN or the DLPN were closely intermingled. Nevertheless, only 3–11% of the labeled neurons in MT and MST were double-labeled in our various cases. These results indicate that the cortical input to the NOT-DTN and DLPN arises from largely separate neuronal subpopulations in the motion sensitive Areas in the posterior STS. Only a small percentage of the projection neurons bifurcate to supply both targets. These findings are discussed in relation to the optokinetic and the smooth pursuit system. J. Comp. Neurol. 444:144–158, 2002. © 2002 Wiley-Liss, Inc.
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cortical input to the nucleus of the optic tract and dorsal terminal nucleus not dtn in macaques a retrograde tracing study
Cerebral Cortex, 2001Co-Authors: C Distler, Klauspeter HoffmannAbstract:Using retrograde tracing methods, we investigated the cortical projection to the nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT-DTN) in macaque monkeys. Tracer injections at electrophysiologically identified recording sites in the NOT-DTN resulted in retrogradely labelled neurons in layer V of various cortical Areas. The strongest projection always arose from the middle Temporal Area (MT) and the adjoining cortex anterior to MT in the superior Temporal sulcus. A less dense projection came from the middle superior Temporal Area (MST). In addition, retrogradely labelled cells were consistently found in Areas V1 and V2 at moderate to high density. Furthermore, sparse to moderate labelling occurred in prestriate Area V3. These findings were compared with the label resulting from control injections into the superior colliculus in two additional cases. Our results indicate that the cortical input to the NOT-DTN as the sensorimotor interface for the pathway subserving stabilizing eye movements during the optokinetic reflex and smooth pursuit mainly arises from the motion-sensitive Areas MT and MST in the superior Temporal sulcus, as well as from Areas V1 and V2. Clearly the projection to the NOT-DTN does not arise from a single cortical Area.
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synchronization of neuronal activity during stimulus expectation in a direction discrimination task
The Journal of Neuroscience, 1997Co-Authors: Simone Cardoso De Oliveira, Alexander Thiele, Klauspeter HoffmannAbstract:The dorsal pathway of the primate brain, especially the middle Temporal Area (MT or V5) and the superior middle Temporal Area (MST or V5a), is strongly involved in motion detection. The relation between neural firing rates and psychophysical performance has led to the assumption that the neural code used by these Areas consists of the relative discharge rates of neuronal populations. As an additional neural code, Temporal correlation of neural activity has been suggested. Our study addresses the involvement of such a code in awake monkeys performing a motion discrimination task. We found significant Temporal correlations between simultaneously recorded pairs of units in Areas MT and MST and other extrastriate cortical Areas. Units recorded from the same electrode were more frequently synchronized than units recorded from different electrodes placed within the same or different cortical Areas. Activity synchronization was present in the expectation period before stimulus presentation and could not be induced de novo by the stimulus. Rather, we found a contrast-dependent reduction of correlation strength on stimulus onset. Correlation strength did not vary systematically with stimulus directions. We conclude that under the conditions of this study, Temporal decorrelation of MT and MST neurons could be used to detect the stimulus, but synchronization does not convey specific information about its direction of motion and therefore is unlikely to contribute to performance in our direction discrimination task. Activity synchronization in the period before stimulus onset could be related to attentive expectation.
Zhiqiang Meng - One of the best experts on this subject based on the ideXlab platform.
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transcranial direct current stimulation of the frontal parietal Temporal Area attenuates smoking behavior
Journal of Psychiatric Research, 2014Co-Authors: Zhiqiang Meng, Chang LiuAbstract:Many brain regions are involved in smoking addiction (e.g. insula, ventral tegmental Area, prefrontal cortex and hippocampus), and the manipulation of the activity of these brain regions can show a modification of smoking behavior. Low current transcranial direct current stimulation (tDCS) is a noninvasive way to manipulate cortical excitability, and thus brain function and associated behaviors. In this study, we examined the effects of inhibiting the frontal-parietal-Temporal association Area (FPT) on attention bias to smoking-related cues and smoking behavior in tobacco users. This inhibition is induced by cathodal tDCS stimulation. We tested three stimulation conditions: 1) bilateral cathodal over both sides of FPT; 2) cathodal over right FPT; and 3) sham-tDCS. Visual attention bias to smoking-related cues was evaluated using an eye tracking system. The measurement for smoking behavior was the number of daily cigarettes consumed before and after tDCS treatment. We found that, after bilateral cathodal stimulation of the FPT Area, while the attention to smoking-related cues showed a decreased trend, the effects were not significantly different from sham stimulation. The daily cigarette consumption was reduced to a significant level. These effects were not seen under single cathodal tDCS or sham-tDCS. Our results show that low current tDCS of FPT Area attenuates smoking cue-related attention and smoking behavior. This non-invasive brain stimulation technique, targeted at FPT Areas, might be a promising method for treating smoking behavior.
