2008
, 2008
Rule-Rationality versus Act-Rationality
Lecture
Tuesday, December 30, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Rule-Rationality versus Act-Rationality
Prof. Yisrael Aumann
Nobel Prize Laureate in Economics, 2005
The Center for the Study of Rationality
Hebrew University, Jerusalem
People's actions often deviate from rationality, i.e., self-interested behavior. We propose a paradigm called rule-rationality, according to which people do not maximize utility in each of their acts, but rather follow rules or modes of behavior that usually---but not always---maximize utility. Specifically, rather than choosing an act that maximizes utility among all possible acts in a given situation, people adopt rules that maximize average utility among all applicable rules, when the same rule is applied to many apparently similar situations. The distinction is analogous to that between Bentham's "act-utilitarianism'' and the "rule-utilitarianism'' of Mill, Harsanyi, and others. The genesis of such behavior is examined, and examples are given. The paradigm may provide a synthesis between rationalistic neo-classical economic theory and behavioral economics.
Nonlinearity, memory, and phase transitions in learning
Lecture
Thursday, December 25, 2008
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Nonlinearity, memory, and phase transitions in learning
Dr. Ilya Nemenman
Computer, Computation and Statistical Sciences Division & Center for Nonlinear Studies
Los Alamos National Laboratory
Abstracting from physiological details, I will present a theory that suggests an explanation behind critical periods in learning as a natural consequence of learning dynamics under a small and realistic set of assumptions. Surprisingly, the same theory offers an explanation for other animal learning phenomena, such as the tendency to reverse to the status quo following a transient learning experience. Additionally, the theory suggests simple experiments that can be used to prove or refute it. If the time permits, as a commercial for future results, I will finish the talk with a brief overview of recent attempts at LANL for petascale simulations of the mammalian visual cortex.
Salience-based selection: How does the brain ignore saliency?
Lecture
Tuesday, December 23, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Salience-based selection: How does the brain ignore saliency?
Dr. Carmel Mevorach
Behavioral Brain Sciences Centre
University of Birmingham UK
At any particular time the brain is bombarded with an almost infinite amount of visual information. Efficient behaviour, then, relies on a process of attentional selection which is required to filter out irrelevant stimuli and to prioritize the processing of relevant events. Importantly, this attentional prioritisation process needs to be flexible in order to be responsive to changes in behavioural relevance. Thus, bottom-up cues for attention must be modulated by top-down information, reflecting the goals of behaviour. In recent years, considerable neurobiological evidence has accumulated indicating that flexible visual selection is controlled by a fronto-parietal network within the brain. In particular, the posterior parietal cortex (PPC) has been implicated both when spatial selection is required and when selection is non-spatial. In a series of recent studies we have used converging operations to demonstrate a link between the PPC and a form of non-spatial selection – selecting on the basis of the relative salience of the stimuli. Using variants of the classic Global/Local task we orthogonally manipulated the level of shape that participants responded to and the salience of that information. Using experimental techniques such as neuropsychological studies, Trans-cranial Stimulation (TMS) and functional imaging (fMRI) we show that the PPC is sensitive to the relative saliency of the information so that selection can be based on whether the target or the distractor are more salient. Most importantly, we provide evidence for distinct roles played by the right and left PPC in selection and suppression of saliency, respectively. The data may also suggest how such complementary forms of selection are implemented in the brain.
Representation of the visual field in object-selective cortex
Lecture
Wednesday, December 17, 2008
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Representation of the visual field in object-selective cortex
Dr. Rory Sayres
Dept of Psychology, Stanford University
Functional MRI (fMRI) studies have defined a series of visual processing regions in the human cortex, which are believed to enable visual recognition behaviors through a hierarchy of processing stages. At the higher stages in this hierarchy lie regions which preferentially respond to images of intact objects compared to other visual stimuli, a set of regions collectively termed object-selective cortex. Within object-selective cortex exist category-selective regions, which prefer particular categories of images over others (e.g., faces, body parts, houses or scenes). Initially these regions were considered non-retinotopic, but increasing evidence indicates substantial retinal position selectivity, and in some cases retinotopy, in these regions.
What is the representation of the visual field in object-selective regions? Are separate object- and category-selective regions part of a single map or embedded within a set of distinct visual field maps? We scanned seven subjects on separate experiments to localize object/category-selective regions, and measure visual field maps (GE 3T scanner). For retinotopic experiments, subjects viewed moving bar stimuli containing different stimuli, including slowly drifting checkerboards and frontal face images. The bars extended out to around 14° eccentricity from the fovea, and had a width of ~2.6°. We employed a recently-developed method for estimating population receptive fields
(pRFs) using fMRI (Dumoulin and Wandell, Neuroimage, 2008), which estimates pRF center and size for each cortical location.
Face-containing bars produced substantially larger responses than checkerboards along the fusiform gyrus, improving our ability to measure visual field maps in these regions. Eccentricity maps revealed two foveal representations, which may correspond to visual field map clusters previously identified as VO and VT (Wandell et al., Neuro-opth. Jpn., 2006). These foveas are within or adjacent to fusiform face-selective regions, and separated by smoothly-varying extra-foveal maps which are less face-selective. For several subjects, pRF sizes systematically increased with eccentricity in face-selective regions. The distribution of pRF sizes were substantially larger than in earlier visual cortex, but comparable to recent measurements made in lateral occipital cortex.
We find two spatially separate face-selective regions along the fusiform gyrus, with comparable visual field coverage, separated by a representation of intermediate eccentricities. This indicates these two regions are likely to fall within different visual field maps. Current work addresses possible effects of low-level visual features (e.g. spatial frequency) and stimulus visibility in driving the observed face-selective retinotopic responses. I will also present some preliminary data from retinotopic mapping with house-containing bars, and an examination of retinotopic organization in house- or scene-selective cortical regions.
Active sensing: from natural stimulus statistics to auditory object classification in echolocating bats
Lecture
Tuesday, December 16, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Active sensing: from natural stimulus statistics to auditory object classification in echolocating bats
Yossi Yovel
(Post-doc Ulanovsky Group)
Department of Neurobiology, WIS
Echolocating bats perceive their surroundings acoustically. They continuously emit sonar signals and analyze the returning echoes, which enables them to orient in space and acquire food in complete darkness. Natural echoes along with other natural sounds compose a major part of the bat's sensory world, and have likely played a key evolutionary role in shaping the design of the bat's echolocation system and the auditory computations in the bat brain. However, the statistics of natural complex echoes, as well as how bats utilize them, are poorly understood – especially in the context of sonar-based object classification. The goal of this work was to elucidate the natural acoustical stimuli in the bat's world. I will present data on the statistical properties of complex echoes from various classes of plants and will compare them to what is known about natural images. In addition I will use a machine learning approach to discuss ways that bats may use to classify these stimuli. Finally, I will also describe behavioral experiments that aimed to understand the strategy used by bats to classify natural stimuli.
Optogenetics: Application to Neuroscience and Neuropsychiatry
Lecture
Monday, December 15, 2008
Hour: 11:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Optogenetics: Application to Neuroscience and Neuropsychiatry
Prof. Karl Deisseroth
Depts of Bioengineering & Psychiatry, Stanford University
Optogenetics, synthesizing microbial opsins and solid-state optics, has achieved the goal of millisecond-precision bidirectional control of defined cell types in freely behaving mammals, but has not yet been widely applied to neuroscience and neuropsychiatry experimental challenges. First, relevant to important basic science questions, we have now successfully developed methods to target and control several classes of modulatory neurons in behaving mammals and intact neural tissue, and we are probing and quantifying measures of altered circuit performance under optogenetic control of defined circuit elements to address longstanding questions about neural circuit dynamics. Second, relevant to neuropsychiatric disease questions, we have used this approach for depth targeting of hypothalamic cells (in this case, the hypocretin/orexin cells in the lateral hypothalamus), establishing for the first time a causal relationship between frequency-dependent activity of genetically defined neurons important in clinical neuropsychiatric disease and a complex orchestrated mammalian behavior. We also are now applying fast optical control and optical imaging to animal models of depression, Parkinson’s Disease, and altered social behavior relevant to autism. Insights into both normal circuit function and disease mechanisms are beginning to emerge from this multidisciplinary technological approach.
Prof. Deisseroth is hosted by the students of the Department of Neurobiology, as a part of the departmental students-invited visiting scientist program.
Optogenetics:Technology Development
Lecture
Sunday, December 14, 2008
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Optogenetics:Technology Development
Prof. Karl Deisseroth
Depts of Bioengineering& Psychiatry, Stanford University
In 1979, Francis Crick delineated the major challenges facing neuroscience and called for a technology by which all neurons of just one type could be controlled, “leaving the others more or less unaltered”. A new set of technologies now called optogenetics, synthesizing microbial opsins and solid-state optics, has achieved the goal of millisecond-precision bidirectional control of defined cell types in freely behaving mammals. ChR2 was the first microbial opsin brought to neurobiology, where we initially found that ChR2-expressing neurons can fire blue light-triggered action potentials with millisecond precision, as a result of depolarizing cation flux, without addition of chemical cofactors; this approach has since proven versatile across a variety of preparations. Second, in work stimulated by the finding that the all-trans retinal chromophore required by microbial opsins appears already present within mammalian brains, so that no chemical cofactor need be supplied, we found that neurons targeted to express the light-activated chloride pump halorhodopsin from Natronomonas pharaonis (NpHR) can be hyperpolarized and inhibited from firing action potentials when exposed to yellow light in intact tissue and behaving animals; because of the excitation wavelength difference, the two optical gates can be simultaneously used in the same cells even in vivo5. Third, we employed genomic strategies to discover and adapt for neuroscience a third major optogenetic tool, namely a cation channel (VChR1) with action spectrum significantly redshifted relative to ChR2, to allow tests of the combinatorial interaction of cell types in circuit computation or behavior. Fourth, we have developed genetic targeting tools for versatile use of microbial opsins with existing resources including cell type-specific promoter fragments or Cre-LoxP mouse driver lines suitable for a wide variety of neuroscience investigations. Finally, we have developed integrated fiberoptic and solid-state optical approaches to provide the complementary technology to allow specific cell types, even deep within the brain, to be controlled in freely behaving mammals.
Prof. Deisseroth is hosted by the students of the Department of Neurobiology, as a part of the departmental students-invited visiting scientist program.
Minerva-Weizmann Workshop on Active Sensing in Touch Vision and Smell
Conference
Tuesday, December 2, 2008
Hour:
Location:
As Our Brain Is, So We Are
Lecture
Monday, December 1, 2008
Hour: 12:15
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
As Our Brain Is, So We Are
Prof. Fred Travis
Center for Brain, Consciousness, and Cognition
Maharishi University of Management, Fairfield, IA
Brain functioning underlies perception of outer objects and supports behavioral responses to environmental challenges. As brain circuits mature in the first 20 years of life, so mental abilities emerge. This talk will examine the relation between brain maturation—synaptogenesis and myelination— and levels of cognitive, moral, and ego development. Learning disabilities, such as ADHD and reading disabilities will be explored in light of associated brain patterns. Effects of experiences on brain functioning will also be examined including effects of restrictive experiences such as stress, drug use and fatigue, and enhancing experiences, such as Transcendental Meditation practice. High levels of human potential will be discussed in terms of enhanced brain functioning.
Role of dopamine systems in addiction
Lecture
Wednesday, November 26, 2008
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Role of dopamine systems in addiction
Prof. Marco Diana
Laboratory of Cognitive Neuroscience
Dept of Drug Sciences, University of Sassari, Italy
Dopamine neurons of the VTA, that project to the Nucleus Accumbens, have been involved in the initial rewarding properties of addicting compounds and, more appropriately, in the long-lasting changes observed after chronic drug administration and subsequent withdrawal. Indeed, alcohol, opiates cannabinoids and other substances provoke, upon withdrawal, a drastic and marked reduction of dopaminergic tone. In addition, aversive, non drug-related stimuli also reduce dopaminergic physiological tone. Furthermore, recent human studies reported an attenuated response to methylphenidate in alcoholic subjects and a lower (than controls) dopaminergic tone. These changes are paralleled by a lower number of D2 receptors and suggest a general “impoverishment” of dopamine transmission in the addicted brain. Accordingly, a dopamine deficit correlated with alcohol craving, which was associated with a high relapse risk. Similar results were reported for nicotine withdrawn rats.
This hypodopaminergic state could be the target of therapies aimed at restoring the deficient dopamine transmission observed after chronic drug administration in preclinical and clinical investigations.
Pages
2008
, 2008
Rule-Rationality versus Act-Rationality
Lecture
Tuesday, December 30, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Rule-Rationality versus Act-Rationality
Prof. Yisrael Aumann
Nobel Prize Laureate in Economics, 2005
The Center for the Study of Rationality
Hebrew University, Jerusalem
People's actions often deviate from rationality, i.e., self-interested behavior. We propose a paradigm called rule-rationality, according to which people do not maximize utility in each of their acts, but rather follow rules or modes of behavior that usually---but not always---maximize utility. Specifically, rather than choosing an act that maximizes utility among all possible acts in a given situation, people adopt rules that maximize average utility among all applicable rules, when the same rule is applied to many apparently similar situations. The distinction is analogous to that between Bentham's "act-utilitarianism'' and the "rule-utilitarianism'' of Mill, Harsanyi, and others. The genesis of such behavior is examined, and examples are given. The paradigm may provide a synthesis between rationalistic neo-classical economic theory and behavioral economics.
Nonlinearity, memory, and phase transitions in learning
Lecture
Thursday, December 25, 2008
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Nonlinearity, memory, and phase transitions in learning
Dr. Ilya Nemenman
Computer, Computation and Statistical Sciences Division & Center for Nonlinear Studies
Los Alamos National Laboratory
Abstracting from physiological details, I will present a theory that suggests an explanation behind critical periods in learning as a natural consequence of learning dynamics under a small and realistic set of assumptions. Surprisingly, the same theory offers an explanation for other animal learning phenomena, such as the tendency to reverse to the status quo following a transient learning experience. Additionally, the theory suggests simple experiments that can be used to prove or refute it. If the time permits, as a commercial for future results, I will finish the talk with a brief overview of recent attempts at LANL for petascale simulations of the mammalian visual cortex.
Salience-based selection: How does the brain ignore saliency?
Lecture
Tuesday, December 23, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Salience-based selection: How does the brain ignore saliency?
Dr. Carmel Mevorach
Behavioral Brain Sciences Centre
University of Birmingham UK
At any particular time the brain is bombarded with an almost infinite amount of visual information. Efficient behaviour, then, relies on a process of attentional selection which is required to filter out irrelevant stimuli and to prioritize the processing of relevant events. Importantly, this attentional prioritisation process needs to be flexible in order to be responsive to changes in behavioural relevance. Thus, bottom-up cues for attention must be modulated by top-down information, reflecting the goals of behaviour. In recent years, considerable neurobiological evidence has accumulated indicating that flexible visual selection is controlled by a fronto-parietal network within the brain. In particular, the posterior parietal cortex (PPC) has been implicated both when spatial selection is required and when selection is non-spatial. In a series of recent studies we have used converging operations to demonstrate a link between the PPC and a form of non-spatial selection – selecting on the basis of the relative salience of the stimuli. Using variants of the classic Global/Local task we orthogonally manipulated the level of shape that participants responded to and the salience of that information. Using experimental techniques such as neuropsychological studies, Trans-cranial Stimulation (TMS) and functional imaging (fMRI) we show that the PPC is sensitive to the relative saliency of the information so that selection can be based on whether the target or the distractor are more salient. Most importantly, we provide evidence for distinct roles played by the right and left PPC in selection and suppression of saliency, respectively. The data may also suggest how such complementary forms of selection are implemented in the brain.
Representation of the visual field in object-selective cortex
Lecture
Wednesday, December 17, 2008
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Representation of the visual field in object-selective cortex
Dr. Rory Sayres
Dept of Psychology, Stanford University
Functional MRI (fMRI) studies have defined a series of visual processing regions in the human cortex, which are believed to enable visual recognition behaviors through a hierarchy of processing stages. At the higher stages in this hierarchy lie regions which preferentially respond to images of intact objects compared to other visual stimuli, a set of regions collectively termed object-selective cortex. Within object-selective cortex exist category-selective regions, which prefer particular categories of images over others (e.g., faces, body parts, houses or scenes). Initially these regions were considered non-retinotopic, but increasing evidence indicates substantial retinal position selectivity, and in some cases retinotopy, in these regions.
What is the representation of the visual field in object-selective regions? Are separate object- and category-selective regions part of a single map or embedded within a set of distinct visual field maps? We scanned seven subjects on separate experiments to localize object/category-selective regions, and measure visual field maps (GE 3T scanner). For retinotopic experiments, subjects viewed moving bar stimuli containing different stimuli, including slowly drifting checkerboards and frontal face images. The bars extended out to around 14° eccentricity from the fovea, and had a width of ~2.6°. We employed a recently-developed method for estimating population receptive fields
(pRFs) using fMRI (Dumoulin and Wandell, Neuroimage, 2008), which estimates pRF center and size for each cortical location.
Face-containing bars produced substantially larger responses than checkerboards along the fusiform gyrus, improving our ability to measure visual field maps in these regions. Eccentricity maps revealed two foveal representations, which may correspond to visual field map clusters previously identified as VO and VT (Wandell et al., Neuro-opth. Jpn., 2006). These foveas are within or adjacent to fusiform face-selective regions, and separated by smoothly-varying extra-foveal maps which are less face-selective. For several subjects, pRF sizes systematically increased with eccentricity in face-selective regions. The distribution of pRF sizes were substantially larger than in earlier visual cortex, but comparable to recent measurements made in lateral occipital cortex.
We find two spatially separate face-selective regions along the fusiform gyrus, with comparable visual field coverage, separated by a representation of intermediate eccentricities. This indicates these two regions are likely to fall within different visual field maps. Current work addresses possible effects of low-level visual features (e.g. spatial frequency) and stimulus visibility in driving the observed face-selective retinotopic responses. I will also present some preliminary data from retinotopic mapping with house-containing bars, and an examination of retinotopic organization in house- or scene-selective cortical regions.
Active sensing: from natural stimulus statistics to auditory object classification in echolocating bats
Lecture
Tuesday, December 16, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Active sensing: from natural stimulus statistics to auditory object classification in echolocating bats
Yossi Yovel
(Post-doc Ulanovsky Group)
Department of Neurobiology, WIS
Echolocating bats perceive their surroundings acoustically. They continuously emit sonar signals and analyze the returning echoes, which enables them to orient in space and acquire food in complete darkness. Natural echoes along with other natural sounds compose a major part of the bat's sensory world, and have likely played a key evolutionary role in shaping the design of the bat's echolocation system and the auditory computations in the bat brain. However, the statistics of natural complex echoes, as well as how bats utilize them, are poorly understood – especially in the context of sonar-based object classification. The goal of this work was to elucidate the natural acoustical stimuli in the bat's world. I will present data on the statistical properties of complex echoes from various classes of plants and will compare them to what is known about natural images. In addition I will use a machine learning approach to discuss ways that bats may use to classify these stimuli. Finally, I will also describe behavioral experiments that aimed to understand the strategy used by bats to classify natural stimuli.
Optogenetics: Application to Neuroscience and Neuropsychiatry
Lecture
Monday, December 15, 2008
Hour: 11:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Optogenetics: Application to Neuroscience and Neuropsychiatry
Prof. Karl Deisseroth
Depts of Bioengineering & Psychiatry, Stanford University
Optogenetics, synthesizing microbial opsins and solid-state optics, has achieved the goal of millisecond-precision bidirectional control of defined cell types in freely behaving mammals, but has not yet been widely applied to neuroscience and neuropsychiatry experimental challenges. First, relevant to important basic science questions, we have now successfully developed methods to target and control several classes of modulatory neurons in behaving mammals and intact neural tissue, and we are probing and quantifying measures of altered circuit performance under optogenetic control of defined circuit elements to address longstanding questions about neural circuit dynamics. Second, relevant to neuropsychiatric disease questions, we have used this approach for depth targeting of hypothalamic cells (in this case, the hypocretin/orexin cells in the lateral hypothalamus), establishing for the first time a causal relationship between frequency-dependent activity of genetically defined neurons important in clinical neuropsychiatric disease and a complex orchestrated mammalian behavior. We also are now applying fast optical control and optical imaging to animal models of depression, Parkinson’s Disease, and altered social behavior relevant to autism. Insights into both normal circuit function and disease mechanisms are beginning to emerge from this multidisciplinary technological approach.
Prof. Deisseroth is hosted by the students of the Department of Neurobiology, as a part of the departmental students-invited visiting scientist program.
Optogenetics:Technology Development
Lecture
Sunday, December 14, 2008
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Optogenetics:Technology Development
Prof. Karl Deisseroth
Depts of Bioengineering& Psychiatry, Stanford University
In 1979, Francis Crick delineated the major challenges facing neuroscience and called for a technology by which all neurons of just one type could be controlled, “leaving the others more or less unaltered”. A new set of technologies now called optogenetics, synthesizing microbial opsins and solid-state optics, has achieved the goal of millisecond-precision bidirectional control of defined cell types in freely behaving mammals. ChR2 was the first microbial opsin brought to neurobiology, where we initially found that ChR2-expressing neurons can fire blue light-triggered action potentials with millisecond precision, as a result of depolarizing cation flux, without addition of chemical cofactors; this approach has since proven versatile across a variety of preparations. Second, in work stimulated by the finding that the all-trans retinal chromophore required by microbial opsins appears already present within mammalian brains, so that no chemical cofactor need be supplied, we found that neurons targeted to express the light-activated chloride pump halorhodopsin from Natronomonas pharaonis (NpHR) can be hyperpolarized and inhibited from firing action potentials when exposed to yellow light in intact tissue and behaving animals; because of the excitation wavelength difference, the two optical gates can be simultaneously used in the same cells even in vivo5. Third, we employed genomic strategies to discover and adapt for neuroscience a third major optogenetic tool, namely a cation channel (VChR1) with action spectrum significantly redshifted relative to ChR2, to allow tests of the combinatorial interaction of cell types in circuit computation or behavior. Fourth, we have developed genetic targeting tools for versatile use of microbial opsins with existing resources including cell type-specific promoter fragments or Cre-LoxP mouse driver lines suitable for a wide variety of neuroscience investigations. Finally, we have developed integrated fiberoptic and solid-state optical approaches to provide the complementary technology to allow specific cell types, even deep within the brain, to be controlled in freely behaving mammals.
Prof. Deisseroth is hosted by the students of the Department of Neurobiology, as a part of the departmental students-invited visiting scientist program.
As Our Brain Is, So We Are
Lecture
Monday, December 1, 2008
Hour: 12:15
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
As Our Brain Is, So We Are
Prof. Fred Travis
Center for Brain, Consciousness, and Cognition
Maharishi University of Management, Fairfield, IA
Brain functioning underlies perception of outer objects and supports behavioral responses to environmental challenges. As brain circuits mature in the first 20 years of life, so mental abilities emerge. This talk will examine the relation between brain maturation—synaptogenesis and myelination— and levels of cognitive, moral, and ego development. Learning disabilities, such as ADHD and reading disabilities will be explored in light of associated brain patterns. Effects of experiences on brain functioning will also be examined including effects of restrictive experiences such as stress, drug use and fatigue, and enhancing experiences, such as Transcendental Meditation practice. High levels of human potential will be discussed in terms of enhanced brain functioning.
Role of dopamine systems in addiction
Lecture
Wednesday, November 26, 2008
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Role of dopamine systems in addiction
Prof. Marco Diana
Laboratory of Cognitive Neuroscience
Dept of Drug Sciences, University of Sassari, Italy
Dopamine neurons of the VTA, that project to the Nucleus Accumbens, have been involved in the initial rewarding properties of addicting compounds and, more appropriately, in the long-lasting changes observed after chronic drug administration and subsequent withdrawal. Indeed, alcohol, opiates cannabinoids and other substances provoke, upon withdrawal, a drastic and marked reduction of dopaminergic tone. In addition, aversive, non drug-related stimuli also reduce dopaminergic physiological tone. Furthermore, recent human studies reported an attenuated response to methylphenidate in alcoholic subjects and a lower (than controls) dopaminergic tone. These changes are paralleled by a lower number of D2 receptors and suggest a general “impoverishment” of dopamine transmission in the addicted brain. Accordingly, a dopamine deficit correlated with alcohol craving, which was associated with a high relapse risk. Similar results were reported for nicotine withdrawn rats.
This hypodopaminergic state could be the target of therapies aimed at restoring the deficient dopamine transmission observed after chronic drug administration in preclinical and clinical investigations.
Interaction between the amygdala and the prefrontal cortex in emotional memory
Lecture
Tuesday, November 25, 2008
Hour: 12:30
Location:
Jacob Ziskind Building
Interaction between the amygdala and the prefrontal cortex in emotional memory
Dr. Mouna Maroun
Department of Neurobiology and Ethology
University of Haifa
The amygdala and the medial prefrontal cortex interact to guide emotional behavior. Alterations in the balance between these two structures can lead to persistent fear associations and to the development of anxiety disorders.
In this talk I will present work from my laboratory studying the interaction between these two structures in normal conditions and when exposed to a fearful or stressful experience.
We have recently found that fear and extinction learning induce differential changes in these two structures that could hint on the mechanisms by which these structures encode memories of fear and safety.
Pages
2008
, 2008
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2008
, 2008
Minerva-Weizmann Workshop on Active Sensing in Touch Vision and Smell
Conference
Tuesday, December 2, 2008
Hour:
Location:
Benoziyo Center for Neurological Diseases - Fourth Annual Symposium
Conference
Sunday, September 21, 2008
Hour:
Location: