2008
All events, 2008
Strong Loops in the Neocortex
Lecture
Wednesday, August 13, 2008
Hour: 12:15
Location:
Wolfson Building for Biological Research
Strong Loops in the Neocortex
Prof. Henry Kennedy
Dept of Integrative Neuroscience
INSERM, France
Hierarchy provides a major conceptual framework for understanding structure-function relationships of the cortex (Felleman and Van Essen, Cerb Cortex 1991). Feedforward (rostral directed) projections link areas in an ascending series and have a driving influence; feedback (caudal directed) projections link areas in a descending series and have a modulatory influence. This has led to the suggestion that feedforward projections are uniquely reciprocated by feedback projections i.e no strong loops (Crick and Koch, Nature 1998). We have re-examined this issue by making retrograde tracer injections in 22 areas spanning the occipital, parietal, temporal and frontal lobes. Injections were placed in areas V1, V2, V4 TEO, STPa, STPm, STPp, AudPba, AudPbp, 5, 7a, 7b, F1, 2, 8a, 45b, 9/46d, 9/46v, 46d, F5, ProM, 24c. High frequency sampling allows determination of indices of laminar distribution (SLN) and the relative strength (FLN) of connections (Vezoli et al., The Neuroscientist 2004). Analysis shows an inverse relationship between strength of connection and distance and revealed many (30%) hitherto unknown long-distance connections. Elsewhere we have shown that cortico-cortical projections form a smooth gradient: long-distance ascending connections are strongly feedforward (high SLN XX 100%) and on approaching the injection site have progressively lower SLN values (reaching 51%); likewise long-distance descending connections are strongly feedback (low SLN XX 0) and approaching the injection site reduce SLN 49% (Barone and Kennedy, J. Neurosci. 2000). The Felleman and Van Essen data is strictly hierarchical (no strong loops). A topological model of our data shows small world features (high cluster index and short average path distances) and five strong loops. Strong loops link frontal areas with occipital (areas 45-V4, 8A-V4), temporal (areas 45-TEO, 46-TEO) and parietal (areas 8A-7A, 46-7A) areas. The areas participating in strong loops exhibit high degrees of connectivity and constitute the hubs promoting small world attributes in the cortical architecture. The strong loops make it possible to go from V4 to all higher areas and back to V4 by uniqely feedforward pathways in an average of 3 and a maximum of 8 steps. One consequence of these anti-hierarchical connections is that the computations carried out in the supragranular layers of the cortex (Douglas and Martin, Annual Rev Neurosci. 2004) can be widely distributed in large-scale cortical networks mediating top-down control.
Extended Access to Self-Administered Cocaine –A Model for Cocaine Addiction
Lecture
Tuesday, August 12, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Extended Access to Self-Administered Cocaine –A Model for Cocaine Addiction
Dr. Osnat Ben-Shahar
Dept of Psychology
University of California Santa Barbara
Animal models used to study neuronal mechanisms of drug addiction most commonly rely upon either repeated experimenter-administered cocaine or drug-administration protocols that result in stable patterns of drug-taking. However, it is well established that differences in the route of administration (IV vs. IP or SC) and in the control over administration (self-administered vs. experimenter-administered) lead to differences in cocaine-induced neurochemical effects. In addition, the neural consequences of cocaine administration are different when tested in the middle of the administration protocol, immediately after the last administration of cocaine, or after 2, 14 or 60 days of withdrawal. Finally, the frequency and size of the daily-dose of cocaine are important factors determining the nature of the changes induced by cocaine. It would seem, then, that if we are to better understand the neuroadaptations that underlie the development of addiction in humans, animal models that mimic as closely as possible the human situation should be employed. Hence, my lab uses an animal model that employs an IV route of administration (as opposed to IP or SC), requiring self-administration (as opposed to experimenter-administered), under conditions (based on Ahmed & Koob, 1998) that distinguish the effects of short versus extended daily access to cocaine upon both behavior and neural substrates. This permits the investigation of neuroadaptations associated with the transition from the drug-naïve state to controlled drug-use, versus the further adaptations associated with the transition from controlled to compulsive drug-use. The differences we found, in both behavior and underlying neuronal adaptations, between controlled and compulsive drug-states, will be discussed in this talk.
Neural circuits for sensory-guided decisions in rats
Lecture
Monday, August 4, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Neural circuits for sensory-guided decisions in rats
Dr. Gidon Felsen
Cold Spring Harbor Laboratory
We are interested in how the nervous system controls movements based on sensory-cued spatial choices. To this end, we have been studying how rats use olfactory stimuli to select, initiate, execute, and evaluate directional movements. We reasoned that the superior colliculus (SC), a midbrain structure, could play a critical role in these processes, since it is known to be involved in several species in processing sensory input and producing orienting movements.
We tested this idea by using tetrodes to record simultaneously from several single neurons in the SC of rats performing a sensory-guided spatial choice task. In this task, an odor cue delivered at a central port determines whether water will be delivered upon entry into the left or right reward port. After sampling the odor, a well-trained rat will, in one fluid movement, withdraw from the odor port, orient left or right, and enter the selected reward port. This task thus requires that a freely moving animal make a spatial choice, while also affording reliable timing of task events and a large number of trials. In this context, not only did a substantial majority of SC neurons encode choice direction during a goal-directed movement, but many also predicted the upcoming choice, maintained selectivity for it after movement completion, or represented the trial outcome.
In order to determine whether the observed neural activity is causally related to the movement, we used the GABAA agonist muscimol to unilaterally inactivate the SC in rats performing the spatial choice task. If SC output were necessary for initiating contralateral movements, we would expect inactivation to bias the rat towards ipsilateral choices. Indeed, we found that muscimol, but not saline, biased the rat ipsilaterally, and this bias was dosage-dependent.
Our results demonstrate that the SC provides a rich representation of information relevant for several aspects of the control of orienting movements. These representations are necessary for executing appropriate movements. Together, these findings suggest a general role for the SC in behavior requiring sensory-guided navigation.
Hippocampal place field representation of the environment: Encoding, retrieval and remapping
Lecture
Tuesday, July 29, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Hippocampal place field representation of the environment: Encoding, retrieval and remapping
Prof. Etan Markus
University of Connecticut
When a rat runs through a familiar environment, the hippocampus retrieves a previously stored spatial representation of the environment. When the environment is modified a new representation is seen, presumably corresponding to the hippocampus encoding the new information. I will present single unit data on examining the issue of how the “hippocampus decides” whether to retrieve an old representation or form a new representation.
Visuo-Motor Mirror Neurons in Human Frontal and Temporal Lobes
Lecture
Tuesday, July 15, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Visuo-Motor Mirror Neurons in Human Frontal and Temporal Lobes
Dr. Roy Mukamel
UCLA
Recently, a unique population of neurons in the monkey ventral pre-motor cortex and in the rostral inferior parietal lobe, have been shown to respond during both execution of a goal-directed action and the perception of a goal-directed action performed by someone else. Since the activity of these motor neurons ‘reflects’ the perceived actions, these neurons have been termed mirror neurons. Due to their unique response properties, these neurons have been implicated in various behaviors such as imitation and empathy. Moreover, a dysfunction of this neural system has been implicated in various disorders such as autism. In humans, there is accumulating evidence from various techniques, supporting the existence of a parallel mirror neuron system however direct evidence is still lacking. We recorded extra-cellular activity of single neurons in medial pre-frontal and medial temporal regions of 23 epileptic patients while performing and observing hand movements and facial gestures. We found that 13.5% of the recorded neurons in both frontal and temporal lobes exhibited visuo-motor mirror properties. A subset of these mirror neurons responded with excitation action-observation and inhibition to action-execution suggesting a possible mechanism for inhibition of unwanted imitation. Our data supports a revision of the current definition of mirror neurons to include not only motor neurons that respond also to the perception of actions performed by others but also perceptual neurons in temporal lobe, responding to actions performed by oneself.
Gateways to tactile perception: Parallel processing of pain and somatosensation
Lecture
Tuesday, July 8, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Gateways to tactile perception: Parallel processing of pain and somatosensation
Prof. Asaf Keller
University of Maryland
Vibrissal information is relayed to the barrel cortex through at least two parallel pathways: a lemniscal pathway involving the ventroposterior medial thalamic nucleus (VPM), and a paralemniscal pathway involving the posteromedial nucleus (POm). I will review the role of the lemniscal system, focusing on the mechanisms by which VPM shapes the response properties of neurons in cortical barrels. I will argue that although analyses of these properties (e.g. receptive field structure and angular preference) have illuminated the process of input transformation in sensory pathways, they may have only limited ethological role. I will show that this lemniscal pathway is critical for temporal coding of somatosensory inputs. In the paralemniscal pathway, and in POm in particular, neurons respond poorly and unreliably to physiologically relevant stimuli. I will show that the GABAergic nucleus zona incerta (ZI) regulates POm activity is a state-dependent manner. This regulation is mediated by the cholinergic activating system, which enhances POm activity during states of arousal and vigilance. However, even in these states, POm neurons fail to reliably encode sensory inputs. I will show that POm is critically involved in coding noxious stimuli. Specifically, I will present evidence in support of the hypothesis that the phenomenon of central pain may be the result of suppressed inhibitory regulation of POm activity.
DC Magnetic Fields Produced by the Human Body
Lecture
Thursday, July 3, 2008
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
DC Magnetic Fields Produced by the Human Body
Prof. David Cohen
Biomag Group Leader (ret.), MIT Magnet Lab,& Assoc. Prof. of Radiology, Harvard Med. School
This is a review of measurements made mostly at the MIT Biomag Lab during the period of 1969 to 1983, partly in collaboration with Prof. Yoram Palti. These measurements are usually unique, in that their current sources are difficult to be seen with electric potentials. They are timely today because the new multi-channel SQUID systems are now being made capable of measuring DC fields from the head (and other organs). Our measurements were essentially a mapping over the whole body. DC fields were found almost everywhere, from many internal sources. They were larger over the limbs and head than over the torso proper, except over the abdomen, where it was largest. Over the head, there were puzzling signals from vicinity of healthy hair follicles, suggesting that so-called neural sources of the dcMEG could be overshadowed by more superficial sources. One major mechanism for generating these fields generally appeared to be a change in the K+ concentration in the vicinity of long excitable fibers. Overall, we concluded that DC fields are a rich and complex phenomena, including the dcMEG.
Information theory and the perception-action-cycle
Lecture
Tuesday, July 1, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Information theory and the perception-action-cycle
Prof. Naftali Tishby
School of Computer Science & Engineering and
Interdisciplinary Center for Neural Computation
The Hebrew University, Jerusalem
I will argue that living organisms can be characterized by their abilities to exchange information with their environment through sensing and acting. Moreover, the optimal interaction of an organism with its environment is determined by the information it can extract and store from the past about the future of its environment, on multiple time scales. Its optimal achievable performance is therefore bounded by the predictive-information of the environment, in some analogy with the entropy and channel-capacity bounds in Shannon's theory of communication. In that sense, life utilizes the predictability of its environment and act in order to increase its predictive capacity.
This conceptual and quantitative framework can allow us to design and analyze experiments in neuroscience in a new way. I will discuss some recent applications to auditory and motor physiology.
Wiring mechanisms in the mammalian somatosensory system
Lecture
Tuesday, June 24, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Wiring mechanisms in the mammalian somatosensory system
Dr. Avraham Yaron
Dept of Biological Chemistry, WIS
During development, the basic wiring of the nervous system is established by connecting trillions of neurons to their target cells. To reach their correct targets, neurons extend axons that are guided by cues in the extracellular environment.
The talk will describe our efforts to understand the mechanisms of axonal guidance using the somatosensory system as a model; with special focus on the role of the Semaphorins family of guidance cues in the process.
Grouping by synchrony and precise temporal patterns in the visual cortex: evidence from voltage-sensitive dye imaging
Lecture
Sunday, June 22, 2008
Hour: 10:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Grouping by synchrony and precise temporal patterns in the visual cortex: evidence from voltage-sensitive dye imaging
Dr. Hamutal Slovin
Bar Ilan University
Accumulating psychophysical and physiological evidence suggest the involvement of early visual areas in the process of visual integration and specifically in local facilitation of proximal and collinear stimuli. To investigate the early integration mechanisms at the population level, we performed voltage-sensitive dye imaging that is highly sensitive to subthreshold population activity, and imaged from the primary visual cortex (V1) and extrastriate cortex (V2) of a behaving monkey. The animal was trained on a simple fixation task while presented with collinear or non-collinear patterns of small gratings, Gabors or short oriented bars. Facilitation in terms of increased amplitude activity at the corresponding retinotopic site of the target was observed for low contrast targets presented as part of collinear or non-collinear pattern. The facilitation effect and its time course depended on the target flanker separation distance, suggesting the role of horizontal connections. Next, we compared the dynamics of cortical response. We found that the time course of responses increased faster in the collinear pattern as compared with the non-collinear pattern. Finally, to study synchronization, we calculated the spatial correlation of pixels at the target location and found that correlation was higher for the collinear pattern, suggesting that the neuronal code for collinear versus non-collinear pattern may be carried by synchronization and response dynamics rather than simply maximal amplitude of response.
These results suggest that neuronal population activity in area V1 is involved in local visual integration processes, and specifically in the increased sensitivity for low-contrast visual stimuli surrounded by high contrast flankers. In the second part of my talk I will discuss repeating spatio-precise spatio-temporal patterns. Numerous studies of neuronal coding have reported precise time relations among spikes in cortical neurons. Here our main goal was to study whether information processing in the cortex involves precise spatio-temporal patterns and to detect and characterize those patterns among neuronal populations exploiting voltage-sensitive dye imaging (VSDI) in visual cortical areas of a fixating monkey. Our preliminary results demonstrate that spatio-temporal patterns do exist above chance level (p<0.0001). The spatial characteristics of those patterns are consistent with physiological studies regarding the interplay between different visual areas, and the temporal characteristics show that the majority of the patterns appear in a range of 10-20ms apart
Pages
2008
All events, 2008
Neural circuits for sensory-guided decisions in rats
Lecture
Monday, August 4, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Neural circuits for sensory-guided decisions in rats
Dr. Gidon Felsen
Cold Spring Harbor Laboratory
We are interested in how the nervous system controls movements based on sensory-cued spatial choices. To this end, we have been studying how rats use olfactory stimuli to select, initiate, execute, and evaluate directional movements. We reasoned that the superior colliculus (SC), a midbrain structure, could play a critical role in these processes, since it is known to be involved in several species in processing sensory input and producing orienting movements.
We tested this idea by using tetrodes to record simultaneously from several single neurons in the SC of rats performing a sensory-guided spatial choice task. In this task, an odor cue delivered at a central port determines whether water will be delivered upon entry into the left or right reward port. After sampling the odor, a well-trained rat will, in one fluid movement, withdraw from the odor port, orient left or right, and enter the selected reward port. This task thus requires that a freely moving animal make a spatial choice, while also affording reliable timing of task events and a large number of trials. In this context, not only did a substantial majority of SC neurons encode choice direction during a goal-directed movement, but many also predicted the upcoming choice, maintained selectivity for it after movement completion, or represented the trial outcome.
In order to determine whether the observed neural activity is causally related to the movement, we used the GABAA agonist muscimol to unilaterally inactivate the SC in rats performing the spatial choice task. If SC output were necessary for initiating contralateral movements, we would expect inactivation to bias the rat towards ipsilateral choices. Indeed, we found that muscimol, but not saline, biased the rat ipsilaterally, and this bias was dosage-dependent.
Our results demonstrate that the SC provides a rich representation of information relevant for several aspects of the control of orienting movements. These representations are necessary for executing appropriate movements. Together, these findings suggest a general role for the SC in behavior requiring sensory-guided navigation.
Hippocampal place field representation of the environment: Encoding, retrieval and remapping
Lecture
Tuesday, July 29, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Hippocampal place field representation of the environment: Encoding, retrieval and remapping
Prof. Etan Markus
University of Connecticut
When a rat runs through a familiar environment, the hippocampus retrieves a previously stored spatial representation of the environment. When the environment is modified a new representation is seen, presumably corresponding to the hippocampus encoding the new information. I will present single unit data on examining the issue of how the “hippocampus decides” whether to retrieve an old representation or form a new representation.
Visuo-Motor Mirror Neurons in Human Frontal and Temporal Lobes
Lecture
Tuesday, July 15, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Visuo-Motor Mirror Neurons in Human Frontal and Temporal Lobes
Dr. Roy Mukamel
UCLA
Recently, a unique population of neurons in the monkey ventral pre-motor cortex and in the rostral inferior parietal lobe, have been shown to respond during both execution of a goal-directed action and the perception of a goal-directed action performed by someone else. Since the activity of these motor neurons ‘reflects’ the perceived actions, these neurons have been termed mirror neurons. Due to their unique response properties, these neurons have been implicated in various behaviors such as imitation and empathy. Moreover, a dysfunction of this neural system has been implicated in various disorders such as autism. In humans, there is accumulating evidence from various techniques, supporting the existence of a parallel mirror neuron system however direct evidence is still lacking. We recorded extra-cellular activity of single neurons in medial pre-frontal and medial temporal regions of 23 epileptic patients while performing and observing hand movements and facial gestures. We found that 13.5% of the recorded neurons in both frontal and temporal lobes exhibited visuo-motor mirror properties. A subset of these mirror neurons responded with excitation action-observation and inhibition to action-execution suggesting a possible mechanism for inhibition of unwanted imitation. Our data supports a revision of the current definition of mirror neurons to include not only motor neurons that respond also to the perception of actions performed by others but also perceptual neurons in temporal lobe, responding to actions performed by oneself.
Gateways to tactile perception: Parallel processing of pain and somatosensation
Lecture
Tuesday, July 8, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Gateways to tactile perception: Parallel processing of pain and somatosensation
Prof. Asaf Keller
University of Maryland
Vibrissal information is relayed to the barrel cortex through at least two parallel pathways: a lemniscal pathway involving the ventroposterior medial thalamic nucleus (VPM), and a paralemniscal pathway involving the posteromedial nucleus (POm). I will review the role of the lemniscal system, focusing on the mechanisms by which VPM shapes the response properties of neurons in cortical barrels. I will argue that although analyses of these properties (e.g. receptive field structure and angular preference) have illuminated the process of input transformation in sensory pathways, they may have only limited ethological role. I will show that this lemniscal pathway is critical for temporal coding of somatosensory inputs. In the paralemniscal pathway, and in POm in particular, neurons respond poorly and unreliably to physiologically relevant stimuli. I will show that the GABAergic nucleus zona incerta (ZI) regulates POm activity is a state-dependent manner. This regulation is mediated by the cholinergic activating system, which enhances POm activity during states of arousal and vigilance. However, even in these states, POm neurons fail to reliably encode sensory inputs. I will show that POm is critically involved in coding noxious stimuli. Specifically, I will present evidence in support of the hypothesis that the phenomenon of central pain may be the result of suppressed inhibitory regulation of POm activity.
DC Magnetic Fields Produced by the Human Body
Lecture
Thursday, July 3, 2008
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
DC Magnetic Fields Produced by the Human Body
Prof. David Cohen
Biomag Group Leader (ret.), MIT Magnet Lab,& Assoc. Prof. of Radiology, Harvard Med. School
This is a review of measurements made mostly at the MIT Biomag Lab during the period of 1969 to 1983, partly in collaboration with Prof. Yoram Palti. These measurements are usually unique, in that their current sources are difficult to be seen with electric potentials. They are timely today because the new multi-channel SQUID systems are now being made capable of measuring DC fields from the head (and other organs). Our measurements were essentially a mapping over the whole body. DC fields were found almost everywhere, from many internal sources. They were larger over the limbs and head than over the torso proper, except over the abdomen, where it was largest. Over the head, there were puzzling signals from vicinity of healthy hair follicles, suggesting that so-called neural sources of the dcMEG could be overshadowed by more superficial sources. One major mechanism for generating these fields generally appeared to be a change in the K+ concentration in the vicinity of long excitable fibers. Overall, we concluded that DC fields are a rich and complex phenomena, including the dcMEG.
Information theory and the perception-action-cycle
Lecture
Tuesday, July 1, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Information theory and the perception-action-cycle
Prof. Naftali Tishby
School of Computer Science & Engineering and
Interdisciplinary Center for Neural Computation
The Hebrew University, Jerusalem
I will argue that living organisms can be characterized by their abilities to exchange information with their environment through sensing and acting. Moreover, the optimal interaction of an organism with its environment is determined by the information it can extract and store from the past about the future of its environment, on multiple time scales. Its optimal achievable performance is therefore bounded by the predictive-information of the environment, in some analogy with the entropy and channel-capacity bounds in Shannon's theory of communication. In that sense, life utilizes the predictability of its environment and act in order to increase its predictive capacity.
This conceptual and quantitative framework can allow us to design and analyze experiments in neuroscience in a new way. I will discuss some recent applications to auditory and motor physiology.
Wiring mechanisms in the mammalian somatosensory system
Lecture
Tuesday, June 24, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Wiring mechanisms in the mammalian somatosensory system
Dr. Avraham Yaron
Dept of Biological Chemistry, WIS
During development, the basic wiring of the nervous system is established by connecting trillions of neurons to their target cells. To reach their correct targets, neurons extend axons that are guided by cues in the extracellular environment.
The talk will describe our efforts to understand the mechanisms of axonal guidance using the somatosensory system as a model; with special focus on the role of the Semaphorins family of guidance cues in the process.
Grouping by synchrony and precise temporal patterns in the visual cortex: evidence from voltage-sensitive dye imaging
Lecture
Sunday, June 22, 2008
Hour: 10:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Grouping by synchrony and precise temporal patterns in the visual cortex: evidence from voltage-sensitive dye imaging
Dr. Hamutal Slovin
Bar Ilan University
Accumulating psychophysical and physiological evidence suggest the involvement of early visual areas in the process of visual integration and specifically in local facilitation of proximal and collinear stimuli. To investigate the early integration mechanisms at the population level, we performed voltage-sensitive dye imaging that is highly sensitive to subthreshold population activity, and imaged from the primary visual cortex (V1) and extrastriate cortex (V2) of a behaving monkey. The animal was trained on a simple fixation task while presented with collinear or non-collinear patterns of small gratings, Gabors or short oriented bars. Facilitation in terms of increased amplitude activity at the corresponding retinotopic site of the target was observed for low contrast targets presented as part of collinear or non-collinear pattern. The facilitation effect and its time course depended on the target flanker separation distance, suggesting the role of horizontal connections. Next, we compared the dynamics of cortical response. We found that the time course of responses increased faster in the collinear pattern as compared with the non-collinear pattern. Finally, to study synchronization, we calculated the spatial correlation of pixels at the target location and found that correlation was higher for the collinear pattern, suggesting that the neuronal code for collinear versus non-collinear pattern may be carried by synchronization and response dynamics rather than simply maximal amplitude of response.
These results suggest that neuronal population activity in area V1 is involved in local visual integration processes, and specifically in the increased sensitivity for low-contrast visual stimuli surrounded by high contrast flankers. In the second part of my talk I will discuss repeating spatio-precise spatio-temporal patterns. Numerous studies of neuronal coding have reported precise time relations among spikes in cortical neurons. Here our main goal was to study whether information processing in the cortex involves precise spatio-temporal patterns and to detect and characterize those patterns among neuronal populations exploiting voltage-sensitive dye imaging (VSDI) in visual cortical areas of a fixating monkey. Our preliminary results demonstrate that spatio-temporal patterns do exist above chance level (p<0.0001). The spatial characteristics of those patterns are consistent with physiological studies regarding the interplay between different visual areas, and the temporal characteristics show that the majority of the patterns appear in a range of 10-20ms apart
Timing and the olivo-cerebellar system
Lecture
Tuesday, June 17, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Timing and the olivo-cerebellar system
Prof. Yosef Yarom
Hebrew University of Jerusalem
The crystal-like anatomy and circuitry of the cerebellum and its preservation throughout vertebrate phylogeny suggest that it performs a single basic computation. It has been proposed that this basic computation is to create temporal patterns of activity necessary for timing motor, sensory and cognitive tasks. Despite the wide agreement about the involvement of the cerebellum in temporal coordination, there is an ongoing debate as to the neural mechanism that subserves this function. This debate stems from the current dogma that dominates cerebellar research. According to this dogma, PC simple spikes are evoked by input from granule cells and determine cerebellar nuclear (CN) activity, thus governing cerebellar output. The complex spikes, according to this view, serve as an error signal which is used by the system to readjust the simple spike activity.
A novel theory of cerebellar function will be presented. According to this theory, the complex spike, rather than the simple spike, transmits the cerebellar output. The inferior olive generates accurate temporal patterns orchestrated by the cerebellar cortex and implemented in a variety of motor and non-motor tasks. Although this is a radical change of concept, it is well supported by experimental observations and it settles major problems inherent to the current dogma
Incubation of cocaine craving: behavioral and neuronal mechanisms
Lecture
Tuesday, June 10, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Incubation of cocaine craving: behavioral and neuronal mechanisms
Dr. Yavin Shaham
National Institute on Drug Abuse, NIH
Abstract: Using a rat model of drug relapse and craving, we previously found time-dependent increases in cocaine seeking induced by exposure to drug cues after withdrawal from the drug, suggesting that cocaine craving incubates over time. In this lecture, I will first summarize our earlier behavioral and neurophysiological studies on incubation of cocaine craving. I will then discuss in more detail results from more recent studies implicating neuronal activity in the ventromedial prefrontal cortex and glutamate synaptic plasticity in the nucleus accumbens in the incubation of cocaine craving. I will also briefly address the relevance of our rat findings to the understanding of relapse to drug use in humans.
Selected references related to incubation of cocaine craving
Grimm JW, Hope B, Wise RA, Shaham Y (2001) Incubation of cocaine craving after withdrawal. Nature 412:141-142
Grimm JW, Lu L, Hayashi T, Su TP, Hope BT, Shaham Y (2003) Time dependent increases in brain-derived neurotrophic factor (BDNF) protein levels within the mesolimbic dopamine system following withdrawal from cocaine: implications for incubation of cocaine craving. The Journal of Neuroscience 23:742-747
Lu L, Dempsey J, Liu S, Bossert J, Shaham Y (2004) A single infusion of BDNF into the ventral tegmental area induces long-lasting potentiation of cocaine-seeking after withdrawal. The Journal of Neuroscience 24:1604-1611
Lu L, Grimm JW, Hope BT, Shaham Y (2004) Incubation of cocaine craving after withdrawal: a review of preclinical data. Neuropharmacology 47(S1): 214-227 (invited review for a special issue commemorating 30 years of NIDA research)
Lu L, Hope BT, Dempsey J, Liu S, Bossert JM, Shaham Y (2005) Central amygdala ERK signaling pathway is critical to incubation of cocaine craving. Nature Neuroscience 8:212-219
Shaham Y, Hope BT (2005) The role of neuroadaptations in relapse to drug seeking. Nature Neuroscience 8:1437-1439 (special issue on Neurobiology of Addiction)
Lu L, Uejima JL, Gray SM, Bossert JM, Shaham Y (2007) Systemic and central amygdala injections of the mGluR2/3 agonist LY379268 attenuate the expression of incubation of cocaine craving. Biological Psychiatry 61:591-598
Koya E, Uejima J, Wihbey K, Bossert JM, Hope BT, Shaham Y (2008) Role of ventral medial prefrontal cortex in incubation of cocaine craving. Neuropharmacology (in press, for a special issue commemorating 35 years of NIDA research))
Conrad KL, Tseng K, Uejima J, Reimers J, Heng L, Shaham Y, Marinelli M, Wolf ME (2008) Formation of accumbens GluR2-lacking AMPA receptors mediates incubation of cocaine craving. Nature (in press)
Pages
2008
All events, 2008
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