CiteULike: Ключевое слово pptg

Reward Prediction Error Computation in the Pedunculopontine Tegmental Nucleus Neurons

Yasushi Kobayashi — 2007-06-29T02:35:43-00:00

Annals of the New York Academy of Sciences, Vol. 1104, No. 1. (May 2007), pp. 310-323.

Muscarine reduces calcium-dependent electrical activity in substantia nigra dopaminergic neurons.

RS Scroggs — 2007-11-23T09:06:18-00:00

J Neurophysiol, Vol. 86, No. 6. (December 2001), pp. 2966-2972.

The effect of muscarine on Ca2+ dependent electrical activity was studied in dopamine (DA) neurons located in the substantia nigra pars compacta (SNc) in brain slices from young rats, using sharp electrodes. In most DA neurons tested, muscarine (50 microM) reduced the amplitude of spontaneous oscillatory potentials and evoked Ca2+-dependent potentials recorded in the presence of TTX. Muscarine also reduced the amplitude of the slow afterhyperpolarization (sAHP) following action potentials in most DA neurons. These data suggest that muscarine reduces Ca2+ entry in SNc DA neurons. The reduction of the amplitude of the sAHP by muscarine in DA neurons may facilitate bursting initiated by glutamatergic input by increasing the frequency at which DA neurons can fire. The reduction of the sAHP via activation of muscarinic receptors in vivo may provide a mechanism whereby cholinergic inputs to DA neurons from the tegmental peduncular pontine nucleus could modulate dopamine release at dopaminergic targets in the brain.

Pedunculopontine tegmental nucleus controls conditioned responses of midbrain dopamine neurons in behaving rats.

WX Pan — 2005-06-29T22:22:19-00:00

J Neurosci, Vol. 25, No. 19. (11 May 2005), pp. 4725-4732.

Midbrain dopamine (DA) neurons respond to sensory cues that predict reward. We tested the hypothesis that projections from the pedunculopontine tegmental nucleus (PPTg) are involved in driving this DA cell activity. First, the activity of PPTg and DA neurons was compared in a cued-reward associative learning paradigm. The majority of PPTg neurons showed phasic responses to the onset of sensory cues, at significantly shorter latency than DA cells, consistent with a PPTg-to-DA transmission of information. However, unlike DA cells, PPTg responses were almost entirely independent of whether signals were associated with rewards. Second, DA neuron responses to the cues were recorded in free-moving rats during reversible inactivation of the PPTg by microinfusion of local anesthetic. The results showed clear suppression of conditioned sensory responses of DA neurons after PPTg inactivation that was not seen after saline infusion or in non-DA cells. We propose that the PPTg relays information about the precise timing of attended sensory events, which is integrated with information about reward context by DA neurons.

Subcortical control of dopamine neurons: the good, the bad and the unexpected.

RD Stewart — 2007-02-23T06:38:47-00:00

Brain Res Bull, Vol. 71, No. 1-3. (11 December 2006), pp. 1-3.

The function of the phasic dopamine signal, seen in response to salient and rewarding stimuli, has been heavily debated. The reward prediction error hypothesis has been criticised for the suggestion that such a complex signal could be derived at short latencies, relying only on subcortical inputs. However, as more has been learnt about the nature of the subcortical inputs, we are led to challenge this criticism. Here we suggest that the subcortical inputs can indeed support complex calculations and that it would be unwise to underestimate their processing capabilities. Whilst our analysis cannot differentiate between the reward prediction error hypothesis and its opponents, it does suggest that the initial argument against a prediction error is incorrect.

Afferent modulation of dopamine neuron firing differentially regulates tonic and phasic dopamine transmission

Stan Floresco — 2006-12-07T09:27:27-00:00

Nat Neurosci, Vol. 6, No. 9. (2003), pp. 968-973.

Regulation of firing of dopaminergic neurons and control of goal-directed behaviors

Anthony Grace — 2007-04-04T14:05:09-00:00

Trends in Neurosciences, Vol. In Press, Corrected Proof

There are several brain regions that have been implicated in the control of motivated behavior and whose disruption leads to the pathophysiology observed in major psychiatric disorders. These systems include the ventral hippocampus, which is involved in context and focus on tasks, the amygdala, which mediates emotional behavior, and the prefrontal cortex, which modulates activity throughout the limbic system to enable behavioral flexibility. Each of these systems has overlapping projections to the nucleus accumbens, where these inputs are integrated under the modulatory influence of dopamine. Here, we provide a systems-oriented approach to interpreting the function of the dopamine system, its modulation of limbic-cortical interactions and how disruptions within this system might underlie the pathophysiology of schizophrenia and drug abuse.

Electrophysiological characteristics of substantia nigra neurons in organotypic cultures: spontaneous and evoked activities.

J Rohrbacher — 2007-02-20T16:12:36-00:00

Neuroscience, Vol. 97, No. 4. (2000), pp. 703-714.

Morphological and electrophysiological characteristics of dopaminergic and non-dopaminergic neurons in the substantia nigra and their postsynaptic responses to stimulation of the tegmental pedunculopontine nucleus were studied in rat organotypic triple cultures. These cultures consisted of the subthalamic nucleus explant, ventral mesencephalic explant, inclusive of the substantia nigra and the mesopontine tegmentum explant, inclusive of the tegmental pedunculopontine nucleus, prepared from one- to two-day-old rats. Intracellular sharp and whole-cell recordings were obtained from three- to eight-week-old organotypic cultures. Recorded neurons were identified as dopaminergic and non-dopaminergic neurons with tyrosine hydroxylase immunohistochemistry. Dopaminergic neurons had long duration action potentials, prominent afterhyperpolarization, time-dependent inward and outward rectification and strong frequency adaptation. Spontaneous firing patterns varied from regular, irregular to burst firing. Non-dopaminergic neurons had short duration action potentials, in general no rectifying currents, and maintained high firing frequencies. Spontaneous firing patterns in these neurons were irregular or burst firing. Morphological analysis of the recorded neurons labeled with neurobiotin revealed that non-dopaminergic neurons had more extensive arborization of higher-order dendrites than dopaminergic neurons. Dopaminergic and non-dopaminergic neurons receive glutamatergic and cholinergic excitatory inputs from the tegmental pedunculopontine nucleus.These results indicate that morphological and electrophysiological characteristics of substantia nigra neurons in the organotypic culture are generally similar to those reported in in vitro slice and in vivo studies. However, spontaneous activities of dopamine neurons observed in the organotypic culture preparation more closely resemble those in in vivo preparation compared to in vitro preparation.