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Annotation

Matsuda Y, Marzo A, Otani S. The presence of background dopamine signal converts long-term synaptic depression to potentiation in rat prefrontal cortex. J Neurosci . 2006 May 3 ; 26(18):4803-10. PubMed Abstract

Comments on Paper and Primary News
Primary News: Priming the LTP Pump—Dopamine Delivers in Prefrontal Cortex

Comment by:  Andreas Meyer-Lindenberg
Submitted 15 May 2006 Posted 15 May 2006
  I recommend this paper

I think this is an interesting paper, as it shows that alterations in tonic dopaminergic stimulation can result in a pronounced and qualitative switch (LTD to LTP) in the behavior of prefrontal neurons. Although the concept of tonic versus phasic dopaminergic stimulation has been adopted widely by the schizophrenia research community, the majority of the preclinical work has focused on acute changes in dopamine concentration and on subcortical structures, especially the nucleus accumbens, and from my perspective as a clinical researcher, it is welcome to see some data that extend to prefrontal cortex and longer timescales, although it must be emphasized that this paper concerns results from rats, in slices in vitro, using tetanic stimulation, and that the pretreatment with dopamine lasted for 40 minutes only. With these caveats, it is exciting to see that pretreatment with dopamine after what the authors presume is a 4-hour period of neurotransmitter depletion during slice preparation produces LTP after a weak tetanic stimulus, compared to LTD that the same stimulus evoked...  Read more


View all comments by Andreas Meyer-Lindenberg

Primary News: Priming the LTP Pump—Dopamine Delivers in Prefrontal Cortex

Comment by:  Patricia Estani
Submitted 3 June 2006 Posted 3 June 2006
  I recommend this paper

Primary News: Priming the LTP Pump—Dopamine Delivers in Prefrontal Cortex

Comment by:  Terry Goldberg
Submitted 20 June 2006 Posted 20 June 2006

Matsuda et al. demonstrate that priming D1 and D2 receptors may induce LTP; otherwise, LTD develops. To elaborate, a weak tetanic stimulation and dopamine stimulation produces LTD. However, if dopamine is perfused for 12 to 40 minutes at D1 and D2 receptors and a tetanic stimulus is provided, LTP, a form of cellular learning associated with memory, develops. This study has potentially important implications for understanding the cause of prefrontally based failures in information processing in schizophrenia. It gives additional weight to arguments that reduced dopaminergic tone at the cortical level is responsible for at least some of the cognitive problems associated with the disorder.

It also helps make sense out of some otherwise anomalous data in the literature. For instance, in manipulations of several tests of purported attentional control and vigilance problems, findings appeared more consistent with difficulties in constructing a representation than with attention per se in target detection (e.g.,   Read more


View all comments by Terry Goldberg

Primary News: Priming the LTP Pump—Dopamine Delivers in Prefrontal Cortex

Comment by:  Satoru Otani
Submitted 22 July 2006 Posted 24 July 2006

In his June 20 comment, Dr. Goldberg raised an important question concerning our paper: how our results, showing the necessity of D1+D2 receptor coactivation for prefrontal LTP induction and priming, fit into the scheme proposed by Seamans et al., 2001, that is, the differential roles played by D1 and D2 receptors for prefrontal cortex (PFC) cognitive processes.

I think I have to first point out that the dependency of PFC long-term potentiation (LTP) induction (let alone "priming" now) on DA receptor subtypes may vary among subpopulations of PFC synapses. In ventral hippocampus (HC)-PFC synapses, LTP induction requires D1 but not D2 receptors (Gurden et al., 2000). This in vivo study fits with the idea that HC-PFC projection and its D1 receptor-mediated modulation are critical in spatial information processing (working memory) and encoding of this information. However, recent in vivo results of Yukiori Goto at the...  Read more


View all comments by Satoru Otani

Primary News: Priming the LTP Pump—Dopamine Delivers in Prefrontal Cortex

Comment by:  Jeremy Seamans
Submitted 26 July 2006 Posted 27 July 2006

Drs. Goldberg and Otani raise some excellent points in their comments on the Matsuda et al. paper. As Dr. Otani alluded to in his latest comment, it is useful to define exactly what is being modulated under different experimental conditions and how this all relates to prefrontal cortex (PFC) function in general.

Dr Otani’s studies investigate synaptic plasticity induced by tetanic stimulation and how this process is modulated by tonic dopamine (DA). Long-term potentiation/long-term depression (LTP/LTD) induced by tetanic stimulation has provided us with perhaps the best model of the cellular basis of long-term memory and has been proposed to underlie, among other things, various aspects of long-term spatial memory and declarative memory. LTP is a long-lasting, passive, associational memory mechanism, unlike working memory that is transient in nature, relies on active processing and is not associational. Therefore, in PFC, it would be highly unlikely that LTP/LTD is the neural mechanism of working memory. However, to solve a working memory problem, one must manipulate...  Read more


View all comments by Jeremy Seamans
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