Thu, 21 Aug 2008 15:33:29 BST CiteULike: awooga's 5ht2a http://www.citeulike.org/user/awooga/tag/5ht2a CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/awooga/article/2464926 <i>J. Cogn. Neurosci., Vol. 17, No. 10. (1 October 2005), 1497.</i><br /><br />Increasing evidence suggests a link between attention, working memory, serotonin (5-HT), and prefrontal cortex activity. In an attempt to tease out the relationship between these elements, this study tested the effects of the hallucinogenic mixed 5-HT1A/2A receptor agonist psilocybin alone and after pretreatment with the 5-HT2A antagonist ketanserin. Eight healthy human volunteers were tested on a multiple-object tracking task and spatial working memory task under the four conditions: placebo, psilocybin (215 microg/kg), ketanserin (50 mg), and psilocybin and ketanserin. Psilocybin significantly reduced attentional tracking ability, but had no significant effect on spatial working memory, suggesting a functional dissociation between the two tasks. Pretreatment with ketanserin did not attenuate the effect of psilocybin on attentional performance, suggesting a primary involvement of the 5-HT1A receptor in the observed deficit. Based on physiological and pharmacological data, we speculate that this impaired attentional performance may reflect a reduced ability to suppress or ignore distracting stimuli rather than reduced attentional capacity. The clinical relevance of these results is also discussed. Using Psilocybin to Investigate the Relationship between Attention, Working Memory, and the Serotonin 1A and 2A Receptors Olivia Carter David Burr John Pettigrew Guy Wallis Felix Hasler Franz Vollenweider J. Cogn. Neurosci., Vol. 17, No. 10. (1 October 2005), 1497. 2008-03-04T14:07:41-00:00 2005 J. Cogn. Neurosci. 17 10 1497 5ht1a 5ht2a attention hallucinagenics magic-mushrooms serotonin working-memory http://www.citeulike.org/user/awooga/article/2444095 <i>Cereb. Cortex, Vol. 15, No. 1. (1 January 2005), pp. 1-14.</i><br /><br />Serotonin is involved in psychiatric disorders exhibiting abnormal prefrontal cortex (PFC) function (e.g. major depression, schizophrenia). We examined the effect of the stimulation of the dorsal and median raphe nuclei (DR and MnR, respectively) on the activity of PFC neurons. Electrical stimulation of DR/MnR inhibited 66% (115/173) of pyramidal neurons in the medial PFC (mPFC). The rest of the cases exhibited orthodromic excitations, either pure (13%) or preceded by short-latency inhibitions (20%). Excited neurons had a lower pre-stimulus firing rate than those inhibited. Excitations evoked by MnR stimulation had a shorter latency than those evoked by DR stimulation. WAY-100635 [a 5-hydroxytryptamine1A (5-HT1A) antagonist] and the selective gamma aminobutyric acidA (GABAA) antagonist picrotoxinin partially antagonized DR/MnR-evoked inhibitions, suggesting the involvement of 5-HT1A- and GABAA-mediated components. The presence of a direct DR/MnR-mPFC GABAergic component is suggested by the short latency of evoked inhibitions (9 +/- 1 ms), faster than those evoked in the secondary motor area (20 +/- 3 ms), and that of antidromic spikes evoked by DR/MnR stimulation in mPFC pyramidal neurons (15 +/- 1 ms). Stimulation of the DR/MnR with paired pulses enhanced the duration of inhibitions and turned some excitations into inhibitions. Thus, the DR/MnR control the activity of mPFC pyramidal neurons in vivo in a complex manner, involving 5-HT-mediated excitations and GABA- and 5-HT-mediated inhibitions. 10.1093/cercor/bhh104 Modulation of the Activity of Pyramidal Neurons in Rat Prefrontal Cortex by Raphe Stimulation In Vivo: Involvement of Serotonin and GABA Victoria Puig Francesc Artigas Pau Celada doi:10.1093/cercor/bhh104 Cereb. Cortex, Vol. 15, No. 1. (1 January 2005), pp. 1-14. 2008-02-28T16:15:26-00:00 2005 Cereb. Cortex 15 1 1 14 5ht1a 5ht2a electrophysiology gabaergic-inhibition in-vivo neuromodulation prefrontal-cortex serotonin