Serotonin and Dopamine: Unifying Affective, Activational, and Decision Functions

Serotonin, like dopamine (DA), has long been implicated in adaptive behavior, including decision making and reinforcement learning. However, although the two neuromodulators are tightly related and have a similar degree of functional importance, compared with DA, we have a much less specific understanding about the mechanisms by which serotonin affects behavior. Here, we draw on recent work on computational models of dopaminergic function to suggest a framework by which many of the seemingly diverse functions associated with both DA and serotonin—comprising both affective and activational ones, as well as a number of other functions not overtly related to either—can be seen as consequences of a single root mechanism.     

A GAP-43-like protein in cat visual cortex

We have purified a protein that changes in relative concentration during the development of the kitten visual cortex. It resembles GAP-43 (a neuronal protein that is expressed at elevated levels during periods of development and regenerative axon growth) in the following respects: (1) it is an acidic protein (pI = 4.7) whose electrophoretic mobility on SDS-PAGE is similar to, but lower than rat GAP-43, suggesting that the cat protein is larger; (2) its electrophoretic mobility varies with the acrylamide concentration in a manner that is characteristic of GAP-43; (3) its concentration in kitten forebrain is elevated during early postnatal development; (4) the sequence of ten consecutive amino acids from a chemically generated fragment matches the expected sequence from GAP-43; and (5) its amino-acid content also matches GAP-43. We conclude that our purified protein is cat GAP-43. Immunoblots with an antibody prepared against rat GAP-43 suggested that the concentration of GAP-43 in the visual cortex declines with age.     

Isolation of a gene encoding an integral membrane protein from the vicinity of a balanced translocation breakpoint associated with DiGeorge syndrome

Deletions within 22q11 have been associated with a wide varietyof birth defects embraced by the acronym CATCH22 and includingthe DiGeorge syndrome, Shprintzen syndrome (velocardiofacialsyndrome) and congenital heart disease. It is not known howmany genes contribute to this phenotype. Previous studies haveshown that a balanced translocation disrupts sequences withinthe shortest region of deletion overlap for DiGeorge syndrome.A P1 clone was isolated which spans this breakpoint and usedto isolate a cDNA encoding a transmembrane protein expressedin a wide variety of tissues. This gene (called IDD) is notdisrupted by the translocation, but maps within 10 kb of thebreakpoint. Mutation analysis of five affected cases with nopreviously identified chromosome 22 deletion was negative, buta potential protein polymorphism was discovered. No deletionsor rearrangements were detected in these patients followinganalysis with markers closely flanking the breakpoint, datawhich emphasize that large (i. e. over 1 Mb) interstitial deletionsare the rule in DiGeorge syndrome. The proximity of IDD to thebalanced translocation breakpoint and its position within theshortest region of deletion overlap indicate that this genemay have a role, along with other genes, in the CATCH22 haploinsufficiencysyndromes.     

穴位坦线配合中药治疗银屑病疗效观察

０　引言　银屑病是一原因不明的常见皮肤病,临床以慢性、复发性,表面覆盖有多层的银白色鳞屑,境界清楚的红斑、丘疹为特征．３ａ来我们采用穴拉埋线配合自拟中药验方治疗银屑病４６例,取得较好疗效．１　对象和方法１．１　对象　本组４６（男２１,女２５）例,年龄...     

The effect of varying stimulus intensity on NMDA-receptor activity in cat visual cortex

1. A study was made of the relative contribution of N-methyl-D-aspartate (NMDA) and non-NMDA receptors to the visual responses of cells in different layers of the cat visual cortex at different levels of excitatory drive (which was varied by altering the stimulus contrast). 2. Receptive fields were mapped for 121 cells in area 17 of cat cortex. Cells were characterized to determine the optimal visual stimulus, the brightness of which was then varied relative to background luminance to construct a contrast-response (C-R) curve for each cell. Curves were made during control conditions and during application of agonists (NMDA and quisqualate) and/or antagonists [(D)-2-amino-5-phosphonovaleric acid (D-APV) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)] to examine the excitatory amino acid components of the visual response. 3. Threshold responses were obtained with stimuli between 1/60 and 1.8 X background luminance. The cell response, measured by firing rate, was linearly related to stimulus contrast over 1-2 decades and saturated at higher contrasts. 4. Application of APV reduced the slope of the linear portion of the C-R curve for cells located in layers II and III (average reduction, 59% of control). APV did not decrease the threshold to stimulation. The "just suprathreshold" responses to stimulation were reduced by the same proportion as the saturation responses for individual cells. The principal effect was therefore to reduce the gain of the C-R curve in these layers. 5. Application of APV reduced the spontaneous activity of cells located in layers IV, V, and VI with little if any effect on the gain of the C-R curve. This suggests a tonic background level of NMDA-receptor activation in these layers, which is not directly related to the visual response. 6. Low levels of NMDA increased the gain of the C-R curve in layers II/III and V/VI. On the other hand, low levels of quisqualate increased the overall level of firing without affecting the gain of the C-R curve. NMDA did not increase the gain of the curve in layer IV. 7. These experiments show that visual stimuli that produce just suprathreshold responses activate NMDA receptors. The degree of activation is proportionally the same for small responses and large responses for an individual cell. Rather than finding a threshold for NMDA-receptor activation, a continuous range of NMDA-receptor influence was observed over the entire response range.(ABSTRACT TRUNCATED AT 250 WORDS)