Two trends have marked the development of U.S. cable television news in recent years: a blurring of hard and soft news and an increase in overt partisanship. This paper reports the results of 2 studies that provide insight into the nature and impact of these trends. The first study analyzes national survey data to identify the factors that lead political partisans to choose particular cable television news networks and programs. The second study employs experimental methods to demonstrate how viewers’ partisan leanings influence their perceptions of content from CNN, Fox News, and The Daily Show. We found evidence of a relative hostile media phenomenon, in which partisans perceive more bias in programs that do not align with their own political perspective. Furthermore, the results indicate that partisanship informs viewers’ perceptions of news content as interesting and informative.
SUMMARY1. Group Ia EPSPs were recorded from lumbosacral motoneurones in anaesthetized cats after almost complete section of the relevant dorsal roots. The EPSPs were usually of small amplitude (median value of 230 1V) and an averaging device was used to improve the definition of their time course.2. From a total of over 500 averaged EPSPs a smaller number (342) were subjected to analysis. The other EPSPs were rejected either because they showed signs of multiple origin in the rising phase of their time course (see Methods) or because the resting membrane potential of the cell was less than 50 mV. All the selected EPSPs had their rise time (from the 10 to the 90 % level) and half-width measured, and a semilogarithmic plot of their decay time course was made.3. 252 of the EPSPs showed an exponential decline in their later time course and the slope of this line was used to give an estimate of the membrane time constant. The range of the time constant for different motoneurones was 2 3-12 9 msec, with a mean value of 5-8 msec.4. In ten cells an EPSP was recorded which was judged to be generated exclusively by synaptic knobs located on the soma. J. J. B. JACK AND OTHERSThe estimated value of a ranged from 18 to 65. A positive correlation was found between ax and Tm, indicating that for these EPSPs the duration of current injection was independent of the membrane time constant. The peak time of the wave form of current injection was between 0.1 and 0*25 msec.The estimates ofpO, were not thought to be very accurate. A lower limit of 4 was assumed and the highest measured value was 12, but in three cells the time course of the EPSP could not be fitted even with a very high value of p,,. Some possible explanations for this discrepancy are mentioned in the Discussion.The electrotonic length of the dendrites (L) was usually greater than l O A and ranged between 0 75 and 1-5 A. Evidence for an open-circuit termination of the dendrites was found in some cells.5. The normalized values of the rise time and half-width were used to make an electrotonic distance allocation to the 246 EPSPs which were judged to be non-somatic. The method of allocation was not precise because individual values of p, and L were not available for these motoneurones. Instead, a maximum possible range was assumed: for po,, 4-25; for L, 0-75-1*5. The range of a was also assumed, from 12 to 100. With these values the motoneurone model (Jack & Redman, 1971 b) was used to set limits within which the normalized rise time and half-width of all EPSPs, generated by current at a single point, should lie. Twenty of the 246 EPSPs lay outside these boundary lines and hence they did not receive a distance allocation. The remaining 226 were assigned values between 0-2 and 1F6 A (in 0-2 A steps); the majority of the allocations (183) were to the proximal electrotonic part of the dendrites (0-2, 0-4 or 0-6 A).The relationship of these distance allocations to the histological results of Conradi (1969) is discussed.6. It is concluded that there is no good evidence a...
The relative numbers and locations of neurons projecting to the "forelimb" region of the precentral motor cortex were studied in three monkeys by using the retrograde transport of horseradish peroxidase. Within the forelimb area of the motor cortex itself, there are extensive and profuse interconnections. However, regions within this area receive afferents from very few neurons in other parts of the motor cortex representing hindlimb or head movements. Most of the motor cortical representation of the forelimb in the anterior bank of the central sulcus is devoid of callosal connections. In both the ipsilateral and contralateral hemispheres, the premotor (lateral area 6) and supplementary motor (medial area 6) areas dominate quantitatively the inputs to the motor cortical representation of the forelimb. The afferents from the premotor area are restricted and come from a region immediately behind the arcuate spur and adjacent parts of the superior and inferior limbs of the arcuate sulcus in the floor, caudal bank, and caudal lip of that sulcus. From the supplementary motor area (SMA), afferents originate from its whole rostrocaudal extent. Thalamic nuclear regions projecting to a restricted zone in the anterior bank of the central sulcus are recipients of cerebellar and somatosensory outputs. Involvement of more anterior parts of the motor cortex by the tracer labels thalamocortical cells, which are targets of pallidal output also. Within the first somatosensory cortex, cytoarchitectonic areas 1, 2, and 3a project to area 4. The projection from area 3a may provide one pathway by which short-latency peripheral inputs, especially from muscles, reach the motor cortex.
The cells of origin of the corticostriatal projection have been identified in squirrel monkeys by the use of the retrograde horseradish peroxidase method. In the subfields of the somatic sensory, motor, parietal and frontal areas of the cortex, cells projecting to the ipsilateral striatum are relatively sparsely distributed and form a group of small- to medium-sized pyramidal cells with an average somal diameter from area to area of 14-16 mum. Such cells are found only in layer V of the cortex (mainly in the more superficial parts of the layer). Since they are consistently smaller than the pyramidal cells of layer V that project to the brainstem and spinal cord and since they lie outside layer VI which gives rise to corticothalamic axons, the corticostriatal axons are unlikely to be collaterals of axons projecting to other sites. The cells of origin of the crossed corticostriatal projection are also found in layer V and are pyramidal cells with somal diameters in the same range as above. They are found only in areas 4, 8, and 6. Studies with the anterograde, autoradiographic method in rhesus, cynomologous and squirrel monkeys, indicate that the somatic sensory areas project to most of the antero-posterior extent of the ipsilateral putamen. Subareas 3a, 3b, 1 and 2 of the somatic sensory cortex project to the same region and the projection overlaps similarly extensive projections from the motor and certain other areas of the cortex. However, in each case the pattern of terminal labeling is in the form of interrupted clusters, strips and bands. A single small injection of the cortex is associated with only one or two such clusters of terminal labeling. This seems to imply that individual corticostriatal fibers end in a very restricted manner and that the terminal ramifications of fibers from one cortical area may alternate in the putamen with those arising in other areas.
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