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131.
Timothy?H.?GoldsmithEmail author Byron?K.?Butler 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2005,191(10):933-951
Budgerigars, Melopsittacus undulatus, were trained to discriminate monochromatic lights from mixtures of two comparison lights. The addition of small amounts
of UV (365 nm) to blue or yellow lights dramatically changed the color for the birds. Hue matches showed the birds to be dichromatic
both at long wavelengths (only P565 and P508 active) and at short wavelengths (only P370 and P445 active because of screening
of P508 and P565 by cone oil droplets). In mid-spectrum (only P445 and P508 active), a hue match was achieved, but the results
were more complicated because two opponent neural processes were activated. All observed hue matches were in quantitative
agreement with calculations of relative quantum catch in the pairs of participating single cones and point to the presence
of a minimum of three opponent neural processes. For the hue matches at mid- and short wavelengths, the calculations also
predict peak values of absorbance of the cone oil droplets associated with P508 and P445. Relative intensity of the training
light affected difficult matches at long but not short wavelengths, likely due to achromatic signals from the double cones.
With suitable training, birds could make intensity discriminations at short wavelengths, where the double cones have diminished
sensitivity. 相似文献
132.
U.?LangemannEmail author M.?A.?Zokoll G.?M.?Klump 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2005,191(10):889-901
In a behavioral experiment, we investigated how efficiently barn owls (Tyto alba) could detect changes in the spectral profile of multi-component auditory signals with stochastic envelope patterns. Signals
consisted of one or five bands of noise (bandwidth 4, 16, or 64 Hz each; center frequencies 1.02, 1.43, 2.0, 2.8, 3.92 kHz).
We determined increment thresholds for the 2 kHz component for three conditions: single-band condition (only the 2 kHz component),
all five noise bands with the envelope fluctuations of the bands being either correlated or uncorrelated. Noise bandwidth
had no significant effect on increment detection. Increment thresholds for the different conditions, however, differed significantly.
Thresholds in correlated conditions were generally the lowest of all conditions, whereas, thresholds in uncorrelated conditions
mostly resulted in the highest thresholds. This can be interpreted as evidence for comodulation masking release in barn owls.
If the increment in the 2 kHz component is balanced by decrementing the four flanking bands in amplitude, increment detection
thresholds are not affected. The data suggest that the barn owls used information from simultaneous spectral comparison across
different frequency channels to detect spectral changes in multi-component noise signals rather than sequential comparison
of overall stimulus levels. 相似文献
133.
Associations between δ13C values and leaf gas exchanges and tree-ring or needle growth, used in ecophysiological compositions, can be complex depending
on the relative timing of CO2 uptake and subsequent redistribution and allocation of carbon to needle and stem components. For palaeoenvironmental and
dendroecological studies it is often interpreted in terms of a simple model of δ13C fractionation in C3 plants. However, in spite of potential complicating factors, few studies have actually examined these relationships in mature
trees over inter- and intra-annual time-scales. Here, we present results from a 4 years study that investigated the links
between variations in leaf gas-exchange properties, growth, and dated δ13C values along the needles and across tree rings of Aleppo pine trees growing in a semi-arid region under natural conditions
or with supplemental summer irrigation. Sub-sections of tissue across annual rings and along needles, for which time of formation
was resolved from growth rate analyses, showed rapid growth and δ13C responses to changing environmental conditions. Seasonal cycles of growth and δ13C (up to ~4‰) significantly correlated (P<0.01) with photosynthetically active radiation, vapour pressure deficit, air temperature, and soil water content. The irrigation
significantly increased leaf net assimilation, stomatal conductance and needle and tree-ring growth rate, and markedly decreased
needle and tree-ring δ13C values and its sensitivity to environmental parameters. The δ13C estimates derived from gas-exchange parameters, and weighted by assimilation, compared closely with seasonal and inter-annual
δ13C values of needle- and tree-ring tissue. Higher stomatal conductances of the irrigated trees (0.22 vs. 0.08 mol m−2 s−1 on average) corresponded with ~2.0‰ lower average δ13C values, both measured and derived. Derived and measured δ13C values also indicated that needle growth, which occurs throughout the stressful summer was supported by carbon from concurrent,
low rate assimilation. For Aleppo pine under semi-arid and irrigated conditions, the δ13C of tree-ring and needle material proved, in general, to be a reasonable indicator of integrated leaf gas-exchange properties. 相似文献
134.
Daniel?M.?A.?Pessoa Eduardo?S.?Perini Lívia?S.?Carvalho Carlos?Tomaz Valdir?F.?PessoaEmail author 《International journal of primatology》2005,26(1):147-158
We assessed the color discriminations by golden-headed lion tamarins (Leontopithecus chrysomelas) via a series of tasks involving a behavioral paradigm that maximizes the naturalness of the stimuli. The stimuli were pairs of Munsell color chips used in earlier experiments with human dichromats. We tested 3 male and 3 female monkeys with stimuli of random brightness values in order to assure that discriminations were based on color rather than brightness cues. Results indicate that each male and one female presented random performances for stimuli resembling hue conditions under which tamarins forage: oranges vs. greens. Two females exhibited discriminations consistent with allelic trichromacy. Findings indicate the presence of an M/L cone opsin polymorphism, a condition of most platyrrhines that is characterized by dichromatic and/or trichromatic females and dichromatic males. Interspecific differences in allelic frequency among lion tamarins raises the possibility that habitat fragmentation is affecting heterozygous frequencies, a trend that could impact tamarin foraging efficiency. 相似文献
135.
To find a simple and reliable oxygen electrode-based method to estimate the values of alternative pathway activity (V
alt) and its contribution to total respiration V
alt/V
t) in aged potato (Solanum tuberosum L.) tuber slices, we compared conventional hydroxamate-inhibiting method, improved hydroxamate-inhibiting method with 2,6-dichlorophenol indophenol (DCPIP), and the oxygen isotope discrimination (OID) method. The values of V
alt and V
alt/V
t obtained with an improved hydroxamate-inhibiting method with DCPIP in 12-h- and 24-h-aged slices were about twice higher than those with the conventional hydroxamate-inhibiting method. Only a relatively small difference in the values of V
alt and V
alt/V
t obtained by the OID method and the improved hydroxamate-inhibiting method with DCPIP in 12-h and 24-h-aged slices was observed. These results indicated that the improved hydroxamate-inhibiting method with DCPIP could be considered as a new, simple, and reliable technique for the noninvasive assay of the AP activity.From Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 311–315.Original English Text Copyright © 2005 by Hou, Zhou, Kong, Liang, Zhang.This article was submitted by the authors in English.This revised version was published online in April 2005 with a corrected cover date. 相似文献
136.
137.
138.
Carl Erick Hagmann 《Behavioural processes》2010,85(2):99-110
Rhythmic grouping and discrimination is fundamental to music. When compared to the perception of pitch, rhythmic abilities in animals have received scant attention until recently. In this experiment, four pigeons were tested with three types of auditory rhythmic discriminations to investigate their processing of this aspect of sound and music. Two experiments examined a meter discrimination in which successively presented idiophonic sounds were repeated in meters of different lengths in a go/no-go discrimination task. With difficulty, the birds eventually learned to discriminate between 8/4 and 3/4 meters constructed from cymbal and tom drum sounds at 180 beats per minute. This discrimination subsequently transferred to faster tempos, but not to different drum sounds or their combination. Experiment 3 tested rhythmic and arrhythmic patterns of sounds. After 40 sessions of training, these same pigeons showed no discrimination. Experiment 4 tested repetitions of a piano sound at fast and slow tempos. This discrimination was readily learned and showed transfer to novel tempos. The pattern of results suggests that pigeons can time periodic auditory events, but their capacity to understand generalized rhythmic groupings appears limited. 相似文献
139.
Pigeons were trained in a new procedure to test for visual binding errors between the dimensions of color and shape. In Experiment 1, pigeons learned to discriminate a target compound from 15 non-target compounds (constructed from four colors and shapes) by choosing one of two hoppers in a two-hopper choice task. The similarity of the target to non-target stimuli influenced choice responding. In Experiment 2, pigeons learned to detect a target compound when presented with a non-target compound within the same trial under conditions of simultaneity and sequentiality. Non-target trials were arranged to allow for the testing of binding errors (i.e., false identifications of the target on certain non-target trials). Transient evidence for binding errors in two of the birds occurred at the start of two-item training, but decreased with training. The experiments represent an important step toward developing a framework for the evaluation of visual feature binding in nonhumans. 相似文献
140.