A Novel Form of Memory for Auditory Fear Conditioning at a Low-Intensity Unconditioned Stimulus

Fear is one of the most potent emotional experiences and is an adaptive component of response to potentially threatening stimuli. On the other hand, too much or inappropriate fear accounts for many common psychiatric problems. Cumulative evidence suggests that the amygdala plays a central role in the acquisition, storage and expression of fear memory. Here, we developed an inducible striatal neuron ablation system in transgenic mice. The ablation of striatal neurons in the adult brain hardly affected the auditory fear learning under the standard condition in agreement with previous studies. When conditioned with a low-intensity unconditioned stimulus, however, the formation of long-term fear memory but not short-tem memory was impaired in striatal neuron-ablated mice. Consistently, the ablation of striatal neurons 24 h after conditioning with the low-intensity unconditioned stimulus, when the long-term fear memory was formed, diminished the retention of the long-term memory. Our results reveal a novel form of the auditory fear memory depending on striatal neurons at the low-intensity unconditioned stimulus

Long-Term Memory Deficits in Pavlovian Fear Conditioning in Ca(2+)/Calmodulin Kinase Kinase α-Deficient Mice

Signaling by the Ca(2+)/calmodulin kinase (CaMK) cascade has been implicated in neuronal gene transcription, synaptic plasticity, and long-term memory consolidation. The CaM kinase kinase α (CaMKKα) isoform is an upstream component of the CaMK cascade whose function in different behavioral and learning and memory paradigms was analyzed by targeted gene disruption in mice. CaMKKα mutants exhibited normal long-term spatial memory formation and cued fear conditioning but showed deficits in context fear during both conditioning and long-term follow-up testing. They also exhibited impaired activation of the downstream kinase CaMKIV/Gr and its substrate, the transcription factor cyclic AMP-responsive element binding protein (CREB) upon fear conditioning. Unlike CaMKIV/Gr-deficient mice, the CaMKKα mutants exhibited normal long-term potentiation and normal levels of anxiety-like behavior. These results demonstrate a selective role for CaMKKα in contextual fear memory and suggest that different combinations of upstream and downstream components of the CaMK cascade may serve distinct physiological functions

The need for quantitative methods in syntax and semantics research

The prevalent method in syntax and semantics research involves obtaining a judgement of the acceptability of a sentence/meaning pair, typically by just the author of the paper, sometimes with feedback from colleagues. This methodology does not allow proper testing of scientific hypotheses because of (a) the small number of experimental participants (typically one); (b) the small number of experimental stimuli (typically one); (c) cognitive biases on the part of the researcher and participants; and (d) the effect of the preceding context (e.g., other constructions the researcher may have been recently considering). In the current paper we respond to some arguments that have been given in support of continuing to use the traditional nonquantitative method in syntax/semantics research. One recent defence of the traditional method comes from Phillips (2009), who argues that no harm has come from the nonquantitative approach in syntax research thus far. Phillips argues that there are no cases in the literature where an incorrect intuitive judgement has become the basis for a widely accepted generalisation or an important theoretical claim. He therefore concludes that there is no reason to adopt more rigorous data collection standards. We challenge Philips' conclusion by presenting three cases from the literature where a faulty intuition has led to incorrect generalisations and mistaken theorising, plausibly due to cognitive biases on the part of the researchers. Furthermore, we present additional arguments for rigorous data collection standards. For example, allowing lax data collection standards has the undesirable effect that the results and claims will often be ignored by researchers with stronger methodological standards. Finally, we observe that behavioural experiments are easier to conduct in English than ever before, with the advent of Amazon.com's Mechanical Turk, a marketplace interface that can be used for collecting behavioural data over the internet.National Science Foundation (U.S.) (Grant No. 0844472

Different Root and Shoot Responses to Mowing and Fertility in Native and Invaded Grassland

Grassland root responses to mowing and fertility are less well known than shoot responses, even though as much as 90% of productivity in semiarid grasslands occurs belowground. Thus, understanding root responses may aid the management of invasive grassland species such as Agropyron cristatum (L.) Gaerth (crested wheatgrass). We asked whether root responses reflect shoot responses to mowing and fertility in native grassland with and without a major component of crested wheatgrass. We subjected grasslands in northern Montana to 5 yr of mowing at two nitrogen (N) levels and followed root responses with minirhizotrons. Surprisingly, the roots of both native and invaded grasslands were unaffected by mowing and N addition, despite significant changes in shoot mass across both vegetation types. Root length was significantly greater beneath areas heavily occupied by crested wheatgrass (363 m · m-2 image ± 200, mean ± standard deviation [SD]) than areas comprising largely native grassland (168 m · m-2 image ± 128 SD). Also, no interactions occurred between year and any other factor, indicating that there were no changes in belowground responses over the 5 yr examined. In contrast, shoot mass was significantly reduced by mowing (not mowed, 612 g · m-2 ± 235 SD; mowed, 239 g · m-2 ± 81 SD) and was significantly increased by N addition (no added N, 380 g · m-2 ± 215 SD; added N, 488 g · m-2 ± 287 SD). In conclusion, 5 yr of mowing decreased shoot mass, but not root mass. On the other hand, 5 yr of N addition increased shoot mass, but not root mass. Given that most production and competition in grasslands occurs belowground, this suggests that mowing may not be a successful tool for reducing crested wheatgrass root length, regardless of soil fertility. © 2014 The Society for Range Management.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information