Prestimulus theta in the human hippocampus predicts subsequent recognition but not recall

Human theta (4?8 Hz) activity in the medial temporal lobe correlates with memory formation; however, the precise role that theta plays in the memory system remains elusive (Hanslmayr and Staudigl, 2014 ). Recently, prestimulus theta activity has been associated with successful memory formation, although its specific cognitive role remains unknown (e.g., Fell et al., 2011). In this report, we demonstrate that prestimulus theta in the hippocampus indexes encoding that supports old‐new recognition memory but not recall. These findings suggest that human hippocampal prestimulus theta may preferentially participate in the encoding of item information, as opposed to associative information. © 2014 Wiley Periodicals, Inc.     

Recognizing spatial patterns: a noisy exemplar approach

Models of categorization typically rely on the use of stimuli composed of well-defined dimensions (e.g., Ashby & Maddox (1998) in Choice, decision, and measurement: Essays in honor of R. Duncan Luce, p. 251-301, Mahwah, NJ: Erlbaum). We apply a similar approach to the analysis of recognition memory. Using a version of short-term recognition paradigm (Sternberg, Science 153 (1966) 652), we asked whether NEMO Sternberg's, a noisy exemplar summed-similarity model, could account for variation in mean performance on individual trials. NEMO provided a very good overall fit to recognition data from three experiments. However, its failure to fit data for certain lists of stimuli suggested a revision of the summed-similarity assumption. Our model-based analysis showed that subjects used interitem similarity, in addition to probe-item similarity, as the basis for their decisions. This represents a major departure from existing recognition models that assume subjects' judgments depend exclusively on the summed similarity of the probe to the study items.     

Priming summation in the cerebral hemispheres: evidence from semantically convergent and semantically divergent primes

The ability to activate and to maintain a large and relatively undifferentiated semantic field has been thought to be an important component of lexical semantic processing by the right hemisphere (RH). An implication of this unique propensity of the RH was examined in the present study that included two divided visual field priming experiments with SOAs of 800 and 2500 ms. The experiments investigated the ability of the RH and the left hemisphere (LH) to summate activation from multiple primes followed by a laterally presented ambiguous target word. The priming words either converged onto the same semantic representation (i.e. all three words related to either the dominant or to the subordinate meaning of the target) or diverged onto distinct semantic representations (i.e. two words related to the dominant and one to the subordinate meaning of the target, or vice versa). Results indicated that for either an 800 or 2500 ms stimulus onset asynchrony (SOA) the LH benefited most from three semantically convergent primes that converged onto the dominant meaning of the ambiguous target word. There was no facilitation when three subordinate primes preceded the target. When the primes diverged onto different meanings, there was significant facilitation for the 800 ms SOA only. In contrast, with an 800 ms SOA, the RH benefited only from semantically divergent primes, that diverged onto alternate meanings of the ambiguous target word. With a 2500 ms SOA, the RH benefited from all combinations of primes. The discussion focuses on the implications for language processing of the differences between the two hemispheres in the scope and temporal pattern of the multiple prime effect.     

Confusing exit gunshot wound –“Two for the price of one”

During the post-mortem examination of a 36-year-old shooting victim, two entrance gunshot wounds in the back and only one corresponding exit wound in the chest were detected. The likelihood of a retained fragmented or whole bullet, or an embolic phenomenon was eliminated by full body x-ray examination. The only remaining plausible explanation was that the two bullet tracts had converged within the thorax, eventually exiting through a common exit wound. Dissection of the projectiles’ path confirmed this unusual phenomenon. Autopsy techniques for gunshot wound cases are discussed. Received: 25 May 2001 / Accepted: 20 August 2001     

玻璃体内注射曲安奈德治疗视网膜中央静脉阻塞引起的黄斑水肿

目的：探讨玻璃体内注射丙酮化曲安奈德用于治疗视网膜中央静脉阻塞（CRVO）引起黄斑水肿的安全性和有效性。方法：在Wisconsin大学和Bascom Palmer眼科研究所．对13例（13只眼）连续的CRVO引起黄斑水肿的患者应用玻璃体内注射丙酮化曲安奈德（4mg）治疗．回顾研究其病历记录。每次玻璃体内注射时应用27G或30G针头通过睫状体平坦部注射。主要结果测量：Snellen视力的变化、黄斑水肿的临床表现、应用光学相干断层扫描仪（OCT）测量中心凹的增厚以及并发症的出现频率。结果：13例患者的平均年龄为67岁（四分位数间距为57—77岁）．注射前症状的平均持续时间为8个月（四分位数间距为4—9个月）。患眼在初诊时的平均视力为20／500．在6个月随诊检查时的平均视力为20／1踟。所有13例患者都完成了6个月的随诊检查。非缺血型CRVO患眼（n=5）的视力有显著的提高．而缺血型CRVO患眼（n=8）没有显著的视力提高。患者没有出现视力下降。初诊时OCT测量的平均中心凹厚度为590μm（视网膜增厚=416μm）。12例患者在1个月随诊检查时OCT测量的平均中心凹厚度为212pm（视网膜增厚=38μm）。13例患者在3个月随诊检查时OCT测量的平均中心凹厚度为193μm（视网膜增厚=19μm）。在3和6个月随诊检查之间．4例患者的黄斑水肿复发．其中3例患者再次接受了曲安奈德的注射。这3例患者中的2例经过再次治疗视力提高。在6个月随诊检查时．13例患者OCT测量的平均中心凹厚度为281μm（视网膜增厚=107μm）。没有发生视网膜脱离或眼内炎等并发症。1例患者出现了眼压的升高．应用2种房水生成抑制剂治疗得以控制。结论：在部分CRVO引起黄斑水肿的患者中．玻璃体内注射曲安奈德可能是一种有效的治疗方法。与缺血型CRVO患者相比．非缺血型CRVO患者可以获得更令人满意的效果。部分患者可能需要重复治疗。在本组患者中未发现严重的并发症。     

Contribution of changes in click rate and intensity on diagnosis of multiple sclerosis by brainstem auditory evoked potentials

Brainstem auditory evoked potentials (BAEPs) were recorded in 51 patients with different degrees of certainty with respect to multiple sclerosis (MS): Definite, probable and possible ( McAlpine et al. 1972). Click stimuli were presented at various intensities and rates which were thought to stress the auditory pathways. The main types of abnormal BAEP traces were the absence of some of the brainstem waves (in the presence of a normal audiogram), prolonged brainstem transmission time (BTT) and abnormal amplitude ratio. In the definite MS group, average BTT was prolonged and average amplitude ratio was more than two standard deviations greater than the corresponding parameter in the normal group. The stressful manoeuvres of increasing click repetition rate and lowering click intensity increased the degree of abnormality of BAEP traces. There was no case in which the response to standard click stimuli (75 dB HL, 10 or 20 per sec) showed a normal trace while increasing the stimulus repetition rate and/or decreasing intensity showed a pathological response. The pathophysiology of BAEP traces in MS is discussed.     

Preservation of episodic visual recognition memory in aging

Visual episodic recognition memory was assessed in young (mean age 22.5 years) and older (mean age 74.1 years) adults. To isolate purely visual memory, recognition was tested with sets of briefly-presented compound sinusoidal gratings, which minimized age-related differences in visual processing, and resisted verbal encoding. Recognition was measured after delays of 1, 2 or 4 seconds. Overall, neither accuracy of recognition nor speed of response differed significantly between groups, or with probe delay, which strengthens recent claims that visual memory tends to be spared during the course of normal aging.