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The ability to remember unique past events (episodic memory) may be an evolutionarily conserved function, with accumulating evidence of episodic-(like) memory processing in rodents. In humans, it likely contributes to successful complex social networking. Rodents, arguably the most used laboratory models, are also rather social animals. However, many behavioural paradigms are devoid of sociality, and commonly-used social spontaneous recognition tasks (SRTs) are open to non-episodic strategies based upon familiarity. We address this gap by developing new SRT variants. Here, in object-in-context SRTs, we asked if context could be specified by the presence/absence of either a conspecific (experiment 1) or an additional local object (experiment 2). We show that mice readily used the conspecific as contextual information to distinguish unique episodes in memory. In contrast, no coherent behavioural response emerged when an additional object was used as a potential context specifier. Further, in a new social conspecific-in-context SRT (experiment 3) where environment-based change was the context specifier, mice preferably explored a more recently-seen familiar conspecific associated with contextual mismatch, over a less recently-seen familiar conspecific presented in the same context. The results argue that, in incidental SRT conditions, mice readily incorporate conspecific cue information into episodic-like memory. Thus, the tasks offer different ways to assess and further understand the mechanisms at work in social episodic-like memory processing.

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Aims: Flexor hallucis longus (FHL) tendon transfer is a well-recognized technique in the treatment of the neglected tendo Achillis (TA) rupture. Patients and Methods: We report a retrospective review of 20/32 patients who had undergone transtendinous FHL transfer between 2003 and 2011 for chronic TA rupture. Their mean age at the time of surgery was 53 years (22 to 83). The mean time from rupture to surgery was seven months (1 to 36). The mean postoperative follow-up was 73 months (29 to 120). Six patients experienced postoperative wound complications. Results: The mean postoperative Achilles tendon Total Rupture Score (ATRS) was 83 (40 to 100) and the mean American Orthopaedic Foot & Ankle Society (AOFAS) score was 94.3 (82 to 100). Tegner scoring showed a mean reduction of one level from the pre-injury level of activity. There was a mean reduction of 24% (4 to 54) in dynamometer-measured strength of ankle plantarflexion, in comparison with the non-operated side. The hallux had a mean of only 40% (2 to 90) strength of plantarflexion in comparison with the contralateral side. Conclusion: We conclude that transtendinous FHL transfer for neglected TA ruptures, with a long harvest to allow reattachment of the triceps surae, provides reliable long-term function and good ankle plantarflexion strength. Despite the loss of strength in hallux plantar flexion, there is little comorbidity from the FHL harvest. Cite this article: Bone Joint J 2018;100-B:584-9.

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Place and grid cells in the rodent hippocampal formation tend to fire spikes at successively earlier phases relative to the local field potential theta rhythm as the animal runs through the cell's firing field on a linear track. However, this 'phase precession' effect is less well characterized during foraging in two-dimensional open field environments. Here, we mapped runs through the firing fields onto a unit circle to pool data from multiple runs. We asked which of seven behavioural and physiological variables show the best circular-linear correlation with the theta phase of spikes from place cells in hippocampal area CA1 and from grid cells from superficial layers of medial entorhinal cortex. The best correlate was the distance to the firing field peak projected onto the animal's current running direction. This was significantly stronger than other correlates, such as instantaneous firing rate and time-in-field, but similar in strength to correlates with other measures of distance travelled through the firing field. Phase precession was stronger in place cells than grid cells overall, and robust phase precession was seen in traversals through firing field peripheries (although somewhat less than in traversals through the centre), consistent with phase coding of displacement along the current direction. This type of phase coding, of place field distance ahead of or behind the animal, may be useful for allowing calculation of goal directions during navigation.

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The hippocampal formation (HF) plays a key role in novelty detection, but the mechanisms remain unknown. Novelty detection aids the encoding of new information into memory-a process thought to depend on the HF and to be modulated by the theta rhythm of EEG. We examined EEG recorded in the HF of rats foraging for food within a novel environment, as it became familiar over the next five days, and in two more novel environments unexpectedly experienced in trials interspersed with familiar trials over three further days. We found that environmental novelty produces a sharp reduction in the theta frequency of foraging rats, that this reduction is greater for an unexpected environment than for a completely novel one, and that it slowly disappears with increasing familiarity. These results do not reflect changes in running speed and suggest that the septo-hippocampal system signals unexpected environmental change via a reduction in theta frequency. In addition, they provide evidence in support of a cholinergically mediated mechanism for novelty detection, have important implications for our understanding of oscillatory coding within memory and for the interpretation of event-related potentials, and provide indirect support for the oscillatory interference model of grid cell firing in medial entorhinal cortex.

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In a retrospective review of the radiographs taken for 113 acute scaphoid fractures, each view was assessed for the clarity of demonstration of the fracture. The X-rays on which diagnosis of fracture were made, were taken between 0 and 16 days after injury (mean, 2 days). Whenever a lateral, supinated oblique or elongated view was taken, the fracture was always seen clearly on an alternative view. We recommend the use of four views at initial presentation of suspected scaphoid fracture: PA and lateral to assess carpal alignment, with pronated oblique and ulnar deviated PA to detect the fracture.

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A model of place-cell firing is presented that makes quantitative predictions about specific place cells' spatial receptive fields following changes to the rat's environment. A place cell's firing rate is modeled as a function of the rat's location by the thresholded sum of the firing rates of a number of putative cortical inputs. These inputs are tuned to respond whenever an environmental boundary is at a particular distance and allocentric direction from the rat. The initial behavior of a place cell in any environment is simply determined by its set of inputs and its threshold; learning is not necessary. The model is shown to produce a good fit to the firing of individual place cells, and populations of place cells across environments of differing shape. The cells' behavior can be predicted for novel environments of arbitrary size and shape, or for manipulations such as introducing a barrier. The model can be extended to make behavioral predictions regarding spatial memory.

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The present study assesses the ability of four listeners with high-frequency, bilateral symmetrical sensorineural hearing loss to localize and detect a broadband click train in the frontal-horizontal plane, in quiet and in the presence of a white noise. The speaker array and stimuli are identical to those described by Lorenzi et al. (in press). The results show that: (1) localization performance is only slightly poorer in hearing-impaired listeners than in normal-hearing listeners when noise is at 0 deg azimuth, (2) localization performance begins to decrease at higher signal-to-noise ratios for hearing-impaired listeners than for normal-hearing listeners when noise is at +/- 90 deg azimuth, and (3) the performance of hearing-impaired listeners is less consistent when noise is at +/- 90 deg azimuth than at 0 deg azimuth. The effects of a high-frequency hearing loss were also studied by measuring the ability of normal-hearing listeners to localize the low-pass filtered version of the clicks. The data reproduce the effects of noise on three out of the four hearing-impaired listeners when noise is at 0 deg azimuth. They reproduce the effects of noise on only two out of the four hearing-impaired listeners when noise is at +/- 90 deg azimuth. The additional effects of a low-frequency hearing loss were investigated by attenuating the low-pass filtered clicks and the noise by 20 dB. The results show that attenuation does not strongly affect localization accuracy for normal-hearing listeners. Measurements of the clicks' detectability indicate that the hearing-impaired listeners who show the poorest localization accuracy also show the poorest ability to detect the clicks. The inaudibility of high frequencies, "distortions," and reduced detectability of the signal are assumed to have caused the poorer-than-normal localization accuracy for hearing-impaired listeners.

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The ability to localize a click train in the frontal-horizontal plane was measured in quiet and in the presence of a white-noise masker. The experiment tested the effects of signal frequency, signal-to-noise ratio (S/N), and masker location. Clicks were low-pass filtered at 11 kHz in the broadband condition, low-pass filtered at 1.6 kHz in the low-pass condition, and bandpass filtered between 1.6 and 11 kHz in the high-pass condition. The masker was presented at either -90, 0, or +90 deg azimuth. Six signal-to-noise ratios were used, ranging from -9 to +18 dB. Results obtained with four normal-hearing listeners show that (1) for all masker locations and filtering conditions, localization accuracy remains unaffected by noise until 0-6 dB S/N and decreases at more adverse signal-to-noise ratios, (2) for all filtering conditions and at low signal-to-noise ratios, the effect of noise is greater when noise is presented at +/- 90 deg azimuth than at 0 deg azimuth, (3) the effect of noise is similar for all filtering conditions when noise is presented at 0 deg azimuth, and (4) when noise is presented at +/- 90 deg azimuth, the effect of noise is similar for the broadband and high-pass conditions, but greater for the low-pass condition. These results suggest that the low- and high-frequency cues used to localize sounds are equally affected when noise is presented at 0 deg azimuth. However, low-frequency cues are less resistant to noise than high-frequency cues when noise is presented at +/- 90 deg azimuth. When both low- and high-frequency cues are available, listeners base their decision on the cues providing the most accurate estimation of the direction of the sound source (high-frequency cues). Parallel measures of click detectability suggest that the poorer localization accuracy observed when noise is at +/- 90 deg azimuth may be caused by a reduction in the detectability of the signal at the ear ipsilateral to the noise.

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We compare estimates of three-dimensional brain activity extracted from averaged and from selected single-trial magnetoencephalographic signals, in order to study activation sequences related to motor preparation, inhibition, and movement, cued on two tones (S1 and S2). We studied all possible hand-ear combinations in a right-handed subject in both initiation and inhibition, and found some marked differences between combinations. Averaging revealed activity in the right motor cortex in all combinations requiring movement inhibition, irrespective of laterality of finger and ear, and in the contralateral motor cortex during movement (but considerably reduced for the task with the practiced ear and finger). These activation patterns are seen in single trials with variability of latency but not position. In the average signal, a long silent period between the warning and imperative stimuli is seen; in single trials, however, recurring sequences of activation linking frontal and posterior areas are seen throughout the analysis period in all combinations. These results show that single-trial analysis is needed to understand all the significant neural correlates of this task.

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OBJECTIVE: To compare the performance and cost-effectiveness of cryopreserved homograft cardiac valves prepared on site to valves prepared commercially. DESIGN: A review of all patients who received homograft heart valves between January 1990 and December 1993, with cost-effectiveness analysis. Follow-up ranged from 1 to 37 months (mean 12 months). SETTING: Tertiary-care adult and pediatric hospitals. PATIENTS: All consecutive patients receiving homograft heart valves in either the aortic or right ventricular outflow tract (RVOT) position since on-site preparation of cryopreserved cardiac valves began in 1990. Forty-three patients received 47 homograft valve replacements: 18 in the aortic position and 29 in the RVOT position. No patients were lost to follow-up. MAIN OUTCOME MEASURES: Valve function as assessed by patient survival, actuarial freedom from reoperation and Doppler echocardiographic assessment of transvalvar gradients and valvar insufficiency. Cost-effectiveness as assessed by a formal evaluation of on-site costs compared with current prices for commercially prepared valves. RESULTS: There were four operative deaths but no late deaths. Four valves were removed. Freedom from reoperation at 3 years was 100% for aortic valve replacement and 85% for RVOT reconstruction. Echocardiographic follow-up of 34 of the remaining 39 patients showed mild or no insufficiency in 24 valves, moderate insufficiency in 8 valves and severe, but not clinically significant, insufficiency in 2 valves. The cost of on-site preparation of the valves was $1363 compared with $5040 for the commercially prepared valves, a cost saving for the group of $172,819. CONCLUSION: On-site preparation is an effective method of preparing cryopreserved cardiac valves and permits significant cost savings.

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We have used ultraviolet melting techniques to study the effect on stability of incorporating the nucleoside analogue 2'-deoxy-3-deazaadenosine (d3cA) into the duplex 5'-d(CGCAATCG)-3'-d(GCGTTAGC). Our results demonstrate that the successive replacement of dA by d3CA increasingly destabilises the duplex. The destabilising effect of this analogue is considerably enhanced as the pH is lowered and the results are consistent with protonation of 3-deazaadenine (probably at N-1) contributing to duplex destablisation. Surprisingly, the incorporation of d3CA does not significantly affect the binding of distamycin-A.

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Minkler, Gofman and Tandy (1970a, b) have recently reported data on the karyotype constitutions of human tissue culture cell lines and human tumours, as gathered by a semi-automatic chromosome analysis system. The data appears to show a relationship between the relative number of "number 16" chromosomes and malignancy. We have tested the ability of the "cutting line" approach they used to correctly classify chromosomes from a sample of 723 cells from 100 normal subjects. The cutting line scheme gave very different results from those of an experienced cytogeneticist. The method also failed to give correct average numbers of chromosomes per class. We are thus led to question the conclusions reached by Minkler et al. It appears possible that their relatively consistent finding of an excess of "number 16" chromosomes in their largely hyperploid material may be an artefact of their classification scheme, arising from measurement normalization problems, rather than a reflection of a real excess of "number 16" or even of "number 16-like" chromosomes.

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