Distinct Actin and Lipid Binding Sites in Ysc84 Are Required during Early Stages of Yeast Endocytosis.

During endocytosis in S. cerevisiae, actin polymerization is proposed to provide the driving force for invagination against the effects of turgor pressure. In previous studies, Ysc84 was demonstrated to bind actin through a conserved N-terminal domain. However, full length Ysc84 could only bind actin when its C-terminal SH3 domain also bound to the yeast WASP homologue Las17. Live cell-imaging has revealed that Ysc84 localizes to endocytic sites after Las17/WASP but before other known actin binding proteins, suggesting it is likely to function at an early stage of membrane invagination. While there are homologues of Ysc84 in other organisms, including its human homologue SH3yl-1, little is known of its mode of interaction with actin or how this interaction affects actin filament dynamics. Here we identify key residues involved both in Ysc84 actin and lipid binding, and demonstrate that its actin binding activity is negatively regulated by PI(4,5)P2. Ysc84 mutants defective in their lipid or actin-binding interaction were characterized in vivo. The abilities of Ysc84 to bind Las17 through its C-terminal SH3 domain, or to actin and lipid through the N-terminal domain were all shown to be essential in order to rescue temperature sensitive growth in a strain requiring YSC84 expression. Live cell imaging in strains with fluorescently tagged endocytic reporter proteins revealed distinct phenotypes for the mutants indicating the importance of these interactions for regulating key stages of endocytosis.

Relevance of early head CT scans following neurosurgical procedures: an analysis of 892 intracranial procedures at Rush University Medical Center.

OBJECT: Early postoperative head CT scanning is routinely performed following intracranial procedures for detection of complications, but its real value remains uncertain: so-called abnormal results are frequently found, but active, emergency intervention based on these findings may be rare. The authors' objective was to analyze whether early postoperative CT scans led to emergency surgical interventions and if the results of neurological examination predicted this occurrence. METHODS: The authors retrospectively analyzed 892 intracranial procedures followed by an early postoperative CT scan performed over a 1-year period at Rush University Medical Center and classified these cases according to postoperative neurological status: baseline, predicted neurological change, unexpected neurological change, and sedated or comatose. The interpretation of CT results was reviewed and unexpected CT findings were classified based on immediate action taken: Type I, additional observation and CT; Type II, active nonsurgical intervention; and Type III, surgical intervention. Results were compared between neurological examination groups with the Fisher exact test. RESULTS: Patients with unexpected neurological changes or in the sedated or comatose group had significantly more unexpected findings on the postoperative CT (p < 0.001; OR 19.2 and 2.3, respectively) and Type II/III interventions (p < 0.001) than patients at baseline. Patients at baseline or with expected neurological changes still had a rate of Type II/III changes in the 2.2%-2.4% range; however, no patient required an immediate return to the operating room. CONCLUSIONS: Over a 1-year period in an academic neurosurgery service, no patient who was neurologically intact or who had a predicted neurological change required an immediate return to the operating room based on early postoperative CT findings. Obtaining early CT scans should not be a priority in these patients and may even be cancelled in favor of MRI studies, if the latter have already been planned and can be performed safely and in a timely manner. Early postoperative CT scanning does not assure an uneventful course, nor should it replace accurate and frequent neurological checks, because operative interventions were always decided in conjunction with the neurological examination.

A novel actin-binding motif in Las17/WASP nucleates actin filaments independently of Arp2/3.

BACKGROUND: Actin nucleation is the key rate-limiting step in actin polymerization, and tight regulation of this process is critical to ensure that actin filaments form only at specific regions of the cell. Las17 is the primary activator of Arp2/3-driven actin nucleation in yeast and is required for membrane invagination during endocytosis. Its mammalian homolog, WASP, has also been studied extensively as an activator of Arp2/3-driven actin polymerization. In both Las17 and WASP, actin nucleation activity is attributed to an ability to bind actin through a WH2 domain and to bind Arp2/3 through an acidic region. The central region of both Las17 and WASP is rich in proline residues and is generally considered to bind to SH3-domain-containing proteins. RESULTS: We have identified a novel actin-binding activity in the polyproline domain of both yeast Las17 and mammalian WASP. The polyproline domain of Las17 is also able to nucleate actin filaments independently of Arp2/3. Mutational analysis reveals that proline residues are required for this nucleation activity and that the binding site on actin maps to a region distinct from those used by other nucleation activities. In vivo analysis of yeast strains expressing las17 mutated in the WH2 domain, one of its proline motifs, or both shows additive defects in actin organization and endocytosis, with the proline mutant conferring more severe phenotypes than the WH2 mutant. CONCLUSIONS: Our data demonstrate a new actin-binding and nucleation mechanism in Las17/WASP that is required for its function in actin regulation during endocytosis.

Frameless deep brain stimulation using intraoperative O-arm technology. Clinical article.

OBJECT: Correct lead location in the desired target has been proven to be a strong influential factor for good clinical outcome in deep brain stimulation (DBS) surgery. Commonly, a surgeon's first reliable assessment of such location is made on postoperative imaging. While intraoperative CT (iCT) and intraoperative MR imaging have been previously described, the authors present a series of frameless DBS procedures using O-arm iCT. METHODS: Twelve consecutive patients with 15 leads underwent frameless DBS placement using electrophysiological testing and O-arm iCT. Initial target coordinates were made using standard indirect and direct assessment. Microelectrode recording (MER) with kinesthetic responses was performed, followed by microstimulation to evaluate the side-effect profile. Intraoperative 3D CT acquisitions obtained between each MER pass and after final lead placement were fused with the preoperative MR image to verify intended MER movements around the target area and to identify the final lead location. Tip coordinates from the initial plan, final intended target, and actual lead location on iCT were later compared with the lead location on postoperative MR imaging, and euclidean distances were calculated. The amount of radiation exposure during each procedure was calculated and compared with the estimated radiation exposure if iCT was not performed. RESULTS: The mean euclidean distances between the coordinates for the initial plan, final intended target, and actual lead on iCT compared with the lead coordinates on postoperative MR imaging were 3.04 ± 1.45 mm (p = 0.0001), 2.62 ± 1.50 mm (p = 0.0001), and 1.52 ± 1.78 mm (p = 0.0052), respectively. The authors obtained good merging error during image fusion, and postoperative brain shift was minimal. The actual radiation exposure from iCT was invariably less than estimates of exposure using standard lateral fluoroscopy and anteroposterior radiographs (p < 0.0001). CONCLUSIONS: O-arm iCT may be useful in frameless DBS surgery to approximate microelectrode or lead locations intraoperatively. Intraoperative CT, however, may not replace fundamental DBS surgical techniques such as electrophysiological testing in movement disorder surgery. Despite the lack of evidence for brain shift from the procedure, iCT-measured coordinates were statistically different from those obtained postoperatively, probably indicating image merging inaccuracy and the difficulties in accurately denoting lead location. Therefore, electrophysiological testing may truly be the only means of precisely knowing the location in 3D space intraoperatively. While iCT may provide clues to electrode or lead location during the procedure, its true utility may be in DBS procedures targeting areas where electrophysiology is less useful. The use of iCT appears to reduce radiation exposure compared with the authors' traditional frameless technique.

Medically intractable temporal lobe epilepsy in patients with normal MRI: surgical outcome in twenty-one consecutive patients.

INTRODUCTION: Abnormal MRI findings localizing to the mesial temporal lobe predict a favorable outcome in temporal lobe epilepsy surgery. The purpose of this study is to summarize the surgical outcome of patients who underwent a tailored antero-temporal lobectomy (ATL) with normal 1.5 T MRI. Specifically, factors that may be associated with favorable post-surgical seizure outcome are evaluated. METHODS: A retrospective analysis of the Rush University Medical Center surgical epilepsy database between 1992 and 2003 was performed. Patients who underwent an ATL and had a normal MRI study documented with normal volumetric measurements of hippocampal formations and the absence of any other MRI abnormality were selected for this study. Demographic information was collected on all patients. Seizure outcomes were evaluated using Engel's classification. A two-sided Fisher exact test with Bonferroni correction was performed in statistical analyses. RESULTS: Twenty-one (21) patients met the inclusion criteria of normal 1.5 T MRI and underwent a tailored temporal lobectomy. Mean age at time of surgery was 28 years (SD=8.1, range 11-44) and mean duration of the seizure disorder was 13.4 years (range 2-36). Risk factors for epilepsy included head injury (n=4), encephalitis (n=3), febrile seizures (n=2), and 12 patients had no risk factors. Pathological evaluation of resected tissue revealed no abnormal pathology in 12/21 patients (57%). After a mean 4.8 years follow-up post-surgical period, 15/21 (71%) patients were free of disabling seizures (Engel I outcome). At 8.3 years follow-up, 13/21 (62%) patients had similar results. Absence of prior epilepsy risk factors was the only statistically significant predictor of an Engel class I outcome (p<0.0022). CONCLUSION: Patients with medically intractable epilepsy and normal MRI appear to benefit from epilepsy surgery. Absence of prior epilepsy risk factors may be a positive prognostic factor.

Occult middle fossa encephaloceles in patients with temporal lobe epilepsy.

OBJECTIVE: Middle fossa encephaloceles are rare structural defects previously reported to cause complex partial seizures. Their debated etiology is either by failed union of temporal and sphenoid bone ossification centers or by erosion of the middle fossa floor secondary to pressure phenomena. Although magnetic resonance imaging (MRI) often reveals abnormalities, the actual encephalocele may not be identified preoperatively. METHODS: We present three cases of middle fossa encephaloceles that were identified intraoperatively and provide a review of the relevant literature. RESULTS: All three of our case presentations demonstrate patients with medically intractable epilepsy and intraoperative findings of middle fossa encephaloceles. In all patients, careful retrospective analysis of preoperative imaging provided clues to these encephaloceles, although none were suspected before surgery. After resection of the area all patients had improved seizure outcome. CONCLUSION: Middle fossa encephaloceles should be recognized as a potential source of epileptic pathology in patients with complex partial seizures. Although only 12 cases are reported in the literature, we believe that this phenomenon may be more common than previously recognized. We suggest that simple resection of the encephalocele alone may result in long-lasting, excellent seizure outcomes without amygdalohippocampectomy.

The effects of sleeping position on ventilatory responses to carbon dioxide in premature infants.

BACKGROUND: The prone sleeping position, particularly in prematurely born infants, is associated with an increased risk of sudden infant death syndrome. A possible mechanism is an impaired ability to respond to respiratory compromise. The hypothesis that the ventilatory response to a carbon dioxide (CO(2)) challenge in convalescent, prematurely born infants would be lower in the prone compared with the supine position was therefore tested. METHODS: In each position, ventilatory responses to increasing levels of inspired CO(2) were assessed. The airway pressure change after the first 100 ms of an occluded inspiration (P(0.1)) and the maximum inspiratory pressure with an occluded airway during crying (P(imax)) were measured; the ratio of the P(0.1) to the P(imax) at each inspired CO(2) level and the slope of the P(0.1)/P(imax) response were calculated. Chest and abdominal wall asynchrony was assessed using inductance plethysmography and functional residual capacity (FRC) measured using a helium gas dilution technique. RESULTS: Eighteen infants with a median postmenstrual age of 35 (range 35-37) weeks were studied. In the prone versus the supine position, the mean P(0.1) (p=0.002), the mean P(imax) (p=0.006), the increase in P(0.1) with increasing CO(2) (p=0.007) and the P(0.1)/P(imax) response slope (p=0.007) were smaller. Thoracoabdominal asynchrony was not significantly influenced by position or inspired CO(2). FRC was higher in the prone position (p=0.019). CONCLUSIONS: Convalescent, prematurely born infants have a reduced ventilatory response to CO(2) challenge in the prone position, suggesting they may have an impaired ability to respond to respiratory compromise in that position.

Neuro-critical care skills training using a human patient simulator.

BACKGROUND: Neurosurgical trainees regularly encounter critical care situations. Traditionally, education was accomplished through lecture and experience. Increasingly, human patient simulators (HPS) are employed, allowing trainees to sharpen skills in a safe and realistic environment. We describe our experience using HPS in neurosurgical training. METHODS: We developed a critical care training program for residents and medical students using HPS. We used a hi-fidelity, lifelike Human Patient Simulator™ (HPS™) produced by Medical Education Technologies, Inc.™ to simulate realistic scenarios for trainee education. Topics included spinal shock, closed head injury, and cerebral vasospasm. A three-way evaluation model was employed to test validity, including pre- and post-exercise testing, survey feedback, and videotaped replay. The simulation exercises were conducted by a neuro-critical care attending, a senior neurosurgical resident, and a HPS technician. RESULTS: We currently have 29 participants. On a 20-point critical care multiple-choice exam for these participants, average improvement has been 4.5 points or 25%. In subgroup analysis, average improvement was 4.75 points (24%) amongst neurosurgery residents, 3.07 points (18%) amongst neurology residents, 7 points (38%) amongst general surgery residents, and 7 points (38%) amongst senior medical students. Post-exercise evaluations were overwhelmingly positive. CONCLUSIONS: Neurosurgical critical care education is important for safe and effective care for patients. Clinical experience and didactic lectures help trainees obtain a solid knowledge base, but do not provide the benefit for learning in a fail-safe environment. Through the use of HPS, we have enhanced the critical care education of our trainees.

Position and ventilatory response to added dead space in prematurely born infants.

OBJECTIVES: Prematurely born infants are at increased risk of sudden infant death syndrome (SIDS) if slept prone. WORKING HYPOTHESIS: Prematurely born infants would have an impaired response to an added dead space and lower respiratory muscle strength in the prone compared to the supine position. STUDY DESIGN: Prospective study. PATIENT-SUBJECT SELECTION: Twenty-five infants, median gestational age of 30 (range 26-32) weeks. METHODOLOGY: The infants were studied supine and prone at a median of 36 weeks postmenstrual age. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The maximum inspiratory occlusion pressure generated (MIOP) and the pressure generated over the first 100 msec (P(0.1)) during airway occlusion were assessed. RESULTS: The median time constant was longer (26 (range 8-106) sec vs. 22 (range 6-92) sec (P = 0.045)) and the median MIOP (P = 0.001) and P(0.1) (P = 0.003) were lower in the prone compared to the supine position. CONCLUSION: Prematurely born infants have a dampened response to tube breathing and reduced respiratory muscle strength in the prone compared to the supine position, which may contribute to their increased vulnerability to SIDS in the prone position.

Fabrication of highly-ordered TiO(2) nanotube arrays and their use in dye-sensitized solar cells.

Highly ordered TiO(2) nanotubes were successfully fabricated using a nanoporous alumina templating method. A modified sol-gel route was used to infiltrate the alumina pores with Ti(OC(3)H(7))(4) which was subsequently converted into TiO(2) nanotubes. The average external diameter, tube lengths, and wall thickness achieved were 295 nm, 6-15 microm, and 21-42 nm, respectively. Diffraction data reveals that the nanotubes consist solely of the anatase phase. Dye-sensitized solar cells using TiO(2) nanotube arrays as the working electrode yielded power conversion efficiencies as high as 3.5% with a maximum incident photon-to-current conversion efficiency of 20% at 520 nm.

The WASP homologue Las17 activates the novel actin-regulatory activity of Ysc84 to promote endocytosis in yeast.

Actin plays an essential role in many eukaryotic cellular processes, including motility, generation of polarity, and membrane trafficking. Actin function in these roles is regulated by association with proteins that affect its polymerization state, dynamics, and organization. Numerous proteins have been shown to localize with cortical patches of yeast actin during endocytosis, but the role of many of these proteins remains poorly understood. Here, we reveal that the yeast protein Ysc84 represents a new class of actin-binding proteins, conserved from yeast to humans. It contains a novel N-terminal actin-binding domain termed Ysc84 actin binding (YAB), which can bind and bundle actin filaments. Intriguingly, full-length Ysc84 alone does not bind to actin, but binding can be activated by a specific motif within the polyproline region of the yeast WASP homologue Las17. We also identify a new monomeric actin-binding site on Las17. Together, the polyproline region of Las17 and Ysc84 can promote actin polymerization. Using live cell imaging, kinetics of assembly and disassembly of proteins at the endocytic site were analyzed and reveal that loss of Ysc84 and its homologue Lsb3 decrease inward movement of vesicles consistent with a role in actin polymerization during endocytosis.

Incidental retrieval of emotional contexts in post-traumatic stress disorder and depression: an fMRI study.

In the present study, we used fMRI to assess patients suffering from post-traumatic stress disorder (PTSD) or depression, and trauma-exposed controls, during an episodic memory retrieval task that included non-trauma-related emotional information. In the study phase of the task neutral pictures were presented in emotional or neutral contexts. Participants were scanned during the test phase, when they were presented with old and new neutral images in a yes/no recognition memory task. fMRI results for the contrast between old and new items revealed activation in a predominantly left-sided network of cortical regions including the left middle temporal, bilateral posterior cingulate, and left prefrontal cortices. Activity common to all three groups when correctly judging pictures encoded in emotional contexts was much more limited. Relative to the control and depressed groups the PTSD group exhibited greater sensitivity to correctly recognised stimuli in the left amygdala/ventral striatum and right occipital cortex, and more specific sensitivity to items encoded in emotional contexts in the right precuneus, left superior frontal gyrus, and bilateral insula. These results are consistent with a substantially intact neural system supporting episodic retrieval in patients suffering from PTSD. Moreover, there was little indication that PTSD is associated with a marked change in the way negatively valenced information, not of personal significance, is processed.

Spinal epidural abscess associated with infliximab treatment for psoriatic arthritis. Case report.

Tumor necrosis factor-alpha inhibitors are used to treat numerous chronic inflammatory and rheumatological diseases, such as Crohn disease, rheumatoid arthritis, and psoriatic arthritis. Because the mechanism of these inhibitors is to decrease the body's inflammatory response, the primary complication of treatment is infection. The authors present the first case of a spinal epidural abscess in a patient receiving long-term infliximab therapy for severe psoriatic arthritis. Infliximab and its side-effect profile are discussed, along with other associated complications.

Bistability in doped organic thin film transistors.

Organic thin film transitors (TFTs) with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid), PEDOT:PSS, as the active layer and cross-linked, layer-by-layer assembled poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) multilayers as the gate dielectric layer were investigated. A combination of spectroscopic data and device performance characteristics was used to study the behavior of these TFT devices under a variety of controlled environmental test conditions. It was shown that depletion and recovery of the device can be induced to occur by a means that is consistent with the electrochemical oxidation and reduction of water contained in the film. In addition to acting as a reactant, moisture also acts as a plasticizer to control the mobility of other species contained in the film and thereby permits bistable operation of these devices. Raman spectroscopy was used to show that the observed device switching behavior is due to a change in the PEDOT doping level.

Fabrication of organic thin-film transistors using layer-by-layer assembly.

Layer-by-layer assembly is presented as a deposition technique for the incorporation of ultrathin gate dielectric layers into thin-film transistors utilizing a highly doped organic active layer. This deposition technique enables the fabrication of device structures with a controllable gate dielectric thickness. In particular, devices with a dielectric layer comprised of poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) bilayer films were fabricated to examine the properties of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as the transistor active layer. The transistor Ion/off ratio and switching speed are shown to be controlled by the gate bias, which is dependent upon the voltage applied and the number of bilayers deposited for the gate dielectric. The devices operate in the depletion mode as a result of dedoping of the active layer with the application of a positive gate bias. The depletion and recovery rate are highly dependent on the level of hydration in the film and the environment under which the device is operated. These observations are consistent with an electrochemical dedoping of the conducting polymer during operation.

Task and content modulate amygdala-hippocampal connectivity in emotional retrieval.

The ability to remember emotional events is crucial for adapting to biologically and socially significant situations. Little is known, however, about the nature of the neural interactions supporting the integration of mnemonic and emotional information. Using fMRI and dynamic models of effective connectivity, we examined regional neural activity and specific interactions between brain regions during a contextual memory retrieval task. We independently manipulated emotional context and relevance of retrieved emotional information to task demands. We show that retrieval of emotionally valenced contextual information is associated with enhanced connectivity from hippocampus to amygdala, structures crucially involved with encoding of emotional events. When retrieval of emotional information is relevant to current behavior, amygdala-hippocampal connectivity increases bidirectionally, under modulatory influences from orbitofrontal cortex, a region implicated in representation of affective value and behavioral guidance. Our findings demonstrate that both memory content and behavioral context impact upon large scale neuronal dynamics underlying emotional retrieval.

Modulation of retrieval processing reflects accuracy of emotional source memory.

There is considerable evidence that encoding and consolidation of memory are modulated by emotion, but the retrieval of emotional memories is not well characterized. Here we manipulated the emotional context with which affectively neutral stimuli were associated during encoding, allowing us to examine neural activity associated with retrieval of emotional memories without confounding the emotional attributes of cue items and the retrieved context. Using a source memory procedure we were also able to compare how retrieval processing was modulated when the emotional encoding context was recollected or not. An interaction between emotional encoding context and accuracy of source memory revealed that successful retrieval of emotional context was associated with activity in left amygdala, and a left frontotemporal network including anterior insula, prefrontal cortex and cingulate. In contrast, when contextual retrieval was unsuccessful, items encoded in emotional contexts elicited enhanced activity in right amygdala and a right-lateralized network that included extrastriate visual areas. These findings indicate distinct effects of emotion on successful and unsuccessful retrieval of source information, including lateralization of amygdala responses.

Open Bankart repair versus arthroscopic repair with transglenoid sutures or bioabsorbable tacks for Recurrent Anterior instability of the shoulder: a meta-analysis.

BACKGROUND: In published comparative studies, it remains unknown if arthroscopic techniques for performing Bankart repair for anterior shoulder instability equal the success of open repair. HYPOTHESIS: The current literature supports a lower rate of recurrent instability after open Bankart repair compared to arthroscopic repair with bioabsorbable tacks or transglenoid sutures. STUDY DESIGN: Meta-analysis. METHODS: A Medline search identified all randomized controlled trials or cohort studies that directly compared open repair to arthroscopic techniques of Bankart repair for traumatic, unilateral, recurrent anterior instability. Data collected from each study included patient demographics, surgical technique, rehabilitation, outcome, and complications. RESULTS: Six studies met all inclusion criteria. There were 172 patients in the arthroscopic group (90 patients with transglenoid sutures, 77 patients with arthroscopic tacks, and 5 patients with suture anchors) and 156 patients in the open group. The groups were similar in demographic characteristics. When comparing the arthroscopic to the open group, there was a significantly higher rate of recurrent dislocation (12.6% vs 3.4%; P = .01) and total recurrence (recurrent dislocation or subluxation) (20.3% vs 10.3%; P = .01). In addition, there was a higher proportion of patients with an excellent or good postoperative Rowe score in the open group (88%) than in the arthroscopic group (71%) (P = .01). CONCLUSIONS: Arthroscopic Bankart repair using transglenoid sutures or bioabsorbable tacks results in a higher rate of recurrence of instability compared to open techniques. Studies comparing open repair to newer arthroscopic techniques using suture anchor fixation and capsular plication are necessary.

Event-related potential correlates of the retrieval of emotional and nonemotional context.

In two experiments, we examined event-related potentials (ERPs) elicited in an old/new recognition memory test by emotionally neutral visual objects that, at encoding, had been associated with neutrally, negatively, or positively valenced background contexts. In Experiment 2, subjects also judged the context in which the item had been studied. In Experiment 1, "left parietal" old/new ERP effects were elicited by correctly recognized items. Items encoded in emotional contexts, but not those studied in neutral contexts, elicited additional effects early in the recording epoch over lateral temporal scalp and, later, over left temporo-frontal scalp. In Experiment 2, "left parietal" and "right frontal" ERP effects were elicited by recognized items that attracted correct source judgments. Additional effects, an early lateral temporal positivity and a late-onset, left-sided positivity, were elicited by items studied in emotionally valenced contexts and attracting correct source judgments. Together, the findings indicate that retrieval processing is influenced by the emotional valence of the context in which an item is encoded, regardless of whether contextual information is task relevant.

Remembrance of odors past: human olfactory cortex in cross-modal recognition memory.

Episodic memory is often imbued with multisensory richness, such that the recall of an event can be endowed with the sights, sounds, and smells of its prior occurrence. While hippocampus and related medial temporal structures are implicated in episodic memory retrieval, the participation of sensory-specific cortex in representing the qualities of an episode is less well established. We combined functional magnetic resonance imaging (fMRI) with a cross-modal paradigm, where objects were presented with odors during memory encoding. We then examined the effect of odor context on neural responses at retrieval when these same objects were presented alone. Primary olfactory (piriform) cortex, as well as anterior hippocampus, was activated during the successful retrieval of old (compared to new) objects. Our findings indicate that sensory features of the original engram are preserved in unimodal olfactory cortex. We suggest that reactivation of memory traces distributed across modality-specific brain areas underpins the sensory qualities of episodic memories.