Sparse codes for speech predict spectrotemporal receptive fields in the inferior colliculus.

We have developed a sparse mathematical representation of speech that minimizes the number of active model neurons needed to represent typical speech sounds. The model learns several well-known acoustic features of speech such as harmonic stacks, formants, onsets and terminations, but we also find more exotic structures in the spectrogram representation of sound such as localized checkerboard patterns and frequency-modulated excitatory subregions flanked by suppressive sidebands. Moreover, several of these novel features resemble neuronal receptive fields reported in the Inferior Colliculus (IC), as well as auditory thalamus and cortex, and our model neurons exhibit the same tradeoff in spectrotemporal resolution as has been observed in IC. To our knowledge, this is the first demonstration that receptive fields of neurons in the ascending mammalian auditory pathway beyond the auditory nerve can be predicted based on coding principles and the statistical properties of recorded sounds.

N-of-1 Trial in Person with Pontine Stroke Receiving Repetitive Transcranial Magnetic Stimulation to Improve Hand Function.

Stroke characteristics vary widely between individuals making it difficult to assess the value of stroke rehabilitation interventions. To eliminate inter-subject variability, this study used an N-of-1 randomized, controlled design to explore the efficacy of repetitive transcranial magnetic stimulation (rTMS) in one unique individual with pontine stroke. We hypothesized that five days of active 6-Hz primed, low-frequency rTMS to the contralesional primary motor area (M1), combined with finger movement tracking training, would accomplish greater gains in hand function than sham rTMS combined with tracking training. We assessed hand function (Box and Block test and finger tracking test), cortical activation (laterality index during functional magnetic resonance imaging), and cortical excitability (interhemispheric inhibition testing (IHI) with transcranial magnetic stimulation (TMS)). Diffusion tensor imaging (DTI) assessed the integrity of his corticospinal tracts at baseline. Results showed no improvement in the Box and Block or finger tracking tests, unreliable IHI findings, and no change in laterality index following active rTMS. DTI suggested truncation of the left corticospinal tract (CST) at the pons. His non-dexterous hand movements combined with no elicitable motor evoked potentials with TMS to ipsilesional M1 and his DTI findings lead us to speculate a reticulospinal mechanism for preserving his rudimentary paretic hand control. We conclude that rTMS combined with tracking training was not effective in the absence of CST pathways and that research is needed to confirm markers of reticulospinal function in humans as an alternative to defective CST function.

HIV long-term non-progressors maintain brisk CD8 T cell responses to other viral antigens.

OBJECTIVE: To examine the specificity of heightened CD8 cell responses in HIV-1-infected long-term non-progressors. DESIGN: Cross-sectional study examining CD8 cell responses to hepatitis C virus (HCV) peptides in HCV-HIV LTNP (n = 6), HCV-HIV progressors (n = 11), HCV singly infected patients (n = 32), HCV singly infected patients with self-limited disease (n = 10), HIV singly infected progressors (n = 7) and HCV-negative, HIV-negative controls (n = 10). METHODS: The frequency of HCV-reactive interferon gamma-producing cells in peripheral blood was assayed by enzyme linked immunospot assay using a panel of 61 HCV-1-derived peptides. RESULTS: Five of six HCV-HIV LTNP had HCV-specific CD8 responses. In contrast, responses were observed in 2 of 32 HCV singly infected patients, 2 of the 10 HCV singly infected patients with self-limited disease, and 0 of 11 HCV-HIV progressors (P < 0.001). Both frequency of HCV-specific CD8 cells and number of HCV peptides recognized were greater in HCV-HIV LTNP than in other groups. CONCLUSIONS: HIV-infected LTNP maintain heightened CD8 cell responses to HCV in addition to heightened HIV specific responses. Common mechanisms may underlie preservation of CD8 immune responses in these individuals. An improved understanding of these mechanisms will help to gain insight into protective antiviral immunity as well as to the means whereby these viruses impair host defenses.

Port site metastasis of ovarian carcinoma remote from laparoscopic surgery for benign disease.

BACKGROUND: The use of laparoscopic surgical procedures has continued to expand due to the many advantages that this surgical approach offers. However, as we continue to realize the benefits and expand the scope of laparoscopic procedures, new complications may occur. CASE: This is the case of a 77-year-old gravida 2 para 2 who underwent exploratory laparotomy and surgical staging with optimal cytoreduction for Stage IIIC papillary serous ovarian carcinoma in February 1998. Her past surgical history was significant for total abdominal hysterectomy and left salpingo-oophorectomy in 1955 for symptomatic leiomyomata and for a laparoscopic cholecystectomy in July 1997. After initial platinum-based chemotherapy, she presented with an enlarging nodule at the right upper quadrant laparoscopic port site. Fine needle aspiration confirmed recurrent papillary serous ovarian carcinoma. After a discussion of her options, she elected to undergo surgical resection with postoperative salvage chemotherapy. CONCLUSION: Port site recurrences have been previously reported in patients who underwent initial surgical evaluation for ovarian carcinoma utilizing the laparoscopic approach. However, it is unusual for recurrent cancer to appear in port sites or operative incisions not related to the initial cancer surgery. This report serves to caution the gynecologic oncologist that the first evidence of recurrence may be at a laparoscopic port site from prior benign gynecologic or nongynecologic surgery.

Comprehensive determinant mapping of the hepatitis C-specific CD8 cell repertoire reveals unpredicted immune hierarchy.

While CD8 cells are thought to play an important role in the control hepatitis C infection, low frequencies of virus-specific cells and high numbers of potential determinants have made it challenging to obtain direct and comprehensive data regarding fine specificity and clonal size of the CD8 cells involved. Most assays suited for measuring CD8 cell frequencies require prior knowledge of immune dominant peptides. While there are excellent algorithms for predicting MHC-peptide binding strength for particular class I alleles, it is unknown how accurate these algorithms are in predicting the actual determinant recognized in an individual coexpressing other class I alleles. We used a high throughput ELISPOT approach to test for responses to every possible 9-mer determinant within the 191 residue hepatitis C core protein in addition to 61 previously defined CD8 cell determinants. The amino acid sequence of each determinant recognized was compared with HLA-binding predictions for the expressed class I alleles. These data show feasibility for and importance of comprehensive direct ex vivo monitoring, an approach which should facilitate design of antiviral immunotherapeutic strategies.