Biomedical subjects
P Patton
Publications and source records attributed to P Patton.
Preimplantation genetic diagnosis.
Preimplantation genetic diagnosis (PGD) has now been used in human fertility centers for a decade. To this end, diagnostic analysis is conducted on polar bodies or single blastomeres from biopsied embryos before the embryos are transferred, allowing the selection of normal embryos before a pregnancy has been established. Advances in technology available for PGD are described, including fluorescent in situ hybridization (FISH), interphase chromosome conversion, comparative genomic hybridization (CGH), fluorescent polymerase chain reaction (PCR), multiplex PCR, and whole genome amplification. These techniques support the diagnosis of a number of diseases at the single-cell level.
The effects of telencephalic lesions on visually mediated prey orienting behavior in the leopard frog (Rana pipiens). II. The effects of limited lesions to the telencephalon.
Unilateral removal of the telencephalon in the leopard frog, Rana pipiens, produces a contralateral deficit in visual prey orienting behavior [Patton and Grobstein, 1997]. In mammals, such deficits are most commonly associated with damage to the isocortex, a pallial derived structure. In contrast, we here report that in leopard frogs, lesions that remove substantial areas of one telencephalic lobe, including virtually the entire pallium, have no discernible effect on visual orienting behavior. Restricted lesions to the ventrocaudal telencephalon, however, produce an effect that closely resembles that produced by the complete removal of one telencephalic lobe. The 'critical area' that is both included in all lesions that are effective in producing a severe deficit and excluded from all ineffective lesions includes a portion of the caudal striatum. The striatum is known to play a significant role in anuran vision. It thus seems likely that the deficit produced by unilateral removal of the telencephalon in the leopard frog is due specifically to the removal of the caudal striatum. Unilateral lesions to the striatum have previously been shown to produce a contralateral deficit in visual orienting behavior in cats, and a role for the striatonigral pathway in the production of the visual orienting deficit that follows visual cortex lesions has been proposed. The current findings call attention to the possible general importance of the striatum in the control of vertebrate visual orienting behaviors.
The effects of telencephalic lesions on visually mediated prey orienting behavior in the leopard frog (Rana pipiens). I. The effects of complete removal of one telencephalic lobe, with a comparison to the effects of unilateral tectal lobe lesions.
In this paper, we report studies aimed at characterizing the relationship between forebrain and midbrain systems involved in the control of prey orienting behavior in the leopard frog. In frogs, unilateral forebrain lesions, like unilateral tectal lobe lesions, have their most prominent effects in the contralateral monocular visual field. Such lesions produce partial reductions in response frequency in the binocular visual field as well. Similar sequelae follow unilateral tectal lobe removal. These findings suggest that the effects of unilateral forebrain removal can be largely attributed to removal of a facilitating influence on the tectal lobe on the same side of the brain. In the case of both forebrain and midbrain lesions, behavior was assayed not only in terms of the frequency with which animals responded to stimuli at various locations in the visual field (as is usually done) but also in terms of the latency of whatever responses were observed. A striking inverse relationship between response frequency and response latency was found, both in lesioned and in normal frogs. This relationship has not previously been noticed, doesn't appear to be an obvious consequence of any existing models of the neuronal circuitry underlying anuran orienting behavior, and is difficult to account for in terms of the time scales associated with axonal conduction times and synaptic delays. It may be easier to account for in terms of the responses to perturbation of large interacting systems of neurons, and this possibility seems worthy of further exploration.
The role of the Internet in systems integration.
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A computational model of vertical signal propagation in the primary visual cortex.
A computational model of the flow of activity in a vertically organized slab of cat primary visual cortex (area 17) has been developed. The membrane potential of each cell in the model, as a function of time, is given by the solution of a system of first order, coupled, non-linear differential equations. When firing threshold is exceeded, an action potential waveform is "pasted" in. The behavior of the model following a brief simulated stimulus to afferents from the dorsal lateral geniculate nucleus (dLGN) is explored. Excitatory and inhibitory post-synaptic potential (E and IPSP) latencies, as a function of cortical depth, were generated by the model. These data were compared with the experimental literature. In general, good agreement was found for EPSPs. Many disynaptic inhibitory inputs were found to be "masked" by the firing of action potentials in the model. To our knowledge this phenomenon has not been reported in the experimental literature. The model demonstrates that whether a cell exhibits disynaptic or polysynaptic PSP latencies is not a fixed consequence of anatomical connectivity, but rather, can be influenced by connection strengths, and may be influenced by the ongoing pattern of activity in the cortex.
A computational model of the vertical anatomical organization of primary visual cortex.
A method for modeling anatomical connectivity for a vertically organized slab of cortical tissue in mammalian primary visual cortex has been developed. The modeled slab covers 500 x 500 microns of cortical surface and extends vertically throughout the full depth of the cortex. The model slab was divided into 6 laminae and neuronal somata were distributed in three dimensions through the slab in accordance with experimentally derived cell densities. Axonal and dendritic arborizations were modeled as line segments. A total of 17 morphological types of neurons were included. Connectivity was established based on proximity between axonal and dendritic arbors. There is good general agreement between the vertical distribution of connections generated by the model and the vertical distribution of synapses observed for cat area 17. In all layers, fewer connections were generated in the model than synapses in cat area 17. This is due, at least in part, to the exclusion of long range intracortical projections and sources of afferent input other than the dorsal lateral geniculate nucleus from the model. The connection scheme described here will be used in conjunction with a physiology model to model vertical signal flow, and will be expanded further to model receptive fields of cortical neurons.
Diagnosis of cornual obstruction by transcervical fallopian tube cannulation.
Interstitial fallopian tube obstruction (IFTO) occurs in 15% of hysterosalpingograms (HSG) performed for infertility. Conventional HSG or laparoscopy may not differentiate cornual spasm or other temporary cause from true obstruction. We used transcervical cannulation of the proximal oviduct with a 3-F Teflon catheter and flexible guidewire 0.018 inch (0.043 cm) in diameter under hysteroscopic or fluoroscopic guidance to evaluate IFTO in 28 patients. Fluoroscopic catheterization techniques with selective salpingography demonstrated patency in 84% of obstructed tubes. Hysteroscopic cannulation with direct visualization by laparoscopy or laparotomy was successful in 92%. In one patient, perforation of the isthmus occurred without sequelae. Transcervical coaxial cannulation of the proximal oviduct is an effective method for evaluating cornual obstruction.
Literacy and self-reported educational levels in relation to Mini-mental State Examination scores.
BACKGROUND AND OBJECTIVES: Because of its brevity and ease of use, the Mini-mental State Examination (MMSE) is commonly used to screen and follow patients with cognitive impairment. This pilot study attempted to determine the relationships between literacy, age, and self-reported educational level and the total MMSE score. METHODS: Cross-sectional analysis of all patients was followed by a family practice group at five local nursing homes. The associations between the patients' MMSE scores; literacy, as measured by the Rapid Estimate of Adult Literacy in Medicine (REALM); self-reported educational level; and age were determined using Pearson's correlation coefficient and stepwise multivariate linear regression. RESULTS: A total of 105 patients completed the study. Linear regression analysis showed that MMSE scores were significantly predicted by REALM score (P < .001) and the patient's age (P < .02). However, after accounting for REALM score and age, the self-reported educational level was not related to the MMSE score (P < .8). A significant relationship was seen between the REALM score and the subjects' self-reported educational levels (r = .44, P < .001) but not the subjects' ages (r = -.17, P < 0.09). A significant linear correlation was found between the MMSE and REALM scores (r = .71, P < .0001) and a significant inverse correlation was seen between MMSE scores and the patients' ages (r = -.28, P < .004). The correlation coefficient between the patients' MMSE scores and the self-reported educational levels was .33 (P < .0007). CONCLUSIONS: Practitioners who rely on the MMSE should be aware that patients may score in the demented range because they cannot read well enough to accurately complete the test. Literacy testing with REALM or other instruments may help identify such patients.