Recursos de colección

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Brain and Cognitive Sciences - Master's degree

Mostrando recursos 1 - 20 de 30

  1. A prefrontal source of visual target enhancement in the macaque area V4

    Ghadooshahy, Azriel (Azriel Sion)
    The ventral pre-arcuate area (VPA) in the primate prefrontal cortex has recently been found to play an important role in feature-based selection of visual targets in the context of a naturalistic free-gaze visual search task. While VPA neuronal activation was found to be necessary for behavioral performance as well as target selection in the FEF, its role in the broader context of the visual system remains to be addressed. To this end, we have interrogated the role of the VPA in mediating the effects of feature attention in the macaque visual area V4 by recording in V4 with and without...

  2. Improved methods for rapid and scalable tissue clearing and labeling

    Murray, Evan (Evan T.)
    Combined measurement of diverse molecular and anatomical traits that span multiple levels remains a major challenge in biology. Here, we introduce a simple method that enables proteomic imaging for scalable, integrated, high-dimensional phenotyping of both animal tissues and human clinical samples. This method, termed SWITCH, uniformly secures tissue architecture, native biomolecules, and antigenicity across an entire system by synchronizing the tissue preservation reaction. The heat- and chemical-resistant nature of the resulting framework permits multiple rounds (>20) of relabeling. We have performed 22 rounds of labeling of a single tissue with precise co-registration of multiple datasets. Furthermore, SWITCH synchronizes labeling reactions...

  3. Chronic stress-dependent activation of somatostatin neurons in the nucleus accumbens facilitates maladaptive eating behaviors

    Liu, Elizabeth, S.M. Massachusetts Institute of Technology
    Stressors are known to impact eating behaviors. However, recapitulating the intricate interplay between chronic stress and aberrant human eating patterns in an animal model remains a challenge. Notably, binge eating, a diagnostic feature associated with many types of eating abnormalities, particularly pertains to the binge eating disorder. To more closely investigate the etiology underlying eating behavior-associated maladaptation, the present study provides a novel and ethologically relevant animal model based on predatory odor stress. My data show that chronic stress in female mice selectively increases consumption of highly palatable, but not the regular, diet, when it is presented during a limited...

  4. Knockout of the glutamate transporter GLT-1 specifically from neurons drastically alters transcriptome profiles in CA3, CA1, and Striatum

    Houston, Alexander Cory Wright
    Precise regulation of glutamate homeostasis is critical for normal brain function, as its disruption can impair excitatory transmission and result in neurodegenerative and neuropsychiatric disorders. Critical to maintaining glutamate homeostasis is a family of sodium-dependent glutamate transporters. GLT-1, the major glutamate transporter, is responsible for >90% of brain glutamate uptake. While previously thought to exist solely on astrocytes, the Rosenberg lab has identified GLT-1 as the major, if not only, glutamate transporter associated with excitatory terminals, particularly in CA3 pyramidal neuron axon terminals within CA3 and CA1 as well as in cortical layer V pyramidal neuron axon terminals within striatum....

  5. Generation and tuning of learned sensorimotor behavior by multiple neural circuit architectures

    Lynn, Michael (Michael Benjamin)
    Organisms have a remarkable ability to respond to complex sensory inputs with intricate, tuned motor patterns. How does the brain organize and tune these motor responses, and are certain circuit architectures, or connectivity patterns, optimally suited for certain sensorimotor applications? This thesis presents progress towards this particular problem in three subprojects. The first section re-analyzes a large data set of single-unit recordings in zebra finch area HVC during singing. While HVC is known to be essential for proper expression of adult vocalization, its circuit architecture is contentious. Evidence is presented against the recently postulated gesture-trajectory extrema hypothesis for the organization...

  6. Investigating the influence of LH-projecting BLA neurons upon motivated behavioral responding and appetitive learning

    Eckhardt, Christine
    To optimize survival, organisms must be able to learn contingencies between external stimuli and rewards and appropriately respond to these associations. Deficits in reward-related learning or reward-seeking are thought to occur in a host of psychopathologies, including depression (Drevets, 2001), eating disorders (Wagner et al., 2007), and substance abuse (Wrase et al., 2007), such that improved understanding of reward processing could potentially aid in the development of therapies. Two neural regions, the basolateral amygdala (BLA) and lateral hypothalamus (LH), are both implicated in reward processing (Adamantidis et al., 2007; Anand and Brobeck, 1951; Brobeck, 1946; Gutierrez et al., 2011; Hoebel...

  7. Benchmarking models of the ventral stream

    Ardila, Diego S.M. Massachusetts Institute of Technology
    This work establishes a benchmark by which to measure models of the ventral stream using crowd-sourced human behavioral measurements. We collected human error patterns on an object recognition task across a variety of images. By comparing the error pattern of these models to the error pattern of humans, we can measure how similar to the human behavior the model's behavior is. Each model we tested was composed of two parts: an encoding phase which translates images to features, and a decoding phase which translates features to a classifier decision. We measured the behavioral consistency of three encoder models: a convolutional...

  8. Anthropomorphic bias in naming

    Turkel, William J. (William Joseph), 1967-
    by William Joseph Turkel.

  9. Individual differences in sentence processing

    Troyer, Melissa L
    This thesis aims to elucidate shared mechanisms between retrieval in sentence processing and memory retrieval processes in nonlinguistic domains using an individual differences approach. Prior research in individual differences in sentence processing has provided conflicting evidence as to whether the same memory mechanisms operate in linguistic processing, potentially a quite specialized cognitive domain, and in other, more general areas of cognition (Just & Carpenter, 1992; Caplan & Waters, 1999). This question has been primarily addressed from the point of view of capacity-based theories of working memory (Baddeley, 1986). Under these theories, verbal working memory is either comprised of multiple components...

  10. Viral delivery of recombinant growth hormone to rescue effects of chronic stress on hippocampal learning

    Saenz, Christopher M
    Chronic stress has been linked to variation in gene regulation in the hippocampus (HIP) among other areas. These lead to cytoskeletal and volumetric rearrangements in various nuclei of the central nervous system and are thought to contribute to several stress-sensitive disorders. One such gene that has been shown to be downregulated in HIP in response to stress is somatotropin, colloquially known as growth hormone (GH). These experiments were conducted to develop a novel assay for examination of working memory in rats and explore the nature of stress-induced impairment of hippocampal function and determine whether infusion of a modified herpes simplex...

  11. Prism adaptation in a case of cerebellar agenesis

    Rendon, Regina A
    Normal subjects adapt quickly to the displacing effects of prism goggles. A measure of this adaptation comes from the negative aftereffects in reaching that subjects show after the prism goggles are removed. Neural circuitry within the cerebellar cortex has been implicated as the site of plasticity for visuomotor adaptation. An opportunity to test a 15-year-old boy, A.C., with near complete cerebellar agenesis allowed us to determine whether cerebellar structures are critical for prism adaptation to occur. A.C. was tested on two separate occasions, twice using his left hand, and once using his right hand. He wore prism goggles while pointing...

  12. Synaptic plasticity in the MyosinVa mutant mouse

    Tunca, Cansu, 1977-
    The trafficking of essential proteins into spines is an important aspect of synaptic plasticity. MyosinVa, an actin-based motor protein, has been implicated in the synaptic delivery of AMPARs during LTP [1]. However an earlier study showed that LTP and LTD were unaffected in the MyosinVa-null dilute-lethal mice [2]. To evaluate the role of MyosinVa in synaptic plasticity, we studied different forms of LTP and LTD in the CA1 region of the hippocanmpus from MyosinVa dominant negative mutant flailer mouse using field potential recordings. Flailer mice showed no impairment of LTP or NMDAR-dependent LTD, consistent with the findings of the study...

  13. Judicious imitation : children differentially imitate deterministically and probabilistically effective actions

    Hooppell, Catherine Amanda Jane
    Three studies look at whether the assumption of causal determinism (the assumption that all else being equal, causes generate effects deterministically) affects children's imitation of modeled actions. We show that, even when the frequency of an effect is matched, both preschoolers and toddlers imitate actions more faithfully when modeled actions are deterministically rather than probabilistically effective. A third study suggests that preschoolers' imitation is affected, not just by whether the agent's goal is satisfied but also by whether the action is a reliable means to the goal. Children's tendency to generate variable responses to probabilistically effective modeled actions could support...

  14. Center-embedding and self-embedding in human language processing

    Thomas, James David, 1969-
    by James Davis Thomas.

  15. Seeking the neural basis of grammar : English noun and verb morphological processing investigated with rapid event-related fMRI and intracortical electrophysiology

    Sahin, Nedim T. (Nedim Turan), 1975-
    (cont.) the functionality of the fMRI data analysis and visualization tools used at Massachusetts General Hospital. I analyze and interpret an 18-subject fMRI experiment I ran using the new task design and software tools. Finally, I present preliminary findings on linguistic questions as well as the nature of fMRI signal, using direct Electrophysiological data recorded from electrodes implanted in the brains of two Epilepsy patients. These patients had electrodes implanted through or near classical language areas of their brains, as a necessary clinical step in locating and surgically removing the seizure-causing tissue. The main findings of this thesis are: 1.)...

  16. Development of and proposed applications for tetrodes in functional mapping of rodent sensorimotor striatum

    Iyengar, Deepa Radhakrishna, 1972-
    The Wilson-McNaughton tetrode preparation for awake, behaving rodents was adapted by a group of investigators for use in dorsolateral striatum. Measures were taken to improve the reliability of reaching the target area in the brain and the stability of the implanted tetrode drive over several weeks of recording. Novel methods were developed to confirm the dorsoventral level of tetrodes at intermediate stages of advancement during recording, and to reconstruct estimated directions and distances of recorded sources from tetrodes by post-hoc analysis. Alternative methods of source separation and data visualization were implemented. Additional refinements to improve unit separation within and across...

  17. Qualitative representation for recognition

    Thoresz, Keith John, 1972-
    by Keith John Thoresz.

  18. Qualitative representation for recognition

    Thoresz, Keith John, 1972-
    This thesis describes a representation for objects and scenes that is stable against variations in image intensity caused by illumination changes and tolerant to image degradations such as sensor noise. The representation, called a ratio-template, uses low-resolution ordinal contrast relationships as its matching primitives. The choice of these primitives was inspired not only by considerations of computational simplicity and robustness, but also by current knowledge of the early stages of visual processing in the primate brain. The resulting representation is biologically plausible, although there is currently no evidence to suggest that the representation is actually used by the primate visual...

  19. Issues in parallel stereo matching

    Gillett, Walter Eisner
    by Walter Eisner Gillett.

  20. Short-term recall of sentences : conceptual representation or plausible reconstruction

    Johnson, Susan Carol
    by Susan Carol Johnson.

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