(provided by candidate): The broad aim of the proposed research is to investigate how declarative memory processes within the medial temporal lobe (MIL) circuit are modulated by cognitive goals that bias processing toward the learning or the retrieval of information. Experiment 1 will use high-resolution functional MRI (fMRI) to test whether the MIL subregions that show novelty effects (greater activity to new vs. old stimuli) during encoding also exhibit recollection effects (greater activity to remembered old stimuli vs. new stimuli) during episodic retrieval. Such a finding would support a conceptualization of MIL function in which MTL processing of sensory stimuli is not dictated by their mnemonic history, but rather by one's mnemonic goals at the time of encounter. Experiment 2 will use high-resolution fMRI to assess whether there are circumstances in which MIL cortical regions-which typically show a diminished response to previously encountered relative to novel stimuli-can invert this response pattern and actively contribute to the recollection of sensory details associated with prior stimulus encounters. Given the distinct sensory inputs to the perirhinal and parahippocampal cortices, the engagement of these regions during episodic recollection is predicted to depend critically on the whether object-based or spatially-based information is being recollected. Experiment 3 will bear on the hypothesis that the ability to modulate the response profile of MTL regions in accordance with mnemonic goals depends on control mechanisms subserved by prefrontal cortex. Moreover, posterior parietal cortex is hypothesized to monitor mnemonic signals emerging from MTL or to direct attention to the internally-represented contents of retrieved memories. Experiment 3 will use whole-brain fMRI and functional connectivity analyses to examine how prefrontal and parietal regions interact with MTL to facilitate novelty encoding and episodic recollection. Delineating the manner in which MTL responses are influenced by top- down control signals will advance mechanistic accounts of declarative memory and provide insights into how mnemonic control processes break down when PFC and/or MTL function is compromised by schizophrenia, attention-deficit hyperactivity disorder, depression, aging, or dementia. Relevance: This research will use functional MRI to examine how our behavioral goals influence the neural processing of sensory information, serving either to promote new learning or the retrieval of relevant details from long-term memory. Characterizing how these control processes influence specific mechanisms within the medial temporal lobes will help us better understand the nature of memory impairments in clinical conditions that affect these structures, such as schizophrenia, depression, and dementia.
| Rissman, Jesse; Wagner, Anthony D (2012) Distributed representations in memory: insights from functional brain imaging. Annu Rev Psychol 63:101-28 |
| Rissman, Jesse; Greely, Henry T; Wagner, Anthony D (2010) Detecting individual memories through the neural decoding of memory states and past experience. Proc Natl Acad Sci U S A 107:9849-54 |
| Carr, Valerie A; Rissman, Jesse; Wagner, Anthony D (2010) Imaging the human medial temporal lobe with high-resolution fMRI. Neuron 65:298-308 |
