Short-term maintenance of information is a fundamental aspect of human cognition that is compromised by a wide variety of mental health disorders including: Schizophrenia, ADHD, substance abuse disorders, Alzheimer's disease, Parkinson's disease, and AIDS related dementia. A deeper understanding of the basic neural mechanisms underlying short-term maintenance will lead to improved diagnostic, prognostic, and therapeutic procedures for these disorders. The proposed research will focus on three types of short-term maintenance: sensory attention, motor intention, and working memory. It is widely believed that sustained neural activity during a delay interval is the mechanism by which the brain performs these three cognitive processes. Posterior parietal cortex (PPC) has emerged as a particular focus for research on sustained delay-period activity related to attention, intention, and working memory. The proposed experiments will use fMRI to measure cortical activity in human subjects while they perform three closely related but complementary tasks that differ in their dependence on sensory attention, motor intention, and working memory. In the first task, subjects will perform an eye movement to a remembered location. In the second task, subjects will detect a luminance decrement at a cued location. In the third task, subjects will detect a small shift in the remembered location of a target. These three tasks place differential demands on intention, attention, and working memory. The first task emphasizes motor intention; in this task subjects will make eye movements to remembered locations whereas in the other two tasks they will have to accurately hold fixation. The second task emphasizes sensory attention; in this task subjects will attend to targets that are constantly illuminated whereas in the other two tasks they will remember the locations of targets that are no longer visible. The third task emphasizes spatial working memory; in this task subjects will remember the location of a target for later comparison whereas no spatial comparison is involved in the other two tasks. These three tasks will be used to achieve two central aims concerning the homology between human and monkey PPC and the functional role of human PPC in sensory attention, motor intention, and working memory.
The first aim i s to define each of several cortical areas, using experimental protocols that measure topographic representations of attention, intention, and working memory.
The second aim i s to test the hypothesis that these now pre-defined human cortical areas are functionally homologous to cortical areas in monkey PPC (particularly monkey area LIP), and to test the hypothesis that behavioral performance of each of the three tasks depends on the level of delay-period activity in these human cortical areas.
| Brennan, Jonathan; Nir, Yuval; Hasson, Uri et al. (2012) Syntactic structure building in the anterior temporal lobe during natural story listening. Brain Lang 120:163-73 |
| Pestilli, Franco; Carrasco, Marisa; Heeger, David J et al. (2011) Attentional enhancement via selection and pooling of early sensory responses in human visual cortex. Neuron 72:832-46 |
| Hasson, Uri; Malach, Rafael; Heeger, David J (2010) Reliability of cortical activity during natural stimulation. Trends Cogn Sci 14:40-8 |
| Offen, Shani; Gardner, Justin L; Schluppeck, Denis et al. (2010) Differential roles for frontal eye fields (FEFs) and intraparietal sulcus (IPS) in visual working memory and visual attention. J Vis 10:28 |
| Dinstein, Ilan; Thomas, Cibu; Humphreys, Kate et al. (2010) Normal movement selectivity in autism. Neuron 66:461-9 |
| Herrmann, Katrin; Montaser-Kouhsari, Leila; Carrasco, Marisa et al. (2010) When size matters: attention affects performance by contrast or response gain. Nat Neurosci 13:1554-9 |
| Reynolds, John H; Heeger, David J (2009) The normalization model of attention. Neuron 61:168-85 |
| Lauritzen, Thomas Z; D'Esposito, Mark; Heeger, David J et al. (2009) Top-down flow of visual spatial attention signals from parietal to occipital cortex. J Vis 9:18.1-14 |
| Offen, Shani; Schluppeck, Denis; Heeger, David J (2009) The role of early visual cortex in visual short-term memory and visual attention. Vision Res 49:1352-62 |
| Gardner, Justin L; Merriam, Elisha P; Movshon, J Anthony et al. (2008) Maps of visual space in human occipital cortex are retinotopic, not spatiotopic. J Neurosci 28:3988-99 |
Showing the most recent 10 out of 16 publications
