What'' and where'' in visual working memory: A computational neurodynamical perspective for integrating fMRI and single-neuron data

被引:88
作者
Deco, G
Rolls, ET [4 ]
Horwitz, B
机构
[1] ICREA, Barcelona, Spain
[2] Univ Pompeu Fabra, Barcelona, Spain
[3] Univ Oxford, Oxford OX1 2JD, England
[4] Natl Inst Deafness & Other Commun Disorders, Brain Imaging & Modeling Sect, NIH, Bethesda, MD 20892 USA
关键词
D O I
10.1162/089892904323057380
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Single-neuron recordings, functional magnetic resonance imaging ( fMRI) data, and the effects of lesions indicate that the prefrontal cortex (PFC) is involved in some types of working memory and related cognitive processes. Based on these data, two different models of the topographical and functional organization of the PFC have been proposed: organization-by-stimulus-domain, and organization-by-process. In this article, we utilize an integrate-and-fire network to model both single-neuron and fMRI data on short-term memory in order to understand data obtained in topologically different parts of the PFC during working memory tasks. We explicitly model the mechanisms that underlie working-memory-related activity during the execution of delay tasks that have a "what''-then-"where'' design ( with both object and spatial delayed responses within the same trial). The model contains different populations of neurons ( as found experimentally) in attractor networks that respond in the delay period to the stimulus object, the stimulus position, and to combinations of both object and position information. The pools are arranged hierarchically and have global inhibition through inhibitory interneurons to implement competition. It is shown that a biasing attentional input to define the current relevant information ( object or location) enables the system to select the correct neuronal populations during the delay period in what is a biased competition model of attention. The processes occurring at the AMPA and NMDA synapses are dynamically modeled in the integrate-and-fire implementation to produce realistic spiking dynamics. It is shown that the fMRI data characteristic of the dorsal PFC and linked to spatial processing and manipulation of items can be reproduced in the model by a high level of inhibition, whereas the fMRI data characteristic of the ventral PFC and linked to object processing can be produced by a lower level of inhibition, even though the network is itself topographically homogeneous with no spatial topology of the neurons. This article, thus, not only presents a model for how spatial versus object short-term memory could be implemented in the PFC, but also shows that the fMRI BOLD signal measured during such tasks from different parts of the PFC could reflect a higher level of inhibition dorsally, without this dorsal region necessarily being primarily spatial and the ventral region object-related.
引用
收藏
页码:683 / 701
页数:19
相关论文
共 64 条
[1]  
Abeles A, 1991, CORTICONICS
[2]   Model of global spontaneous activity and local structured activity during delay periods in the cerebral cortex [J].
Amit, DJ ;
Brunel, N .
CEREBRAL CORTEX, 1997, 7 (03) :237-252
[3]   Task-specific neural activity in the primate prefrontal cortex [J].
Asaad, WF ;
Rainer, G ;
Miller, EK .
JOURNAL OF NEUROPHYSIOLOGY, 2000, 84 (01) :451-459
[4]   Neural activity in the primate prefrontal cortex during associative learning [J].
Asaad, WF ;
Rainer, G ;
Miller, EK .
NEURON, 1998, 21 (06) :1399-1407
[5]  
Baddeley A., 1986, WORKING MEMORY
[6]   Stable and rapid recurrent processing in realistic autoassociative memories [J].
Battaglia, FP ;
Treves, A .
NEURAL COMPUTATION, 1998, 10 (02) :431-450
[7]   Effects of neuromodulation in a cortical network model of object working memory dominated by recurrent inhibition [J].
Brunel, N ;
Wang, XJ .
JOURNAL OF COMPUTATIONAL NEUROSCIENCE, 2001, 11 (01) :63-85
[8]   Dynamics of blood flow and oxygenation changes during brain activation: The balloon model [J].
Buxton, RB ;
Wong, EC ;
Frank, LR .
MAGNETIC RESONANCE IN MEDICINE, 1998, 39 (06) :855-864
[9]   A model for the coupling between cerebral blood flow and oxygen metabolism during neural stimulation [J].
Buxton, RB ;
Frank, LR .
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM, 1997, 17 (01) :64-72
[10]   A NEURAL BASIS FOR VISUAL-SEARCH IN INFERIOR TEMPORAL CORTEX [J].
CHELAZZI, L ;
MILLER, EK ;
DUNCAN, J ;
DESIMONE, R .
NATURE, 1993, 363 (6427) :345-347