PubMed Health⌕ Search

PubMed · 10412065

Feedback interactions between neuronal pointers and maps for attentional processing.

Abstract

Neural networks combining local excitatory feedback with recurrent inhibition are valuable models of neocortical processing. However, incorporating the attentional modulation observed in cortical neurons is problematic. We propose a simple architecture for attentional processing. Our network consists of two reciprocally connected populations of excitatory neurons; a large population (the map) processes a feedforward sensory input, and a small population (the pointer) modulates location and intensity of this processing in an attentional manner dependent on a control input to the pointer. This pointer-map network has rich dynamics despite its simple architecture and explains general computational features related to attention/intention observed in neocortex, making it interesting both theoretically and experimentally.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

R Hahnloser, R J Douglas, M Mahowald, K Hepp. 1999. Feedback interactions between neuronal pointers and maps for attentional processing.. https://doi.org/10.1038/11219

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Deficits in language-mediated mental operations in patients with schizophrenia.

We found previously that a subgroup of schizophrenic patients who passed screening tests of attentional competence showed memory deficits on word memory tasks, but were comparable with controls on tone memory tasks. To better understand the nature of language-specific memory deficits in this subgroup of patients, the present experiment was designed to bypass early perceptual processing of verbal material and determine if patients continue to show impaired performance on verbal memory tasks. Patients who passed the screening tests ('discriminator' patients; DSz) received four serial position tasks. In two, familiar sounds or line drawings were presented and subjects were required to remember the word associated with each stimulus item. In the other two, subjects received hard-to-label auditory and visual stimuli (birdsongs or snowflakes).DSz patients showed large memory deficits compared with controls when required to remember words associated with the familiar sounds or drawings, providing clear evidence of deficits in verbal memory processes independent of sensory processing of verbal stimuli. The interaction between diagnosis and labeling was highly significant, confirming that these patients have particular difficulty with verbal as opposed to non-verbal memory. This was particularly striking on the auditory tests where two patients out-performed all controls on the birdsong test, but were below all controls on the easy-to-label sounds test. The verbal memory tests were easier than the non-verbal memory tests for controls, thus deconfounding task difficulty and deficit specificity.

Attention↗

Attending to objects: costs or benefits?

The single-object advantage is said to occur when performance is faster and/or more accurate when the two targets to be compared appear on one object than when they appear on two different objects. The single-object advantage has been interpreted to suggest that attention can select objects rather than unparsed regions of visual space. In five experiments we explored whether directing attention to one object rather than two objects produces a benefit or a minor cost. Participants were required to compare two target features that belonged to one object, to two objects, or did not belong to any object. In addition, we varied the relevance to the task of object-related global information, such as symmetry of the object and perceptual cluttering of the background. Results showed that attending to one object in comparison to attending to no object produced a benefit only when object-related global information was relevant to the task. In contrast, when object-related global information was irrelevant to the task, attending to one object produced a cost. Thus, it can be concluded that attending to an object does not produce an absolute benefit, but rather produces a smaller cost than attending to two objects.

Attention↗

Infant sensitivity to distributional information can affect phonetic discrimination.

For nearly two decades it has been known that infants' perception of speech sounds is affected by native language input during the first year of life. However, definitive evidence of a mechanism to explain these developmental changes in speech perception has remained elusive. The present study provides the first evidence for such a mechanism, showing that the statistical distribution of phonetic variation in the speech signal influences whether 6- and 8-month-old infants discriminate a pair of speech sounds. We familiarized infants with speech sounds from a phonetic continuum, exhibiting either a bimodal or unimodal frequency distribution. During the test phase, only infants in the bimodal condition discriminated tokens from the endpoints of the continuum. These results demonstrate that infants are sensitive to the statistical distribution of speech sounds in the input language, and that this sensitivity influences speech perception.

Attention↗