Age-related changes in the neural dynamics of bottom-up and top-down processing during visual object recognition: an electrophysiological investigation

ABSTRACTWhen recognizing objects in our environments, we rely on both what we see and what we know. While elderly adults have been found to display increased sensitivity to top-down influences of contextual information during object recognition, the locus of this increased sensitivity remains unresolved. To address this issue, we examined the effects of aging on the neural dynamics of bottom-up and top-down visual processing during rapid object recognition. Specific EEG ERP components indexing bottom-up and top-down processes along the visual processing stream were assessed while systematically manipulating the degree of object ambiguity and scene context congruity. An increase in early attentional feedback mechanisms (as indexed by N1) as well as a functional reallocation of executive attentional resources (as indexed by P200) prior to object identification were observed in elderly adults, while post-perceptual semantic integration (as indexed by N400) remained intact. These findings suggest that compromised bottom-up perceptual processing of visual input in healthy aging leads to an increased involvement of top-down processes to resolve greater perceptual ambiguity during object recognition.

Download Full-text

Fusing bottom-up and top-down pathways in neural networks for visual object recognition

The 2010 International Joint Conference on Neural Networks (IJCNN) ◽

10.1109/ijcnn.2010.5596497 ◽

2010 ◽

Cited By ~ 3

Author(s):

Yuhua Zheng ◽

Yan Meng ◽

Yaochu Jin

Keyword(s):

Neural Networks ◽

Object Recognition ◽

Visual Object ◽

Visual Object Recognition ◽

Top Down ◽

Bottom Up

Download Full-text

A Cortical Mechanism for Triggering Top-Down Facilitation in Visual Object Recognition

Journal of Cognitive Neuroscience ◽

10.1162/089892903321662976 ◽

2003 ◽

Vol 15 (4) ◽

pp. 600-609 ◽

Cited By ~ 533

Author(s):

Moshe Bar

Keyword(s):

Object Recognition ◽

Visual Recognition ◽

Temporal Cortex ◽

Input Image ◽

Initial Guess ◽

Visual Object ◽

Visual Object Recognition ◽

Top Down ◽

Bottom Up ◽

Level Information

The majority of the research related to visual recognition has so far focused on bottom-up analysis, where the input is processed in a cascade of cortical regions that analyze increasingly complex information. Gradually more studies emphasize the role of top-down facilitation in cortical analysis, but it remains something of a mystery how such processing would be initiated. After all, top-down facilitation implies that high-level information is activated earlier than some relevant lower-level information. Building on previous studies, I propose a specific mechanism for the activation of top-down facilitation during visual object recognition. The gist of this hypothesis is that a partially analyzed version of the input image (i.e., a blurred image) is projected rapidly from early visual areas directly to the prefrontal cortex (PFC). This coarse representation activates in the PFC expectations about the most likely interpretations of the input image, which are then back-projected as an “initial guess” to the temporal cortex to be integrated with the bottom-up analysis. The top-down process facilitates recognition by substantially limiting the number of object representations that need to be considered. Furthermore, such a rapid mechanism may provide critical information when a quick response is necessary.

Download Full-text