3.6 Attention

Besides iconic memory, visual cognition seems to depend upon an attention

to the visual scene in terms of an alert or arousal state. In fact,

damage to the pathways that make up the arousal systems within the

thalamus and hypothalamus has been shown to impair cognition and

consciousness (see the papers in Parasuraman, 1998). As I have noted

already, selection mechanisms are necessary for visual processing. Animals

attend to certain areas of their visual fi eld that they fi nd interesting, and

attention enhances detection (Wurtz, Goldberg, & Robinson, 1982; Moran

& Desimone, 1985; Posner & Peterson, 1990; Desimone, Chelazzi, &

Duncan, 1994).

Singer (2000) and Kandel et al. (2000) liken attention to a fi ltering

mechanism that both limits the amount of information reaching the

cortex and enhances the responses of neurons in many brain areas relevant

to the processing, storing, and recalling of the visual percept. This makes

sense, since the thalamus, one of the parts of the brain implicated in

attention, is the only mechanism by which information from the CNS

is relayed to the cerebral cortex. Research on monkeys has shown that

when they selectively attend to visual stimuli, the posterior parietal cortex,

S-II neurons at the gateway to the temporal lobe, and V4 neurons in

their brains are active (Steinmetz, Roy, Fitzgerald, Hsiao, Johnson, &

Niebur, 2000).

Besides iconic memory, visual cognition seems to depend upon an attention

to the visual scene in terms of an alert or arousal state. In fact,

damage to the pathways that make up the arousal systems within the

thalamus and hypothalamus has been shown to impair cognition and

consciousness (see the papers in Parasuraman, 1998). As I have noted

already, selection mechanisms are necessary for visual processing. Animals

attend to certain areas of their visual fi eld that they fi nd interesting, and

attention enhances detection (Wurtz, Goldberg, & Robinson, 1982; Moran

& Desimone, 1985; Posner & Peterson, 1990; Desimone, Chelazzi, &

Duncan, 1994).

Singer (2000) and Kandel et al. (2000) liken attention to a fi ltering

mechanism that both limits the amount of information reaching the

cortex and enhances the responses of neurons in many brain areas relevant

to the processing, storing, and recalling of the visual percept. This makes

sense, since the thalamus, one of the parts of the brain implicated in

attention, is the only mechanism by which information from the CNS

is relayed to the cerebral cortex. Research on monkeys has shown that

when they selectively attend to visual stimuli, the posterior parietal cortex,

S-II neurons at the gateway to the temporal lobe, and V4 neurons in

their brains are active (Steinmetz, Roy, Fitzgerald, Hsiao, Johnson, &

Niebur, 2000).