Higher Cognition

Humans easily adapt to altered vision → prisms shift the visual scene by an angular distance

• With enough training a new map of visual space can be formed

Patients with Lesions in the right hemisphere exhibit neglect of the left visual space

• Lateral view of the right hemisphere of the brain to examine the neuroanatomy of patients with contralateral neglect syndrome

• A composite of several patients to estimate the location of the underlying lesions 

• Although the extent of the lesion varied in individual cases, the red and yellow regions were the most often affected

• There is asymmetry in attentional control; normally, the right hemisphere dominates in the control of attention (thick lines) 

Attention

• The directing of cognitive processing resources on a particular aspects of the external or internal environment, or on internal processes such as thoughts or memories 

• It may also be the process that allows selection of some inputs over others

Overt vs. Covert Attention

• Overt attention (eye gaze is explicitly directed to a visual stimulus or location of interest) versus covert attention (directing attention to a part of visual without moving the eye) 

Visual Perception is Influenced by Attention

Attention enhances neuronal responses 

• Neurons in posterior parietal cortex are related to directing attention to objects, places and other stimuli 

• When a monkey is trained to attend a specific stimulus, these neuron are selectively activated as a function of the directed attention 

• Neurons in visual cortex demonstrate preferred orientations 

• When monkeys are presented with a bar of several orientations, the activity of individual neurons changes based on whether the monkey is attending to the bar

• Similarly, when human subjects are instructed to attend to visual stimuli in one visual field there is an increase in the neural activity in the contralateral visual cortex