Selective attention IIIII

What core features of psychopathology affect selective attention

• Lesions

• ADHD

• Schizophrenia

What is hemispatial neglect

• Neurological syndrome associated with unilateral cortical lesions

• Affects 2/4 acute right hemisphere stroke patients

• Presents as a lack of awareness of objects and events contralateral (opposite) the causal lesion

• Deficits in neglect provide a window on attention and spatial representation

How can spatial coordinates be coded in relation to hemispatial neglect

• Spatial coordinates is the position

• Can be coded relative to:

• The individuals centre of gaze (retinotopic)

• An objects central axis (midline)

• Other objects in the scene (alocentric)

Hemispatial neglect (Driver and Halligan, 1991)

When showed visual images patients failed to detect differences on left side of image that fell on the right side of visual midline

How does hemi spatial neglect affect neural circuits

• Deficits associated with extinction and neglect reflect physical damage to neural circuits

• Extinction reflects relative activation rather than absence of response to visual stimulus

• Attentional not perceptual deficit

Attention and psychopathology

• Deficits in attention also characterize many psychiatric syndromes

• Inhibitory deficit of irrelevant stimuli is a core feature of schizophrenia and ADHD

Selective attention and ADHD

• As ADHD is associated with impulsivity and impaired attention control, central deficits are associated with sustained attention and response inhibition

• These have been attributed to disrupted fronto striatal circuits

Features of ADHD regarding selective attention

• Individuals with ADHD have reduced prefrontal volumes compared to controls

• Shows reduced activation in frontal and cingulate regions

• Inhibition of irrelevant information and pre potent responses are crucial for goal directed behavior

(Rubia et al, 2005) selective attention and ADHD

• Used fMRI to contrast neural activation during response inhibiton and error detection in ADHD

• Sampled 16 medication naive adolescents with ADHD and age matched healthy controls

• The ADHD group were slower to respond on go trials and faster to respond on stop trials

• They also made more errors of omission and had more variable RT’S

(Rubia et al, 2005) selective attention and ADHD brain region reults

• Data revealed differential activation of neural circuits associated with attentional control in ADHD

• Reduced activation of prefrontal cortex and anterior cingulate during successful inhibition

• Reduced activation of cingulate cortex when inhibition fails

• Cingulate cortex is associated with dynamic allocation of attention (flexibility)

(Rubia et al, 2005) selective attention and ADHD neurophysiological reults

• Evidence of altered neurophysiological function despite task difficulty being equated and lack of medication in ADHD group

• Changes in neural activation correlated with parental ratings of children on the strengths and difficulties questionnaire

• ADHD is characterized by a distinct pattern of activity across networks of cortical areas associated with attention and control