localisation of function and the structure of the brain

what is localisation of function?

the principle that specific functions have specific locations within the brain

4 lobes in each hemisphere and their functions?

• frontal - controls higher order thinking

• parietal - brings together sensory information to create a holistic picture

• occipital - processing visual stimuli

• temporal - perception and recognition of auditory stimuli

what is hemispheric lateralisation?

division of functions between two hemispheres:

left - language

right - spatial information and recognition

what is contralateral control?

left brain hemisphere controls right side of body

right hemisphere controls left side of body

main brain structures + their locations? x6

• motor cortex - frontal lobe

• somatosensory cortex - parietal lobe

• auditory centre - temporal lobe

• visual cortex - occipital lobe

• wernicke’s area - temporal lobe

• broca’s area - frontal lobe

role of motor cortex?

controls voluntary movement (complex movements) by sending signals to muscles via the brainstem and spinal cord

→ subdivided further where specific areas control specific body parts

what may damage to the motor cortex lead to?

loss of control over fine movements

motor cortex relationship w number of neurons?

correlates number of neurons with level of complexity rather than size

role of somatosensory cortex?

perceives touch, receives information from the skin

somatosensory cortex relationship w number of neurons?

number relates to our sensitivity to touch

role of auditory centre?

processes what the sound is and its location

what can damage in the auditory centre lead to?

hearing problems

how does auditory centre process information?

info received by cochlea via sound waves, travel to auditory centre and then to the brain stem

role of visual cortex?

processes visual information and has several different areas for different types of information e.g. colour, shape, movements

what can damage to visual cortex lead to (x3)?

blindness

left - right visual field

right - left visual field

both - complete blindness

How does visual cortex process info?

visual info → eyes → brain (optic nerve) → thalamus → occipital lobe

role of Broca’s area?

important for speech production + multitasking

how does Broca’s area work?

located close to the area controlling the mouth, tongue and vocal cords

damage to Broca’s area?

problems with speaking

role of Wernicke’s area?

important for understanding speech

how does Wernicke’s area work?

close to the auditory centre

damage to wernicke’s area?

problems understanding spoken words

evaluation of localisation of function (🙂x4, 🙁x3)?

🙂

• supporting evidence from brain scan studies - Peterson et al (1988) demonstrated Wernicke’s area active during listening task and Broca’s area active during reading task

• supporting evidence from lab experiments - Sperry + Gazzaniga (1967) split brain studies

• supporting evidence from neurosurgery- Dougherty et al (2002) found OCD patients who had removed cingulate gyrus showed significant improvements, symptoms and behaviours associated w mental disorders localised within the brain.

• supporting evidence from case studies - Phineas Gage (metal rod through frontal lobe and became aggressive), personality located within frontal lobe

🙁

• connection may be more important than localisation - complicated processes such as learning cannot be located to specific areas, so communication b/w different areas may be more important in controlling specific functions

• individual differences in language areas - Bavelier et al (1997) found silent reading some people show activation in right temporal lobe, left frontal lobe and occipital lobes, showing may not be universal localised areas for processing language

• criticisms of the idea that language production is localised to Broca’s areas - Dronkers et al (2007) re examined brain of Tan using more advanced technology and found other areas of brain also damaged, so speech production issues may not be predominantly due to damage in broca’s area.