Localisation of Function Flashcards
Outline localisation vs holistic
During 19th century, scientists like Broca & Wernicke discovered specific areas of brain associated with particular physical & psychological functions
Before these investigations, scientists supported holistic theory: all parts of brain involved in processing of thought & action
Localisation = different parts of brain perform different tasks & involved with different parts of body, thus if area of brain damaged, function associated with area also affected
Outline hemispheres of the brain
Main part of brain (cerebrum) divided into 2 symmetrical halves called left & right hemisphere
Some of our physical & psychological functions controlled by particular hemisphere (lateralisation)
Generally, activity on left-hand side of body controlled by right hemisphere & vice versa
Outline the somatosensory centre
Located at front of both frontal lobes, separated from motor area by valley (central sulcus)
Somatosensory area = where sensory info from skin is represented
Amount of somatosensory area devoted to particular body part denotes it’s sensitivity
Outline the motor area
Located at back of frontal lobe, controls voluntary movement in opposite side of body
Damage to this area = loss of control over fine movements
Outline the visual centre
Located in occipital lobe at back of brain (AKA visual cortex)
Each eye sends info from right visual field to left visual cortex & vice versa
Damage to left hemisphere can produce blindness in part of right visual field of both eyes
Outline the auditory centre
Located in temporal lobes - analyses speech-based info
Damage produces partial hearing loss - more extensive damage, more extensive loss
Damage to specific area of temporal lobe - Wernicke’s area - may affect ability to comprehend language
Outline Broca’s area
Language restricted to left side of brain for most people
In 1880s Broca identified small area in left frontal lobe responsible for speech production
Damage = Broca’s aphasia - slow, laborious speech lacking in fluency
Outline Wernicke’s area
Located in left temporal lobe & responsible for language understanding
Damage = Wernicke’s aphasia - no problem producing language but can’t understand it, producing nonsense words
Evaluate localisation theory
Strength - EVIDENCE FROM NEUROSURGERY - Damage to brain linked to mental health disorders
E.g. - Neurosurgery last resort method for treating some mental disorders, targeting specific areas of brain. Dougherty et al. (2002) reported on 44 people with OCD who’d undergone cingulotomy. Post-surgical follow up after 32 weeks, 30% had successful response & 14% had partial response
Ex. - Success of procedure suggests behaviours linked with serious mental disorders may be localised
Strength - EVIDENCE FROM BRAIN SCANS
E.g. - Petersen et al. (1988) used brain scans to show WA active during listening task & BA active during reading task. Review of long-term memory studies by Buckner & Petersen (1996) revealed semantic & episodic reside in different parts of prefrontal cortex
Ex. - Objective methods for measuring brain activity provided sound evidence many brain functions localised
Limitation - LANGUAGE LOCALISATION QUESTIONED
E.g. - Review by Tremblay & Dick (2016) found only 2% of modern researchers think language in brain is completely controlled by Broca’s & Wernicke’s areas. Advances in brain imaging mean natural processes in brain can be studied with more clarity than ever before. Seems language function distributed more holistically than first thought
Ex. - Rather than being confined to couple of key areas, language organised more holistically, contradicting localisation theory
