Lesson 6- localisation of functioning

Question 1

sections and regions of the brain

Answer 1

-forebrain, midbrain, hindbrain
-cerebrum, diencephalon, brain stem, cerebellum

Question 2

four main parts of the brain

Answer 2

Cerebrum- largest part of the brain, split into two hemispheres, communicate via corpus collosum, four lobes (frontal-thought and production of speech, occipital lobe-processing of images, temporal-cognitive skills, parietal-sensory information
Diencephalon- just inside cerebrum above brain stem, responsible for sensory information, food intake, body’s sleep cycle, divided into thalamus, hypothalamus, epithalamus
Cerebellum- below and behind cerebrum attached to brain stem, controls motor function, body’s ability to balance, ability to interpret information sent to the brain by senses
Brain stem- governs blood pressure, some reflexes, fight or flight, breathing, heartbeat, motor and sensory neurons travel through brain stem allowing impulses to pass between brain and spinal cord

Question 3

localisation of function

Answer 3

-refers to principle that specific functions such as language, memory have specific locations in the brain
-Franz Gall began the debate over localisation of function in the brain in early 1800s, became extremely influential, opposing view that all or large parts of the brain involved in behaviours
-proposed a persons personality was reflected in the bumps on the skull that in turn reflected functions of the brain lying underneath the bump (phrenology)

Question 4

motor and somatosensory areas

Answer 4

Somatosensory cortex- receives sensroy input from receptors in the skin, located in the parietal lobe, nody surface represented systematicaly, amount of area dedicated to a body part reflects its sensitivity (face and hands take up over half)
Motor cortex- responsible for the generation of voluntary movements, located in the back of the frontal lobe, both hemishperes have one, one side controls muscles on opposite sides of the body, differents parts control different body parts, regions arranged logically next to each other

Question 5

visual and auditory centres

Answer 5

-receives input directly from eyes and ears, damage can lead to blindness/deafness
Visual centre- primary visual centre located in occipital lobe, visual perception requires additional processing in neighbouring cortical areas, here sensation is converted into perception, damage to these areas leads to loss of specific aspects of visual perception eg prosopagnosia
Auditory centre- most lies within temporal lobes in both hemispheres where auditory cortex is found, auditory pathway begins in inner ear where sound waves are converted to nerve impulses which travel via auditory nerve to auditory cortex in the brain

Question 6

language centres (broca)

Answer 6

Brocas area- posterior portion of left frontal lobe, important for speech production
-Paul Broca treated a patient ‘Tan’ who could understand spoken language but could not speak or put his thoughts in writing, studied 8 other patients with similar language problems along with lesions/cuts in left frontal hemisphere, patients with same areas damaged in right hemisphere did not have same problems
-Fedorenko et al 2012 discovered two regions of brocas area, one for language other for cognitive tasks
-damage is known as brocas/expressive aphasia

Question 7

language centres (wernicke)

Answer 7

Wernickes area- posterior portion of left temporal lobe, involved in understanding language
-wernicke proposed language involves separate motor and sensory regions located in different cortical regions
-motor region- located in brocas area close to the area that controls the mouth, tongue and vocal chords
-sensory region- located in wernickes area, close to regions of the brain responsible for auditory and visual input
-neural loop (arcuate fasciculus) running between brocas area and wernickes
-damage known as wernickes/receptive aphasia

Question 8

localisation of function strengths

Answer 8

-Peterson et al (1988) used brain scans to show how wernickes area was active during a listening task and brocas area was active during a reading task, suggestd language is localised, shown through brain scans increases validity as scientific evidence
-Dougherty et al (2002) reported on 44 ocd patients who had undergone brain surgery involving lesioning an area seen responsible for ocd, after 32 weeks found that a third had recovered from the symptoms while 14% had some recovery of the symptoms, shows how certain mental diorders are localised to areas in the brain (neurosurgery)
-case study of Phineas Gage, after accident on railway tracks in 1848 suffered brain damage which forced his temporal lobe out his brain, suffered a complete change of personality suggesting personality may be localised
-support from aphasia studies

Question 9

localisation of function weaknesses

Answer 9

-Karl Lashley (1950) removed areas of the cortex (between 10-50%) in rats brains and found that no area was more important in terms of the rats ability to run the maze, learning to run the maze was not localised, reductionist as it simplifies out behaviour to specific areas
-plasticity/cortical remapping; when brain is damaged and a particular function is lost, the rest of the brain appears to reorganise itself to attempt to compensate for the lost function, suggests other parts of the brain could compensate
-evidence for individual differences in response to various activities and localisation ;Bavelier et al (1997) found a large variability in individual patterns of activation across individuals; Harasty et al (1997) found gender differences in size of brocas and wernickes area, women having proportionally larger brocas and wernickes area than men, may be because womens greater use of language, suggests localisation is generalisable for all humans