Localisation of function in the brain

What did scientists Paul Broca and Karl Wernicke discover

That specific areas of the brain are associated with particular physical and psychological functions

What theory did scientists typically support before these investigations

The holistic theory of the brain - that all parts of the brain are involved in the processing of thoughts and action

What did scientists Paul Broca and Karl Wernicke discover

That specific areas of the brain are associated with particular physical and psychological functions

What theory did scientists typically support before these investigations

The holistic theory of the brain - that all parts of the brain are involved in the processing of thoughts and action

What is the idea of localisation of function

The idea that different areas of the brain are responsible for specific behaviours, processes, or activities

What does the localisation of function theory mean if a part of the brain gets injured

That the function associated with that area will also be affected

What is the main part of the brain called and what is it divided into

Cerebrum - divided into two symmetrical halves called the left and right hemisphere

What is lateralisation

The idea that some of our physical and psychological functions are controlled by a specific hemisphere

What is activity on the left side of the body controlled by (and vice versa)

The right hemisphere

What is the cortex of both hemisphere divided into

Four centres called lobes

What is a lobe

Part of an organ that is separate in some way from the rest

What are the 4 lobes

The frontal lobe, parietal lobe, occipital lobe, temporal lobe

What is at the back of the frontal lobe, what does it control, and what would happen if there was damage to it

The motor area, it controls voluntary movement in the opposite side of the body. Damage would result in a loss of control over fine movements

What is at the front of the parietal lobes and how is it separated from the motor area

Somatosensory area - separated by a ‘valley’ called the central sulcus

What happens in the somatosensory area

It is where sensory information from the skin is represented

What does the amount of somatosensory area devoted to a particular body part indicate

Its sensitivity, for example, receptors on our face and hands occupy over half of the somatosensory area

Where is the occipital lobe and what is there

At the back of the brain, the visual area (visual cortex)

Where is information from the right visual field sent by each eye (and vice versa)

To the left visual cortex

What can damage to the left hemisphere cause

Blindness in the right visual field of both eyes

What do the temporal lobes house and what does it analyse

The auditory area - analyses speech based information

What can damage to the auditory area cause

Hearing loss and the ability to comprehend language

Which side of the brain are languages restricted to

The left side

What did Paul Broca find in the 1880s and what is the area responsible for

A small area in the left frontal lobe called Broca’s area - responsible for speech production

What does damage to Broca’s area cause

Broca’s aphasia which is slow, laborious speech that lacks fluency

What did Wernicke discover and how

Wernickes area, a region in the left temporal lobe. He was describing people who had no problem producing speech but severe difficulty understanding it - they could speak fluently but with no meaning

What is Wernicke’s area responsible for and what happens if damaged

Responsible for language understanding - results in Wernicke’s aphasia if damaged - they will produce nonsense words (neologisms)

What is a strength of localisation theory

Damage to areas of the brain has been linked to mental disorders. Cingulotomy involves isolating a region called the cingulate gyrus which is involved in OCD. Darin Dougherty et al. (2002) reported on 44 people with OCD. At post-surgical follow up after 32 weeks, about 30% met the criteria for successful response to surgery, and 14% had partial response. The success shows that behaviours associated with particular mental disorders may be localised

What is a strength of brain scans

Steven Petersen et al. (1988) used brain scans to show how Wernicke’s area was active during a listening task, and Broca’s area was active during a reading task. Also a review of long-term memory studies by Buckner and Petersen (1996) revealed that semantic and episodic memories reside in different parts of the prefrontal cortex. This shows objective methods for measuring brain activity have shown that brain functions are localised

What is a counterpoint to the previous evaluation point

Karl Lashley (1950) removed areas of the cortex (between 10% and 50%) in rats that were learning the route through a maze. No area was proven to be more important than any other area in terms of the rat’s ability to learn the route. The process of learning seemed to require every part of the cortex rather than being confined to a specific area. This suggests that higher cognitive processes, like learning, are not localised but distributed in a more holistic way in the brain

What is a limitation of language localisation

A review by Anthony Dick and Pascale Tremblay (2016) found that only 2% of modern researchers think that language in the brain is completely controlled by Broca and Wernicke’s area. Advances in brain imaging techniques, like fMRI, mean that neural processes in the brain can be studied with more clarity than ever before. It seems that language function is distributed far more holistically in the brain than first thought. Language streams have been identified across the cortex including brain regions in the right hemisphere as well as subcortical regions in the thalamus. This suggests that rather than being confined to a couple of key areas, language may be organised more holistically in the brain, contradicting localisation theory