Localisations Of Function In The Brain Flashcards
The four types of lobe in the brain
Frontal- consciousness, speech production and movement
Parietal lobe- perception
Occipital lobe- vision
Temporal lobe- speech recognition and hearing
Subsections of the lobes
Motor cortex- a region of the frontal lobe involved in regulating movement. Outgoing info
Somatosensory cortex- an area of the parietal lobe that processes sensory information such as touch. Incoming info
Visual cortex- a part of the occipital lobe that receives and processes visual information
Auditory cortex- located in the temporal lobe and concerned with the analysis of speech- based information
Case study: Phineas Gage (1848)- support for localisation of function
- He was the first patient from whom we learned something about the relation between personality and the function of the front parts of the brain.
- An accidental explosion caused an iron rod to penetrate his cheek and brain.
- He still remained consciousness and physically recovered, however after the accident, his personality changed to be disrespectful, stubborn and impatient
- This suggests that certain areas of the brain are localised, and Gage received damage to the part that controlled personality and mood
Motor cortex
- responsible for generation of voluntary motor movements
- located in frontal lobe
- it is found on both hemispheres: motor cortex on right hemisphere controlling muscles on left side of body and vice versa
- damage to this area may result in loss of control over fine movements
- different parts of the motor cortex control different parts of the body
- these regions are arranged logically: the region that controls the foot is next to the region that controls the leg. This is so if there is damage to the area, you won’t have impairment in random parts of the body.
Somatosensory cortex
- detects sensory events from different regions of the body
- found in the parietal lobe
- dedicated to the processing of sensory info related to touch: different area have more receptors than others making them more sensitive, such as the skin
- both hemispheres have a somatosensory cortex
- the cortex on one side of the brain receives info from the opposite side of the body
Visual centres
- located in the visual cortex in the occipital lobe
- each eye sends information from the right visual field to the left visual cortex and from the the left visual field to the right visual cortex. This means damage to the left hemisphere can produce blindness in the right visual field of both eyes.
- visual cortex contains different areas that process different types of visual info such as colour, shape and movement
Auditory centres
- found in temporal lobes of both sides of the brain.
- sound waves are converted to nerve impulses, then travel to the brain for decoding. The auditory cortex then recognises it and may result in appropriate response.
- damage may produce partial hearing loss; the more extensive the damage, the more the extensive the hearing loss.
Lashley et al (rats experiment)- against localisation of function
- he conducted research on rat’s in a lab experiment to test localisation of function.
- he trained rats to run a maze, and then gradually destroyed areas of the brain, while making them run the maze each time.
- he found that no one area had a great impact on the rat’s ability to run the maze, it was the rats complete destruction of the brain that prohibited them from running the maze.
- from this he concluded that all area of the brain are equally important for functioning in the brain, and there is not specialisation of function.
- He proposed the ‘equipotentiality theory’ stating that all areas of the brain are equally important for functioning in the brain, and there is not specialisation of function
Broca’s area
- An area of the frontal lobe of the brain in the left hemisphere (in most people) responsible for speech production
- It moves the muscles that are required to speak
- Damage to Broca’s area causes Broca’s aphasia which is characterised by speech that is slow, laborious and lacking fluency
Wernicke’s area
An area of the temporal lobe in the left hemisphere (in most people) responsible for language comprehension
Broca’s experiment (Tan)- support for localisation of function
- Paul Broca treated a patient called ‘Tan’ - he was unable to speak other than this one word (but did understand language)
- he also studied 8 other patients who had similar language deficits, along with lesions in their left frontal hemisphere
- patients with damage to their right frontal hemisphere did not have the same language problems.
Labelled diagram of brain
