🟢 Biopsychology - Localisation of Function Flashcards
What is localisation of brain function
Certain areas of the brain have particular functions
What is the outer layer of both hemispheres called and how thick is it
Cerebral cortex, 3mm thick
Areas of the brain to remember
Motor, somatosensory, visual, auditory and the language centres (brocas and wernickes)
What was franz gall’s theory
Theory of phrenology, looking at the structure of the skull to determine a persons character
Replaced by localisation of function
Where is the motor cortex located
Back of the frontal lobe
Responsibility of the motor cortex
Generation of voluntary motor movements
Is the Motor cortex on both hemispheres
Yes
Mortar cortex on right controls muscles on left side of the body. Motor cortex on left controls muscles on the right side of the body
What can damage to the motor cortex cause
Loss of control over fine movements
Arrangement of motor cortex
Different parts of the motor cortex controls different parts of the body, these are arranged logically. For example the region controlling the foot is next to the region that controls the leg. Meaning of damage occurs in mc, may only damage particular part of the body
Where is the somatosensory cortex located
In the parietal lobe, next to motor cortex
Role of somatosensory cortex
Detects sensory events from different regions of the body
What separates the motor area and the somatosensory cortex
‘Valley’ called central sulcus
Process used by the somatosensory cortex
Uses sensory information from the skin to produce sensations such as touch pressure, pain, temperature which is then localised to specific body regions
How does the amount of somatosensory area in a particular body part affect sensivity
The amount of somatosensory area devoted to a particular body part denotes its
sensitivity. For example receptors in our face and hands occupy over half of the
somatosensory area.
Is the Somatosensory cortex in both hemispheres
Yes, The cortex on one side of the brain receives sensory info from the opposite side of
the body
Where are visual centres located
Back of brain in occipital lobe
Role of visual centres
Process visual information
Process of processing visual information
- Begins at Retina, light enters and strikes the photoreceptors
- Nerve impulses from retina travels to areas of the brain via the optic nerve
- Some travel to areas of the brain involved In coordination of circadian rhythms . Most terminate in the thalamus which acts at a relay station passing info to visual cortex
Information about visual fields and cortex
Each eye sends visual information from the right visual fields to the left visual cortex and then from the left visual field to the right visual cortex
Does the visual cortex contain different areas
Semantic and episodic memories reside in died
Where are the auditory centres located
In temporal lobes on both sides of the brain
Process of processing auditory information
Begins in cochlea in inner ear, sound waves are converted to nerve impulses. Pit stop at the brain step where basic decoding happens, then onto thalamus which acts as a relay station and carries out further processing of auditory stimulus. Then via the auditory nerve to the auditory cortex. Sound has already been largely decoded by this point and in the auditory cortex it is recognised and results in an appropriate response
What does damage to the auditory centre causes
Produce partial hearing loss, the more extensive the damage, the more extensive the hearing loss
One case study for the localisation of function
Phineas Gage (1848)
Who was Phineas gage and what was his accident
Foreman of a railway construction gang. On September 13th 1848 an accidental explosion of a charge he has sent blew his tamping iron through his head. The tamping iron was 3 feet 7 inches long and weighed 13 1/2 pounds. Went in point first under his left cheek bone and completely out through the top of his head. Landing about 25 to 30 yards behind him
Why was Phineas gage Significant?
First patient from whom we learned something about the relation between personality and the function of the front parts of the brain.
Characteristics of Phineas gage before the accident
- well capable and efficient foreman
- well balanced
- shrewd, smart businessman
- sociable
Characteristics of Phineas gage after the accident
-, disrespectful
- impatient and stubborn
- unable to create and stick to future plans
- “no longer gage”
What does the Phineas gage case study show
The localisation of function, how different functions. Damage to the frontal lobe affected his decision-making and social interactions, but other functions (like movement and memory) remained intact.
Study against localisation of function
Karl Lashley (1950)
Conclusion of the Karl Lashley study
Higher cognitive functions such as processes involved in learning are not localised but distributed in a more holistic way in the brain
Process of Karl Lashley study
Lashley trained rats to navigate mazes, then lesioned (damaged) different areas of their brains to see if memory was lost. No single area was responsible for memory loss, suggesting that memory is distributed across the brain.
Limitations of Lashley research
He only studied rats so his findings make not be applicable to humans. Later studies showed that memory functions are localised (tulving)
Limitations of Gage’s case study
- Lack of scientific control: no control group to compare his behaviour before and after, report on accounts rather than observations
- No brain scans: damage may have been less extensive than originally thought
- Some same that Gage recovered and later lived a relatively normal life
- Small sample size, findings cannot be generalised to everyone
What did tulving et al (1994) reveal
Semantic and episodic memories reside in different parts of the prefrontal cortex
What is the Broca’s area
An area of the frontal lobe of the brain in the left hemisphere , responsible for speech production
What is the wernicke’s area
An area of the temporal lobe, in the left hemisphere responsible for language comprehension
Who was Paul broca
1880s
Surgeon who identified area in the left frontal lobe responsible for speech production
What does damage to the Broca’s area cause
Broca’s aphasia
What is Broca’s aphasia
Trouble with speech production, speech consists of small simple sentences, mainly verbs and nouns. Reading and writing not affected
Paul Broca’s research
Treated a patient called ‘Tan’ who was unable to speak other than this one word but didn’t understand language. Also studied 8 other patients who had similar language deficits along with damage in their left and right frontal hemisphere.
Found damage in left hemisphere had problems with speech, right hemisphere had problems no problems with speech
Where is the wernickes area
Temporal lobe on the left hemisphere only
Dronkers et al 2007 study
VS LOCALISATION OF FUNCTION
Conducted MRIs scans on Tan’s brain, to try to confirm Broca’s findings. Although lesion in Broca’s area, there was evidence to suggest other areas may have contributed to the failure in speech production . Suggests that Broca’s area may not be the only region responsible for speech production and the deficits found in patients with Broca’s aphasia could be the result of damage to other neighbouring regions
Karl Wernickes research and findings
Had patients who could speak but had severe difficulties understanding it. Wernicke identified an area in the temporal lobe as being responsible for language comprehension
• Patients who have Wernicke’s aphasia would often produce nonsense words (neogogisms) as part of the content of their speech. Wernicke proposed that language involves separate motor and sensory regions located in different
cortical regions. The motor region, located in Broca’s area, is close to the area that controls the mouth, tongue and vocal cords. The sensory region, located in Wernicke’s area, is close to regions of the brain responsible for auditory and visual input.
What is wernickes aphasia
Trouble with speech comprehension. Can’t produce meaningful sentences but can string words together but why they say is nonsensical
Turk et al 2002
patient JW who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere . Eventually leading to the ability to speak about the information resented to either side of the brain. Suggests that perhaps localisation is not fixed and that the brain can adapt following damage to certain areas
