What does Cognition refer to?
Cognition refers to our knowledge and the beliefs, thoughts and ideas that we have about ourselves and our environment.
What are Cognitive Processes?
Cognitive Processes include those mental processes involved in acquiring, retaining and using knowledge.
What is aphasia?
Aphasia is the impairment of language caused by damage to the brain (usually by stroke). Aphasia can affect talking, reading, writing and understanding others but it does not affect intelligence.
How many Australians are estimated to have Aphasia as a result of stroke?
The Australian Aphasia Association estimates that about 80,000 Australians have Aphasia as a result of stroke (2010)
What is Broca's Aphasia?
Discovered by Paul Broca, a young surgeon in 1861 after performing an autopsy on Tan (a long-term patient with significant speech difficulties) showed damage to a particular region of the brain. It was then later supported by similar case studies.
People with Broca's Aphasia REALIZE they can't speak.
Characteristics of Broca's Aphasia:
- Speech is non-fluent
- Partial or complete loss of the ability to recall names
- Articulation difficulties
- Speech lack grammar
- Difficulty in writing
- Possible comprehension difficulties
What is agrammatism?
When speech lacks grammar. Speech that does not follow the grammatical rules - it lack syntax.
What is Anomia?
Partial or complete loss of the ability to recall names
What is 'location of function'?
Linking a location of the brain with a specific function. Broca's Aphasia is an example of this.
What is 'expressive aphasia'?
Broca's aphasia is a result of damage to Broca's area (located in the left temporal lobe) and, often, surrounding areas, and is referred to as expressive aphasia.
A person with Broca's aphasia has difficulty expressing themselves in words or sentences but their ability to comprehend speech is largely unaffected.
What is Wernicke's Aphasia?
Wernicke's Aphasia results from damage to Wernicke's Area, located in the left temporal lobe near the parietal lobe boundary. A person with Wernicke's Aphasia has difficulty understanding written and spoken language and in producing written and spoken language that makes sense to others.
Often referred to as Receptive Aphasia.
Unlike Broca's Aphasia, people with Wernicke's Aphasia talk freely and rapidly but, while they utter many words, they say very little that makes any sense.
People with it don't realize they can't speak/understand language.
- Speech is fluent
- Nonsense words are used
- Difficulty understanding both written words and spoken language
- Difficulty producing both written and spoken language that makes sense to others.
Why is generalising the findings of case studies difficult?
3 Limitations of generalising case study findings:
- Our Brains are unique and the precise location of Broca's and Wernicke's Area varies between people
- Brain scans reveal that many areas of the brain are associated with language use and this pattern of brain activation changes depending on the person and how language is being used at any given moment.
- Aphasia results from brain damage, usually due to a stroke. The extent of brain damage varies between people, and often is widespread and affects several areas of the brain. Therefore, the extent of the effects on language will be different in different people.
What is Spatial Neglect?
- Disorder, where the person affected, systematically ignores stimuli most frequently from the left visual field generally due to damage in the right parietal lobe.
- People can, and are usually, unaware they have spatial neglect
What are split-brain studies?
In split-brain studies, patients undergo surgery to sever the corpus callosum, the thick band of about 200 million nerve fibre connecting the right and left hemispheres.
This operation is called Commissurotomy and prevents communication between the two hemispheres on higher cortical levels.
These operations are done as a last resort to treat severe epilepsy and generally work well with little side effects.
What happens when a word is flashed in the left visual field of a split brain patient?
Because the left hemisphere is dominant for verbal processing, the patients answer matches the word.
What happens when a word is flashed to the right visual field of a split brain patient?
The right hemisphere cannot share information with the left, so the patient is unable to say what he saw, but can draw it.
What are the two (broadly divided) methods of investigating the brain?
Invasive - where the experimenter physically interferes with the brain
Non-Invasive - where the brain is researched without physical interference
What is transduction?
Converting visual light energy (light waves within our visual spectrum) into electrochemical energy (nerve impulses). This conversion of energy is called transduction and the energy is then transmitted along the optic nerve to the brain.
What are photoreceptors?
The retina contains a layer of nerve cells called photoreceptors that convert visual light energy into electrochemical energy.
What is the optic chiasm?
Each eye has its own optic nerve and these meet and cross over information at the optic chiasm.
Who are Sperry and Gazzaniga?
Roger Sperry (won the Nobel prize) and Michael Gazzaniga where the pioneers of the split-brain procedure and research behind it.
They initially worked with cats and monkeys and eventually began to work with human participants.
They devised an experimental situation in which different stimuli could be presented to either of a person's two hemispheres independently. To do this, they relied on the visual input from the eyes.
What are the limitations in generalising results from split-brain patients?