6. Biopsychology Flashcards
How do cells transmit information to each other?
By using electrical signals
What is a cell called if it can both transmit and receive electrical signals?
Neuron
Or neuronal cell
Cells use electrical signals to communicate with one another. What is the name of these electrical signals?
Action potentials or Nerve impulses
What are the 4 main structural components of a neuron?
- Dendrites
- Cell body
- Axon
- Axon terminal
Describe the process of how action potentials travel across the neuron.
- Small wave of positively charged particles flow into dendrites
- Causes an increase in voltage throughout the cell
- Particles then travel to cell body + If the change in voltage is large enough, the action potential is triggered
- Activation potential travels down axon to reach axon terminal
What process needs to occur for two neurons to communicate?
Synaptic transmission
Synaptic transmission
The process where the activation potential is transferred from the axon terminal of one neuron to the dendrite of another
Draw the structure of the synapse
Outline the process of synaptic transmission.
- Action potential arrives at pre-synaptic terminal, causing synaptic vesicles to travel to pre-synaptic membrane
- Synaptic vesicles fuse with pre-synaptic membrane, causing neurotransmitters to be released into synaptic cleft
- Neurotransmitters difuse across the synaptic cleft and towards the post-synaptic terminal, where they bind with receptors
- Receptors then change shape, allowing + charged particles from synaptic cleft to enter dendrite
- Once neurotransmitters have bound the receptors, they diffuse back into synaptic cleft - They are then removed by re-uptake proteins located on pre-synaptic membrane - (Process is called re-uptake)
- If the charge is large enough, then an action potential can be triggered, causing the cycle to repeat itself
What is the name of the process that involves removing neurotransmitters from the synaptic cleft, after they have bound to a receptor?
Re-uptake
Important to note: Neurotransmitters are recycled in this stage
Why does synaptic transmission only occur in only one direction?
- Synaptic vesicles which contain the neurotransmitters are only released from the pre-synaptic membrane
- Receptors, (which neurotransmitters bind to), are only located on the post-synaptic membrane
- Diffusion of neurotransmitters means they can only move from a high to a low concentration
What are the two types of neurotransmitter?
- Excitatory
- Inhibitory
What was the aim of Sperry’s study?
To examine the extnet to which hemispheres are specialised for specific functions
What was the procedure used by Sperry?
- 11 Ps
- All Ps have had corpos collosum split
- Split-brain patient is presented with a stimulus to either their right or left visual field
- Vision is organised contralatterally; therefore, stimuli placed in the left visual field will be represented in the right hemisphere and vice versa
- P would focus on a dot in the centre of the screen, while information was presented to a specific visual field
- After being shown stimulus, patient is asked to respond to it:
- a. The describe what you see task meant patients had to say what they saw
- b. The tactile task involved the P describing what they felt or by selecting an object that felt similar
- c. Drawing task meant Ps had to cover there eyes and draw the stimulus they saw
What were the results of Sperry’s study?
- Patient could point to a matching stimulus no matter which side the stimulus was presented to
What did Sperry conclude?
- LH is dominant in terms of speech and language
- Language is lateralised to the LH - Wernicke’s area and the Brocca
- RH is dominant in terms of visual-motor skill
- Communication and connectivity of the hemispheres is as important as specific functions
AO3: 2 generalisability points of Sperry’s study.
1 - Small sample size of ‘different’ Ps
* Split-brain surgery is a rare procedure
* Only a small number of Ps can be studied
* These Ps are also ‘different’ from the rest of the population
* This matters because, results cannot be generalised
2 - External validity
- Limited external validity, as stimulus was selectively presented to one visual field
- This doesn’t happen in real-life and therefore lacks mundane realism
- In real life, split-brain patients will compensate for severed corpus collosum by having access to both visual fields
- This means the results cannot necessarily be generalised to split-brain patients
AO3: 1 reliability point of Sperry’s study.
AO3: 1 application point of Sperry’s study.
- Strong applications to hemispherical lateralisation
- Small sample size with unique surgery allowed Sperry to prove that both language formation and comprehension are hemispherically lateralised to the left hemisphere
- This matters because……………..
AO3: 1 validity point of Sperry’s study.
- Lacks temporal validity
- More recent studies have contradicted the results
- Ex: Some studies have proven that language isn’t lateralised to the left hemisphere and some language tasks can be performed if stimulus is presented to left visual field
- This matters because the results may no longer be applicable
- Results may have differed due to technological advancement in the areas of scanning and surgery
Hemispheric Lateralisation Further Evaluation Point: EB Case Study
- 2 year old boy known as EB had a large tumour in his left hemisphere
- When the doctor removed the tumour, they removed almost all of his left hemisphere
- Because psychologists believed language to be hemispherically lateralised to LH, they thought he would never be able to use language again
- However, after years of rehabilitation, his language skills started to improve
- Daneli did tests on EB to test which parts of his brain were active during language task
- Control Group = LH
- EB = RH
- This is due to recruitment of homologous areas
- This case study matters, because it shows there are exceptions to Sperry’s conclusion
However, a counterpoint could be that this was a case study, which means that the results wouldn’t be largely generalisable
Localisation of function
The concept that certain function in the brain being carried out in specific areas
Ex: Broca’s area is specific to language production
