Lecture 16- Behaviour, Language and Learning Flashcards
What is behaviour?
- A complex collection of actions, conscious/unconscious, voluntary/involuntary
- Often involving interaction with others and in response to an internal or external stimulus
What systems are largely in control of behaviour?
-Mostly under control of nervous and endocrine systems
What is the role of prefrontal cortex?
- Organizes thoughts and actions
- Intimately invovled in “executive function” : cognitive function, social behaviour, recall past information/ that not currently in the environment in order to help plan future events.
Where is the prefrontal cortex?
Prefrontal is (roughly) the part of the frontal lobes anterior to motor areas (pre-central gyrus and SMA)
How does the prefrontal cortex control behaviour?
Emotional & cognitive processes in prefrontal cortex exert control over behaviour by activity that originates in the ventromedial area and which passes to premotor & motor cortex
In general what does damage to the prefrontal cortex cause?
Patients with damaged prefrontal cortex typically experience an abnormal emotional state with unusual behaviour due to lack of concentration and ability to plan. Also changes to emotional capacity/ personality.
What is a lobotomy?
- Common neurosurgical procedure used in 1940’s & 50’s, on patients with “mental illness”
- Thought that mental illness was due to networks of neurons becoming “caught in fixed destructive circuits leading to obsessive ideas and deliria”
- Surgical severing of major tracts in prefrontal cortex
- Following the procedure death was common, most survivors were confused, emotionally blunted, major personality changes (because damage to prefrontal cortex).
What did Pinneas Cage show?
- Railway worker that had rod but through prefrontal cortex in accident but survived
- Showed huge personality changes : became irreverent, profane, disinterested, obstinate, unreliable
What hemisphere is language concentrated to in most people?
In the left for 90% of people
What are the language areas of the brain close to?
Language areas of brain close to areas responsible for sensory
and motor functions of lips, tongue, mouth, and to auditory cortex
What is Wernicke’s aphasia?
- Defect in comprehension speech due to damage to Wernicke’s area.
- Known as fluent aphasia because individuals can still speak in perfect sentences the content just doesn’t make sense. They are also often unaware (no stress).
What is brocca’s aphasia?
- Defect in speech production due to damage to Brocca’s area
- This is a non-fluent aphasia (expressive) as causes stunted, stammering speech that makes perfect sense just is slow to get out
- Patients aware and often frustrated cause they know what they want to say just can’t get it out.
What is learning?
- Learning is the acquisition & storage of information as a result of experience.
- Results in a change in likelihood of a behaviour in response to a stimulus
What is memory?
Memory is the storage mechanism for what is learned.
What are the two types of memory? What key areas of the brain are important for them?
-Declarative memory – retention & recall of conscious experiences
that can be put into words (declared) : Hippocampus, amygdala, limbic
system crucial in making them, though not in storing (long term storage in many cortical regions, incl. pre-frontal & association
cortex)
-Procedural memory - memory of how to do things independent of conscious understanding (know how to walk, talk without thinking about it): Sensorimotor cortex, cerebellum, basal nuclei crucial
What is the difference between short term and long term memory?
-Short-term memory records & retains info for seconds-minutes. Typically associated with ability to focus attention. Requires ongoing electrical activity. Involves hippocampus typically limited to recall of
about 5 items.
-Long-term memories may be stored for years. Requires permanent changes in brain function and/or structure. Likely involves long-term changes in strength of specific synapses (Long-term potentiation).
What is the term for short-term memories to be converted to long term memories and what effects this occurring?
May be converted to long-term memories by consolidation
- Emotional impact
- Survival value
- Repetition
- Links to existing memories
What are the two types of amnesia?
- Retrograde amnesia: loss of memories held from a period before the incident that caused the memory los. Typically short term memories gone and long term retained e.g. can’t remember events right before the accident.
- Anterograde amnesia: inability to consolidate short term into long term memories. Typically due to damage to limbic system & hippocampus
What famous patient showed anterograde amnesia?
-HM had amygdala & hippocampus removed as treatment for
epilepsy.
-Result: able to make normal short term memories, but no long
term ones
-Could recall events from years ago, but nothing beyond a minute or two post-surgery
What is long term potentiation?
- Increase in synaptic strength as a consequence of recent activity (burst)
- Usually results in long lasting improvement in signal strength at the potentiated synapses
- A lot of different forms of LTP and cellular mechanisms exist.
What is the opposite of LTP?
LTD: long term depression
What is long term potentiation the early phase?
- Not protein synthesis dependent
- Glutamate acts on NMDA receptor , Ca influx at post- synaptic site, CaMKII activated, AMPA receptors (nonNMDA glutamate receptors) phosphorylated & inserted into membrane.
- Cell becomes more sensitive to Glutamate, so future Glutamate release leads to larger postsynaptic response
- Other mechanisms may lead to enhanced release of neurotransmitter
What is long term potentiation the late phase?
- Requires transcription and protein synthesis
- Protein kinases activated by early LTP events
-Extracellular signal- regulated kinase (ERK) activates transcription
factors that initiate synthesis of proteins that support long-term changes to synaptic structure and morphology
-This process important for maintenance of long-term memories
