lecture 7- the temporal lobe Flashcards
how the different regions of the brain are physiologically different
-they have different neuronal organisation, different connections to other brain areas
-so should have different roles in cognitive processing
function of temporal lobe - basic
you can think of it as a lexicon for the meaning of things
kluver bucy syndrome 1930
-tried to understand what the temporal lobe does
-monkey experiment
-removed the lobe in monkeys do see what happens
-monkeys can hear and see but ‘no longer clearly understands meaning of sights, sounds’
-poor memory
-examine things regardless of danger: fire , broken glass
-eat everything , meat and feces !
-mate everything: other sex, same sex, inanimate objects
-tame : lose fear of / aggressiveness towards humans
-so 1) they dont recognise what they are 2) lose memory ability 3) emotional changes
semantic dementia
-what is it
-what part of the brain does it affect
-symptoms
-what other problems can it lead to if it spreads
Progressive neurodegenerative disorder characterized by loss of semantic memory (verbally and non verbally
-affects temporal (and frontal) lobe first
-language symptoms are most obvious (anomia: problems with finding nouns rather than verbs)
-as the disease spreads, problems with prosopagnosia and object agnosia, memory , personality and emotion
main problems in the brain due to temporal lobe damage
-what do these main problems have in common7
-problems with
recognition
memory
emotion
-all these things define the meaning of things
auditory input - a component of the temporal lobe
-this is the home of the audtitory cortex, whereas the analysis of visual input occurs in the occipital lobe, auditory signal are processed in the temporal lobe
where is auditory information from the auditory cortex sent
Auditory information is then from auditory cortex sent into Wernicke’s area where words are recognized.
(part of the brain in control of understanding speech)
what happens when there are lesions to auditory cortex vs lesions to Wernicke’s area
-lesions to auditory cortex impair sound perception in general whereas lesions to Wernicke’s area only impairs speech perception
- disrupted links between sounds and meaning
where does the temporal lobe receive visual input
Temporal lobe receives visual input from occipital lobe.
It is involved in identifying the stimuli ‘seen’ by the visual cortex
associative agnosia
-Patient with damage to temporal lobe is unable to recognize objects.
He can see whole form of shapes (no problem copying figures)
Disruption not of vision but of object recognition
(so would be able to describe an object but not recognise it)
-disrupted associations between visual and meaning/language nodes
associative agnosia
-objects can often be recognised when….
-when perceived through a different modality
-specific failure to link vision (but not touch) to knowledge
(it is not memory loss, its the loss of being able to associate what you see with what you know)
damage only affects areas/ connections that are involved in only the visual identification of objects ?
how can associative agnosia be selective for different stimulus classes
-what does this tell us
-agnosia can be selective for different stimulus classes
eg patients who have lost the ability to recognise artefacts eg tools
Different areas involved in identifying built things and animals/plants?
associative agnosia
-can they access actions related to objects
Can still often access the actions you can do with the objects, and(mis-)identify objects in this way!
guy seems to not be able to identify object as a lock but knows what to do with it
prosopagnosia
-damage to temporal lobe
-problem with face recognition
patients can see a face, but cannot link it to any knowledge they have about the person
problems people with prosopagnosia struggle with
-very hard to recognise people outside their usual contexts
-very socially disruptive , sufferers develop coping strategies such as memorizing mannerisms, voices, etc colour coding their children
-very hard to follow movie plots
_____ _______ and ____ _____ suggest specialised brain regions for different stimulus categories
double dissociations and brain imaging
examples of specialised brain regions for different stimulus categories
-fusiform face area
-body area
-LOC things
-parahippocampal place area
emotional and memory systems
-the amygdala and threat
“the human amygdala is a pivotal area of the brain for triggering a state of fear. While the patient is able to experience other emotions, such as happiness and sadness, she is unable to feel fear. This suggests that the brain is organized in such a way that a specific brain region - the amygdala - is specialized for processing a specific emotion - fear
evidence that amygdala plays a role in fear experiment
-video shows a robot thing in a box
-sends rat into box with food and robot thing, rat wants food but is scared of robot
- same rat without amygdala isnt scared and doesnt run away and retrieves the food - showing amyglada plays a role in fear
where do people look when they interact with someone
-in normal person
-in person with amygdala damage
-in a normal person (average of 5 healthy controls the person looks at ones face on the eys around the centre mainly little at the lips
-in a person with amygdala damage a person looks down at the lips more and in random spots not even the face alot
pavlovian learning
-conditioning someone with a stimulus to learn a certain response
eg the dog training condition (before conditioning , food makes dogs salivate but a bell wont. after conditioning with the food and bell, the bell alone can make the dog salivate)
-uninteresting stimulus becomes motivationally relevant and enables anticipation results
amygdala and emotional meaning
explain the learning
- Relatively ‘dumb’ system that learns what happens when exposed to relevant stimuli.
When stimulus is re-encountered appropriate emotional response is elicited.
Not only for fear, but other emotions, i.e. sexual stimuli, smiling faces, food, loss in games, etc.
Makes sure emotional stimuli are processed, and induces appropriate emotional state
connected to the hypothalamus
Receives information from all areas of the body, and compares them with biological set points
. Acts on both the endocrine and autonomous nervous system to control:
- blood sugar level
- hormone levels
- temperature
prepares the animal for different types of behaviour (the four Fs: fight, flight, feeding and mating
henry molaison case
-what did he sufer with
-what surgery did he have
-what happened after the surgery / how did he act
Severe epilepsy, about 10 seizures aweek, from age 9 onwards
. Did not respond to anticonvulsants.
In September 1953, 27 years old, surgery to bilaterally remove medial temporal lobes (Hippocampus
‘He was a very gracious man, very patient, always willing to try these tasks. And yet every time I walked in the room, it was like we’d never met.”
-he lost ability to form memories
-anterograde amnesia
-retrograde amnesia
Anterograde amnesia – since lesion: suggests problem with transferring new experiences into memory.
Retrograde amnesia – prior to lesion: also some problems here
-past memory encoding takes several years
henry suffered from the ability to form memories
-look at graph retrograde first and after surgery is anterograde
different memory systems
what else did it effect
Can learn new motor tasks (Intact procedural memory
basal ganglia?)
Intact working memory (keep things in mind for the time needed to solve the task) and long term planning (solves tower of Hanoi task quickly, but does not remember playing it before)
prefrontal cortex.
what does the temporal lobe do in summary
Identifies things
Triggers emotional response
Encodes them in memory
Different parts of the temporal lobe responsible each of these functions.
together, they provide you with the meaning of things
