Lecture 5 - Frontal & Temporal Lobes Flashcards
What are the diverse functions of the temporal lobe ?
- Sensory processing (auditory, visual, olfactory)
- Object recognition, categorization & memorizing
- Spatial navigation
- Affective processing
What structures & cortices are in the temporal lobe ?
- Sensory regions : primary auditory & olfactory cortices
- Association regions : visual & auditory association cortices
- Subcortical structures : hippocampus & amygdala
What are the functions of the amygdala & hippocampus ?
- Amygdala : linking sensory information to emotions
- Hippocampus (& paralimbic region) : long-term memory formation
What specific functions of the auditory areas are localized in the L-hemisphere?
Speech sounds :
- Recognition
- Temporal dissociation
- Comprehension
What specific functions of the auditory areas are localized in the R-hemisphere?
Musical sounds :
- Frequency, pitch, timbre, rhythm, harmony
- Recognition of musical instruments
- Link to emotion & memory
What’s the region in the secondary visual area specialized in processing faces ?
Fusiform face area (FFA)
What’s the region of the secondary visual area specialized in processing places or complex scenes ?
- Parahippocampal place area
- Fusiform gyrus (complex scenes)
What are the different connections of the temporal lobe ?
- Between superior & ventral temporal lobe (STS stream)
- From auditory areas to parietal cortex (dorsal stream)
- From primary auditory & visual areas to the temporal pole (ventral stream)
What is the role of the STS in sensory processing ?
- Categorizing auditory & visual stimuli into object categories
- Cross-modal matching
How does the STS contribute to social cognition ?
- Analyzing social meaning of facial expression, body gesture, vocalization, gaze direction…
- Theory of Mind (ToM)
What are the 2 major projections of the temporal lobe ?
- Medial temporal projection (to hippocampus and/or amygdala) : LTM
- Frontal lobe projection : working memory, language, evaluation of emotional meaning of stimuli
What are the perceptual disorders linked to temporal cortex’ dysfunction ?
- Disorders of auditory, visual or odor perception
- Memory dysfunction
- Affect & personality
- Object & word categorization
What’s the difference between L-R temporal lobes ?
- R temporal lobe : non-verbal information (music, sounds, pictures
- L temporal lobe : verbal information, word recognition & categorization, speech comprehension
What happens if the L primary auditory cortex is damaged ?
- Auditory agnosia : general inability to perceive & identify complex sounds despite intact hearing
- Verbal auditory agnosia : word deafness
What specific symptoms are associated with damage to the L auditory areas ?
- Problems with discrimination of sounds
- Evaluating temporal order of sounds
- “people talk too quickly”
- Linked to Wernicke’s aphasia
What happens if the R primary auditory cortex is damaged ?
- Problems in musical perception
- Congenital amusia : tone deafness
What specific symptoms are associated with damage to the R auditory areas ?
- Problems in musical perception
- Amusica : not being able to recognize song
What specific symptoms are associated with damage to the L ventral stream ?
- Problems processing verbal information (auditory or written)
- Associative agnosia
- Word recognition (alexia)
- Problems with semantic categorization
- Problems using contextual information to extract meaning of verbal information
- Recall of verbal memory
What specific symptoms are associated with damage to the R ventral stream ?
- Problems processing non-verbal information
- Apperceptive agnosia
- Impairment in visual recognition : difficulty copying complex figures, unable to recognize faces in ambiguous shadow
What symptoms can we expect of temporal lobe lesions on personality & affect ?
- Affective & personality changes
- Egocentrism, paranoia, psychosis, burst of anger
- Hallucinatory experiences
- Loss of fear response
What’s the role of the frontal lobe ?
- Connects sensory & spatial information with action plans
- Controls behavior
- Inhibits inappropriate responses
- Planning, decision-making, motivation
- Keeps track of what already happened & what is to come (working memory)
- Cognitive control : ignoring irrelevant external stimuli
How does the frontal lobe guide decision-making and control behavior ?
- Weighs expected costs & benefits of behavior
- Integrates current sensory input with past experiences
- Adjust behavior to the environment
What does the Marshmallow Test illustrate about decision-making ?
- Ability to choose between a smaller immediate reward & a delayed larger reward
- Short-term vs long-term benefits
What are the 3 major divisions of the frontal lobe ?
- Motor & premotor cortex
- Prefrontal cortex
- Medial frontal cortex (MFC) & anterior cingulate
What are the main subdivisions of the prefrontal cortex ?
- Dorsolateral prefrontal cortex
- Orbitofrontal cortex
- Ventromedial cortex
In which of the frontal lobe’s functions are the motor & premotor cortices involved ?
Decision-making & motor planning
In which of the frontal lobe’s functions is the prefrontal cortex involved ?
Working memory
In which of the frontal lobe’s functions are the MFC & anterior cingulate involved ?
Error detection & weighting of expected costs & benefits (for decision-making)
From which areas does the DLPFC receive information ?
Posterior cortex areas :
- (Parietal) dorsal stream : executed movements
- (Temporal) ventral stream : objects in the environment
What are the main functions of the DLPFC ?
- Temporal/working memory
- Order of events
- Selecting behavior based on memory
- Problem solving
From which areas do the orbitofrontal cortex & ventromedial PFC receive & project information ?
- Receive from : Temporal lobe : auditory area (STG), visual stream (ITG), polymodal area (STS) & amygdala
- Projects to : amygdala, hypothalamus & brainstem
What are the orbitofrontal cortex & ventromedial PFC’ main functions ?
- Control blood pressure, heart rate, respiration…
- Physiological changes associated with emotional responses
- Flight-fight response
How do the orbitofrontal cortex and ventromedial PFC contribute to future planning and decision making ?
- Keep track of future outcomes
- Retrieve information about expected outcomes
- Use learned norms, rules & personal experiences to guide actions
Why is the orbitofrontal cortex important for social behavior ?
- Socially appropriate behavior
- Adjusting to context
How does the ventromedial PFC influence behavior ?
- Guides actions based on past experiences (external associative learning) & personal references (internal goals)
- Balance immediate reactions with LT goals & social norms
What are the primary functions of the medial frontal cortex and cingulate ?
- Weighting information to guide decisions
- Cognitive, affective & behavioral control
What functions are associated with the anterior cingulate cortex ?
- Evaluate expected value of stimuli (benefits, rewards…)
- Episodic memory
- Default mode network
What roles does the middle cingulate cortex play in decision making ?
- Expected costs of action (effort, pain…)
- Process pain
- Detect errors
What is the function of the posterior cingulate cortex ?
- Guide & plan decisions
- Works with premotor regions
What are the disorders link to dysfunction of the frontal lobe ?
- Disturbance of motor function
- Loss of divergent thinking
- Environmental control of behaviour
- Poor temporal memory
- Impaired social behaviour
What problems arise from damage to the primary motor cortex ?
- Problems with fine motor sequences
- Loss of force, speed & strength
What motor issues are associated with damage to the premotor cortex ?
Problems with whole-body motor sequences
What is the role of the frontal eye fields, and what issues can arise from their dysfunction ?
- Frontal eye fields : control eye gaze & visual search tasks
- Lesion : problems with directing eye movements
What motor planning issues are associated with the dorsolateral prefrontal cortex ?
- Planning series of movements or actions
- Issues with facial movements
What is corollary discharge and its role in motor control ?
- Corollary discharge : cancelling out the sensation of movement by matching the motor plan with sensory feedback, ensuring the worlds appear stationary when moving the eyes
What are the effects of corollary discharge dysfunction on limb movements ?
- Heavy limbs
- Fatigue, simple movements are effortful
What are the effects of frontal orbitofrontal lobe lesions on behavior ?
- Poor performance on verbal & design fluency tests
- Loss of spontaneous behaviour
- Loss of motivation
- Lethargy, apathy & difficulty initiating behaviour
What are the signs of frontal lobe damage ?
- Low output
- Shaky script
- Rule breaking
- Perseverance
What is divergent thinking ?
Ability to generate many different ideas or solutions to a problem (creativity & out-of-the-box thinking)
What are the effects of frontal lobe lesions on environmental control of behavior ?
- Poor response inhibition
- Poor adjustment to changing environment (perseveration)
- Risk-taking/rule-breaking
- Self-regulation/episodic memory
- Associative learning
Poor working/temporal memory is linked to a lesion to which area of the frontal lobe ?
DLPFC
To what symptoms is linked poor temporal/working memory ?
- Problems identifying objects
- Problems recognize/find location objects & events
- Problems with temporal order of events
What are the symptoms of impaired social behaviour linked to frontal lobe’s lesions ?
- Difficulty understanding meaning of facial expressions
- Unpredictable, defiant, moody behavior
- Pseudo-psychopathy (disinhibition, lack of tact & manners…)
- Pseudo-depressive behavior (lack of initiative, indifference…)
What are the different frontal lobe-task ?
- Verbal & design fluency
- Delayed non-matching to sample task
- Wisconsin cart sorting test
- Iowa gambling task
- STROOP task
- Rey complex figure task
