Lecture 9- Frontal & Parietal lobe Flashcards
What are longitudinal fissures?
Separates right and left hemisphere
What are fissures?
Deep sulci/grooves
What are the 4 parietal lobe boundaries?
-Central sulcus (Rolandic fissure)
-Lateral sulcus (Sylvian fissure)
-Parieto-occipital fissure
-Macro-anatomical
What is the central sulcus
(parietal lobe)
Boundary w/ frontal lobe
What is the lateral sulcus?
(Parietal lobe)
Boundary w/ temporal lobe
What is the Parieto-occipital fissure?
(Parietal lobe)
Boundary w/ occipital lobe
What is the Macro-anatomical?
(parietal lobe)
Means based on sulci/gyri
What are the 3 aspects of the post central gyrus?
Central sulcus
Postcentral sulcus
Postcentral gyrus
What are the 3 aspects posterior parietal lobe?
Superior parietal lobe
Intraparietal sulcus
Inferior parietal lobule
What are the 5 major functional subdivisions of the parietal lobe?
-Primary Somatosensory Cortex
-Intraparietal sulcus and superior parietal lobule
-Right inferior parietal lobe
-Left anterior inferior parietal lobe
-Left posterior inferior parietal lobule
What is the soma?
Body
What is the main role of the primary somatosensory cortex?
Processing info about body sensations eg touch, pain, proprioception (map of various body part locations)
-Can be divided into 4 subdivisions (1,2,3a,3b)
What is the input and output of the primary somatosensory cortex
Input mainly from thalamus and motor cortex
Output mainly to motor cortex and posterior parietal cortex
What happened in the Penfield + Boldrev (1937) study?
Inserted electrodes in somatosensory cortex of epileptic patients just before operating.
He stimulated different parts of somatosensory cortex and recorded sensations reported by patients.
Led to creation of simplified (partially incorrect) somatotopic map.
What does Wilder Penfield’s somatotopic map show?
Some body parts have larger dedicated area than others. -Also known as somatosensory homunculus
How and why criticises the somatotopic map?
Seelke et al (2012) says may not be as simple as depicted by Penfield as can have more detailed subdivisions
What is the Somatosensory cortex?
-Our brain is more dynamic than we assume. -Functional reorganisation of S1 can occur within 24hrs
How did Kolasinki et al (2016) support the idea of the Somatosensory cortex?
The little and ring finger were glued together.
Functional reorganisation happens in less than 24 hrs as brain began to think the 2 glued fingers as one. -Mirror box in which ‘ghost’ pain can be removed by making brain believe the pain isn’t there
What is the overarching concept of the Intraparietal sulcus and superior parietal lobule?
Overarching concept of vision for action within the dorsal visual stream such as:
-Interact w/ object
-Where is body relative to object
What is the classic neuropsychological syndrome after bilateral legions?
Bálint syndrome (Jackson et al., 2009)
What is Optic ataxia?
Deficit in visually guided reaching movements (Anderson et al, 2014)
What is Oculomotor apraxia?
Inappropriate fixation of gaze and difficulties in voluntarily shifting fixation to other objects
What is Simultanagnosia?
Impaired ability to perceive multiple items in a visual display
What are the 3 mechanisms involved in cognitive functions?
Visuospatial working memory
Mental rotation
Arithmetic
What is visuospatial working memory
(mechanisms of cog function)
Link to representing the location of objects, coding what is relevant.
What is mental rotation?
(mechanisms of cog function)
Link to manipulating objects
What is Arithmetic?
(mechanisms of cog function)
Link to moving eyes / hands to count, spatial layout
What does the Right inferior parietal lobule do?
Detect salient events in environ so can shift attention
What does Singh-curry + Husain (2009) say about the right inferior parietal lobule?
Detecting and encoding of salient or novel events (bottom-up attention) -Sustaining attention on current task goals
What is the key role of the right inferior parietal lobule?
Maintaining attention on current task goal as well as encoding of salient events so that task-sets can be speedily reconfigured to deal with new challenges
eg block defender as well still dribbling
What does lesions in the right inferior parietal label cause?
Lesions in area can lead to Hemispatial neglect
What does the Left anterior inferior parietal lobule do?
Use objects in appropriate way, pantomime object use
What does Reynaud et al (2016 study say about the left anterior inferior parietal lobule?
-Understanding tool-use actions
Lesions in area can lead to Apraxia w/ possible impairments eg
-Imitation of gestures -Communicative gestures -Real tool use
What does the Left posterior inferior parietal lobule do?
Detect salient events in one’s thoughts
What does Seghier (2012) say about the left posterior inferior parietal lobule?
If we are detecting bottom up info, what does it affect?
Semantic and number processing, Reading and comprehension, memory retrieval, theory of mind, default mode processing (mind wandering)
What does Cabeza et al (2012) say about the left posterior inferior parietal lobule?
Integrative account for more posterior areas
-Bottom-up attention to internally generated stimuli (thoughts). -Contrasts from the right inferior parietal lobule which relies on bottom-up info from environmental stimuli.
Why is function of different areas difficult to understand?
Animal models might not work for these areas.
What separates the Frontal lobe and Parietal lobe?
The central sulcus
What runs down the side of the frontal lobe?
Cingulate sulcus
Cingulate gyrus
What are the 3 main subdivisions of the frontal lobe?
-Primary Motor cortex (M): giant Betz cells in layer V. -Premotor cortex (PM): no granular cells in layer IV. -Prefrontal cortex (PF):granular cells in layer IV
What are the subdivisions of the frontal lobe based on?
Based on cytoarchitectonics (looks at cell structures within them)
What does Brodmann’s (1909) cytoarchitectonic map show?
Shows how there are many areas within the brain
What is the motor cortex?
(frontal lobe)
-Control of skeletal muscles together with other structures: most notable, basal ganglia, thalamus, cerebellum. -Roughly somatotopically organised
What is the premotor cortex (High order motor control)
Frontal lobe
-Movement planning, selection, sequencing, inhibitory control of motor cortex (supplementary motor area on medial side of hemisphere).
How does the 2 Milner (1964) studies show the traditional approach of studying the neuropsychology of the prefrontal cortex?
-Verbal fluency eg writing down as many words beginning with F in one minute.
-Wisconsin card sorting task eg preservation as continue to use “no longer correct rule” in which asked to either ignore shape or colour and identify the other.
What are 2 other traditional ways of studying the neuropsychology of prefrontal cortex?
-Tower of London task (Shallice, 1982) in which asked to move one ball at a time from one column to another.
Shows need for planning
-Stroop task (Perret, 1974)
What are 4 issues regarding the traditional approach of studying the prefrontal cortex?
-Sensitivity
-Specificity
-Not all patients e/ frontal lesions have difficulties
-Some patients w/ non lesions have difficulties
What is Sensitivity regarding issues studying prefrontal cortex?
Ability of test to identify those with prefrontal lesions and are impaired.
What is Specificity regarding issues studying pre frontal cortex?
Ability of test to not identify those impaired by lesions in other areas.
What was Stuss & Alexander’s (2007) recent approach to studying prefrontal Cortex?
Basic approach- Devise simple tests for single processes, manipulate difficulty and context (complex processes), based on Norman and Shallice’s supervisory attention system
-used lesion-symptom mapping eg simple and choice RT, go/no go
What was Stuss & Alexander’s (2007) conclusions about the prefrontal Cortex?
-Lateral PFC (executive function)- Left= Task setting, Right= Monitoring.
-Dorsomedial PFC (Energisation)- Process of initiating and sustaining any response.
-Orbital PFC- Behavioural and emotional self-regulation
-Polar PFC- Metacognition= thinking about thinking
What are 3 evaluations of Stuss & Alexander’s (2007)
Lesion-symptom mapping is interesting= Further refined with modern structural MRI as voxel-based lesions symptom mapping.
Exact processes are still unclear= Are the tasks really process pure and are the appropriate labels chosen (cover all deficits).
Problems w/ patient studies= small sample sizes, lesions restricted to grey/white but not both.
What are 2 evaluations of function of LPFC
Adaptivity- per se is plausible but is restricted (not every area can represent everything)
Hierarchical organisation- per se is plausible but exact processes associated with the different areas are still unclear. Relationship to Stuss’ neuropsychological results not clear
What is needed for accurate study of neuropsychology of prefrontal cortex?
Computational models combined with experimental evidence (brain imaging, brain stimulation, lesion)
