the cerebral cortex- lecture 9

Question 1

key features of the forebrain

Answer 1

1. right hemisphere
2. corpus collosum
3. left hemisphere

the cerebral cortex is contralateral (on opposite side of the body or head)

Question 2

organisation of the cerebral cortex

Answer 2

1. cortex is made up of 6 seperate layers
2. the laminae are stacked in columns

Question 3

cortex is made up of up to 6 seperate layers

Answer 3

laminae- vary in thickness and prominence in different parts of cortex depending on the purpose they serve-laminae V realtes to muscle control (its thickest in motor cortex), laminae IV relates to the senses, its thickest in sensory cortex BUT is extremely thin in the motor cortex where it is less functional

Question 4

laminae are stacked in columns

Answer 4

cells that perform similar functions are arranged in the same column so all cells in a particular column respond to the same stimuli, macro-columns= general functions, micro-columns= more specific functions

Question 5

mapping the cortex

Answer 5

• the crotex can be divided into many sub regions based the thickness of the laminae, the structure of cells within each laminae
• structures can then be related to brain functions and behaviours
• the cortex can be divided into 4 main areas (lobes)
• frontal lobe, parietal lobe, occipital lobe, temporal lobe

Question 6

occipital lobe

Answer 6

• the most prosterior (caudal) part of the cortex, comprises the primary visual cortex/striate cortex
• the main target for axons from thalamic nuclei concerned with vision
• destruction of any part of striate cortex can cause cortical blindness in a related part of visual field

Question 7

parietal lobes

Answer 7

• lie between the occipital lobe and central sulcus
• sensation and perception
• damage to the parietal lobes produces- deficits in tactile function, disorders of body image, right-left confusion, problems with spatial ability, sensory neglect (ignoring one side of the body/features in the world)
• includes somatosensory cortex- areas of the somatosensory cortex correspond to senses on different parts of the body

Question 8

temporal lobes

Answer 8

• the lateral portions of each hemisphere (near the temples)
• both temporal lobes are richly connected to other lobes, sensory systems limbic system and basal ganglia

Question 9

3 key functions of temporal lobe

Answer 9

1. memory
2. emotion and mood
3. auditory and (some) visual perception

Question 10

1. memory (temporal lobe)

Answer 10

the hippocampus is crucial for memory, case of HM- during temporal lobe surgery for epilepsy the hippocampus was damged, intellect, personality and perception intact BUT HM was unable to form new memories (anterograde amnesia)

Question 11

2. emotion and mood (temporal lobe)

Answer 11

the amygdala, involved in emotional processing, is activated in resonse to emotional stimuli (e.g. pictures of emotional expressions like fear and disgust), amygdala damage often results in inability to- show appropriate responses to stimuli, recognise emotion in others

Question 12

3. auditory and (some) visual perception

Answer 12

focusing attention on relevant auditory info, perception of music and speech, wernickes area- wernickes aphasia- inability to understand words or arrange words into coherent speech

Question 13

frontal lobes

Answer 13

• frontal lobes extend from the central sulcus and cover the anterior of brain
• key areas= primary motor cortex, premotor cortex, frontal cortex, prefrontal cortex, brocas area
• the whole area acts as a ‘control centre’ as it recieves input from thalamic nuclei, limbic system, hypothalamus and other lobes

Question 14

brocas area

Answer 14

• named after paul broca
• 1861, broca treted patient who lost inability to speak fluently but could still understand speech
• autopsy revealed the damage was localised to specific region on left hemisphere of frontal cortex (brocas area)
• damage to this area called brocas aphasia- slow deliberate, non-fluent speech, but comprehension of speech can be unimpaired

Question 15

motor cortex

Answer 15

• divided into sections
• each section is responsible for movement of different body areas through neuronal connections

Question 16

frontal cortex

Answer 16

forms about a third of the frontal lobes

Question 17

roles of prefrontal cortex

Answer 17

mostly involved in higher order processes

• planning and evaluation
• event monitoring
• monitoring emotions
• working memory (retaining info for short periods of time)

Question 18

damage to prefrontal cortex

Answer 18

• prefrontal lobotomies- surgical disconnection of the prefrontal cortex
• rationale- lobotomised primates became tamer with few side effects so applied the same to humans with range of psychiatric problems
• results- calmed people own (but not as often as hoped) BUT loss of social inhibitions and emotional expression, increased apathy, inability to plan, problms with working memory so pratice generally ceased in 1970s (with a few recorded cases in 80s and 90s)