Cerebral Cortex Flashcards
What is the cerebrum
Cerebral hemispheres and diencephalon
- includes subcortical structures
- basal ganglia
- amygadala
What is the Diencephalon
- center of cerebrum
- thalamus
- hypothalamus
- epithalamus
- subthalamus
Thalamus
What is it?
what are important nuclei in the thalamus and their function?
- relay station
- Relay Nuclei: convey info from the sensory system (except olfactory)
- motor loops from thalamus received info from the basal ganglia or cerebellum to the cortex
- assoication nuclei: process emotional and memory info or integrate different types of sensations
- nonspecific nuclei: regulate consciousness, arousal and attenion
What happens with thalamic lesions
- contralateral sensory loss: interruptions of ascending pathways (proprioception primary)
- thalamic pain syndrome: rare contralateral pain without provocation
- lateral pulsion/pusher syndrome:
Pusher syndrome
- Altered perception of the body’s orientation in relation to gravity
- Active pushing with unaffected side results in tendency to fall toward hemiparetic side
- May resolve about 6 months post CVA
- tend to fall toward hemiparetic side
Hypothalamus
- homeostatsis
- eating behavior
- reproductive and defenseive behaviors
- helps regulate circadian rhythms
- helps with emotional expressions
- regulates endocrine functions: growth, metabolism, reproductive
- activation of sympathetic nervous system
- all carried out by hypothalamic control via regulation of secretions from the pituitary
Epithalamus
- Pineal gland = major structure of the epithalamus; helps regulate circadian rhythm
- influences: pituitary, islet of langerhands (pancreas), Parathyriod, adrenal gland
Subthalamus
- has connections with basal ganglia
- helps with motor control
Subcortical white matter
- Projection fibers
- commissural fibers
- associated fibers
Subcortical white matter
Projection fibers/bundles
- Extend from subcortical structures to the cerebral cortex,
- from cerebral cortex to spinal cord, brainstem, basal ganglia, and thalamus.
- Travel through internal capsule
Subcortical white matter
Association Fibers
- Connect cortical regions within the same hemisphere (gyri or lobes with a cerebral hemisphere)
Subcortical white matter
Commissural Fibers
- Largest Group=Corpus Callosum-links right and left hemispheres (links like structures); other links right and left temporal lobes
Pyramidal cells
- Most common type of cortical neuron—short axons
- Apical dendrite: extends toward the surface of the cortex
- Almost all travel through white matter as projection, commisural, or association fibers.
What is brodmann’s area
- Used to designate cortical locations (types of cells)
- Numbered areas of functional importance (numbered in the order they were studied)
- Variable from brain to brain
- Used by clinicians and researchers for reference purposes
look at flow of cortical information
function of
1. primary sensory cortex
2. secondary sensory cortex
3. assoication cortex
4. motor planning areas
5. primary motor cortex
- primary sensory cortex: Simple sensory discrimination (ntensity vs quality)
- secondary sensory cortex: recognition of sensation
- assoication cortex: goal selection, planning, monitoring, interpretation of sensation, emotions, memory, processing
- motor planning areas: movement compoisition, sequencing
- primary motor cortex: cortical motor output
primary sensory cortex
Primary somatosensory
function/lesion will cause
function:
- discriminates shape, texutre or size of oject
Lesions causes:
- loss of tactile localization and conscious proprioception
Primary sensory cortex
Primary auditory
Function:
- conscious discrimination of loudness and pitch of sounds
Lesions cause:
- loss of localization of sounds
Primary sensory cortex
Primary visual
function:
- distinguishes intensity of light, shape, size and location of objects
Lesions cause:
- homonymous hemianopia
a field loss deficit in the same halves of the visual field of each eye
Primary sensory cortex
Primary vestibular
functions:
- discriminates amoung head positions and head movements
- contributes to perception of vertical
lesions cause:
- change in awareness of head position and movement and perception of vertical,
- lateropulsion
Secondary sensory cortex
Secondary somatosensory cortex
function:
- stereognosis and memory of tactile and spatial environment
Lesions cause:
- astereognosis
Secondary sensory cortex
Secondary visual
- analysis of motion,
- color
- recognition of visual objects
- understanding of visual spatial relationships
- control of visual fixation
Lesions cause:
- visual agnosia or optic ataxia
visual agnosia-Inability to visually recognize objects despite having intact vision
Secondary sensory cortex
Secondary auditory
function:
- classification of sounds
Lesions cause
- auditory agnosia
Motor planning/motor cortex
Primary motor cortex
- function: selective motor control
lesions cause
- paresis
- loss of selective motor control
- spastic dysarthria
Motor planning/motor cortex
Premotor cortex
function:
- initiation of movement
- orientation planning
- control of bimanual and sequential movements
Lesions cause:
- apraxia = motor agnosia-knowledge of how to perform a task is lost
Motor planning/motor cortex
Brocas area
Function:
- motor programming of speech (usually o n the left side)
Lesions cause:
- broca’s aphasia with left sided lesion
- Broca’s aphasia=difficulty expressing self through words or writing
Motor planning/motor cortex
Inferior frontal gyrus in hemisphere dominat for emtional, social and spatial processing
function:
- planning nonverbal communication
- emotional gestures, tone of voice, usually in the right hemisphere
Lesions cause:
- difficulty producing nonverbal communication
Primary Motor cortex lesions
- loss of fractionation of movement
- dyarthria
- alien hand syndrome
- Alien Hand Syndrome-involuntary, uncontrollable movement of the upper limb(limb may raise unexpectedly with movement, unintentionally grab objects)
Motor Planning area lesions
- apraxia: decreased knowledge of how to preform a task
- less cues are better
- broca’s aphasia: difficulty expressing self through words or writing
Assoicated areas with sensory and motor cortexes
- not directly involved with sensation or movement
- cortex-controls behavior, interprets sensation, processes info and memories
- recalls name of object, sound it makes, associates memories and decides what to do with it.
- Damage to prefrontal cortex=personality changes, apathy, lack of emotion and insight
- Prefrontal cortex responsible for executive functions=working memory, judgement, planning, abstract reasoning, dividing attention, sequencing an activity.
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What is frontotemporal dementia
- a group of disorders that occur when nerve cells in the frontal and temporal lobes of the brain are lost
- this causes the lobes to shrink
- FTD can affect behavior, personality, language and movement
Emotions and slef awareness: primary structures
- medial prefrontal cortex
- temporal lobe
Emotions and self awareness: other strucutres involved
- Anterior insula
- Ventral striatum
- Amygdala
- Brodman’s area 25
- Medial thalamic nuclei
Emotional loop
“cortico-basal ganglia-thalamic loop”-links emotion, cog, and motor systems
What does the medial prefrontal cortex and temporal lobe do
- Involved with emotions, self-awareness, and motivation; emo expression
- perceives others’ emotions, makes assumptions about what other people believe and their intentions,
- lesion=apathy, lack of emo/insight/initiation
- In schizophrenia it is less active than normal (they wrongly interpret emo, intentions, etc)
Ventral striatum:
- determines reward seeking behavior, responds to conditioned stimuli
- area 25, amygdala and the ventral prefrontal cortex generate sad mood and depression
Amygdala
- generates feelings of fear and disgust,
- interprets facial expressions, body language, and social signals.
- Essential for social behavior and emotional learning.
- emotions tied to decision making
How do we regulate our emotions
- automatic/non-conscious
- voluntary
regulate our emotions
Automatic/non-conscious
- ignoring, denying, or leaving an emotional situation, sustaining particular beliefs about a situation, and controlling behavior after an emotion has been generated
- rostral cingulate cortex - direct attention away from emotional stimuli
- med and central prefrontal cortex
Regulating emotions
Voluntary
- deciding not to express anger toward a situtation
- Ventral prefrontal cortex
- lesions here = emtional libility
rostral cingulate cortex
Emotional lability
- abnormal mood shifts
- Involuntary inappropriate emotional expression-laughing/crying
- Emotions triggered by non-specific stimuli
- present most with ALS, TBI, MS
Emotion vs mood
- mood tends to be sustained subjective ongoing emotional experience
- Emotion-short term subjective experience (Lundy) Learned response elicited by sensory stimuli that produce physiologic changes(heart, resp, sweating, etc), motor changes (mm tensing, facial expressions, extra movement) and motivate us to action(attraction, avoidance, crying, etc) Culmination of emotions leads to feelings (happy, sad, etc)
Amygdala lesions
- bilateral lesion=no fear, even when threatened, poor decision making, unable to interpret facial expression.
- Memory/emotions intact. (Bundy/Lundy example)
- Social pragmatics -the social use of language and how individuals interact with others.
Medial and ventral prefrontal cortex and anterior cingulate gyrs in emotion
- regulate emotional behaviors
Role of emotions
- unconscious
- conscious
- decision making
- affects other systems such as motor, immune, cardio, digestive
Stress response
- emotion system percieved threat/stress
- sends signals to hypothalamus
- hypothalamus stimulates pituitary
- pituitary stimulates adrenal gland
- adrenal gland releases cortisol
Working memory
- maintains goal relevant information for a short time essential for language problem solving, mental navigation, reasoning
- essential for multitasking
Declarative memory
immediate
short term
long term
structures:
- medial temporal lobe
- medial temporal cortex
- hippocampus
Declarative memory stages
- encoding: process info
- consolidate: stabilizes memories
- retrieval
- loss of declarative memories = amnesia
Procedural memory
- Recall of skills and habits
- motor and parietal cortex: learing the new skill
- basal ganglia: learned movement sequencing
- cerebelllum: ability to automatically adjust movement and posture during a skill
Stages of
procedural memory
- Cognitive-Beginner is trying to understand the task and find what works (may talk their way through it)
- Assocition-refines the task
- Automatic-Less attn. required (able to multitask, hold a conversation etc)
Speech and language
Wernicke’s area
- left temporoparietal cortex
- comprehension
- lesion = wernicke’s/receptive aphasia
- cannot understand speech
- reading: visual assoication
- writing is brocas and wernicke’s
Brocas area
- left frontal cortex
- language output
- lesion = brocas/expressive aphasia
- cannot speak but can understand
- writing = brocas and wernicke’s
- global aphasia if both areas lost
Right hemisphere and communication
- nonverbal communcation
- social pramatics: the social use of language and how individuals interact with others
- spatial relationships (hemi-spatial neglect/personal neglect/heminattention)
Personal neglect
- typically occurs with right sided parietal damage
- Unilateral lack of awareness of sensory stimuli
- Unilateral lack of personal hygiene and grooming
- Unilateral lack of movement of the limbs
Consciousness
- general level of arousal
- attention
- selection of object of attention
- motivation and initiation
- requires specific NT produced in brainstem
- sent via reticular activing system to brain
NT for consciousness
- general arousal level = serotonin
- attention = NE, locus ceruleus
- Goal-mediated attention = ACh, anterior cingulate gyrus
- motivation and initiation (motor and cognitive) = dopamine
