Lecture_15_Clinical Neuroscience Flashcards
Clinical Neuroscience
- Cognitive symptoms
- Treatments have cognitive side-effects
- Cognitive risk and protective factors for disorders
Neurovascular Units
The brain is intimately linked to the rest of the body
- Neurons, glia and blood vessels work together in the brain
- Anything that influences one part of the neurovascular unit will influence the others
- Brain activity and blood flow are intimately linked
- The brain pulses with blood flow
- FMRI
3 Types of Congenital Disorders
- Malformative Lesions
- Destructive Lesions
- Migrational Lesions
Malformative Lesions
The brain didn’t form in the right structure
- E.g. Callosal dysgenesis
Destructive Lesions
Damage caused by infection, trauma etc.
Migrational Lesions
Structural abnormalities caused by incorrect cell migrations during development
2 Types of Acquired Brain Injury
- Traumatic
- Non-traumatic
Traumatic Brain Injury
EXTERNAL events that damage the brain
- E.g. car crash, violence, sports injuries etc
Non-traumatic Brain Injury
INTERNAL events that damage the brain
E.g. stroke, cancer, infection, anoxia (lack of oxygen) etc
Neurodegenerative Diseases
- Alzheimer’s
- Parkinson’s
- Multiple sclerosis
Callosal Agenesis/Dysgenesis
A complete absence of corpus callosum in the brain, or often, it is much smaller than in most people
Callosal Dysgenesis: Cognitive
Impairments
- Worse social communication and emotion recognition
- Slower processing speed
- Relatively poor complex problem solving
- But, IQ may be in the normal range
Corpus Collosum
Connects the two hemispheres
- Homotopic organization: Cortical areas in one hemisphere are connected to the same area in the other hemisphere
Commissures
Connections between hemispheres
Why cognitive impairments are not much more obvious in Callosal Dysgenesis?
The corpus callosum is not the only connection between the hemispheres
- When the largest doesn’t develop correctly
- It’s likely that some of the others adapt to carry addition inter- hemispheric information
Callosal Dysgenesis: EF
In fMRI
- Easy problem-solving tasks: Normal
- Complex tasks: Abnormal
Stroke
- Interruption to blood flow long enough
- To cause tissue damage
2 Types of Stroke
- Hemorrhagic
- Ischemic
Hemorrhagic Stroke
Blood vessel bleeds into the brain
Ischemic Stroke
A vessel becomes blocked and tissue is starved of blood
3 Main Arteries to the Brain
- Anterior cerebral artery
- Middle cerebral artery
- Posterior cerebral artery
Anterior Cerebral Artery
Medial Fronto-Parietal
Middle Cerebral Artery
- Lateral Fronto-Parietal
- Dorsal Temporal
Posterior Cerebral Artery
- Lateral Parietal
- Ventral Temporal
- Occipital
Optic Ataxia
‘How’ processing
- The inability to accurately point to or reach for objects under visual guidance
Stroke in which cerebral artery would cause optic ataxia?
Posterior cerebral artery stroke
Visual Agnosia
‘What’ processing
- A difficulty in recognizing objects
Stroke in which cerebral artery would cause visual agnosia?
Posterior cerebral artery stroke
Prosopagnosia
The inability to recognize faces
Stroke in which cerebral artery would cause prosopagnosia?
Posterior cerebral artery stroke
Alexia
The inability to comprehend written or printed words
- Can’t read
Stroke in which cerebral artery would cause alexia?
Posterior cerebral artery stroke
Broca’s area & Wernicke’s areas
Language processing
- Left hemisphere
Aphasia
Broca’s area & Wernicke’s areas at the left hemisphere
- Sara Scott
Stroke in which cerebral artery would cause aphasia?
Left middle cerebral artery stroke
Hemispatial Neglect
Ignore one side of the object
Stroke in which cerebral artery would cause Hemispatial Neglect?
Right middle cerebral artery stroke
Stroke in which cerebral artery would cause dysexecutive syndrome?
Anterior cerebral artery stroke
Patient K.C., H.M., & E.P.
Hippocampal damage
- Amnesia
- Declarative memory impaired
- Non-declarative memory intact: emotion or feeling of trust
Stroke in which cerebral artery could damage the hippocampus?
Posterior cerebral artery stroke
Bilateral Damage
Usually more severe than unilateral damage
Alzheimer’s Disease
Memory loss
- Loss of brain tissue
- The sulci and ventricles are substantially enlarged
- Hippocampus is much affected
- Loss of acetylcholine -> hippocampus
Mini-Mental State Examination
(MMSE)
Test of dementia
- No EF, visuospatial
MoCA: Montreal Cognitive Assessment
Test of dementia
- EF, visuospatial
Parkinson’s Disease
- An idiopathic disorder: Occurs without an obvious cause
- Substantia nigra loss
1. Impaired motor loops - Akinesia: Slower and smaller movements
- Rigidity
- Tremor and gait freezing
2. Impaired executive loops
3. Impaired motivational loops - Clinical apathy
Substantia Nigra
- A part of the midbrain
- It is black because it contains cells that produce dopamine
- To basal ganglia and striatum
Basal Ganglia
Corticostriatal loops between striatum and the cortex.
- Several interconnected areas of grey matter
- Without the dopamine input, the basal ganglia cannot function well
Treatment of Parkinson’s
Aims to restore the normal activity of the corticostriatal circuits.
1. Dopamine medication
- Effective
- But causes disabling side effects with long-term use
2. Deep-brain stimulators
- Basal ganglia.
- Improves motor function
- A mixed effect on cognition, some abilities become worse
Schizophrenia
- Negative symptoms: Avolition and lack of motivation
- Positive symptoms: Delusions, hallucinations, thought disorder
- Onset between ages 20 and 40
- Lifelong disability
- Ventricles are bigger than healthy population
Cognitive Neuropsychology
Disease that causes specific impairments is useful in cognitive psychology
Dissociation
Cognitive process is impaired caused by a disease
- Or the study of brain parts that responsible for cognitive abilities from diseases
Problem with Dissociation Method
If a patient fails Task A after brain damage, there could be lots of explanations for it
Double Dissociation Method
Compare 2 patients with 2 different diseases
- Who has the exact opposite pattern of task performance
- The cognitive performance appear to be separate processes
- Provides strong evidence for the modularity of cognitive functions
Modularity of Cognitive Functions
A common way to view the mind in cognitive psychology
- In fact, that the mind is modular is a basic assumption of cognitive neuropsychology
