Basal Ganglia - Physiology Flashcards
What is the basal ganglia
Consists of a number of subcortical nuclei
Grouping is related to funtion
What is the basic feedback circuit of the basal ganglia
Receives information from several sources - including the cortex
Feeds information back to the cortex via the thalamus
What can the components of the basal ganglia be divided into
Input nuclei
Output nuclei
Intrinsic nuclei
What is the order of the nuclei components
Input nuclei receives information
Relayed to the intrinsic nuclei for processing
Further passed to the output nuclei
What are the input nuclei
Caudate nucleus
Putamen
What are intrinsic nuclei
External globus pallidus
Subthalamic nucleus
Pars compacta of the substantia nigra
What are the output nuclei
Internal globus pallidus
Pars reticula of the substantia nigra
Where are the caudate nucleus and putamen found
Telencephalon
What is the neostriatum
Collective term for the caudate nucleus and putamen
What is the globus pallidus divided into
External and internal domains
Functionally different
Where does the subthalamic nucleus lie
Diencephalon
Where is the substantia nigra
Mesencephalon
Divided into two parts
- pars compacta
- pars recticularis
Where does the caudate nucleus lie
Forms the lateral wall of the lateral ventricle
Is the caudate nucleus grey or white matter
Grey matter
Where does the internal capsule lie
During development the caudate nucleus is separated from the putamen by this
Is the internal capsule white or grey matter
White matter
What is the lentiform nucleus
Globus pallidus
Putamen
Anatomically related
Share no functional relationship
Is the lentiform nucleus grey or white matter
Grey matter
What forms the lateral aspect of the lentiform nucleus
Putamen
What separates the internal and external globus pallidus
Medial medullary lamina
What separates the putamen and external globus pallidus
Lateral medullary lamina
Is the external capsule white or grey matter
White matter
Is the claustrum part of the basal ganglia
No
Once thought to be part of it
Is the claustrum white or grey matter
Thin bundle of grey matter
Is the extreme capsule white or grey matter
White matter
Where is the subthalamic nucleus
Inferior to thalamus
Right above substantia nigra
What is the simple term of the function of the basal ganglia
Feedback mechanism
What is the main function of the basal ganglia
Motor refinement
Prevents exaggerated and excessive movements
Reducing excitatory input of the cerebral cortex
What is another function of the basal ganglia
Modulating cognitive and emotional responses
What is the role of the putamen
Motor loop
Receives inputs from motor and somatosensory cortices
Projects back to motor area
What is the role of the caudate nucleus
Receives input from cortical association areas
Projects to prefrontal areas
What is the role of the ventral striatum
Emotion
Receives inputs from the limbic system
What is the arterial supply of the basal ganglia
Majority from the middle cerebral artery
What are upper motor neurones
Motor command originates in motor cortex pyramidal cells - in layer 5,6 grey matter
Define basal ganglia
A group of structures beneath the cortex that act as ‘gate keeper’ for control of motor systems (muscles)
Where does the basal ganglia receive input from
Mainly excitatory
From many areas of the cortex
Glutamate - neurotransmitter
What is the neurotransmitter basal ganglia receive inputs from
Glutamate
What is the out put of the basal ganglia
Mainly inhibitory
What is the neurotransmitter for the output of the basal ganglia
GABA
What are the 5 principle nuclei of the basal ganglia
Substantia nigra (pars compacta and pars reticulata)
Caudate and putamen (striatum)
Globus pallidus (internal and external)
Subthalamic nucleus
What are the conditions which lead to motor resources
Energy balance (feeding)
Fluid balance (drinking)
Threat (escape)
What is the limbic system
Epicentre for emotional and behavioural expression
What are the functions of the limbic system
5 Fs
Feeding - satiety and hunger
Forgetting - memory
Fighting - emotional response
Family - sexual reproduction and maternal instincts
Fornicating - sexual arousal
What are the two lobes of the limbic system
Cortical (limbic lobe)
Subcortical
What is the limbic lobe components
Orbital frontal cortex
Hippocampus
Insular cortex
Cingulate gyrus
Parahippocampal gyrus
What is the role of the hippocampus
Long-term memory
What is the role of the insular cortex
Desires
Cravings
Addictions
What is the role of the cingulate gyrus
Neuropathic pain and nociception
What is the role of the parahippocampal gyrus
Path for communication between cortical association areas and hippocampus
What are the subcortical components
Amygdala
Olfactory bulb
Hypothalamus
Anterior and dorsalmedial nuclei of the thalamus
Septal nuclei
What is the role of the amygdala
Fear
Anxiety responses
What is the role of the olfactory bulb
Olfactory input about smells detected in nasal cavity
What is the hypothalamus role in the limbic system
Final output
Name the order of the circle of papez
Cingulate gyrus
Parahippocampal gyrus
Entorhinal cortex
Subiculum
Lateral and medial mammillary nuclei
Anterior thalamic nucleus
Internal capsule
Cingulate gyrus
What is the uncus the home of
Amygdala
What are the functions of the hypothalamus
Sexual arousal
Emotional response
Endocrine regulation
Sexual development
Thermoregulation
Regulation of satiety and hunger
Osmoregulation
What is the basics of the limbic system
Collection of structures involved in processing emotion and memory
Includes the hippocampus, amygdala, hypothalamus
What is the circle of papez
Interactions between the cerebral cortex and hypothalamus in order for emotional behaviour to be consciously perceived
What is the detailed communication pathway of the circle of papez
Uses prefrontal and alveolar tracts
by fornix and fimbria - information can be transmitted to the mamillary bodies
Mamillary bodies communicate with the anterior thalamic nucleus
Internal capsule takes information from the thalamus to the cingulate gyrus - then returns impulses to the entorhinal area via the cingulum
What is contained in the rostral (upper) part of the basal ganglia
Striatum - putamen, caudate nucleus
Globus pallidus - internal and external
What is contained in the caudal (lower) part of the basal ganglia
Subthalamic nucleus
Substantia nigra
What does not enough dopamine cause
Increased muscle tone
Reduced movements
What does too much dopamine cause
Decreased muscle tone
Overshooting movements
Is Parkinson’s disease too much or too little dopamine
Not enough
Why is there not enough dopamine in Parkinsons disease
Loss of the substantia nigra
Describe the pathology of parkinsons disease
Loss of substatia nigra means no stimulation of the striatum and globus pallidus and no stimulation to the subthalamic nucleus
Results in direct communication from the cortex to the striatum and globus pallidus to the thalamus
No control
Dishibition of inhibitory STN - increased overall inhibition of basal ganglia motor output
What is the role of the substantia nigra
Dopaminergic nucleus which plays a critical role in modulating motor movement and reward functions
What is the role of the striatum
Planning and modulation of movement pathways
Reward processing and motivation
Decision making
Working memory
Eye movements
