Basal Ganglia and Thalamus Flashcards
Why is it called white matter?
Myelination —> glistening white appearance
Masses of gray matter found deep within the cortical white matter
Area of the brain that can help modify, integrate, enhance, lessen the gross motor movements
Other fxns:
Regulate somatomotor activity by means of numerous feedback circuits with each other and ultimately with the cerebral cortex
Basal ganglia
Neurons in the basal ganglia
DAMAGE: produce extrapyramidal movement syndromes
Putamen + globus pallidus
Looks like the lens of the eye when put together
Lentiform nucleus
Where do our neurons come from?
Primitive stem cells lie near ventricular wall. They migrate.
Stem cells left behind in the subcortical area -> gray matter in the basal ganglia
Are they interconnected? Or kalat-kalat? Anatomically not together, but in terms of function, closely interconnected with one another
Do they relate to neurons in the cerebral cortex? YES
Most modern trunk?/tract in our body
Corticospinal tract, aka pyramidal tract
More functions of the basal ganglia
Integrates feeling and movement Suppress unwanted motor behavior Allow feelings of pleasure and ecstasy Enhances motivation Shifts and smoothes fine motor behavior Initiates internally generated movement (but can be overtaken by the cerebral cortex)
Does the basal ganglia reçeives input from the spinal cord?
Unfortunately, NONE
Caudate nucleus + Putamen
Striatum
Lentiform nucleus + Caudate nucleus
Corpus striatum
Internal capsule. Where from?
All the processes in Area 4 (Brodmann’s classification)
Part of the corticospinal tract
Lateral to the external capsule is a thin sheet of gray matter called?
Calustrum
External to it: Extreme capsule (white matter)
vs
Corpus striatum: gray matter
True sexual arousal will always start from where?
Above (brain)
Which part? Hypothalamus!
Site of pyramidal decussation
Medulla
Implication: Lesion in the right, felt on the left
Pain and temperature is mediated by…
Spinothalamic tract
Sensation, proprioception
Mediated by?
Fasciculus gracilis
Fasciculus cuneatus
(Ascending tracts) - from senses to the brain
Most supreme of all the tracts
Corticospinal tract / Pyramidal fiber tract
Other tracts are labeled as extrapyramidal tract
Identify
Carry melanin pigments -> reason for pigmented appearance
Substantia nigra - dopaminergic (inhibitory)
*dopamine- both excitatory and inhibitory
Subthalamic nuclei - glutaminergic (excitatory)
Connection of basal ganglia with the cerbral cortex
DIRECT
Cortex -> Caudate and putamen -> Ext and int globus pallidus -> Thalamus -> Cortex
What pathway facilitates movement?
EXCITATORY
Direct
Dopamine acts on D1 receptors
What pathway inhibits movement?
Indirect (makes sidetrips to substantia nigra and subthalamic nucleus)
Melanin pigments in substatia nigra
What pars?
Pars compacta
Inhibitory or excitatory?
Glutamate
GABA
Excitation
Inhibition (much produced)
We go trough a series of inhibition and excitation
Output is where the series ends
REMEMBER
Not all neurotransmitters are excitatory
Most abundant neurotransmitter in the brain?
In the basal ganglia?
Glutamate
GABA
What structure is intimately connected with spinal cord to modulate movement?
Cerebellum
Spinocerebellar tract
Hyperkinetic movement
Quick, lightning-fast movements of face and upper extremities
Tic
Hyperkinetic movement
Oscillatory, rythmic, regular movement affecting one or more body parts
Tremor
Hyperkinetic movement
Involuntary, irregular, purposeless, non-rythmic, abrupt, rapid, unsustaomed movements that seem to flow from one body part to another
Chorea
Hyperkinetic movement
Slow, writing, continuous involuntary movement
Athetosis
Hyperkinetic movement
Twisting movements that tend to be sustained at the peak of movement, frequently repetitive and often progress to prolonged abnormal postures
Dystonia
Hyperkinetic
Sudden, brief, shock-like involuntary movements caused by muscular contractions
Myoclonus
Hypokinetic movement
Seen in shizophrenia, development of fixed postures, retention of limbs for an indefinite period of time
Catatonia
Hypokinetic movement
Includes fatigue…
Hypothyroidism
Hypokinetic movement TRAP: Tremors at rest Rigidity Akinesia / bradykinesia Postural instability (propulsion and retropulsion)
Nonmotor impairment: cognitive, hallucinations, delusions, sleep disturbances
Parkinson’s disease
Releases melatonin
Pineal gland
Processes all somatic sensory information namely pain, temperature, light touch, position and vibration
ALL modalities of sensation except olfactory (CN 1)
Final relay station before reaching the primary cortex
Thalamus
Pain sensation of face
Ventral posterior nucleus of thalamus
Function of the central nuclei
Receives input from ARAS (Ascending reticular..)
Seat of our consciousness
Reticular formation of the thalamus
Other name of pre-motor cortex
Supplementary motor cortex
