Basal Ganglia (Nuclei)

sudden, rapid, jerky, purposeless movement involving limbs, trunk, or face Seen in parkinsons' huntingtons disease and SLE

Chorea

Lenticular fasciculus (dorsal) Ansa lenticularis (ventral) THese two join together to form thalamic fasciculus en route to thalamic nuclei (ventral anterior and ventral lateral)

Describe the pallidothalamic fibers.

Augmentation, facilitation or inhibition of components of the complex actions including initiation and acceleration of voluntary movements, inhibition of extraneous movements and stopping volitional movements

Describe the specific role of the basal ganglia in voluntary movement.

Distortion or impairment of voluntary movement

Dyskinesia

Striatopallidal Subthalamic nucleus (fasciculus) to palidum

Major input to the pallidum

Corticostriate fibers (cortex to striatum) Thalamostriate fibers (thalamus intralaminar nuclei to striatum) Nigrostriatal

Major input to the striatum

Striatopallidal Striatonigral (pars reticulata)

Major output from striatum

Spinothalamic (pain and temperature) Corticospinal and corticonuclear (descending motor pathways)

What tracts are running via the internal capsule to the thalamic region?

frontal and limbic cortex

Where do the signals from the mediodorsal nuceli head?

In the ventral straium between the putamen and the caudate nucelus

Where is the nucleus accumbens located?

Tonic inhibition

What suppresses voluntary movements?

Death of dopaminergic cells in pars compacta of substantia nigra

Cause of parkinson's disease

Integration of eye movements and visual guidance

Describe the oculomotor loop function.

Cognitive information

The caudate nucleus is primarily concerned with..

Cerebellar fibers

Aside from pallidothalamic fibers, what other fibers does the thalamic fasciculus carry?

Slow, writhing involuntary movements, most often in the hands and larger than chorea

Athetosis

COrpus striatum + Substantia nigra + subthalamic nucleus

Basal nuclei =

No paralysis with lesions in the basal ganglia pathway

Because basal ganglia does not directly innervate mm, what does this mean for a lesion in the area?

Extreme slowness in movement

Bradykinesia

Prefrontal cortex (9,10) - PLAN AND DECIDE --> caudate nucleus of the striatum --> globus pallidus and substantia nigra --> Ventral anterior nucleus and dorsomedial nucelsu of the thalamus back to area 9/10

Closed association loop

Anterior cingulate gyrus (24) + orbitofrontal cortex (10/11) --> ventral striatum (NUCLEUS ACCUMBENS) +caudate nucleus --> ventral pallidum, globus, substantia nigra --> ventral anterior nucleus and dorsomedial nucleus of thalamus

Closed limbic loop.

Supplementary motor cortex (area 6) SEQUENCE--> caudate nucleus and putamen of the striatum --> globus pallidus and substantia nigra of the pallidum --> ventral lateral nucleus of the thalamus back to area 6

Closed motor loop.

Frontal eye field (8) -VISUAL TRACKING --> caudate nucleus of the striatum --> globus pallidus + substantia nigra --> ventral anterior thalamus + dorsomedial nucleus of thalamus back to area 8

Closed oculomotor loop

Lentiform nucleus (putamen and globus pallidus) + caduate nucles

Corpus striatum =

Rigidity, slowness of movement, slumped posture, excessive inhibition with lack of facilitation Resting tremor (no suppression to involuntary movement)

Describe sx of Parkinson's disease

Planning and direction of movement

Describe the association loop function.

Faciltates flow of info through the thalamus resulting in GREATER excitation of the cortex. The function of the direct pathway is to release (disinhibit) the thalamus from TONIC PALLIDAL INHIBITION allowing voluntary movement

Describe the direct pathway through the basal ganglia.

Decreases activity in the thalamus (increased INHIBITION) lessening excitatory output to the cortex. The purpose is tonic suppression of inappropriate movements (tics, chorea, etc) but also terminate volitional movements

Describe the indirect pathway through the basal ganglia.

Emotional and motivational influences on movement

Describe the limbic loop function.

Info relayed from basal ganglia to the motor cortical areas where they influence the UMNs of corticospinala nd corticonuclear tracts

Describe the motor loop function.

Unilateral chorea characterized by violent, forceful mvmts of the proximal muscles due to injury to subthalamus, most often

Hemiballismus

Cerebral motor cortex, the cerebellum, and the basal ganglia

Motor functions require a complex interaction between the...

Emotional and motivational aspects of motor functions

The nucleus accumben is associated with...

Motor functions

The putamen is primarily concerned with..

Extrapyramidal syndromes

Signs and sx of lesions of the basal ganglia are referred to as...

Putamen + caudate nucleus

Striatum =

L-DOpa metabolized to dopamine by dopaminergic cells

Tx of parkinson's disease

Disinhibition

What allows voluntary movements to occur?

Premotor cortex (6) - orientation Posterior parietal cortex (7) - visual guidance

What are the additional inputs for the open association loop?

Medial and lateral temporal lobe Hippocampus - memory Amygdala - emotions Entorhinal area (24) olfactory info

What are the additional inputs for the open limbic loop?

Somatosensory cortex (3,2,1) - sensory info primary motor cortex (4) - execute premotor cortex (6) via corticostriate fibers - orientation

What are the additional inputs for the open motor loop?

PRefrontal cortex (9/10) - plan and decide Posterior parietal cortex (7) - visual guidance Superiro colliculus - Visual reflexes

What are the additional inputs for the open oculomotor loop?

Caudate nucleus (in corpus stratium) Putamen and globus pallidus (in lentiform nucleus of corpus stratium) Subthalamic nucleus Substantia nigra

What are the five major nuclei of the basal ganglia?

Motor Association (cognitive) Oculomotor Limbic

What are the four major loops of the basal nuclei?

Pallidothalamic fibers (pars interna of globus pallidus) Pallidosubthalamic fibers Pallidonigral fibers Thalamocortical fibers

What are the major outputs from pallidum?

Striatonigral, nigrostriatal Subthalamic fasciculus (pallidum to subthalamic nucleus)

What are the reciprocal connections?

Precise control of starting, stopping, force, timing, duration and coordination of muscle contraction

What are the subcortical functions in voluntary movement?

Putamen Globus pallidus

What is contained in the lentiform nucleus?

Pallidum

What is inhibitory to the thalamus?

Striatum

What is the input gate to the basal ganglia

Thalamus

What is the interface between the basal ganglia and the cortex

Pallidum

What is the output gate to the absal ganglia?

Functional association between the putamen and the caudate nucleus

What is the striatum?

Facilitate voluntary movement by getting started, keeping going and stopping an action

What kinds of movements does the basal ganglia excite?

Tremors Tics Chorea

What kinds of movements does the basal ganglia inhibit?

Movemnt

What signals does the ventral anterior and lateral nuclei of the thalamus relay?

Thalamus

what is excitatory to the cortex