Cerebellum Basal Ganglia Synapses Circuits Lecture Eleven Circuits

Cerebellum & Basal Ganglia Synapses & Circuits Lecture Eleven

Circuits

Circuits Cerebellum Basal Ganglia

Cerebellum Cerebellar diseases provide clues about function. Disorders manifest in four symptoms: Hypotonia. Resistance to passive limb movements. Astasia-Abasia. Loss of the ability to maintain a steady limb or body posture across multiple joints (astasia). Loss of ability to maintain upright stance against gravity (abasia). Ataxia. Abnormal execution of multi-jointed voluntary movements. Action Tremor at the end of movement.

Cerebellum: Distinct Anatomical Regions

Cerebellum: Distinct Anatomical Regions

Cerebellum: Distinct Functional Regions

Cerebellar Microcircuits Four organizing principles: Cerebellar Cortex: Five types of neurons organized into three layers. Each layer performs a different task. 2 inhibitory cell processing Molecular Layer contains types: stellate & basket output Purkinje Layer input Granular Layer contains Purkinje cells contains the glomerulus

Cerebellar Microcircuits Four organizing principles: Cerebellar Cortex: Five types of neurons organized into three layers. Each layer performs a different task. 2 inhibitory cell processing Molecular Layer contains types: stellate & basket output Purkinje Layer input Granular Layer contains Purkinje cells contains the glomerulus Differential Afferent Codes: Mossy fibers VS climbing fibers. Purkinje/Molecular Layer Granular Layer GC MF Originates in spinal cord & brain stem. Form excitatory synapses onto granule cells. CF Originates in olivary nucleus. Wraps around the Purkinje neuron like a vine.

Cerebellar Microcircuits Four organizing principles: Cerebellar Cortex: Five types of neurons organized into three layers. Each layer performs a different task. 2 inhibitory cell processing Molecular Layer contains types: stellate & basket output Purkinje Layer input Granular Layer contains Purkinje cells contains the glomerulus Differential Afferent Codes: Mossy fibers VS climbing fibers. Purkinje/Molecular Layer Granular Layer GC MF Originates in spinal cord & brain stem. Form excitatory synapses onto granule cells. CF Originates in olivary nucleus. Wraps around the Purkinje neuron like a vine.

Cerebellar Microcircuits Four organizing principles: Local & Long Range Cerebellar Cortex: Five types of neurons organized into three layers. Each layer performs a different task. 2 inhibitory cell processing Molecular Layer contains types: stellate & basket output Purkinje Layer input Granular Layer contains Purkinje cells contains the glomerulus Differential Afferent Codes: Mossy fibers VS climbing fibers. Purkinje/Molecular Layer Granular Layer GC MF Originates in spinal cord & brain stem. Form excitatory synapses onto granule cells. CF Originates in olivary nucleus. Wraps around the Purkinje neuron like a vine. E/I Signals Compared: In deep nuclei & cerebellar cortex. Recurrent loops: In deep nuclei & cerebellar cortex.

Cerebellar Microcircuits Four organizing principles: Cerebellar Cortex: Five types of neurons organized into three layers. Each layer performs a different task. 2 inhibitory cell processing Molecular Layer contains types: stellate & basket output Purkinje Layer input Granular Layer contains Purkinje cells contains the glomerulus Differential Afferent Codes: Mossy fibers VS climbing fibers. Purkinje/Molecular Layer Text books are Granular Layerold. GC MF How. CFabout now? Originates in spinal cord & brain stem. Form excitatory synapses onto granule cells. Originates in olivary nucleus. Wraps around the Purkinje neuron like a vine. E/I Signals Compared: In deep nuclei & cerebellar cortex. Recurrent loops: In deep nuclei & cerebellar cortex.

Emerging Perspectives

Error Hypothesis

Dynamic Encoding

Dynamic Encoding

General Function: The Basal Ganglia Movement: Traditional view biased by prominent movementbased disorders (Parkinson & Huntington). Nonmotor: Basal ganglia dysfunction also associated with complex behavioral and neuropsychiatric disorders. Consist of several interconnected nuclei. Striatum: major input structure of basal ganglia. Includes caudate nucleus & putamen (separated by internal capsule). Globus pallidus: contains 2 separate nuclei (external & internal). Internal structure is major output structure of basal ganglia. External contains circuits intrinsic to basal ganglia. Substantia nigra: contains pars compacta and pars reticulata (another major output). Subthalamic nucleus: small nucleus between the thalamus & substantia nigra.

Basal Ganglia Pathways

Basal Ganglia Pathways Medium Spiny Neuron (MSN)

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): Skeletomotor. Oculomotor. Associative. Limbic.

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): Skeletomotor. Oculomotor. Associative. Limbic.

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): What it boils down to is what subset of MSN’s are activated GPo direct indirect Glut GABA CTX MSN GPi Thal cortical output

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): What it boils down to is what subset of MSN’s are activated GPo direct indirect Glut GABA CTX MSN GPi Thal cortical output

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): What it boils down to is what subset of MSN’s are activated GPo direct indirect Glut GABA CTX MSN GPi Thal cortical output

4 Cortico-BG-TC Circuits 1 circuit template. Cortex BG Thalamus 4 functions, 4 circuits (highly topographic): What it boils down to is what subset of MSN’s are activated GPo direct indirect Glut GABA CTX MSN GPi Thal cortical output