Basal ganglia 101

Basal Ganglia 101

Journal Club

September 9, 2010

Anatomy

Bird’s eye view

Basal Ganglia Components

• Neostriatum: Caudate nucleus and putamen

• Globus Pallidus: externa and interna

• Substantia Nigra: pars compacta and pars reticulata

• Subthalamic nucleus

• Pedunculopontine nucleus

Caudate nucleus and Putamen

• Receives input from cortex, limbic structures, thalamus, and SNc

• Medium spiny neurons– GABAergic

• Sends output to globus pallidus externa and interna

Globus Pallidus interna (GPi) and Substantia nigra pars reticulata (SNr)

• Output center for the Basal Ganglia

• Receives input from striatum,GPe, SNc and subthalamic nucleus

• Sends efferents to thalamus and brainstem

• GABAergic

Globus Pallidus externa (GPe) and Substantia nigra pars compacta (SNc)

• Modulator• Receives input

from striatum• Sends efferents

to subthalamic nucleus and GPi

Subthalamic Nucleus

• Internal modulator• Receives input from

striatum, frontal cortex, thalamus, brainstem nuclei

• Send efferents to GPi and GPe

• Glutaminergic

Peduncular nucleus (PPN)

• Midbrain locomotor • Cholinergic and

glutaminergic cells

Circuitry

• Information processing loop• Input from cortex, limbic structures,

brainstem nuclei• Output from globus pallidus interna or

substantia nigra par reticulata to thalamus

• Relayed back to cortex

Direct Pathway

•Cortex Striatum (glutaminergic, excitatory signal)

•Striatum GPi/SNr (GABAergic, inhibatory signal)

•GPi/SNr Thalamus (GABA, inhibitory signal)

• Thalamus Cortex (glutaminergic, excitatory signal)

Indirect Pathway•Cortex Striatum (glutaminergic, excitatory signal)•Striatum GPe (GABAergic, inhibatory signal)

•GPe Subthalamic Nucleus (GABAergic, inhibitory signal)• STN GPi/SNr (glutaminergic, excitatory signal)

•GPi/SNr Thalamus (GABAergic, inhibitory signal

•Thalamus Cortex (glutaminergic, excitatory signal)

Reality?

Parallel Loops