1. Medial forebrain bundle – distribution of modulatory inputs; travels through lateral
hypothalamus  rostral direction of contents into cerebral hemisphere
Dopamine – neurons located in midbrain; compact part of substantia nigra  caudate nucleus
and putamen (basal ganglia); ventral tegmental area  limbic structures and cerebral cortex
areas (frontal)
Norepinephrine – neurons found in PNS as postganglionic sympathetic; in CNS located in
medullary reticular formation and locus ceruleus of rostral pons; project to every part of CNS
Serotonin – neurons in raphe nuclei (series of nuclei near midline of brainstem reticular
formation); project everywhere in CNS; involved in levels of attention/arousal
Acetylcholine – neurons play important role in PNS (postganglionic parasympathetics); others
have cell bodies in CNS and axons travel through spinal/cranial nerves (LMNs, preganglionic
sympathetic and parasympathetics neurons); some CNS cholinergic neurons  local
interneurons (putamen and caudate nucleus); located in midbrain reticular formation and Basal
nucleus – large cholinergic neurons in basal forebrain (inferior to anterior commissure) that
project to many areas of cerebral cortex; septal nuclei  hippocampus
2. – Thalamus is the site of an obligatory synapse in nearly every pathway to cerebral cortex
- Efferent pathways (corticospinal tract) can go directly from cortex to destinations
- Collection of fibers interconnecting thalamus and cortex, as well as those going from cortex
to subcortical sites, travels through internal capsule
3. Topography – thalamus in three divisions by thin, vertical sheet of myelinated fibers called
internal medullary lamina; posteriorly this lamina divides thalamus into medial and lateral
divisions; anteriorly, the internal medullary lamina splits to enclose anterior division; thin shell
of gray matter  thalamic reticular nucleus (covers lateral and anterior surfaces of thalamus);
lateral and medial geniculate nuclei appended to posterior, ventral surface of thalamus
-Anterior nucleus in anterior division
- Dorsomedial nucleus (DM) in medial division
Lateral division
- ventrally is series of three nuclei arranged in an anterior  posterior sequence: ventral
anterior (VA), ventral lateral (VL) and ventral posterior nuclei (VPL, VPM for lateral and
medial parts of VP nucleus)
- above VPL/VPM is lateral posterior nucleus (LP), which merges with pulvinar more
posteriorly
4. – most thalamic inputs come from the cerebral cortex itself
- thalamocortical neurons exist in two different physiological states
1. Act like normal neurons and pass along whatever information is delivered to them
2. When slightly hyperpolarized (from reticular nucleus input)  “burst” mode; voltage-gated
Ca2+ channels move from inactivated state  available state (calcium flows in), so a small
depolarization starting from this level causes a long, slow calcium spike on which a burst of
Na+ spikes rides; In this state information transfer is less accurate, but TH for transfer may be
lower
- Thalamic neurons in bursting state during sleep and inattention
- Attention is focused using regulatory inputs to swicth thalamic neurons from burst mode 
accurate-transmission (tonic) mode
5. Thalamic nuclei – either relay or association
Relay nuclei – receive well-defined, discrete input bundles; project to restricted cortical areas
with single functions
Association nuclei – receive inputs from association cortex, and project back to related areas of
association cortex
Look at attached table
Other nuclei- intralaminar nuclei and similar nuclei on ventricular surface of thalamus (midline nuclei) 
no projection to demarcated cortical areas; instead, each receive variety of inputs and projects to
broad cortical area; they set the general level of excitability of large chunks of forebrain
- read chart for reticular nucleus (remember – no projection to cerebral cortex)
- Cerebral cortex, reticular formation, and reticular nucleus form regulatory inputs to
relay/association nuclei; regulatory inputs determine the functional state of thalamic neurons
- Subcortical sites (basal ganglia, cerebellum, retina, spinal cord, long tracts) form specific
inputs that specify the kind of information a given thalamic neuron can pass on to the cortex
6. Internal Capsule
- five parts defined by its relationship to lenticular nucleus
- Anterior limb – between lenticular nucleus and head of caudate nucleus
- Posterior limb – between lenticular nucleus and thalamus
- Genu – region at junction of anterior and posterior limbs
- Internal capsule wraps around lenticular nucleus; Retrolenticular part – is behind lenticular
nucleus; Sublenticular part – under most posterior part of lenticular nucleus
- Above cleft bounded by head of caudate, the lenticular nucleus, and the thalamus, fibers of
internal capsule fan out  corona radiata and enter central white matter of hemisphere 
centrum semiovale
- Cortical efferents remaining in internal capsule funnel down into cerebral peduncle
Portion
Anterior limb
Posterior limb
Retrolenticular part
Sublenticular part
Origin
Anterior nucleus
Dorsomedial (DM)
Motor cortex
Motor cortex
VPL/VPM
Pulvinar
LGN
LGN
MGN
Destination
cingulate gyrus
Prefrontal cortex
Spinal cord
Brainstem
Postcentral gyrus
Association cortex
Visual cortex
Visual cortex
Auditory cortex
Other names
Corticospinal tract
Corticobulbar tract
Optic radiation
Optic radiation
Auditory radiation
7. Blood supply
- Small branches of posterior cerebral artery provide blood supply to thalamus; basilar artery
bifurcates into two posterior cerebral arteries directly inferior to thalamus
- small branches of middle cerebral artery and anterior cerebral artery provide blood supply to
internal capsule; internal capsule is lateral to thalamus and extends anterior to it;