Telencephalon

Prosencephalon

Primary vesicle during development

Becomes: telencephalon and diencephalon

Cerebral cortex

collection of cell bodies, axons, and dendrites

2 hemispheres, right and left

divided in the middle by the longitudinal fissure

contains layers differentiated by the size + connectivity of the cells contained within the layer —> generalization

The cerebral cortex is the outermost layer of the

brain containing gray matter. Responsible for many “higher-order” functions like language and information processing

layers of the cerebral cortex

• generally differentiated by size and connectivity of cells in the layer

• layers are organized by function/anatomical feature

• layers are called lamina

• humans have 3-6 laminae depending on the area of the cortex

• layers are typically numbered using roman numerals

Multiform layer

• innermost layer of the cerebral cortex

• type of cell: primarily fusiform cells

• connection: output to thalamus

• ex: what is the deepest layer?

Layers of the cerebral cortex

• each cortical layer has a primary source of

• cells with similar functions tend to be aligned within

• long ______ extend throughout each layer

• input and primary target for output

• the same layer

• interneurons

Lobes of the cortex

frontal, parietal, temporal, occipital

frontal lobe

movement, higher order cognition, decision making and planning

parietal lobe

processing and integration of sensory input

temporal lobe

hearing, learning and memory

occipital lobe

vision

Primary motor cortex: Area 4

• Location:

• Contains

• Controls

• Source of

• Pre-central gyrus, immediately anterior to central sulcus

• complex map of the body

• voluntary movement of the opposite side

• most neurons in the CST

• Other areas of the brain are involved in motor planning:

  • supplementary motor area

  • premotor area

Primary motor cortex

• input

• output

  • gives rise to the largest

• input

  • basal ganglia

  • cerebellum

  • sensory areas (via the thalamus) from muscles AND skin above the muscles

• output

  • efferent (motor) tracts

    • corticospinal tracts

    • corticobulbar tracts

Primary motor cortex: function

• controls what kind of movement?

• controls ____

• voluntary movement

  • contralateral b/c the tract crosses the midline

  • skilled, precise control of distal limb muscles, especially the flexors of the hand

  • lower portion of face

  • more neurons devoted to hand/face than the rest of the body

• force and speed of movement

Area 6: Pre-Motor and Supplemental Motor

wrap around towards inside of brain

Location:

• anterior to the pre-central gyrus (frontal lobe)

  • (anterior to primary motor area)

• Pre-motor: inferior portion

• Supplemental motor: superior portion

Area 6 output

primary motor cortex

area 6 function

• generation of

• use of _____ and other

• movement that relies on

• movement that is more

• sequences of movement

• vision and other sensory inputs to generate movement

  • various function of the hand

• context

• planned than automatic

area 6: function part 2

• choice of

• uses information from the

• associates visual input with

• orientation of

• uses input from

• course of action, based on sensory input (especially visual input) and context

• PFC and TH to determine movement

• movement

  • orientation of a limb —→ especially hand, to a target

  • planning bimanual and sequential movements

• eyes/head

• CB tp provide background postural stability for function

Area 6: Some differences

Pre-motor

• NEEDS

• activates _____ muscles

• 30% of the

Supplemental motor

• mental rehearsal takes place here —→

• activates ____ muscles

• NO

Pre-motor

• sensory input to function

• proximal

• CST arises from here

Supplemental motor

• learned sequences live here

• distal

• descending pathway arises from here, not motor tract

Frontal Eye fields: Area 8

• Located:

• receives input from the

• involved in

• activated by

• connects with the

  *notice the overlap of the

• anterior to supplemental motor cortex

• lateral geniculate, superior colliculus and areas 4,6

• conjugate eye movement (esp saccades) and constriction of the pupils

• visual stimuli

• brainstem and cerebellum

• frontal eye fields —→ pre-motor cortex and PFC

Primary sensory cortex: Area 3, 1, 2

• location:

• receives info from

• identifies the location

• post central gyrus (parietal lobe)

  • immediately posterior to central sulcus

• receives info from tactile and proprioceptive receptors via the thalamus

• of stimuli and discriminates among various shapes, sizes and textures of objects

homunculus main idea

hands and face have lots of real estate

other association areas

• an association area is an area of the cortex that receives input from

multiple areas and integrates

Primary visual cortex: Area 17, 18, 19

• Location:

• receives

• info from the ___ side

• input is received from the eyes via

• outputs from the visual cortex circle back to the

• occipital lobe

  • immediately posterior to parieto-occipital sulcus

• and interprets all visual input

• left side of the world goes to the right side of the brain

• the retina —→ optic nerve —→ thalamus

• thalamus and other areas of the brain stem

Primary auditory cortex: Area 41, 42

• located in the

• closely associated with the

• the ____ hemisphere is considered the dominant hemisphere for language

• temporal lobe

• auditory association cortex (Wernicke’s Area): Area 22 and Broca’s area (Area 44, 45)

• left

  • so, although there is an auditory cortex on both sides, the left is “more active”

  • lesions (and strokes) to the left hemisphere produce more severe language disorders

Broca’s area (44, 45)

• location

• area of

Wernicke’s area (22)

• location

• area of

what connects them?

broca’s

• frontal lobe

• expression

wernicke’s

• temporal

• reception

Arcuate fasciculus and other peri-Sylvian connects

posterior parietal association area: Area 5, 7

• AKA:

• Location

• Function: integrates

• basically helps you make meaning out of the things

• so, touch and movement go to

• somatosensory association area

• superior parietal lobule; just posterior to primary sensory cortex

• sensory info and gives meaning; stereognosis; visual-motor perception

• you’re touching

• 3, 1, 2 and get shared to 5, 7 for integration

Pre-Frontal Cortex (PFC): Areas 9 - 12

• largest

• involved in

• has bi-directional

• association area in the Frontal Lobe

• higher order mental functions- cognitive skills, judgment, abstract thought, personality, communication

• connections all over the cortex and sub-cortical structures

  • “talks to everybody” needs sensory data and info

  • all association areas, limbic structures, medial nucleus of the thalamus, supplemental motor cortex, reticular system

Possible deficit for frontal lobe

• higher order thinking

• personality disorder (they don’t smile, they don’t cry)

• decision making (abstract thought)

• poor judgment

• memory

• frontal lobe can be damaged by stroke or head trauma (car accident)

Possible deficit for parietal lobe

• unable to make meaning out of sensory input/touch

  • ex: babies putting things in their mouths

• you see this in people who have strokes in the right side

Possible deficit for temporal lobe

• receptive/Wernicke’s aphasia (not able to receive)

• difficulty forming words

• memory, trouble remembering what was said

Possible deficit for occipital lobe

• vision loss/dysfunction

• can’t make meaning based on what you see

• very severe and unusual: blindness

Basal Ganglia

• planning of

• how is the basal ganglia structured?

• movement, drives motor plan

• it consists of pairs with one on each side of the brain

Basal Ganglia

• develops from

• basal ganglia means

• pairs of

• influences movement but no

• influences movement by interacting with

• telencephalon

• large and diverse

• gray matter nuclei located deep within the cerebral cortex

• direct descending pathways from the BG

• many parts of the cortex

What is the most common pathology that occurs when the BG is dysfunctional?

Parkinson’s Disease

Basal Ganglia

5 main components:

other structure:

1. Caudate nucleus

2. putamen

3. globus pallidus

4. subthalamic nucleus

5. substantia nigra

Nucleus accumbens

Caudate/Putamen

Taken together often referred to as the striatum (striatum means “striped”)

Putamen/Globus Pallidus

Taken together, can be referred to as the lentiform (Meaning “lentil” or “lens” shaped)

historically, the ______ was also included as part of the BG

amygdala

BG: caudate

• Head/Body/Tail (no specific boundaries)​

• Amygdala: Anterior top of the tail

BG: putamen

• Lateral portion of BG​

• Ventral Striatum: Anterior/ventral portion, fuses with head of caudate​

• Nucleus Accumbens —> Forms most of the ventral striatum

BG: globus pallidus

• Medial (internal)​

• Lateral (external)

Structures that are not attached to the BG

• Subthalamic Nucleus​

• Substantia Nigra

Substantia Nigra consists of

• Pars Compacta ** → dysfunctional when someone has Parkinson’s

  • ​inner layer (blue)

• Pars Reticulata

BG input

• Input: From nearly all regions of the cortex  Striatum​

  • Data are transferred along a pathway known as “corticostriatal” pathway

BG: output

Output: Via GP and S. Nigra PR to the Thalamus then cortex where it can descend (No direct descending pathways)

Synapses use NT dopamine

BG functions

• regulates muscle contraction, tone and force

• sequencing of movements

• motor learning

• motor planning via connections —> through thalamus → into cortex (and eventually into primary motor cortex)

Caudate function

appears to be primarily cognitive

Intrinsic Basal Ganglia Connections

2 intrinsic Basal Ganglia pathways (Fig 16.7)

Direct and indirect

Intrinsic Basal Ganglia Connections: Direct

Striatum → internal segment of globus pallidus or SN pars reticulata

Net effect: excitation of the thalamus

Intrinsic Basal Ganglia Connections: Indirect

Striatum → external segment of globus pallidus and to the subthalamic nuclei

net effect: inhibition of the thalamus

Dysfunction of the BG

movement disorders

​

• Parkinson’s Disease (PD)​

  • Hypokinetic Movement disorder: TOO LITTLE movement​

• Huntington’s Disease​

  • Hyperkinetic movement disorder: TOO MUCH movement

Physical Therapy and PD

• Degenerative disease of the the BG​​

• Etiology: Unknown​

• Pathology: Degeneration of dopaminergic neurons in the Basal Ganglia, specifically the pars compactus of the Substantia Nigra ​

• Clinical Manifestations → Movement dysfunction​

• “TRAP” – Tremor/Cogwheel Rigidity/Akinesia/Posture

Internal Capsule

• DEF: A collection of projection fibers (white matter) from all parts of the Cortex → Converging towards the Bstem​

  • CST makes up much of the Internal Capsule

• A continuous sheet of fiber that forms the medial boundary of the Lentiform N.​

• Superiorly, the fibers fan out to form a structure knows an the Corona Radiatia

internal capsule can be divided into 3 parts:

• anterior limb

• posterior limb

• genu

Neural Tube also forms cavities:

ventricles

• Ventricles contain ​

• Choroid Plexus, located within all ventricles, does what?

• Ventricles contain Cerebral spinal Fluid (CSF)​

• Choroid Plexus, located within all ventricles, synthesizes CSF

ventricles

• 2 Lateral Ventricles: One in each hemisphere; Extends from frontal lobe to parietal and occipital lobes and reaches laterally into the temporal lobe​

• 3rd Ventricle: Within Diencephalon (Within the thalamus and hypothalamus)​

• 4th Ventricle: Surrounded by the Pons, Medulla and Forms the floor of the Cerebellum

anatomy of the ventricles: lateral ventricles

​

• Frontal (anterior) horn​

• Body​

• Occipital (posterior) horn​

• Temporal (Inferior) Horn

anatomy of the ventricles: third ventricle

cerebral aqueduct

anatomy of the ventricles: fourth ventricle

central canal

C-shaped structures

• the lateral ventricles form a C shape​

• Many structures wrap around the ventricles and thus follow this C-shaped Anatomy​

  • Caudate Nucleus​

  • Corpus Callosum​

  • Fornix

Pathology in the Ventricles: Hydrocephalus

• Causes

  • Excess CSF production → Rare​

  • Obstruction of CSF Flow → Tumor; hemorrhage, congenital malformation

Pathology in the Ventricles: Hydrocephalus

Common Sx:

Treatment

HA, Nausea, Vomiting, decreased/altered vision, altered level of consciousness, altered cognition

may require a drain or shunt → Not done by PT

Meninges defined

• Protective layer of tissue that covers the brain and Spinal Cord​

• Cushions the brain from trauma and protects the brain from infection

Meninges- 3 layers (from outer to inner)

• Dura Mater​

  • Hard outer layer​

• Arachnoid Mater​

  • Creates a space​

  • CSF travels in the space made between the Arachnoid and Pia​

• Pia Mater​

  • Closely adheres to the brain

Blood Brain Barrier

• Specialized permeability barrier between the ​

• Crucial for ​

• Acts as a ​

• Excludes

• Specialized permeability barrier between the capillary endothelium and the extracellular space​

• Crucial for protection and to maintain the homeostasis of the brain​

• Acts as a physical-chemical-metabolic barrier​

• Excludes large, water soluble molecules from diffusing into the CNS and restricts drug permeability to the brain​

  • Making many drugs unable to permeate the brain