Neocortex

Allocortex

•Makes up the rest of the cerebral cortex (10%)

 Paleocortex:  3-5 layers

 Archicortex:  3 layers

 Contain neurons that communicate horizontally with other areas of cortex in those layers

primarily receives impulses (afferent process) the majority of inputs from the thalamus

 primarily projects impulses (efferent process) to subcortical structures other than the thalamus (brainstem, spinal cord, basal ganglia)

 Projects impulses (efferent process) primarily to the thalamus

the "emotional brain"

most primitive areas shared with animals related to survival

 Integrates several phylogenetically older structures

Connects older areas of the brain with newer areas (cerebral cortex) 

 Associated with regulation of emotions like fear and anger; “fight or flight” response (ex. amygdala)

 Associated with memory and learning (ex. hippocampus)

Connects areas of lower levels of processing (old) with areas of more complex processing (new); autonomic and higher order functions

 Major Subcortical Areas (Below the cortex)

Cingulate Gyrus (limbic cortex)

•Has anterior and posterior portions and is further divided within each

•Most associated with the processing emotions, learning and memory

 connects the cingulate gyrus to the parahippocampal gyrus

Parahippocampal Gyrus

*Transitions from neocortex (lateral) → allocortex(medial)

•surrounds the hippocampus

 •plays a role in memory encoding and retrieval

Forms part of the rhinoencephalon – olfactory senses

•Anterior and Posterior Divisions

•Anterior Insular Cortex more directly related to limbic functions

•Plays a role in body awareness, homestasisregulated by the ANS

•Emotions, empathy  

•Involved in decision making

•Calculating expected rewards and punishments in different situations

•Areas of anatomic connections to orbitofrontal areas and amygdala

•Hippocampus

•Part of the Hippocampal Formation:  dentate gyrus, hippocampal gyrus/hippocampus proper, fimbria (white matter → fornix) 

•Surrounded by the parahippocampalgyrus

•Most associated with memory and spatial representation and navigation

•Forming new memories, autobiographical and episodic

•Fight or flight – fear and anger/aggression responses

•Attaches emotions to learning and experience

•Associates these emotions with memories of these experiences (attaches emotions to memories)

•Plays a role in memory consolidation

Septum Pellucidum

•Also referred to as the septum/septal area

•At the midline, between the corpus callosum and the fornix

•Connects limbic lobe to the diencephalon

Olfaction

Olfactory cortex

Memory

Hippocampus/Hippocampal formation

Emotions and Drive

Amygdala

Homeostatic Functions (autonomic and endocrine control)

Hypothalamus

Dentate gyrus

Hippocampal gyrus (hippocampus proper)

Fimbria - white matter “fimbria” that eventually begins to form the leg (crus) of the fornix (textbook)

Fornix – white matter tract - carries info to diencephalon and septal areas

Some distinguish:

Subiculum

Perirhinal/Entorhinal cortex

Major function:

Short-term to long term memory

Has direct influence on hypothalamus, endocrine system

Anterior nucleus of the thalamus (thalamic nuclei) – more specific area of thalamus, sometimes considered major part of limbic system

 Major message center

Integrates all sensory information, except for olfaction

Has reciprocal pathways to and from cortical areas

Additional pathways to basal ganglia, cerebellum

Left hemisphere plays role in speech and language

Autonomic and Endocrine function

Pituitary gland

Also contributes to memory function

Mammillary bodies:  connections with amygdala and hippocampus  

Connects endocrine system to midbrain via the pineal gland

Plays large role in regulation of sleep through processing of melatonin  (circadian rhythms)

Subthalamic nucleus

Projects to many areas, including cortex

Functionally considered part of the basal ganglia

Plays role in inhibition of motor movement

Made up of many subcortical nuclei:

Lentiform/Lenticular nucleus:  Putamen and Globus Pallidus

unable to form memories following an event

unable to recall memory before the event

•Amygdala enlarged

•Following trauma, hypersensitivity/hyperactivity of emotions

•Strong consolidated memories with emotional content 

•Cases of pathology and recovery changed belief that was rigid when filly developed 

•Neurogenesis – “birth” of new neurons

•Led to rehabilitative and attempts at preventative measures

• "master gland" 

neurotransmitter released and diffuses through short distance

response is rapid and brief

coordinates rapid and precise responses

hormones released, carried in the blood to long distance

slow and long lasting response

control activities of long duration (growth, reproduction, metabolism, water and electrolyte regulation)

1. nucleus accumbens - Aversion, motivation, pleasure, reward and 

reinforcement learning; role in addiction.

2. olfactory tubercle (part of olfactory cortex)

 Caudate, Putamen & Globus Pallidus

Cortical Input: Dorsolateral Pre-frontal Coretx

Shows relationship with cognition

Cortical Input: Motor, Pre-motor, Somatosensory cortex

Relationship with Motor System

  has been associated with addiction

Cortical Input: Posterior Parietal, Pre-frontal cortex

Shows relationship with sensory visual areas and eye movement areas

Exerts control over oculomotor reflexes for voluntary movement – focus, direction, tracking 

• Midbrain

•Pons

•Medulla

Contains substantia nigra (BG)

• membrane covering; layers of tissue that cover the brain and spinal cord

• depression or hollowing
• Example: Cranial Fossae of the skull/cranium

• opening
• Example: Foramen Magnum – opening in the base of the skull through which the spinal cord passes

•Falxcerebri

•Tentorium cerebelli  

•Falx Cerebelli

•Diaphrama sella

Descends vertically in the longitudinal fissure

Dural Fold:Tentorium cerebelli

•Crescent- shaped fold that forms the roof over the posterior cranial fossa

 •Covers the upper surface of the cerebellum

 •Supports the occipital lobes of both hemispheres

Dural Folds: Falx Cerebelli

•Below tentorium cerebelli on middle of occipital bone

•Extends into the space between the hemispheres of the cerebellum

Dural Fold: Diaphramasella

•Forms roof of the sellaturcica – a structure that encloses the pituitary gland 

•Immediately below the dura mater

•Bridges over the sulci of the brain

•In some areas – projects into venous sinuses

•Forms arachnoid villi → arachnoid granulations

•Where cerebrospinal fluid enters the bloodstream

•Subarachnoid Space (SAS)

•Separates the arachnoid from pia mater

•Filled with cerebrospinal fluid

•All cerebral arteries and veins, and cranial nerves pass through SAS

Subarachnoid Space (SAS)

•Separates the arachnoid from pia mater

•Filled with cerebrospinal fluid

•All cerebral arteries and veins, and cranial nerves pass through SAS

•Closely adheres to the gyri of the brain

•Fuses with the ependymal cells (membrane lining the ventricles) to form the choroid plexus of ventricles (produces CSF)

• Has three ventricles:
• Lateral, third and fourth ventricles

•Paired – one in each hemisphere

 •Connected to the third ventricle by the intraventricular foramen (or foramen of Munro)

•Small slit between the thalamas 

•Connected to the fourth ventricle by the cerebral aqueduct (or aqueduct of Sylvius)

 •Choroid plexus is above the roof of the fourth ventricle

 •Anterior to the cerebellum, posterior to the pons

•Has a tent-shaped roof, two lateral walls and a floor

1. Arteries

2. Veins

3. Capillaries

•carry blood toward the heart from other parts of the body

•allow exchange of water and chemicals between the blood and tissue

 Four main arteries (and their branches) supply blood to the brain:

•Two Internal Carotid Arteries

•Two Vertebral Arteries

AKA cerebral arterial circle

joins the internal carotid and vertebral arteries 

Comprised of:

•Result of bifurcation (or splitting) of the common carotid artery from the heart

Branches:

•Anterior Cerebral Artery

•Middle Cerebral Artery

•Posterior Cerebral Artery

•Posterior Commmunicating Artery

•Anterior Communicating Artery 

Part of the frontal lobe, a large part of the corpus callosum and part of the caudate and globus pallidus

•Superior division supplies inferior frontal lobe (location of Broca's area)

•Inferior division supplies lateral temporal lobe (location of Wernicke's area)

•Deep branches supply the basal ganglia

Supplies blood to posterior regions of the brain (occipital lobe)

•At base of brain; forms part of the circle of Willis

•Connects the 3 cerebral arteries on the same side (anterior, middle and posterior)

•Connects left and right anterior cerebral arteries (across the longitudinal fissure)

•Forms part of the Circle of Willis

•Arise as branches of subclavian arteries

Branches

•Meningeal Branches

 •supply the dura mater of the posterior cranial fossa

•Posterior spinal artery

•Supplies posterior third of the spinal cord

•Anterior spinal artery

•Supplies anterior two-thirds of the spinal cord

•Posterior inferior cerebellar artery (PICA)

•Supplies part of the cerebellum and the medulla

•Medullary Arteries

•Distributed in the medulla  

 Ischemic

 Hemorrhagic

High cholesterol

Smoking

High blood pressure

Diabetes

Obesity

Physical inactivity

•Rupture of a weakened blood vessel

•Most common causes

 •Uncontrolled hypertension (high blood pressure)

 •Aneurysms – a blood filled balloon-like bulge in the wall of a blood vessel

 •Risk factors:  diabetes, smoking, older age, obesity, alcoholism, infection

•Arteriovenous malformations (AVMs) – abnormal connection between arteries and veins (bypassing capillaries)

•“mini-stroke”

 •Caused by a temporary blood clot in a vessel