The Brain

HOW, WHAT AND WHY???

THE INNER WORKS

COLETTE BEECHER

The Brain

Two Hemispheres

Main areas & systems of communication

Lower Centres: Brain stem (medulla oblongata, Pons and Mid Brain), Thalamus & Hypothalamus.

Higher Centres: Basal Ganglia, Cerebellum, Cerebrum, (including Cortex of the brain, & limbic System.)

INCOMING:RECEIVING SENSORY INFORMATION

All messages heading for the cortex ( Lobes)need to go through the lower centres of the thalamus and the Higher centre of the Basal ganglia. This will include sensory information coming from vision, hearing, and taste

Motor messages, including touch, pressure, & proprioception (position & posture of joints, tendons and muscles) travel through the brain stem, to the Reticular formation (Basal Ganglia) to the Thalamus, signposted to specific areas of the Cortex.

OUTGOING Motor execution

All messages sent by the higher centres (Limbic/Cortex areas to execute voluntary movement/reaction)

will travel via Basal Ganglia, Thalamus, Cerebellum

and Midbrain ( Reticular Formation) before leaving the brain via the brain stem, down to the spinal cord to produce the desired movement/response.

Motor execution

All messages from the lower centres ( Thalamus, Hypothalamus ) to execute simple reflex or autonomic responses

will travel via The Cerebellum, Midbrain ( Reticular

Formation -BG) before leaving the brain via the lower brain stem components (Pons & medulla), down to the spinal cord to produce the desired response.

Main roles

Brain stem: Involuntary respiratory, cardiac, system control.

Hypothalamus and pituitary gland: Involuntary temperature control, thirst, hunger, adrenaline and thyroid hormone production ( Flight/fight responses and release of energy in response to activity)

Thalamus: A cluster of nuclei that operate as a relay system. Messages travel through individual nuclei that will connect specifically to designated cortex areas.

Main Roles

Cerebellum: Connected both to the thalamus and basal ganglia, the cerebellum monitors the production of reflex and voluntary movement, to assist with balance, co-ordination.

The Cerebellum receives messages from the vestibular system (details of speed, balance, posture during movement) and then sends messages back to the cortex, so that the higher centres can adjust any motor plan to refine previous movement.

Main Roles

Basal Ganglia: Also a cluster of nuclei, however these are not necessarily adjacent to one another, nevertheless all nuclei are connected through a system of communication.

The main role of the basal ganglia is to initiate the release of neurotransmitters (chemical transmission) which allow messages to be sent from all areas of the lower and higher centres of the brain.

All messages from the cortex travel through the basal ganglia to the thalamus.

Main Roles

The cerebral Cortex:Four lobes: FrontalParietalOccipital Temporal ( Lies underneath the parietal lobe,

surrounding the basal ganglia and internal capsule)

Frontal lobe divisions

Parietal Lobe subdivisions

Temporal Lobe subdivisions

Subdivisions of the occipital Lobe

Limbic System

Refers to structures comprising of :Amygdala: connected to the hypothalamus & midbrain

HippocampusSeptal area:connected to the hypothalaumus: sex

driveOlfactory gyri: connected to the amygdala

Cingulate gyrus: monitor/evaluates movement & speech – executive functioning