q3l05 - limbic system

BRAIN PARTS RECAP

THE BRAIN SO FAR….

CORPUS CALLOSUM

CEREBRUM

CEREBRAL CORTEX

FRONTAL LOBE

BROCA’S AREA

MOTOR CORTEX

PARIETAL LOBE

SOMATOSENSORY CORTEX

OCCIPITAL LOBE

VISUAL CORTEX

VISUAL ASSOCIATION AREA

TEMPORAL LOBE

Auditory cortex

Auditory association area

Wernicke’s Area

LIMBIC SYSTEM

LIMBIC SYSTEM

KEY PARTS:

1) AMYGDALA2) HIPPOCAMPUS3) HYPOTHALAMUS4) CINGULATE GYRUS

AMYGDALA (Latin for ‘almond’)• Involved in processing emotions (in

particular, learning and remembering emotionally significant events).

• Important in fear responses.

• Links areas of the cortex that process higher cognitive information with systems that control metabolic responses fight or flight

• Damage:Case study – damage to amygdala in both hemispheres. No motor, sensory or cognitive deficits, but when asked to identify photographs of a series of facial expressions, SM could identify every expression but one – FEAR.

HIPPOCAMPUS

• The structure most associated to memory formation.

• An early storage place for long-term memory and involved in the transition of LTM to even more permanent memory.

• Also plays a role in spatial navigation

• Damage:Case study: Clive Wearing had extensive damage to the left and right hippocampus. Intellectual and perceptual abilities intact, but has severe memory impairments, losing ability to form new memories.

• Regulates automatic functions (hunger, thirst, body temperature, sexual activity)

• Controls release of hormones

• Integrates information from many different parts of the brain and is responsive to a variety of stimuli:i) light ii) odoursiii) stressiv) arousal

HYPOTHALAMUS

CINGULATE GYRUS

• Helps regulate emotions and pain.

• Involved in fear and the prediction (and avoidance) of negative consequences and can help orient the body away from negative stimuli.

• Damage: inappropriate emotions, lack of fear, impaired sensation of pain, learning impairments

BRAIN STEM

The Brain Stem

• Consists of a group of structures that lie deep within the brain.

• Plays important role in maintaining homeostasis by controlling automatic functions such as breathing, heart rate, and blood pressure.

• Can organise motor movements such as reflexes, and coordinate with the motor cortex and associated areas to contribute to fine movements of limbs and the face.

In the brain stem…

• Midbrain

• Pons

• Medulla

Midbrain

• Includes structures involved in vision and hearing (tectum) and movement (tegmentum).

Pons• Region most closely associated with breathing and

respiratory rhythms.• Forms a bridge between the cerebrum and

cerebellum• Involved in sensory analysis and is the site at which

auditory information enters the brain.

Medulla

• Formal name – medulla oblongata

• An extension of the spinal cord linking to the brain.

• 3.5cm long and 2cm wide.

• Neither humans nor other animals can survive destruction of the medulla.

• Controls heartbeat, circulation and respiration.

Thalamus

Thalamus

• About 5.7 cm in length

• Processes sensory information as it arrives and transmit it to higher brain centres (the cortex).

• Like a switchboard!

• Not only route messages but also to filter them, highlighting some and de-emphasisingothers.

Damage

• Thalamic lesion linked to synaethesia

• Small but significant reduction in thalamus volume in schizophrenia.

Cerebellum

Cerebellum

• Roughly 10% of total brain weight, but contains more neurons than the rest of the brain combined!

• Responsible for coordinating movement, planning, motor activities, learning and remembering of physical skills.

• Size is a good indicator of its physical capability

• Some recent studies have associated the cerebellum with cognitive functions, such as learning and attention.

Damage

• Tremors

• Muscle weakness

• Inability to walk

• Slurred speech

• Linked to:

• Dyslexia, schizophrenia, multiple sclerosis