Neuro Revision Emily Hodgson. LIMBIC SYSTEM Mamillary bodies Ant. Nucleus of thalamus Cingulate...

Neuro Revision

Emily Hodgson

LIMBIC SYSTEM

Mamillary bodies

Ant. Nucleus of thalamus

Cingulate gyrus

Parahippocampal g

ryus

Hippocampus Entorrhinal cortex

Fornix

R G Tunstall 2014

Limbic system

• Convenient way of describing anatomically interconnected nuclei and cortical structures

• Most nuclei control functions necessary for self and species preservation

• Autonomic and endocrine function, particularly in response to emotional stimuli

• Motivation and reinforcing behaviours• Memory• Olfactory connections – more important in other

species

Hippocampus

• Hippocampus is involved in memory (formation & recall) & is located in the inferior temporal lobe

• Important role in turning short term into long term memory

• Connecting emotions, sounds and smells to memories • Anterograde amnesia – no new memory formation.

Able to recall long term memories • Also involved in navigation and spatial orientation• L. Memories involving language• R. Memories involving spatial/visuo-spatial tasks

Anterograde Amnesia

Retrograde amnesia

• Loss of memory/ unable to recall events occurring before the accident/event etc

• Usually damage to brain other than the hippocampus

Different types of memory

• Short term - <1hr• Long term

– Declarative/explicit – recall of fact/event/knowledge (takes effort)

– Implicit/procedural – learned skills (writing, motor, language)

Korsakoff’s psychosis

• Part of Wernicke-Korsakoff syndrome (Wernicke encephalopathy normally first)

• Mamillary and anterior thalamic damage due to thiamine (B1) deficiency

• Memory loss• Difficulty acquiring new information or skills• Change in personality• Confabulation – invents events to fill the gaps in memory

Cingulate gyrus

• Regulate emotion and pain• Directly drive body’s conscious response to

unpleasant experiences• Fear and prediction (and avoidance) of negative

consequences – important feature of memory• Autonomic area – cardiorespiratory and

digestion • Bladder control• Visual searching

Cingulate gyrus

• Anterior lesions:– Autonomic dysregulation– Emotional disturbances

• Posterior lesions:– Memory/cognitive dysfuction

Amygdala

• Multiple inputs/activators:• Visual & Auditory• Sensory from body• Solitary tract• Olfactory & Limbic system• Hypothalamus

• Multiple Outputs:• Hypothalamus• Hippocampus• Multiple areas of cortex

Controls multiple emotions, responses and systems

• Brings about reactions of:• Fear• Anger• Behavioural emotions

– Sweating, flight, fright, confrontation, mating • Impulsivity• Sexual behaviour & emotions

• Stimulation can:• Increase HR & BP• Reduce saliva• Increase GI motility• Cause irritability• Startle easily• Increase muscle tension• Cause pupil dilation

• Septal nuclei – pleasure • Nucleus accumbens –

– Dopamine activated reward centre– Intense sense of well being– Amphetamine and cocaine activate

Hypothalamus

• Primary output for limbic system• Sexual function, endocrine function,

behaviour and autonomic control• Inputs from most of the body (olfaction,

viscera, retina)• Internal sensors for temp, osmolality, glucose

and sodium conc, hormones

EYES (VISUAL FIELDS)