Brain function & dysfunction Flashcards
What are the divisions of the forebrain?
- Telencephalon - cerebral cortex, basal nuclei, limbic system and olfactory bulbs
- Diencephalon - thalamus, hypothalamus, subthalamus, epithalamus, pituitary and pineal glands
What are the functions of the cerebral cortex?
- Sensory areas - recieve and process info from the senses. Hemispheres recieve info from contralateral side of the body.
- Motor areas - related to controlling voluntary movements. 2 main types (pyramidal system - fine motor skills, direct with no synapses in brain; extrapyramidal - synapses within brainstem nuclei)
- Association areas - produce perception of the world, enabling animal to interact with their environmentr effectively
What are the functions of the limbic system?
- associated with behaviour and emotions
- correlates behaviour and emotion with the ANS
- role in memory
What are the functions of the olfactory bulbs?
- olfaction
- olfactory nerves directly connected to imbic system
What are the functions of the thalamus?
- process and rely sensory information selectively to parts of the cerebral cortex
- translates signals to the cerebral cortex from auditory, somatic, visceral, gustatory and visual systems
- regulates state of arousal, level of consciousness and level of activity
What are the functions of the hypothalamus?
- overall regulation of the endocrine system
- controls ANS
State the neurological signs associated with forebrain dysfunction
- mentation - normal/obtunded/stupor
- change in behaviour can be reported
- seizures can be reported
- contralateral proprioceptive deficits
- contralateral menace response absent
- circling towards side of lesion
What are the 3 main brainstem functions?
- Conduction - all info relayed from the body to the cerebrum and cerebellum must traverse the brainstem
- Cranial nerves - III - XII originate from brainstem
- Integrative functions - involved in CV, resp. control, alertness, awareness and consciousness
Describe the integrative functions of the brainstem
- cardiovascular - medulla oblongata; regulates HR; chemoreceptors detect change in blood pH and CO2 conc.; baroreceptors detect BP change in aortic/carotid bodies; sends nerve impulse to pacemaker via autonomic fibres
- cushing reflex - reponse to hypertension and bradycardia
- respiratory centre - medulla and pons; control rate and depth of resp movements; chemoreceptors detect change in blood pH and CO2 conc.
- ascending reticular activating system - reticular formation; responsible for awake state, level of consciousness and sleep
What are the neurological signs of brainstem dysfunction?
- mentation - normal/obtunded/stupor/coma
- head tilt and wide base stance can be seen
- deficits shown in cranial nerves II to XII
- ipsilateral proprioceptive deficits
- abnormal HR
abnormal breathing pattern
What are the 3 functional divisions of the cerebellum?
- vestibulocerebellum - flocculo-nodular lobe
- spinocerebellum - vermis and paravermis
- neocerebellum - cerebellar hemispheres
What are the functions of the cerebellum?
- coordinate motor function for posture and movement
- acts as a regulator of motor activity
- cerebellar afferents convey proprioceptive info/ info relevant to planning and executing motor activity
Which pathways are involed in conveying proprioceptive info for motor activity?
- Spinocerebellar, vestibulocerebellar, tectocerebellar pathways - input from limbs, body and head (ipsilateral)
- Corticopontocerebellar - input about planned motor activity (contralateral)
- Olivary nucleus - input from extrapyramidal system (contralateral)
State the neurological signs of cerebellar dysfunction
- mentation - normal
- hypermetria, dysmetria (ipsilateral), cerebellar ataxia
- intention tremors
- head tilt (contralateral) and nystagmus (paradoxical vestibular)
Define ‘seizure’
Excessive +/or hypersynchronous electrical activity in the cerebral cortex that results in paroxysmal episodes of abnormal consciousness, motor activity, sensory input +/or autonomic function
