Why can the peripheral nervous system repair itself and recover function while the central nervous system cannot?

- Ancestrally, damage to the CNS would have meant death or loss of function in the body.- There was no point in trying to repair such damage as living through such damage was low.- Hence, in modern day, while we can use medical advances to survive the damage, self-

reparation of the CNS is not possible naturally.

Medulla – deals with the autonomic (involuntary) functions of the body such as breathing, heart rate and blood pressure.

Pons – contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.

Cerebellum – plays an important role in motor control, balance and coordination. Also vaguely linked to cognitive functions such as attention, language, and regulating fear and pleasure responses.

Midbrain – associated with vision, hearing, motor control, sleep/wake, arousal, temperature regulation and pain

Thalamus – filters sensations (input from our sensory systems) before sending the signals to the cerebral cortex. Also contributes to memory (people with lesions on the thalamus experienced profound memory loss) and state of consciousness.

Reticular formation – participates in the control of mood, arousal and sleep. Injury to the RF can result in irreversible coma. Also blocks out repetitive, meaningless stimuli while remaining sensitive to others (allowing us to sleep through “white-noise” but waking up to an alarm or a crying baby).

Basal ganglia – receives input from motor structures, important for movement (controls in/voluntary movements). Also responsible for controlling eye movement.

Hypothalamus – involved with motivation and homeostasis (regulation of body functions such as temperature, thirst, hunger, biological rhythms and sexual activities). Contributes to the 4F behaviours: feeding, fleeing, fighting, fornication

Hippocampus – essential for the formation, storage and retrieval of long-term memories (but not used to store them). Damage to the hippocampus inhibits learning of new information but does not affect past memories.

Cingulate cortex – Anterior cingulate cortex (ACC, front two thirds of the CC) participates with the hypothalamus in the control of the autonomic nervous system, and also decision making, emotion, anticipation of reward, and empathy. Posterior cingulate cortex (PCC, rear third) participates in memory and visual processing.

Amygdala – role in identifying, remembering and responding to fear and aggression.

Nucleus accumbens – important part of the brain’s reward and pleasure circuitry (helps in reinforcement learning and linked to addiction).

 Corpus callosum – correlates positively with verbal memory capacity (dyslexics tend to have smaller/less developed CCs). Connects the left and right hemispheres of the brain and facilitates inter-hemispheric communication. Bi-manual coordination is improved in people with larger CCs (possibly due to more communication between both sides of the brain), especially so in people with musical background.

Frontal lobe – involves the ability to project future consequences resulting from current actions. Choice between good and bad choices (or better and best), making the link between actions (differentiating events through similarities and differences),

overriding and suppression of socially unacceptable behaviours. Damage to the frontal lobe causes a person to not be able to make reasonable decisions -> social problems due to impulsiveness, rashness, unpredictability.

- Prefrontal cortex: involved with the planning of behaviour, judgement and attention.

- Broca’s area: speech/speech comprehension (but does not affect writing – affected people are unable to form comprehensible sentences but are able to convey their thoughts through writing normally).

- Orbitofrontal cortex: role in emotional quotient. Damage to the OC causes deficits in social behaviour and emotional experience, while retaining intelligence, memory, ability to learn, etc.

Occipital lobe – is home to the primary visual cortex, which begins the process of interpreting inputs from the eyes by responding to basic information about an image (such as its borders, shading, colour and movement.

Temporal lobe – home to the primary auditory cortex, which allows us to process incoming sounds. It also processes some higher visual system tasks such as the recognition of familiar faces and objects.

- Wernicke’s area: control of language comprehension. (Affected people are able to form fluent sentences but which make no sense, and which they are unaware of).

Parietal lobe – home to the somatosensory cortex, which help us localize touch, pain, skin temperature and body position. Also processes input about touch and complex input of vision. While the temporal lobe helps in recognition, parietal lobe helps in visual judgement (i.e. how fast something is moving away/towards us).

Somatic nervous system – transmits commands for voluntary movement from the CNS to the muscles and brings sensory inputs back from the muscles to the CNS for processing.

Autonomic nervous system – takes control of automatic body functions such as breathing, heartbeat (but does not mean we can’t take control i.e. we can control our breathing if we want to).

- Sympathetic division (middle part of the spinal cord in the torso and lower back): prepares the body for situations requiring large expenditure of energy (fight or flight situations).

- Parasympathetic division (brain and lowest part of the spinal cord i.e. brackets the sympathetic division): directs the storage of energy (rest and repair of the body).