Greg Detre
Wednesday, 24 May, 2000
Rolls � B&B III
what makes humans special, different and at an advantage is our ability to store and process sensory information, so that we use it better in making effecitve responses to our environment
not only has our neocortex grown through evolution, but the proportions have changed radically
very little of a rat�s cortex is not either primary motor or a projection area for one of the senses
by contrast: in humans, most of the cortex neither reponds in an obvious way to simple sensory stimulation, nor produces movements when electrically activated (= �silent areas�)
prefrontal lobes = form the largest single division of the cortex in humans
diverse output:
extends to the hypothalamus as well as to the striatum, subthalamus and midbrain
receives afferents from:
the correspondingly large dorsomedial nucleus of the thalamus
(which receives from the frontal lobe, but also the hypothalamus and other parts of the limbic system)
�fitful, irreverent,
indulging at times in the grossest profanity (which was not previously his
custom), manifesting but little deference for his fellows, impatient of
restraint or advice when it conflicts with his desires, at times pertinaciously
obstinate, yet capricious and vacillating�
his friends even said that he was actually happier: more carefree + less inhibited afterwards
lesions in the frontal lobes seem to �/span> � anxiety
monkeys worry less when they make mistakes in learning tasks
thought it might help schizophrenics or depressive patients:
1935 = frontal leucotomy
pharmacological agents (more reversible) in 1960s
alleviation of tension + anxiety, better adjustment to work (???), increased weight + energy
sometimes: changes of personality too far (euphoria, tactlessness, lackadaisical approach, lack of social inhibitions)
helped with intractable pain � not analgesia, but loss of the �affekt� of the pain, its unpleasant/emotional quality
�Oh doctor, it�s absolutely appalling, unbearable� � yet smiling, and apparently not really feeling it despite being able to sense it
only minor effect on ordinary intelligence, except:
difficulties in carrying out more than one program of activity simultaneously
inability to organise actions in proper temporal sequence, e.g. trying to prepare a meal
e.g. monkeys, delayed reaction test
monkey behind glass partition in cage
shown a reward in one of two boxes, then both closed
interval of 10 minutes � partition raised
normal monkeys go to the correct box to receive reward
frontal lesion animals: cannot, unless they spend the waiting period concentrating single-mindedly on the correct doors
unit recordings in prefrontal areas during delayed response trials indicate that these are areas are in some sense �waiting to do something�
activity in many units starts up on receipt of the command, then firing is sustained until the response is finally made
= defects in the ability to store a program of action for deferred use
anxiety = side effect of the sense that something has to be done in the future
lack of anxiety sometimes = lack of forethought
similarly, by stripping pain of its significance and meaning for the future, we also relieve its emotional threat