Tuesday 22 November 2011

Frontal Lobes !



One of four main regions of the cerebral cortex is the frontal lobes. They are at the front most region of the cerebral cortex. The frontal lobes are involved in problem solving, decision making, movement and planning. The frontal lobe has 3 main division consisting of the prefrontal cortex and the pre-motor area and the motor area. The pre-motor and motor areas of the frontal lobes contain nerves that control execution of voluntary muscle movement and the prefrontal cortex is responsible for personality and expression and the planning of complex cognitive behaviour..
Although the frontal lobe is the largest lobe in the brain however in routine neurologic examinations it is not usually specifically evaluated as cognitive tasks usually require multiple brain regions both within and outside the frontal lobes and so therefore it can be difficult during examinations. Dysfunctions or damage to the frontal lobes can cause relatively specific clinical syndromes. In most cases when a patients history suggests that they have a dysfunction of the frontal loves neurobehavioral evaluation is necessary.
Lesions of the frontal lobes and deeper brain structures generate relatively distinctive clinical behaviors such as these:






  • The dorsolateral frontal cortex is concerned with planning, strategy formation, and executive function. Patients with dorsolateral frontal lesions tend to have apathy, personality changes, abulia, and lack of ability to plan or to sequence actions or tasks. These patients have poor working memory for verbal information (if the left hemisphere is predominantly affected) or spatial information (if the right hemisphere bears the lesion brunt).
  • The frontal operculum contains the center for expression of language. Patients with left frontal operculum lesions may demonstrate Broca aphasia and defective verb retrieval, whereas patients with exclusively right opercular lesions tend to develop expressive aprosodia.
  • The orbitofrontal cortex is concerned with response inhibition. Patients with orbitofrontal lesions tend to have difficulty with disinhibition, emotional lability, and memory disorders. Patients with such acquired sociopathy, or pseudopsychopathic disorder, are said to have an orbital personality. Personality changes from orbital damage include impulsiveness, puerility, a jocular attitude, sexual disinhibition, and complete lack of concern for others.
  • Patients with superior mesial lesions affecting the cingulate cortex typically develop akinetic mutism.
  • Patients with inferior mesial (basal forebrain) lesions tend to manifest anterograde and retrograde amnesia and confabulation.
The image below shows an MRI that is suggestive of frontotemporal dementia:

Friday 11 November 2011

Main things to remember about emotion!!

Emotion is a literal Latin translation that means “to move” or “to stir up” Emotion is different from “mood” and “affect”. Brewin (1988) is a broad term and subsumes much behaviour, including mood, feeling, attitude, preferences and evaluations.



Mood= Refers to the frame of mind or “emotional state” of a person which is defined by the individuals internal state and not external behaviour.

Emotions= Thought to be briefer more spontaneous and detectable from the appearance of the organism.
The subcortical structures are thought to be involved in regulation of emotion is the hippocampal system and the amygdale.
The cognitive appraisal theory states that emotions are judgements about the extent that the current situation meets your goals. William James argued that emotions are perceptions of changes in the body like heart rate, breathing rate, perspiration and hormone levels. Happiness is a physiological perception, not a judgement and other emotions like anger and sadness are mental reactions to different kinds of physiological stages.
  Measuring and maniuplating emotions
Tools used to measure emotion is the accelerometers for motion, skin conductance sensors to measure excitement level, temperature sensors and also facial recognition through the use of simple webcams.
Emotion is also assessed and manipulated through mood induction by using thought ( getting the person to think of something) to achieve a required state, through the use of films and music a particular mood can be achieved. Reward and punishment using reinforcer’s to trigger an emotion. Emotions can also be manipulated by loud noises, mild electric shocks, words that represent emotional concepts or pictures of emotional scenes.
Examle of emotion testing Lowa Gambling Task
Lowa Gambling Task was created to stimulate real life decision making. The task was introduced Antonion Damasio. The task was presented as a gambling task it looks at the cognition and emotion.The task consists of participants are presented with 4 virtual decks of cards on a computer screen. They are told each time they choose a card they will win some money in the game. Once in a while choosing a card causes the participant to lose some of the money they have earned in the game. The main goal of the game is to gain as much money as possible to win. Every card drawn will earn the participant a reward and sometimes a card could cause them a penalty. Some decks are “bad decks” and some are “good decks” some will lead to more losses than wins over the period of the game and others will lead to more gains and wins. The decks differ from each other in the number of trials.