Saturday, June 2, 2012

Brain - Behaviour Relationships

Depression and Cognitive Complaints Following Mild Traumatic Brain Injury, by Jonathan M. Silver, MD, Thomas McAllister, MD, and David B. Arciniegas,MD (Am. J. Psychiatry 2009 :166:653-661 is a truly elegant paper discussing this subject from experience with detail. It's an essential read for anyone treating pateints with depression and mTBI.
What I am essentially copying here is from Table 1 in this paper. I have seen this information elsewhere and it's standard in neuropsychiatry and behavioural neurology texts.  Like everything else in this paper it was presented here in a readable and easy to comprehend and clinically useful way.

Structure                     Function                           Consequence of Injury                                      


Reticulothalamic system    Arousal                    Impairment of Counsciousness

Reticulocortical system       Arousal, facilitating cortical activity         Hypoarousal,  inattention, impaired information processing

Hypothalamus        Autonomic,, neuroendocrine,                   Dysautonomous, thermoregulation problems, altered feeding behaviours,
                                                    Circadian, some lower level social           endocrine dysfunction, sleep wave cycle disturbances, pathological affect
                              functions                                                        (laughter and anger)

Ventral forebrain             Cholingeric supply to medial and             Impaired information processing in multiple cognitive domains, neo cortical areas                                         particularly attention, memory, and executive functions


Entrorhinal-hippocampal Complex        Multimodal informationa filtering                Impaired sensory gating, attention, working memory and
                                                                      Declarative memory, some aspects of        declarative memory
                                                                      Attention and working memory

Amygdala          Generation of contextually relevant           Affective placidity, Kluver-Bucy-like presentations, alternatively
                                                                       emotional and social behaviour                   anxiety

Anterior/Polar cortex              Semantic memory, semantic aspects        Disturbances in semantic memory, functional communication
                                                                        of language, sensory limbic integration    impairments, impaired sensory-limbic, facial, social and emotional
                                                                        face recognition, social and emotional      processing, impaired social/empathic function
                                                                        processing, "theory of mind"


Ventral frontal cortices       Comportment, control of primitive              Disinhibition, irritability, emotional dysregulation, agitation, aggression
                                                                        ("limbic") behaviours

Anterior Cingulate cortex         Motivation                             Apathy

Inferolateral prefrontal cortex          Working memory                                          Working memory impairments

Dorsolateral prefrontal cortex             Executive function                                         Impairments in complex cognition, including executive control of attention,
                                                                                                                                                    memory, language, motor planning, as well as sequencing, set shifting
                                                                                                                                                     abstraction, judgment, insight

White Matter                                                 Connections between cortical areas         Impaired cognitive, emotional and behavioural functions, supported by
                                                                           particularly in frontal and temporal           affected white matter, slow, inefficient information processing.
                                                                           areas, facilitation of information

My columns got smunched by the editor so it's best to go to the paper. The rest of it is an excellent and must see read.  I've just listed these areas to show where the lesions are being deliniated in a beyond Broca way that's clinically relevant.

This is geographical presentation but then there are the neurochemical transmissions with both facilitating and dampening process.  Coupled to this is the endocrine modulating effects and the fluid these systems sit in, a kind of 'soup' which is affected by quite a variety of spices in addition to sometimes being affected by heat or cold.

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