Thursday, December 11, 2008


Reflexology is not really a part of behavioral neurology. However, it is important as a part of Soviet social psychology history. Reflexology as practiced by Sechenov affected Pavlov and per Bekhterev affected Luria. Understanding the details is less important, in the history of behavioral neurology as understanding a general gmish, or context of reflexology and how it fits into what came later.

Collective Reflexology by Bekhterev was published in 1921, and greatly influenced those who followed, including those who did not agree with it, such as Vygotsky, and those who rose to be more prominent, such as Pavlov. There was no second edition, and it is said that this volume reflects the Revolution in great detail.

At its genesis is the thesis that the mind is the synthesis of the biological brain and the social environment. Evolutionarily, speech enabled abstract thought and writing enabled history. Brain reflexes can be simple (fright or flight)social, primitve (anger, hunger) or complex. Folk psychology or national spirit is said to exist.

According to Sechenov, psychological acts are a series of reflex acts formed through the activity of cerebral structures and which are associated and integrated among themselves. Sechenov started out studying the spinal cord, and reflexes in decapitated frogs scratched on their bellies, and generalized his spinal cord physiology to the brain, postulating connections between sensory inputs and motor responses. Sechenov postulated emotional reflexes as simple reflexes such as those above, complicated by an emotional factor such as hunger, etc. Psychological reflexes are more complex yet, with a psychological factor intervening. Sechenov's physiology research showed eg. central inhibition, an idea that would later permeate Luria's work. Basically, Sechenov reduced psychology to physiology. His students, the so- called Petersburg school, ultimately became muscle physiologists, studying precise rules of excitatory and inhibitory behavior.

Psychophysics further studies the relation between physiology and psychology. eg. the galvanic response, and concerned itself with processes such as fatigue and others.

According to Mecacci, Bekhterev's reductionism was completely different than Sechenov's as it it attempted to explain not only physiology and psychology but also all living phenomena including sociology. Bekhterev was a neurologist, unlike Sechenov and Pavlov ( a gasterenterologist). He supposed that an energy gave rise to physiology, the mind and society. "Associative reflexes" (the equivalent of Pavlov's conditioned reflexes) were due to connections formed between 2 distinct cortical centers. There is a picture (p.20 of Mecacci's book) of someone reading, with connections from the optic nerve to the LGB, the occipital cortex and the language areas. Vygotsky felt the most important part of the work was the elementary (inborn) reflexes such as suck, snout which "form the fundamental nucleus of mental functions."

Pavlov was a GI specialist, who spent the first two decades of his career studying salivation not the brain. Pavlov was criticised for foraying into the CNS and psychology which he did after he won the Nobel Prize. The Central Nervous System (CNS) describing the formation of conditioned reflexes was more conceptual than real and CNS was said to mean "Conceptual Nervous Sytem." It was said by BF Skinner to be analagous to Sherrington's postulate of a synapse in the spinal cord reflex arc, 20 years before the synapse was described. The behavioral act was described in neuroconceptual terms such as inhibition and excitation that were temporary and meant eventually to be replaced by a neurophysiological explanation. The fact that the Soviets misused Pavlov's ideas and made them rigid is not entirely his fault. It was his fault insofar as his ideas wre incompletely expressed and clarified. Later, Konorski and Hebb clarified many of Pavlov's ideas.

Luria utilized the framework of many of Pavlov's idease which only can be understood in the context of. The theory of reciprocal induction is that surrounding an area of excitation is a process of inhibition. Kornilov and Hebb differentiated between elementary and higher cortical activity and from 1925-1935 there was a lot of energy and work going through. Later in the 1950's Pavlov's work became "dogma" that stifled neuropsychological research.

Vygotsky criticises the approaches of Bekhterev (reflexology explains everything), or Kornilov (reactive), Pavlov (conditioned reflexes) and behaviorism (American movement ,independently arising).

Buridano's donkey illustrated the problem. A hungry donkey caught between 2 sacks of hay on either side cannot decide between them and dies of starvation. The 2 sacks produce equal and "opposite" physiological reactions and the behavior of the animal is inhibited. The qualitative leap of "stimulus - means" as illustrated by Leontiev's experiment signified new cerebral connections. Older children could follow rules by grouping colors etc. due to their having "language" a verbal code.

According to Pavlov, a word can assume the value of a conditioned stimulus or an unconditioned stimulus if it caused the pushing of a button. The first signal is activities of analysis and synthesis, and the second signal, peculiar to man, is the activity of analysis and synthesis of words, verbal signals which "make us human." The second signal-- words-- exhibits a strong inhibitory action over the first signal-- sensory analysis -- only in older children. Luria rejected the idea of language as a reflex arc but considered it as standpoint of historical-cultural school as a process that programs and guides behavior not reflexively though. Vygotsky was republished in 1956 and after 1962 there was a Congress that revised the orthodoxy concerning Pavlov.

Friday, December 5, 2008

Genetics of language impairment

Vernes SC et al. A functional genetic link between distinct developmental language disorders. NEJM 359;22:2337-2345.2008

and editorial Strombsword K. The genetics of speech and language impairment NEJM 359; 22:2381-3 2008.

The editorial notes that virtually all cases of familial language disturbance have complex polygenic multifactorial transmission. In addition assessment methods vary. In 1990, a 3 generation British family had autosomal dominant transmission of oral motor and speech dyspraxia. They carried a mutuation of FOXP2 gene which encodes a transcription factor. That protein may also be associted with oral motor apraxia, low noverbal IQ and nonverbal learning disorders. Vernes et al. above reported that FOXp2 downregulates the expression of CNTNAP2, a gene that encodes a neurexin protein. Further, using nonsense word repetition, CNTNAP2 is associated with a specific language impairment. They also suggested a possible relationship with autism. However, results do have some problems which are reviewed.

Pharmacotherapy in restorative neurology

Liepert J. Curr Opin Neurol 2008; 21:639-643.

Levodopa, single 100 mg dose. Mixed results when given alone. Floel et al. showed that if given with rTMS, levodopa increased evoked movements into the trained direction. The authors said it could "enhance the ability to encode a motor memory with training." Restermeyer et al in a doubled blinded crossover trial found no differences.

A recent Cochrane review of studies of amphetamines after stroke for motor recovery concluded that it was not possible to determine whether it made a difference.

Walker -Batson et al. studied 21 subacute aphasic patients with 10 mg amphetamines every fourth day with one hour of speech therapy for ten sessions, and assessed subjects with the Porch Index of Communicative ability. Patients receiving amphetamines improved, and even after 6 months had a trend to improvement. Whiting et al. had a study with two patients, one improved, one did not. Mocobemide did not help aphasia after stroke.

Methylphenidate after stroke with Physical therapy improved motor function using Fugl Meyer Scale and reduced depression. (21 patients were studied). In TBI, it improved mental processing speed more than placebo.

Amantadine reduces agitation and aggression and imporves attention and alertness on DRS and FIM in TBI patients. On PET it is associated with increased left prefrontal activity. It helped executive functions in one study.

Reboxetine improves motor skill acquisition. It improves tapping speed and grip strength after a single dose in 10 stroke patients with a session of physiotherapy.

Piracetam 4.8 mg daily in 203 subacute stroke patients decreased aphasia on Aachener Aphasic Test, including written language and "profile level." In 24 patients, speech therapy plus piracetam improved semantic and syntactic structure of speech. PET showed improvement in left appropriate areas including left transverse temporal gyrus, Wernicke's and Broca's area. Cochrane review said piracetam "may be effective."

Donepezil in 26 patietns with poststroke aphasia helped the Aphasia Quotient but not the Communicative Ability Log. In TBI, 18 chronic patients received for 10 weeks and showed improved memory and sustained attention. Rivastigmine did not appear to help TBI patients with memory except a subtype with poor memory.

SSRI fluoxetine helped walking and ADL's in severely disabled stroke patients. In a PET study it caused hyperactivation in ipsilesional motor cortex. Citalopram helped dexterity but not grip strength in affected hand in a group of stroke patients.

Motor adaptation and motor learning in neurorehabilitation

Amy Bastian Understanding sensorimotor adaptation and learning for rehabilitation. Curr Opin Neurol 2008; 21: 628-633.

Motor adaptation and motor learning are critical for flexibility. Adaptation refers to trial to trial modification of movements based on error feedback, especially change in the pattern or force of direction oof the movement. Once adapted patients cannot revert to prior behavior unless they deadapt. It occurs over tens to hundreds of movements and over minutes to hours, and can occur in all types of movements including reaching, balancing, eye movements and walking. Adaptation may have a rapid and slow phase. Sensory prediction error is the difference between predicted and observed outcome of the movement. They are used to calibrate internal representations of body dynamics and the environment and recalibrate.

Brain may also alter movements to minimize the "costs" including energy demands, fatigue, and others especially during walkingand reaching adaptation.

Lesions are especially important in the cerebellum that decreased trial by trial improvement during adaptation and reduces stored aftereffects. Basal ganglia damage due to PD or HD leaves adaptation intact largely. Cerebral damage slows but does not abolish adaptation with reaching, and does not impair split belt treadmill walking.

Rehabilitation with robots or treadmills are used . In a reaching task, adaptation was rehabilitated more if perturbation (robotic arm) was introduced gradually rather than at full strength. Adaptation after stroke with neglect was long lasting (5 days) in prism task of reaching. Aftereffects can be substantial. After effects can also prove the ability to normalize an action. Learning via repeated adaptation has been less studied than single session learning.

Motor learning is formation of a new motor pattern that occurs via long term practice. One form is tied to adaptation. Motor learning can be blocked by rTMS.