Case Study Summary – Biological Psychology
Word Count – 546
Student Number - 5965772
This Japanese study aimed to investigate and examine the stuttering patterns of five patients with basal ganglia injury. Tani and Sakai were interested in determining the causes and differences between neurogenic stuttering and developmental stuttering. In order to specifically measure the effect the basal ganglia has on the modulation of motor output rather than speech in general the stuttering symptoms experienced by participants could not present signs of aphasic disfluency or dysarthria. If aphasia was ruled out, the role of the basal ganglia in speech and language modulation will consequently be supported. Patient 3, a 50 year old right handed male experienced right hemiparesis and dysarthria in 1996 following a stroke. When later entering hospital due to the worsening of the hemiparesis and dysarthria, a brain MRI revealed multiple cerebral infarctions in the bilateral basal ganglia and the left pons with most lesions appearing in the left putamen; speech disfluency was also noted. Patient 3 first experienced stuttering in November 1997 (Tani and Sakai 2011). When examining the stuttering to determine the implications of the injury, patient 3 took part in speech fluency tests such as the repetition of 20 simple sentences and explanation of 3, 4 frame comic strips (Tani and Sakai 2011). For patient 3, the highest rate of stuttering, measured with the formula: stuttering occurrences / number of segments x 100, occurred during the comic strip task whilst demonstrating a stuttering type of syllable and part word repetitions. Patient 3 also showed accessory behaviours such as closing the eyes and grimacing. Later, The Standard Language Test of Aphasia showed patient 3 to be clear of aphasic disfluency and dysarthria enabling the diagnosis of neurogenic stuttering, therefore implicating the basal ganglia in speech, language and motor fluency. The basal ganglia are a complex heterogeneous collection of interconnected nuclei (Pinel 2011) found on both sides of the thalamus outside and above the limbic system. It can be found within the temporal lobes of the telencephalon and has therefore shown to be highly responsible for cognition, movement coordination and voluntary movement (Pinel 2011). Theories of basal ganglia function are most commonly associated with the modulation of motor output but are also thought to be involved in a variety of cognitive functions (Pinel 2011), for instance the regulation of habit learning or action selection (DeLong and Wichmann 2009). It is the anatomy of the basal ganglia that suggests its role in modulatory function as they are ‘part of neural loops that receive cortical input from various cortical areas and transmit it back to the cortex via the thalamus; many of these loops carry signals to and from the motor areas of the cortex’ (Pinel 2011 pg. 203). Further support for this theory, including the role of basal ganglia thalamic circuits in motor function, can be seen with the research of Kropotov and Etlinger (1998) who suggest that these thalamic circuits play a key role in the initiation, preparation and suppression of our action selections for movement demonstrated through participants with Parkinson’s disorder. This, paired with the work of Tani and Sakai suggests that injury to the basal ganglia disrupts and inhibits the modulation of motor output causing motor disorders such as neurogenic stuttering, therefore supporting the theory that the basal ganglia controls the modulation of motor output. References
Tani, T., & Sakai, Y. (2011). Analysis of five cases with neurogenic stuttering following brain injury in the basal ganglia. Journal of Fluency Disorders. Volume 36, Issue 1, March 2011, pages 1 -16. Pinel, J. (2011)....