A review of Melodic Intonation Therapy (MIT) and pilot of Dynamic Adaptive Speech Reconstruction (DASR) imaging
Authors: Bellapu Abhilasha S. , Wisco Jonathan J. 
Published: May 2022

Introduction

Making mistakes is at the heart of learning. This principle is central to “re‐learning” how to speak and, when applied with music, can elicit a robust brain activation. As simple as a search for the right note provokes a plastic process in normal language development since it activates the right hemisphere homolog of Broca’s area, which “takes over” language functions. This review and pilot experiment examines language neuroplasticity by observing how Melodic Intonation Therapy (MIT), a treatment modality that combines elements of speech, rhythm, and melody, plays a role in language re‐learning and how its limitations can be overcome with a new tool our lab is developing ‐ Dynamic Adaptive Speech Reconstruction (DASR). MIT’s design in combining task modalities of speaking, singing, and tapping to activate Broca’s area is limited by its well‐intentioned, yet subjective interpretation by speech‐language pathologists. DASR, when fully developed, overcomes subjectivity by using an AI algorithm that incorporates MIT data in real‐time in combination with functional Near‐Infrared Spectroscopy (fNIRS) to observe areas of the brain that are actively recruited when a patient attempts to form phrases. The DASR algorithm objectively analyzes patients’ responses, deconstructs the response, associates it with the fNIRS brain activation, measured as the Blood Oxygenation Level Dependent (BOLD) response, and suggests the next request the therapist should ask of the patient. We tested two aspects of DASR in recruiting the right hemisphere homologue of Broca’s area.

Methods

Using fNIRS in two age‐matched, middle‐aged subjects, we measured activation of Broca’s area in response to a set of randomized repeated phrases. Participants were fitted with an electrode skull cap that measures the BOLD response to the cerebral cortex. Each participant performed a series of 21 tasks (20 seconds each) per trial (420 seconds). Each of the 21 tasks consisted of a recited prompt, which the subject was to repeat as precisely as possible. Subjects were asked to speak, sing, intone with an augmented 4th note (added per DASR protocol), and tap a specific rhythm to “happy birthday to you” and to subsequently more difficult analogs of the phrase: “Hippo birdseed two ewes,” then “Ep say feef now jam bob,” and finally “happy birthday to you.” The set of 21 tasks were repeated in a pseudo‐random order for each subject five times. Block design statistical parametric mapping was used to visualize activation.

Results

Broca’s area showed the greatest activation when task modalities were combined, in particular when singing augmented 4th phrases. It is notable that when tapping is added to singing the augmented 4th, Broca’s area activation appears to decrease, but activation of the right lateral frontal lobe increases with each successive trial. Subjects repeating the phrase, “happy birthday to you”, after going through a series of increasingly complex phrases showed recruitment of the right inferior frontal lobe after the subject completes just one series of trials.

Discussion

This review and pilot study demonstrates that fNIRS can be used to visual brain activation of Broca’s area, particularly in conditions of increasing linguistic complexity, and shows immediate recruitment of the right hemisphere homologue of Broca’s area.