Effect of Verb Network Strengthening Treatment (VNeST) on Lexical Retrieval of Content Words in Sentences in Persons with Aphasia

Abstract

BACKGROUND: Verb Network Strengthening Treatment (VNeST) is a semantic treatment that aims to improve lexical retrieval of content words in sentence context by promoting systematic retrieval of verbs (e.g., measure) and their thematic roles (i.e., agent (doer of the action, e.g., carpenter, chef)) and patient (receiver of the action, e.g., lumber, sugar)). VNeST is influenced by Loverso and colleagues (e.g., Loverso, Selinger, and Prescott, 1979), who used "verb as core" treatment to improve sentence production with encouraging results, and McRae and colleagues, who showed that verbs prime typical agents (e.g., pray-nun) and patients (arrest-criminal) (Ferretti, McRae, & Hatherell, 2001) and vice-versa (McRae, Hare, Elman, & Ferretti, 2005). AIMS: There are four specific questions in this study. Does training a set of verbs using VNeST generalize to the ability to produce 1) an agent (carpenter), trained verb (measure), and patient (stairs) in response to novel picture stimuli and 2) an agent (nurse), untrained semantically related verb (weigh), and patient (baby) in response to novel picture stimuli? 3) Are generalization effects maintained?, and 4) Does VNeST generalize to the ability to retrieve nouns and verbs not directly related to treatment items in single word naming, picture description and connected speech tasks? METHODS #ENTITYSTARTX00026; PROCEDURES: Four participants with aphasia participated. Participants received VNeST, which involves retrieval of agent-patient pairs (e.g., chef/sugar, surveyor/land) related to trained verbs (e.g., measure), two times per week. A single subject, repeated probe, multiple baseline experimental design was used. Generalization to sentence production for sentences containing trained verbs and untrained semantically related verbs was tested weekly. OUTCOMES #ENTITYSTARTX00026; RESULTS: Results demonstrated generalization to lexical retrieval of content words in sentences with trained and untrained verbs across participants. Additionally, pre- to post-treatment generalization was observed on single verb and noun naming and lexical retrieval in sentences across a variety of tasks across participants. Generalization to connected speech was observed for 3 of 4 participants. CONCLUSIONS: Though preliminary, these results indicate that VNeST may be effective in promoting generalization from single word naming to connected speech in persons with moderate aphasia. A number of clinical implications related to treatment efficiency are discussed.

Figures

Figure 1

Schematic of the relationship between the verb-thematic network of measure and weigh. Treatment of agent-patient pairs in Verb Network Strengthening Treatment (VNeST) (e.g., carpenter/lumber and chef/sugar) in the context of the trained verb measure will strengthen the connections between the neural substrate for each agent-patient pair and the verb itself. In addition, the semantic representations of closely related verbs, such as weigh, will be strengthened, as will their connections to the neural substrates for their thematic pairs (e.g., butcher/meat), since they are thought to be engaged by the closely related verbs. Consequently, retrieval of both trained and untrained verbs and related thematics should be facilitated.

Figure 2

Participant 1 weekly generalization and control tasks. The first and second graphs indicate a correct production of all three content words -- the agent, verb and patient -- for picture description probes.

Figure 3

Participant 2 weekly generalization and control tasks. The first and second graphs indicate a correct production of all three content words -- the agent, verb and patient -- for picture description probes.

Figure 4

Participant 3 weekly generalization and control tasks. The first and second graphs indicate a correct production of all three content words -- the agent, verb and patient -- for picture description probes.

Figure 5

Participant 4 weekly generalization and control tasks. The first and second graphs indicate a correct production of all three content words -- the agent, verb and patient -- for picture description probes.

Figure 6

Percentage of pre- and post-treatment “complete utterances” in connected speech for all participants.